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Cnooc Ltd – ‘20-F/A’ for 12/31/17

On:  Thursday, 4/19/18, at 5:25pm ET   ·   For:  12/31/17   ·   Accession #:  950103-18-4976   ·   File #:  1-14966

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  As Of                Filer                Filing    For·On·As Docs:Size              Issuer               Agent

 4/19/18  Cnooc Ltd                         20-F/A     12/31/17    4:2.2M                                   Davis Polk & … LLP 01/FA

Document/Exhibit                   Description                      Pages   Size 

 1: 20-F/A      Amendment to Annual Report by a Foreign Private     HTML   1.09M 
                          Issuer                                                 
 4: EX-13.1     Annual or Quarterly Report to Security Holders      HTML      8K 
 2: EX-12.1     Exhbit 12.1                                         HTML     12K 
 3: EX-12.2     Statement re: Computation of Ratios                 HTML     12K 

UNITED STATES 

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 20-F/A

(Amendment No. 1)

(Mark One)

OR

OR

OR

Date of event requiring this shell company report ________________

Commission File Number 1-14966

CNOOC LIMITED 

中國海洋石油有限公司 

(Exact name of Registrant as specified in its charter) 

N/A

 (Translation of Registrant’s name into English)

Hong Kong

(Jurisdiction of incorporation or organization)

65th Floor, Bank of China Tower

One Garden Road, Central

Hong Kong

(Address of principal executive offices)

Jiewen Li

65^th Floor, Bank of China Tower

One Garden Road, Central

Hong Kong

Tel +852 2213 2500

Fax +852 2525 9322 

(Name, telephone, e-mail and/or facsimile number and address of company contact person)

Securities registered or to be registered pursuant to Section 12(b) of the Act.

Securities registered or to be registered pursuant to Section 12(g) of the Act. None 

(Title of Class)

Securities for which there is a reporting obligation pursuant to Section 15(d) of the Act. None 

(Title of Class)

Indicate the number of outstanding shares of each of the issuer’s classes of capital or common stock as of the close of the period covered by the annual report.

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.

Yes ý No ¨

If this report is an annual or transition report, indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934.

Yes ¨ No ý

Note – Checking the box above will not relieve any registrant required to file reports pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 from their obligations under those Sections.

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.

Yes ý No ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).

Yes ¨ No ý

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or an emerging growth company. See definition of “large accelerated filer, “accelerated filer,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company that prepares its financial statements in accordance with U.S. GAAP, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards† provided pursuant to Section 13(a) of the Exchange Act. ¨

† The term “new or revised financial accounting standard” refers to any update issued by the Financial Accounting Standards Board to its Accounting Standards Codification after April 5, 2012.

Indicate by check mark which basis of accounting the registrant has used to prepare the financial statements included in this filing:

U.S. GAAP ¨

International Financial Reporting Standards as issued by the International Accounting Standards Board ý

Other ¨

If “Other” has been checked in response to the previous question, indicate by check mark which financial statement item the registrant has elected to follow.

Item 17 ¨ Item 18 ¨

If this is an annual report, indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).

Yes ¨ No ý

(1)       Not for trading, but only in connection with the registration of American depositary shares.

TABLE OF CONTENTS

Explanatory Note

This Amendment No.1 to our annual report on Form 20-F for the fiscal year ended December 31, 2017, previously filed on April 19, 2018, is being filed solely for the purpose of (i) adding the section of Supplementary Information on Oil and Gas Producing Activities in the Report of Independent Registered Public Accounting Firm in the 2017 Form 20-F; and (ii) making the following corrections to certain typographical errors in the Report of Independent Registered Public Accounting Firm in the 2017 Form 20-F: adding the total amount on “Impairment” of “(10,768)” and the total amount on “Depreciation charge for the year” of “(60,802)” with respect to Item 13 (Property, Plant and Equipment) on page F-46. As required by Rule 12b-15 of the Securities and Exchange Act of 1934, as amended, the Company is also filing and furnishing as exhibits to this Amendment No.1 the certifications required under Section 302 and Section 906 of the Sarbanes-Oxley Act of 2002, respectively.

This Amendment No.1 speaks as of the filing date of the 2017 Form 20-F on April 19, 2018. Other than as set forth above, this Amendment No.1 does not, and does not purport to, amend, update or restate any other information or disclosure included in the 2017 Form 20-F.

ITEM 18. FINANCIAL STATEMENTS

See pages beginning on page F-1 following Item 19.

ITEM 19. EXHIBITS

The following documents are filed as part of this annual report:

_______________________

^* Pursuant to Instruction 2(b)(i) to Item 19 of Form 20-F, we undertake to furnish this document upon request of the Securities and Exchange Commission.

^* Pursuant to Instruction 2(b)(i) to Item 19 of Form 20-F, we undertake to furnish this document upon request of the Securities and Exchange Commission.

*Previously filed.

Signature

The registrant hereby certifies that it meets all of the requirements for filing on Form 20-F/A and that it has duly caused and authorized the undersigned to sign this Amendment No.1 to this annual report on its behalf.

Date: April 19, 2018 

CNOOC LIMITED

CONSOLIDATED FINANCIAL STATEMENTS

FOR THE YEARS ENDED DECEMBER 31, 2015, 2016 AND 2017

TOGETHER WITH REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

INDEX TO FINANCIAL STATEMENTS

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To Shareholders and the Board of Directors of CNOOC Limited

Opinion on the Financial Statements

We have audited the accompanying consolidated statements of financial position of CNOOC Limited (the "Company") and subsidiaries (collectively referred to as "the Group") as of December 31, 2017 and 2016, the related consolidated statements of profit or loss and other comprehensive income, consolidated statements of changes in equity, and consolidated statements of cash flows, for each of the three years in the period ended December 31, 2017, and the related notes (collectively referred to as the "financial statements"). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2017 and 2016, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2017, in conformity with International Financial Reporting Standards issued by the International Accounting Standards Board and Hong Kong Financial Reporting Standards issued by the Hong Kong Institute of Certified Public Accountants.

We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Group's internal control over financial reporting as of December 31, 2017, based on criteria established in Internal Control — Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission and our report dated March 29, 2018 expressed an unqualified opinion on the Group's internal control over financial reporting.

Basis for Opinion

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company's financial statements based on our audits. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

/s/ Deloitte Touche Tohmatsu

Certified Public Accountants

Hong Kong

March 29, 2018

We have served as the Company's auditor since 2013.

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To Shareholders and the Board of Directors of CNOOC Limited

Opinion on Internal Control over Financial Reporting

We have audited the internal control over financial reporting of CNOOC Limited (the "Company") and its subsidiaries (collectively referred to as the "Group") as of December 31, 2017, based on criteria established in Internal Control — Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). In our opinion, the Group maintained, in all material respects, effective internal control over financial reporting as of December 31, 2017, based on criteria established in Internal Control —Integrated Framework (2013) issued by COSO.

We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the consolidated financial statements as of and for the year ended December 31, 2017 of the Group and our report dated March 29, 2018 expressed an unqualified opinion on those financial statements.

Basis for Opinion

The Company’s management is responsible for maintaining effective internal control over financial reporting and for its assessment of the effectiveness of internal control over financial reporting, included in the accompanying "Management’s annual report on internal control over financial reporting". Our responsibility is to express an opinion on the Group’s internal control over financial reporting based on our audit. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Group in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audit in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether effective internal control over financial reporting was maintained in all material respects. Our audit included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, testing and evaluating the design and operating effectiveness of internal control based on the assessed risk, and performing such other procedures as we considered necessary in the circumstances. We believe that our audit provides a reasonable basis for our opinion.

Definition and Limitations of Internal Control over Financial Reporting

A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

/s/ Deloitte Touche Tohmatsu

Certified Public Accountants

Hong Kong

March 29, 2018

CNOOC LIMITED

CONSOLIDATED STATEMENTS OF PROFIT OR LOSS AND OTHER COMPREHENSIVE INCOME

FOR THE YEARS ENDED DECEMBER 31, 2015, 2016 AND 2017

(All amounts expressed in millions of Renminbi/US$, except per share data)

The accompanying notes are an integral part of these financial statements.

CNOOC LIMITED

CONSOLIDATED STATEMENTS OF FINANCIAL POSITION

AS OF DECEMBER 31, 2016 AND 2017

(All amounts expressed in millions of Renminbi/US$)

The accompanying notes are an integral part of these financial statements.

CNOOC LIMITED

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY

FOR THE YEARS ENDED DECEMBER 31, 2015, 2016 AND 2017

(All amounts expressed in millions of Renminbi)

CNOOC LIMITED

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY

FOR THE YEARS ENDED DECEMBER 31, 2015, 2016 AND 2017 (continued)

(All amounts expressed in millions of Renminbi)

The accompanying notes are an integral part of these financial statements.

CNOOC LIMITED

CONSOLIDATED STATEMENTS OF CASH FLOWS

FOR THE YEARS ENDED DECEMBER 31, 2015, 2016 AND 2017

(All amounts expressed in millions of Renminbi/US$)

The accompanying notes are an integral part of these financial statements.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

CNOOC Limited (the "Company") was incorporated in the Hong Kong Special Administrative Region ("Hong Kong") of the People's Republic of China (the "PRC") on August 20, 1999 to hold the interests in certain entities thereby creating a group comprising the Company and its subsidiaries (hereinafter collectively referred to as the "Group"). During the year, the Group was principally engaged in the exploration, development, production and sale of crude oil, natural gas and other petroleum products.

The registered office address of the Company is 65/F, Bank of China Tower, 1 Garden Road, Hong Kong.

In the opinion of the directors of the Company (the "Directors"), the parent and the ultimate holding company of the Company is China National Offshore Oil Corporation ("CNOOC"), a company established in the PRC. In November 2017, CNOOC changed its registered company name which is registered in Chinese pursuant to relevant laws and regulations of China to "中國海洋石油集團有限公司".

Particulars of the principal subsidiaries at the end of the reporting period are as follows:

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

The above table lists the subsidiaries of the Company which, in the opinion of the Directors, principally affected the results for the year or formed a substantial portion of the total assets of the Group. To give details of other subsidiaries would, in the opinion of the Directors, result in particulars of excessive length.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

These financial statements have been prepared in accordance with International Financial Reporting Standards ("IFRSs") issued by the International Accounting Standards Board (the "IASB"), Hong Kong Financial Reporting Standards ("HKFRSs") issued by the Hong Kong Institute of Certified Public Accountants (the "HKICPA"), the Rules Governing the Listing of Securities on The Stock Exchange of Hong Kong Limited (the "Listing Rules") and the Hong Kong Companies Ordinance (Cap. 622). A summary of the significant accounting policies adopted by the Group is set out below.

The IASB has issued a number of new and revised IFRSs that are first effective for the current accounting year commencing January 1, 2017 or later but available for early adoption. The equivalent new and revised HKFRSs consequently issued by the HKICPA have the same effective dates as those issued by the IASB and are in all material aspects identical to the pronouncements issued by the IASB.

The accounting policies adopted are consistent with those of the year ended December 31, 2016, except for the first time adoption of the amendments to IFRSs/HKFRSs effective for the Group’s financial year beginning on January 1, 2017. The adoption of the amendments had no material impact on the accounting policies, the disclosures or the amounts recognized in the consolidated financial statements of the Group. IFRS 9/HKFRS 9 (2009) Financial Instruments has been early adopted by the Company from year 2015.

The Group has not applied the following new and revised IFRSs/HKFRSs, which may be relevant to the Group and have been issued but are not yet effective, in these consolidated financial statements:

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

IFRS 15/HKFRS 15 Revenue from Contracts with Customers

IFRS 15/HKFRS 15 Revenue from Contracts with Customers provides a single model for accounting for revenue arising from contracts with customers, focusing on the identification and satisfaction of performance obligations, and is effective for annual periods beginning on or after 1 January 2018. IFRS 15/HKFRS 15 will supersede IAS 18/HKAS 18 Revenue.

The Company expects to adopt the new revenue standard as of 1 January 2018 using the modified retrospective transition method. Based on our assessment, the Company does not expect the implementation of the standard to have a material effect on its consolidated financial statements.

IFRS 16/HKFRS 16 Leases

IFRS 16/HKFRS 16, which upon the effective date will supersede IAS 17/HKAS 17 Leases, introduces a single lessee accounting model and requires a lessee to recognize assets and liabilities for all leases with a term of more than 12 months, unless the underlying asset is of low value. Specifically, under IFRS 16/HKFRS 16, a lessee is required to recognize a right-of-use asset representing its right to use the underlying leased asset and a lease liability representing its obligation to make lease payments. Accordingly, a lessee should recognize depreciation of the right-of-use asset and interest on the lease liability, and also classify cash payments of the lease liability into a principal portion and an interest portion and present them in the consolidated statement of cash flows. Also, the right-of-use asset and the lease liability are initially measured on a present value basis. The measurement includes non-cancellable lease payments and also includes payments to be made in optional periods if the lessee is reasonably certain to exercise an option to extend the lease, or not to exercise an option to terminate the lease. This accounting treatment is significantly different from the lessee accounting for leases that are classified as operating leases under IAS 17/HKAS 17.

In respect of the lessor accounting, IFRS 16/HKFRS 16 substantially carries forward the lessor accounting requirements in IAS 17/HKAS 17. Accordingly, a lessor continues to classify its leases as operating leases or finance leases, and to account for these two types of leases differently.

The Group is in the process of assessing the impact of application of IFRS 16/HKFRS 16. For the moment, it is not practicable to provide a reasonable estimate of the effect of the application of IFRS 16/HKFRS 16 until the Group completes a detail review.

The Group anticipates that the application of other new and revised IFRSs/HKFRSs that have been issued but are not yet effective will have no material effect on the Group’s consolidated financial statements.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Basis of preparation

These consolidated financial statements have been prepared under the historical cost convention, except for as detailed in the accounting policies notes hereafter. These consolidated financial statements are presented in Renminbi ("RMB") and all values are rounded to the nearest million except when otherwise indicated.

Basis of consolidation

The consolidated financial statements include the financial statements of the Company and its subsidiaries for the year ended December 31, 2017.

The results of subsidiaries are consolidated from the date of acquisition, being the date on which the Group obtains control, and continue to be consolidated until the date that such control ceases. The financial statements of the subsidiaries are prepared for the same reporting period as the parent company, using consistent accounting policies.

The results of subsidiaries are included in the Company's statement of profit or loss and other comprehensive income to the extent of dividends received and receivable. The Company's interests in subsidiaries are stated at cost less any impairment losses.

All intra-group balances, income and expenses and unrealized gains and losses and dividends resulting from intra-group transactions are eliminated in full.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Business combinations and goodwill

Business combinations are accounted for using the acquisition method. The consideration transferred is measured at acquisition date fair value which is the sum of the acquisition date fair values of assets transferred by the Group, liabilities assumed by the Group to the former owners of the acquiree and the equity interests issued by the Group in exchange for control of the acquiree. For each business combination, the Group elects whether it measures the non-controlling interests in the acquiree either at fair value or at the proportionate share of the acquiree's identifiable net assets. All other components of non-controlling interests are measured at fair value. Acquisition related costs incurred are included in profit or loss.

When the Group acquires a business, it assesses the financial assets acquired and liabilities assumed for appropriate classification and designation in accordance with the contractual terms, economic circumstances and pertinent conditions as at the acquisition date. This includes the separation of embedded derivatives in host contracts by the acquiree.

If the business combination is achieved in stages, the Group's previously held equity interest in the acquiree is remeasured to fair value at the acquisition date through profit or loss.

Any contingent consideration to be transferred by the acquirer is recognized at fair value at the acquisition date. Contingent consideration classified as an asset or liability is measured at subsequent reporting dates in accordance with IFRS 9/HKFRS 9 (2009) or IAS 39/HKAS 39, with the corresponding gain or loss being recognized in profit or loss. Contingent consideration that is classified as equity is not remeasured and subsequent settlement is accounted for within equity.

Goodwill is initially measured at cost, being the excess of the aggregate of the consideration transferred, the amount recognized for non-controlling interests and any fair value of the Group's previously held equity interests in the acquiree over the identifiable net assets acquired and liabilities assumed. If the sum of this consideration and other items is lower than the fair value of the net assets of the business acquired, the difference is recognized in profit or loss as a gain on bargain purchase.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Business combinations and goodwill (continued)

After initial recognition, goodwill is measured at cost less any accumulated impairment losses. Goodwill is tested for impairment annually or more frequently if events or changes in circumstances indicate that the carrying value may be impaired. For the purpose of impairment testing, goodwill acquired in a business combination is, from the acquisition date, allocated to each of the Group's cash-generating units, or groups of cash-generating units, that are expected to benefit from the synergies of the combination, irrespective of whether other assets or liabilities of the Group are assigned to those units or groups of units.

Impairment is determined by assessing the recoverable amount of the exploration and production ("E&P") segment, using value in use, to which the goodwill relates. Where the recoverable amount of the cash-generating unit (group of cash-generating units) is less than the carrying amount, an impairment loss on goodwill is recognized. An impairment loss recognized for goodwill is not reversed in a subsequent period.

Where goodwill has been allocated to a cash-generating unit (or group of cash-generating units) and part of the operation within that unit is disposed of, the goodwill associated with the operation disposed of is included in the carrying amount of the operation when determining the gain or loss on the disposal. Goodwill disposed of in these circumstances is measured based on the relative value of the operation disposed of and the portion of the cash-generating unit retained.

Subsidiaries

Subsidiaries are all those entities over which the Group has power over the investee such that the Group is able to direct the relevant activities, has exposure or rights to variable returns from its involvement with the investee and has the ability to use its power over the investee to affect the amount of the investor's returns.

Associates

Based on the Group's ownership percentage (considering its direct ownership as well as potentially exercisable or convertible shares) and other contractual rights, the Group has significant influence over its associates, rather than the power to control.

The Group's investments in associates are stated in the consolidated statement of financial position at the Group's share of net assets under the equity method of accounting, less any impairment losses. Adjustments are made to bring into line any dissimilar accounting policies that may exist. Under the equity method, an investment in an associate is initially recognized in the consolidated statement of financial position at cost and adjusted thereafter to recognize the Group's share of the profit or loss and other comprehensive income of the associate. Unrealized gains and losses resulting from transactions between the Group and its associates are eliminated to the extent of the Group's investments in the associates, except where unrealized losses provide evidence of an impairment of the asset transferred. Goodwill arising from the acquisition of associates is included as part of the Group's investments in associates and is not individually tested for impairment.

Joint arrangements

Certain of the Group's activities are conducted through joint arrangements. Joint arrangements are classified as either a joint operation or joint venture, based on the rights and obligations arising from the contractual obligations between the parties to the arrangement.

Joint control

Joint control is the contractually agreed sharing of control of an arrangement, which exists only when decisions about the relevant activities require unanimous consent of the parties sharing control.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Joint arrangements (continued)

Joint operations

Some arrangements have been assessed by the Group as joint operations as both parties to the contract are responsible for the assets and obligations in proportion to their respective interest, whether or not the arrangement is structured through a separate vehicle. This evaluation applies to both the Group's interests in production sharing arrangements and certain joint operation.

The Group entered into numerous production sharing arrangements or similar agreements in China and overseas countries. The Group's participating interest may vary in each arrangement. The Group, as one of the title owners under certain exploration and/or production licenses or permits, is required to bear exploration (with some exceptions in China), development and operating costs together with other co-owners based on each owner's participating interest. Once production occurs, a certain percentage of the annual production or revenue is first distributed to the local government, which, in most cases, with the nature of royalty and other taxes or expenses, and the rest of the annual production or revenue is allocated among the co-owners.

The Group accounts for the assets, liabilities, revenues and expenses relating to its interest in a joint operation in accordance with the IFRSs/HKFRSs applicable to the particular assets, liabilities, revenues and expenses.

Joint venture

A joint venture is a joint arrangement whereby the parties that have joint control of the arrangement have rights to the net assets of the arrangement.

The Group's investments in joint ventures are stated in the consolidated statement of financial position at the Group's share of net assets under the equity method of accounting, less any impairment losses. Adjustments are made to bring into line any dissimilar accounting policies that may exist. Under the equity method, an investment in a joint venture is initially recognized in the consolidated statement of financial position at cost and adjusted thereafter to recognize the Group's share of the profit or loss and other comprehensive income of the joint venture. Where the profit sharing ratios are different to the Group's equity interest, the share of post-acquisition results of the joint ventures is determined based on the agreed profit sharing ratio. Unrealized gains and losses resulting from transactions between the Group and its joint ventures are eliminated to the extent of the Group's investments in the joint ventures, except where unrealized losses provide evidence of an impairment of the asset transferred. Goodwill arising from the acquisition of joint ventures is included as part of the Group's investments in joint ventures and is not individually tested for impairment.

Related parties

A party is considered to be related to the Group if:

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Related parties (continued)

Impairment of non-financial assets other than goodwill

Where an indication of impairment exists, or when annual impairment testing for an asset is required (other than inventories, deferred tax assets, financial assets and goodwill), the asset's recoverable amount is estimated. An asset's recoverable amount is the higher of the asset's or cash-generating unit's value in use and its fair value less costs of disposal, and is determined for an individual asset, unless the asset does not generate cash inflows that are largely independent of those from other assets or groups of assets, in which case the recoverable amount is determined for the cash-generating unit to which the asset belongs.

An impairment loss is recognized only if the carrying amount of an asset exceeds its recoverable amount. In assessing value in use, the estimated future cash flows are discounted to their present value using a pre-tax discount rate that reflects current market assessments of the time value of money and the risks specific to the asset. An impairment loss is charged to profit or loss in the period in which it arises in those expense categories consistent with the function of the impaired asset.

An assessment is made at the end of each reporting period as to whether there is any indication that previously recognized impairment losses may no longer exist or may have decreased. If such an indication exists, the recoverable amount is estimated. A previously recognized impairment loss of an asset other than goodwill is reversed only if there has been a change in the estimates used to determine the recoverable amount of that asset, but not to an amount higher than the carrying amount that would have been determined (net of any depreciation/amortization) had no impairment loss been recognized for the asset in prior years. A reversal of such an impairment loss is credited to profit or loss in the period in which it arises.

Property, plant and equipment

Property, plant and equipment comprise oil and gas properties, and vehicles and office equipment and others.

For oil and gas properties, the successful efforts method of accounting is adopted. The Group capitalizes the initial acquisition costs of oil and gas properties. Impairment of initial acquisition costs is recognized based on exploratory experience and management judgement and charged to profit and loss as exploration expenses. Upon discovery of commercial reserves, acquisition costs are transferred to proved properties. The costs of drilling and equipping successful exploratory wells, all development expenditures on construction, installation or completion of infrastructure facilities such as platforms, pipelines, processing plants and the drilling of development wells and the building of enhanced recovery facilities, including those renewals and betterments that extend the economic lives of the assets, and the related borrowing costs are capitalized. The costs of unsuccessful exploratory wells and all other exploration costs are expensed as incurred.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Property, plant and equipment (continued)

The Group carries exploratory well costs as an asset when the well has found a sufficient quantity of reserves to justify its completion as a producing well and where the Group is making sufficient progress assessing the reserves and the economic and operating viability of the project. Exploratory well costs not meeting these criteria are charged to expenses. Exploratory wells that discover potentially economic reserves in areas where major capital expenditure will be required before production would begin and when the major capital expenditure depends upon the successful completion of further exploratory work remain capitalized and are reviewed periodically for impairment.

Producing oil and gas properties are depreciated on a unit-of-production basis over the proved developed reserves. Common facilities that are built specifically to service production directly attributed to designated oil and gas properties are depreciated based on the proved developed reserves of the respective oil and gas properties on a pro-rata basis. Common facilities that are not built specifically to service identified oil and gas properties are depreciated using the straight-line method over their estimated useful lives. Costs associated with significant development projects are not depreciated until commercial production commences and the reserves related to those costs are excluded from the calculation of depreciation.

Capitalized acquisition costs of proved properties are depreciated on a unit-of-production method over the total proved reserves of the relevant oil and gas properties.

Vehicles, office equipment and others are stated at cost less accumulated depreciation and impairment losses. The straight-line method is adopted to depreciate the cost less any estimated residual value of these assets over their expected useful lives. The useful lives of vehicles, office equipment and other assets are in line with their beneficial periods.

Where parts of an item of property, plant and equipment have different useful lives, the cost of that item is allocated on a recoverable basis among the parts and each part is depreciated separately.

Residual values, useful lives and the depreciation method are reviewed and, adjusted if appropriate, at each reporting date.

Any gains and losses on disposals of property, plant and equipment (calculated as the difference between the net disposal proceeds and the carrying amount of the asset) are recognized in profit or loss.

Intangible assets (other than goodwill)

The intangible assets of the Group comprise software, gas processing rights of the NWS Project, marketing transportation and storage contracts, drilling rig contracts and seismic data usage rights. Intangible assets with finite lives are carried at cost, less accumulated amortization and accumulated impairment losses. The cost of intangible assets acquired in a business combination is the fair value as at the date of acquisition. Intangible assets with finite lives except for gas processing rights, are amortized on the straight-line basis over the useful economic life and assessed for impairment whenever there is an indication that the intangible asset may be impaired. The amortization period and the amortization method for an intangible asset with a finite useful life are reviewed at least at each financial year end.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Intangible assets (other than goodwill) (continued)

The intangible assets regarding software have been amortized on the straight-line basis over their respective useful lives. The intangible asset regarding the gas processing rights has been amortized upon the commercial production of the liquefied natural gas on a unit-of-production basis over the total proved reserves of the relevant asset. The intangible assets regarding the marketing transportation and storage contracts and drilling rig contracts are amortized over the life of the contracts on the straight-line basis. The intangible assets related to the seismic data usage rights are amortized over the estimated useful life of the seismic data.

Major maintenance and repairs

Expenditure on major maintenance refits or repairs comprises the cost of replacement assets or parts of assets and overhaul costs. Where an asset or part of an asset that was separately depreciated and is replaced, and it is probable that future economic benefits associated with the item will flow to the Group, the replacement expenditure is capitalized. Where part of the asset was not separately considered as a component, the replacement value is used to estimate the carrying amount of the replaced assets which is immediately written off. All other maintenance costs are expensed as incurred.

Research and development costs

All research costs are expensed as incurred.

Expenditure (other than that relating to oil and gas properties discussed above) incurred on projects to develop new products is capitalized and deferred only when the Group can demonstrate the technical feasibility of completing the intangible asset so that it will be available for use or sale, its intention to complete and its ability to use or sell the asset, how the asset will generate future economic benefits, the availability of resources to complete the project and the ability to measure reliably the expenditure during the development. Product development expenditure which does not meet these criteria is expensed when incurred.

Financial assets

All recognized financial assets are subsequently measured in their entirety at either amortized cost or fair value, depending on the classification of the financial assets.

Debt instruments and hybrid contracts that meet the following conditions are subsequently measured at amortized cost less impairment loss:

• the asset is held within a business model whose objective is to hold assets in order to collect contractual cash flows; and

• the contractual terms of the instrument give rise on specified dates to cash flows that are solely payments of principal and interest on the principal amount outstanding.

All other financial assets are subsequently measured at fair value.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Financial assets (continued)

The effective interest method is a method of calculating the amortized cost of a debt instrument and of allocating interest income over the relevant period. The effective interest rate is the rate that exactly discounts estimated future cash receipts (including all fees and points paid or received that form an integral part of the effective interest rate, transaction costs and other premiums or discounts) through the expected life of the debt instrument, or, where appropriate, a shorter period, to the net carrying amount on initial recognition. Interest income for debt instruments measured subsequently at amortized cost is recognized in profit or loss in accordance with the policies set out for "Revenue Recognition" below.

Investments in equity instruments are classified as at FVTPL, unless the Group designates such investment that is not held for trading as at FVTOCI on initial recognition.

A financial asset is held for trading if it has been acquired principally for the purpose of selling it in the near term or it is a derivative that is not designated and effective as a hedging instrument.

Debt instruments that do not meet the amortized cost criteria (see (a) above) are measured at FVTPL. In addition, debt instruments that meet the amortized cost criteria but are designated as at FVTPL are measured at FVTPL. A debt instrument may be designated as at FVTPL upon initial recognition if such designation eliminates or significantly reduces a measurement or recognition inconsistency that would arise from measuring assets or liabilities or recognizing the gains and losses on them on different bases.

Financial assets at FVTPL are measured at fair value at the end of each reporting period, with any gains or losses arising on remeasurement recognized in profit or loss.

On initial recognition, the Group can make an irrevocable election (on an instrument-by-instrument basis) to designate investments in equity instruments as at FVTOCI. The Group has investments in certain equity instruments (publicly traded or non-publicly traded), the purpose of which are not held for trading, but held for medium or long-term strategic purpose. Therefore, those investments in equity securities are designated as at FVTOCI.

Investments in equity instruments at FVTOCI are initially measured at fair value plus transaction costs. Subsequently, they are measured at fair value with gains and losses arising from changes in fair value recognized in other comprehensive income and accumulated in the other reserves. The cumulative gain or loss will not be reclassified to profit or loss on disposal of the investments.

Dividends on these investments in equity instruments are recognized in profit or loss when the Group’s right to receive the dividends is established in accordance with IAS 18/HKAS 18 Revenue, unless the dividends clearly represent a recovery of part of the cost of the investment.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Fair value

The fair value of financial instruments that are traded in active markets at each reporting date is determined by reference to quoted market prices or dealer price quotations, without any deduction for transaction costs.

For financial instruments not traded in an active market, the fair value is determined using appropriate valuation techniques. Such techniques may include using recent arm's length market transactions; reference to the current fair value of another instrument that is substantially the same; a discounted cash flow analysis or other valuation models.

An analysis of fair values of financial instruments and further details as to how they are measured are provided in note 32.

Impairment of financial assets

The Group assesses at each reporting date whether there is any objective evidence that a financial asset, other than those at FVTPL and FVTOCI, or a group of financial assets may be impaired.

In relation to trade and other receivables, a provision for impairment is made when there is objective evidence (such as the probability of insolvency or significant financial difficulties of the debtor and significant changes in the technological, market, economic or legal environment that have an adverse effect on the debtor) that the Group will not be able to collect all of the amounts due under the original terms of an invoice.

If there is objective evidence that an impairment loss on financial assets measured at amortized cost has been incurred, the amount of the loss is measured as the difference between the asset's carrying amount and the present value of estimated future cash flows (excluding future credit losses that have not been incurred) discounted at the financial asset's original effective interest rate (the effective interest rate computed at initial recognition). The carrying amount of the asset is reduced either directly or through the use of an allowance account. The amount of the impairment loss is recognized in profit or loss.

If, in a subsequent year, the amount of the estimated impairment loss decreases and the decrease can be related objectively to an event occurring after the impairment was recognized, the previously recognized impairment loss is reduced either directly or by adjusting the allowance account. Any subsequent reversal of an impairment loss is recognized in profit or loss, to the extent that the carrying value of the asset does not exceed amortized cost at the reversal date.

Derecognition of financial assets

A financial asset (or, where applicable a part of a financial asset or part of a group of similar financial assets) is derecognized when:

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Derecognition of financial assets (continued)

When the Group has transferred its rights to receive cash flows from an asset or has entered into a pass-through arrangement, it evaluates if and to what extent it has retained the risk and rewards of ownership of the asset. When it has neither transferred nor retained substantially all the risks and rewards of the asset nor transferred control of the asset, the Group continues to recognize the transferred asset to the extent of the Group's continuing involvement. In that case, the Group also recognizes an associated liability. The transferred asset and the associated liability are measured on a basis that reflects the rights and obligations that the Group has retained.

Financial liabilities at amortized cost (including interest-bearing loans and borrowings)

Financial liabilities including trade and accrued payables, other payables and accrued liabilities, and interest-bearing loans and borrowings are initially stated at fair value less directly attributable transaction costs and are subsequently measured at amortized cost, using the effective interest method. The related interest expense is recognized in profit or loss.

Gains and losses are recognized in profit or loss when the liabilities are derecognized as well as through the amortization process.

Financial guarantee contracts

A financial guarantee contract is recognized initially at its fair value including transaction costs that are directly attributable to the issue of the guarantee. Subsequent to initial recognition, the liability is measured at the higher of the best estimate of the expenditure required to settle the present obligation at the reporting date and the amount recognized less cumulative amortization.

Derecognition of financial liabilities

Financial liabilities are derecognized when the obligations under the liabilities are discharged, cancelled, or have expired.

When an existing financial liability is replaced by another from the same lender on substantially different terms, or the terms of an existing liability are substantially modified, such an exchange or modification is treated as a derecognition of the original liability and a recognition of a new liability, and the difference between the respective carrying amounts is recognized in profit or loss.

Offsetting of financial instruments

Financial assets and liabilities are offset and the net amount reported in the consolidated statement of financial position, if and only if, there is a currently enforceable legal right to offset the recognized amounts and there is an intention to settle on a net basis, or to realize the assets and settle the liabilities simultaneously.

Inventories and supplies

Inventories primarily consist of oil and supplies, including items for repairs and maintenance of oil and gas properties. Inventories are stated at the lower of cost and net realizable value. Costs of inventories and supplies represent purchase or production cost of goods and are determined on a weighted average basis.

Cash and cash equivalents

Cash and cash equivalents comprise cash at banks and on hand and short term deposits with an original maturity of three months or less.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Provisions

A provision is recognized when a present obligation (legal or constructive) has arisen as a result of a past event and it is probable that a future outflow of resources will be required to settle the obligation, provided that a reliable estimate can be made of the amount of the obligation. When the effect of discounting is material, the amount recognized for a provision is the present value at the reporting date of the future expenditures expected to be required to settle the obligation. The increase in the discounted present value amount arising from the passage of time is included in profit or loss.

Dismantlement liability is recognized when the Group has a present legal or constructive obligation as a result of the past events, and it is probable that an outflow of resources will be required to settle the obligation, and a reliable estimate of the amount of the obligation can be made. A corresponding amount equivalent to the provision is also recognized as part of the cost of the related property, plant and equipment. The amount recognized is the estimated cost of dismantlement, discounted to its present value using a current pre-tax rate that reflects, where appropriate, the risks specific to the liability. Changes in the estimated timing of dismantlement or dismantlement cost estimates are dealt with prospectively by recording an adjustment to the provision, and a corresponding adjustment to property, plant and equipment. The unwinding of the discount on the dismantlement provision is included as a finance cost.

Income tax

Income tax comprises current and deferred tax. Income tax is recognized in the consolidated statement of profit or loss and other comprehensive income, either as an expense as it relates to operating activities or as a component of the applicable categories of other comprehensive income or expense.

Current tax assets and liabilities for the current and prior periods are measured at the amount expected to be recovered from or paid to the taxation authorities. The tax rates and tax laws used to compute the amount are those that are enacted or substantially enacted, by the reporting date, in the countries where the Group operates and generates taxable income.

Deferred tax is provided, using the balance sheet liability method, on all temporary differences at the reporting date between the tax bases of assets and liabilities and their carrying amounts for financial reporting purposes.

Deferred tax liabilities are recognized for all taxable temporary differences, except:

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Income tax (continued)

Deferred tax assets are recognized for all deductible temporary differences, the carryforward of unused tax credits and any unused tax losses to the extent that it is probable that taxable profit and taxable temporary differences will be available against which the deductible temporary differences, the carryforward of unused tax credits and unused tax losses can be utilized, except:

The carrying amount of deferred tax assets is reviewed at each reporting date and reduced to the extent that it is no longer probable that sufficient taxable profit will be available to allow all or part of the deferred tax asset to be utilized. Unrecognized deferred tax assets are reassessed at each reporting date and are recognized to the extent that it is probable that sufficient taxable profit and taxable temporary differences will be available to allow all or part of the deferred tax asset to be utilized.

Deferred tax assets and liabilities are measured at the tax rates that are expected to apply to the period when the asset is realized or the liability is settled, based on tax rates (and tax laws) that have been enacted or substantively enacted at the reporting date.

Deferred tax assets and deferred tax liabilities are offset if a legally enforceable right exists to set off current tax assets against current tax liabilities and the deferred taxes relate to the same taxable entity and the same taxation authority.

Revenue recognition

Revenue is recognized when it is probable that the economic benefits will flow to the Group and when the revenue can be measured reliably, on the following bases:

Oil and gas sales represent the invoiced value of sales of oil and gas attributable to the interests of the Group, net of royalties, obligations to governments and other mineral interest owners. Revenue from the sale of oil and gas is recognized when the significant risks and rewards of ownership have been transferred, which is when title passes to the customer. Revenue from the production of oil and gas in which the Group has a joint interest with other producers is recognized based on the Group’s working interest and the terms of the relevant production sharing contracts. Differences between production sold and the Group’s share of production are not significant.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Revenue recognition (continued)

Oil and gas lifted and sold by the Group above or below the Group's participating interests in the production sharing contracts results in overlifts and underlifts. The Group records these transactions in accordance with the entitlement method under which overlifts are recorded as liabilities and underlifts are recorded as assets at year-end oil prices. Settlement will be in kind or in cash when the liftings are equalised or in cash when production ceases.

The Group has entered into gas sale contracts with customers, which contain take-or-pay clauses. Under these contracts, the Group makes a long term supply commitment in return for a commitment from the buyer to pay for minimum quantities, whether or not it takes delivery. These commitments contain protective (force majeure) and adjustment provisions. If a buyer has a right to get a "make up" delivery at a later date, revenue recognition is deferred. If no such option exists according to the contract terms, revenue is recognized when the take-or-pay penalty is triggered.

Marketing revenues principally represent the sales of oil and gas from the foreign partners under the production sharing contracts and revenues from the trading of oil and gas through the Company’s subsidiaries. The cost of the oil and gas sold is included in “Crude oil and product purchases” in the consolidated statement of profit or loss and other comprehensive income. In addition, the Group’s marketing activities in North America involves entering into contracts to purchase and sell crude oil, natural gas and other energy commodities, and use derivative contracts, including futures, forwards, swaps and options for hedging and trading purposes (collectively derivative contracts). Any change in the fair value is also included in marketing revenue.

Other income mainly represents project management fees charged to foreign partners, handling fees charged to customers, the sales of diluents to third parties and gains from disposal of oil and gas properties and is recognized when the services have been rendered or the properties have been disposed of. Reimbursement of insurance claims is recognized when the compensation becomes receivable.

Dividend income is recognized when the Group's right to receive payment is established.

Interest income is recognized as it accrues using the effective interest method.

The Group presents taxes collected from customers in the consolidated statement of profit or loss and other comprehensive income on a net basis.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Share-based payment transactions

Employees (including directors) of the Group receive remuneration in the form of share-based payment transactions, whereby employees render services as consideration for equity instruments ("equity-settled transactions").

The cost of equity-settled transactions with employees is measured by reference to the fair value at the date at which they are granted. The fair value is determined by using the Black-Scholes option pricing model, further details of which are given in note 26.

The cost of equity-settled transactions is recognized, together with a corresponding increase in equity, over the period in which the performance and/or service conditions are fulfilled. The cumulative expense recognized for equity-settled transactions at the end of the each reporting period until the vesting date reflects the extent to which the vesting period has expired and the Group's best estimate of the number of equity instruments that will ultimately vest. The charge or credit to profit or loss for a period represents the movement in the cumulative expense recognized as at the beginning and end of that period.

No expense is recognized for awards that do not ultimately vest for the Group.

No equity-settled award was cancelled or modified during the years ended December 31, 2015, 2016 and 2017.

The dilutive effect of outstanding options is reflected as additional share dilution in the computation of earnings per share.

Retirement and termination benefits

The Group participates in defined contribution plans in accordance with local laws and regulations for full-time employees in the PRC and other countries in which it operates. The Group's contributions to these defined contribution plans are charged to profit or loss in the year to which they relate.

Borrowing costs

Borrowing costs consist of interest and other costs that an entity incurs in connection with the borrowing of funds. Borrowing costs directly relating to the acquisition, construction or production of a qualifying asset that necessarily takes a substantial period of time to get ready for its intended use or sale are capitalized as part of the cost of the respective assets. All other borrowing costs are expensed in the period in which they are incurred.

Foreign currencies

These consolidated financial statements are presented in RMB. Each entity in the Group maintains its books and records in its own functional currency. Foreign currency transactions recorded by the entities of the Group are initially recorded using their respective exchange rates ruling at the dates of the transactions. Monetary assets and liabilities denominated in foreign currencies are retranslated at the exchange rates ruling at the end of the reporting period. All differences arising on settlement or translation of monetary items are taken to profit or loss. Non-monetary items that are measured in terms of historical cost in a foreign currency are translated using the exchange rates at the dates of the initial transactions. Non-monetary items measured at fair value in a foreign currency are translated using the exchange rates at the date when the fair value was determined. The gain or loss arising on retranslation of a non-monetary item is treated consistently with the recognition of the gain or loss on change in fair value of the item.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Foreign currencies (continued)

The functional currencies of certain entities within the Group are currencies other than RMB. As at the end of the reporting period, the assets and liabilities of these entities are translated into the presentation currency of the Group at the exchange rates ruling at the reporting date, and their statement of profit or loss and other comprehensive income are translated into RMB at the weighted average exchange rates for the year. The resulting exchange differences are included in the cumulative translation reserve. On disposal of a foreign operation, the deferred cumulative amount recognized in equity relating to that particular foreign operation is recognized in profit or loss.

Operating leases

Leases where substantially all the rewards and risks of ownership of assets remain with the lessor are accounted for as operating leases. Where the Group is the lessee, rentals payable under operating leases are charged to profit or loss on the straight-line basis over the lease terms.

Prepaid land lease payments under operating leases in China are initially stated at cost and subsequently amortized on the straight-line basis over the lease terms.

Contingencies

A contingent liability is disclosed when the existence of an obligation will only be confirmed by future events or when the amount of the obligation cannot be measured reliably.

A contingent asset is not recognized in the financial statements, but is disclosed when an inflow of economic benefits is probable.

Significant accounting judgements, estimates and assumptions

The preparation of the consolidated financial statements in accordance with IFRSs and HKFRSs requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Estimates and judgements are continuously evaluated and are based on management's experience and other factors, including expectations of future events that are believed to be reasonable under the circumstances. However, actual outcomes can differ from these estimates.

In the process of applying the Group's accounting policies, the Directors have made the following judgements, estimates and assumptions, which have the most significant effect on the amounts recognized in the consolidated financial statements.

Oil and gas properties are depreciated on a unit-of-production basis at a rate calculated by reference to proved reserves. Commercial reserves are determined using estimates of oil in place, recovery factors and future oil prices, the latter having an impact on the proportion of the gross reserves which are attributable to the host government under the terms of the production sharing contracts. The level of estimated commercial reserves is also a key determinant in assessing whether the carrying value of any of the Group's oil and gas properties has been impaired.

Pursuant to the oil and gas reserve estimation requirements under US Securities and Exchange Commission's rules, the Group uses the average, first-day-of-the-month oil price during the 12-month period before the ending date of the period covered by the consolidated financial statements to estimate its proved oil and gas reserves.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Significant accounting judgements, estimates and assumptions (continued)

The calculation of the unit-of-production rate for oil and gas properties amortization could be impacted to the extent that actual production in the future is different from current forecast production based on proved reserves. This would generally result from significant changes in any of the factors or assumptions used in estimating reserves. These factors could include changes in proved reserves, the effect on proved reserves of differences between actual oil and gas prices and oil and gas price assumptions and unforeseen operational issues.

The Company makes an assessment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable, or when there is any indication that an impairment loss previously recognized for an asset in prior years may no longer exist or may have decreased. In any event, the Company would make an estimate of the asset’s recoverable amount, which is calculated at the higher of the asset’s value in use and its fair value less costs of disposal. The Company recognizes an impairment loss only if the carrying amount of an asset exceeds its recoverable amount. The Company charges an impairment loss to the profit or loss in the period in which it arises. A reversal of an impairment loss is credited to the profit or loss in the period in which it arises.

The calculations of the recoverable amount of assets require the use of estimates and assumptions. The key assumptions include, but are not limited to, future oil and gas prices, future production estimates, estimated future capital expenditures, estimated future operating expenses and the discount rate.

Changes in the key assumptions used, which could be significant, include updates to future pricing estimates, updates to future production estimates to align with the Company's anticipated drilling plan, changes in the Company's capital costs and operating expense assumptions, and discount rate. There is a significant degree of uncertainty with the assumptions used to estimate future cash flows due to various risk factors. The complex economic outlook may also materially and adversely affect the Company’s key assumptions. Changes in economic conditions can also affect the discount rates applied in assessments of impairment.

Actual cash flows are likely to be different from those estimated or forecast since anticipated events frequently do not occur as expected and unforeseen events may arise. The Company's results of operations could be materially and adversely affected for the period in which future impairment charges are incurred.

The sensitivity analysis for the impairment testing involves estimates and judgments to consider numerous assumptions comprehensively. Those assumptions interact on each other and interrelate with each other complexly and do not have fixed patterns along with the changes in price. Accordingly, the Company believes that the preparation of the sensitivity analysis for the impairment testing will be impracticable. Changes in assumptions could affect impairment charges and reversals in the consolidated statement of profit or loss and other comprehensive income, and the carrying amounts of assets in the consolidated statement of financial position.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

Significant accounting judgements, estimates and assumptions (continued)

Dismantlement costs will be incurred by the Group at the end of the operating life of certain of the Group's facilities and properties. The ultimate dismantlement costs are uncertain and cost estimates can vary in response to many factors including changes to relevant legal requirements, the emergence of new restoration techniques or experience at other production sites. The expected timing and amount of expenditure can also change, for example, in response to changes in reserves or changes in laws and regulations or their interpretation. As a result, there could be significant adjustments to the provisions established which would affect future financial results.

Uncertainties exist with respect to the interpretation of complex tax regulations (including those applicable to tax credits) and the amount and timing of future taxable income. Given the wide range of international business relationships and the long term nature and complexity of existing contractual agreements, differences arising between the actual results and the assumptions made, or future changes to such assumptions, could necessitate future adjustments to tax income and expense already recorded. The Group establishes provisions, based on best estimates, for possible consequences of audits by the tax authorities of the respective countries in which it operates. The amount of such provisions is based on various factors, such as the Group's experience of previous tax audits and differing interpretations of tax regulations by the taxable entity and the responsible tax authority. Such differences of interpretation may arise on a wide variety of issues depending on the conditions prevailing in the respective group company's domicile.

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

The Group is engaged worldwide in the upstream operating activities of the conventional oil and gas, shale oil and gas, oil sands and other unconventional oil and gas business. The Group reports the business through three operating and reporting segments: E&P, trading business and corporate. These segments are operating segments whose financial information are reviewed by the Group’s chief operating decision marker when making decisions regarding allocating resources and assessing performance. The geographical information is separately disclosed in (b).

CNOOC LIMITED

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(All amounts expressed in millions of Renminbi unless otherwise stated)

The following table presents the segment financial information for the Group for the years ended December 31, 2015, 2016 and 2017.