Exhibit 15.4





| | TBPE REGISTERED ENGINEERING FIRM F-1580

1100 LOUISIANA SUITE 4600 | HOUSTON,
                                         TEXAS 77002-5294 | FAX
                                         (713) 651-0849




TELEPHONE (713) 651-9191
| | ------------------------------------------------------------------ | ------------------------------------------------------------------ | ----------------------------------------------------------------------------------------







January
20, 2017



CNOOC Limited



c/o Nexen
Energy ULC



801-7th Avenue
S.W.



Calgary,
Alberta T2P 3P7



Canada





Gentlemen:



At
the request of CNOOC Limited (CNOOC), Ryder Scott Company, L.P. (Ryder Scott) has conducted a reserves audit of the estimates
of the proved reserves attributable to certain leasehold and royalty interests of OOGC America, LLC (OOGC) as of December 31,
2016 prepared by OOGC’s engineering and geological staff based on the definitions and disclosure guidelines of the United
States Securities and Exchange Commission (SEC) contained in Title 17, Code of Federal Regulations, Modernization of Oil and Gas
Reporting, Final Rule released January 14, 2009 in the Federal Register (SEC regulations). CNOOC indirectly retains 100 percent
ownership of OOGC. Our reserves audit, completed on January 11, 2017 and presented herein, was prepared for public disclosure
by CNOOC in filings made with the SEC in accordance with the disclosure requirements set forth in the SEC regulations. The estimated
reserves shown herein represent OOGC’s estimated net reserves attributable to the leasehold and royalty interests in certain
properties owned by OOGC and reviewed by Ryder Scott, as of December 31, 2016. The properties reviewed by Ryder Scott incorporate
OOGC reserve determinations and are located in the states of Colorado, Texas, and Wyoming.



The
properties reviewed by Ryder Scott account for all of OOGC’s total net proved reserves as of December 31, 2016. CNOOC has
represented that these properties represent 5 percent of its total company proved reserves on an equivalent barrel basis as of
December 31, 2016. The portions reviewed by Ryder Scott as determined by various metrics are as follows:





|Portions Reviewed             
|------------------------------
|CNOOC Limited                 
|                              
|                              
|Net Liquid Reserves           
|Net Gas Reserves              
|Net Liquid Equivalent Reserves





As
prescribed by the Society of Petroleum Engineers in Paragraph 2.2(f) of the Standards Pertaining to the Estimating and Auditing
of Oil and Gas Reserves Information (SPE auditing standards), a reserves audit is defined as “the process of reviewing certain
of the pertinent facts interpreted and assumptions made that have resulted in an estimate of reserves prepared by others and the
rendering of an opinion about (1) the appropriateness of the methodologies employed; (2) the adequacy and quality of the data
relied upon; (3) the depth and thoroughness of the reserves







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RYDER SCOTT COMPANY PETROLEUM CONSULTANTS


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estimation
process; (4) the classification of reserves appropriate to the relevant definitions used; and (5) the reasonableness of the estimated
reserve quantities.”



Based
on our review, including the data, technical processes and interpretations presented by OOGC, it is our opinion that the overall
procedures and methodologies utilized by OOGC in preparing their estimates of the proved reserves as of December 31, 2016 comply
with the current SEC regulations and that the overall proved reserves for the reviewed properties as estimated by OOGC are, in
the aggregate, reasonable within the established audit tolerance guidelines of 10 percent as set forth in the SPE auditing standards.



The
estimated reserves presented in this report are related to hydrocarbon prices. OOGC has informed us that in the preparation of
their reserve and income projections, as of December 31, 2016, they used average prices during the 12-month period prior to the
“as of date” of this report, determined as the unweighted arithmetic averages of the prices in effect on the first-day-of-the-month
for each month within such period, unless prices were defined by contractual arrangements, as required by the SEC regulations.
Actual future prices may vary significantly from the prices required by SEC regulations; therefore, volumes of reserves actually
recovered and the amounts of income actually received may differ significantly from the estimated quantities presented in this
report. The net reserves as estimated by OOGC attributable to OOGC's interests in properties that we reviewed are summarized below:



SEC PARAMETERS



OOGC’s
Estimates of Net Reserves



Certain Leasehold
and Royalty Interests of



OOGC America,
LLC



|As
    of December 31, 2016
|---------------------------



|                              |  | Proved   
|----------------------------- |  | ---------
|                              |  | Developed
|                              |  | Producing
|Total Net Reserves            |  |          
|Oil/Condensate – MBarrels     |  |          
|Plant Products – MBarrels     |  |          
|Gas – MMcf                    |  |          
|Total Oil Equivalents – MBOE* |  |          



* 6 Mcf
= 1 bbl liquid equivalents



Liquid
hydrocarbons are expressed in thousands of standard 42 gallon barrels (MBarrels). All gas volumes are reported on an “as
sold basis” expressed in millions of cubic feet (MMCF) at the official temperature and pressure bases of the areas in which
the gas reserves are located. The net remaining reserves are also shown herein on an equivalent unit basis wherein natural gas
is converted to oil equivalent using a factor of 6,000 cubic feet of natural gas per one barrel of oil equivalent. MBOE means
thousands of barrels of oil equivalent.



Reserves
Included in This Report



In
our opinion, the proved reserves presented in this report conform to the definition as set forth in the Securities and Exchange
Commission’s Regulations Part 210.4-10(a). An abridged version of



RYDER SCOTT COMPANY PETROLEUM CONSULTANTS


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the
SEC reserves definitions from 210.4-10(a) entitled “Petroleum Reserves Definitions” is included as an attachment to
this report.



The
various proved reserve status categories are defined under the attachment entitled “Petroleum Reserves Status Definitions
and Guidelines” in this report. The proved developed non-producing reserves included herein consist of the shut-in, non-producing
and not yet completed categories.



Reserves
are “estimated remaining quantities of oil and gas and related substances anticipated to be economically producible, as
of a given date, by application of development projects to known accumulations.” All reserve estimates involve an assessment
of the uncertainty relating the likelihood that the actual remaining quantities recovered will be greater or less than the estimated
quantities determined as of the date the estimate is made. The uncertainty depends chiefly on the amount of reliable geologic
and engineering data available at the time of the estimate and the interpretation of these data. The relative degree of uncertainty
may be conveyed by placing reserves into one of two principal classifications, either proved or unproved. Unproved reserves are
less certain to be recovered than proved reserves and may be further sub-classified as probable and possible reserves to denote
progressively increasing uncertainty in their recoverability. At OOGC’s request, this report addresses only the proved reserves
attributable to the properties reviewed herein.



Proved
oil and gas reserves are “those quantities of oil and gas which, by analysis of geoscience and engineering data, can be
estimated with reasonable certainty to be economically producible from a given date forward.” The proved reserves included
herein were estimated using deterministic methods. The SEC has defined reasonable certainty for proved reserves, when based on
deterministic methods, as a “high degree of confidence that the quantities will be recovered.”



Proved
reserve estimates will generally be revised only as additional geologic or engineering data become available or as economic conditions
change. For proved reserves, the SEC states that “as changes due to increased availability of geoscience (geological, geophysical,
and geochemical), engineering, and economic data are made to the estimated ultimate recovery (EUR) with time, reasonably certain
EUR is much more likely to increase or remain constant than to decrease.” Moreover, estimates of proved reserves may be
revised as a result of future operations, effects of regulation by governmental agencies or geopolitical or economic risks. Therefore,
the proved reserves included in this report are estimates only and should not be construed as being exact quantities, and if recovered,
could be more or less than the estimated amounts.



Audit
Data, Methodology, Procedure and Assumptions



The
estimation of reserves involves two distinct determinations. The first determination results in the estimation of the quantities
of recoverable oil and gas and the second determination results in the estimation of the uncertainty associated with those estimated
quantities in accordance with the definitions set forth by the Securities and Exchange Commission’s Regulations Part 210.4-10(a).
The process of estimating the quantities of recoverable oil and gas reserves relies on the use of certain generally accepted analytical
procedures. These analytical procedures fall into three broad categories or methods: (1) performance-based methods; (2) volumetric-based
methods; and (3) analogy. These methods may be used individually or in combination by the reserve evaluator in the process of
estimating the quantities of reserves. Reserve evaluators must select the method or combination of methods which in their professional
judgment is most appropriate given the nature and amount of reliable geoscience and engineering data available at the time of
the estimate, the established or



RYDER SCOTT COMPANY PETROLEUM CONSULTANTS


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anticipated
performance characteristics of the reservoir being evaluated and the stage of development or producing maturity of the property.



In
many cases, the analysis of the available geoscience and engineering data and the subsequent interpretation of this data may indicate
a range of possible outcomes in an estimate, irrespective of the method selected by the evaluator. When a range in the quantity
of reserves is identified, the evaluator must determine the uncertainty associated with the incremental quantities of the reserves.
If the reserve quantities are estimated using the deterministic incremental approach, the uncertainty for each discrete incremental
quantity of the reserves is addressed by the reserve category assigned by the evaluator. Therefore, it is the categorization of
reserve quantities as proved, probable and/or possible that addresses the inherent uncertainty in the estimated quantities reported.
For proved reserves, uncertainty is defined by the SEC as reasonable certainty wherein the “quantities actually recovered
are much more likely than not to be achieved.” The SEC states that “probable reserves are those additional reserves
that are less certain to be recovered than proved reserves but which, together with proved reserves, are as likely as not to be
recovered.” The SEC states that “possible reserves are those additional reserves that are less certain to be recovered
than probable reserves and the total quantities ultimately recovered from a project have a low probability of exceeding proved
plus probable plus possible reserves.” All quantities of reserves within the same reserve category must meet the SEC definitions
as noted above.



Estimates
of reserves quantities and their associated reserve categories may be revised in the future as additional geoscience or engineering
data become available. Furthermore, estimates of reserves quantities and their associated reserve categories may also be revised
due to other factors such as changes in economic conditions, results of future operations, effects of regulation by governmental
agencies or geopolitical or economic risks as previously noted herein.



The
proved reserves, prepared by OOGC, for the properties that we reviewed were estimated by performance methods, analogy, or a combination
of methods. All of the proved producing reserves attributable to producing wells and/or reservoirs that we reviewed were estimated
by performance methods, primarily decline curve analysis, which utilized extrapolations of historical production and pressure
data available through December 2016, in those cases where such data were considered to be definitive. The data utilized in this
analysis were furnished to Ryder Scott by OOGC or obtained from public data sources and were considered sufficient for the purpose
thereof. All of the proved developed non-producing and undeveloped reserves that we reviewed were estimated by the analogy method.
The data utilized from the analogues were considered sufficient for the purpose thereof. All of the proved reserves that were
reviewed are attributable to horizontal wells and locations.



To
estimate economically recoverable proved oil and gas reserves, many factors and assumptions are considered including, but not
limited to, the use of reservoir parameters derived from geological, geophysical and engineering data which cannot be measured
directly, economic criteria based on current costs and SEC pricing requirements, and forecasts of future production rates. Under
the SEC regulations 210.4-10(a)(22)(v) and (26), proved reserves must be anticipated to be economically producible from a given
date forward based on existing economic conditions including the prices and costs at which economic producibility from a reservoir
is to be determined. While it may reasonably be anticipated that the future prices received for the sale of production and the
operating costs and other costs relating to such production may increase or decrease from those under existing economic conditions,
such changes were, in accordance with rules adopted by the SEC, omitted from consideration in conducting this review.



As
stated previously, proved reserves must be anticipated to be economically producible from a given date forward based on existing
economic conditions including the prices and costs at which



RYDER SCOTT COMPANY PETROLEUM CONSULTANTS


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economic
producibility from a reservoir is to be determined. To confirm that the proved reserves reviewed by us meet the SEC requirements
to be economically producible, we have reviewed certain primary economic data utilized by OOGC relating to hydrocarbon prices
and costs as noted herein.



Data
used in this audit were obtained from reviews with OOGC personnel, OOGC files, from records on file with the appropriate regulatory
agencies, and from public sources. In the preparation of this report Ryder Scott have relied, without independent verification,
upon such information furnished by OOGC with respect to property interests, production from such properties, current costs of
operation and development, prices for production, agreements relating to current and future operations and sale of production,
and various other information and data that were accepted as represented. Furthermore, if in the course of our examination something
came to our attention which brought into question the validity or sufficiency of any of such information or data, we did not rely
on such information or data until we had satisfactorily resolved our questions relating thereto or had independently verified
such information or data. A field examination of the properties was not considered necessary for the purposes of this report.
OOGC did not place any limitations on the Ryder Scott work performed.



The
hydrocarbon prices furnished by OOGC for the properties reviewed by us are based on SEC price parameters using the average prices
during the 12-month period prior to the “as of date” of this report, determined as the unweighted arithmetic averages
of the prices in effect on the first-day-of-the-month for each month within such period, unless prices were defined by contractual
arrangements. For hydrocarbon products sold under contract, the contract prices, including fixed and determinable escalations
exclusive of inflation adjustments, were used until expiration of the contract. Upon contract expiration, the prices were adjusted
to the 12-month unweighted arithmetic average as previously described.



The
initial SEC hydrocarbon prices in effect on December 31, 2016 for the properties reviewed by us were determined using the 12-month
average first-day-of-the-month benchmark prices appropriate to the geographic area where the hydrocarbons are sold. These benchmark
prices are prior to the adjustments for differentials as described herein. The table below summarizes the “benchmark prices”
and “price reference” used by OOGC for the geographic areas reviewed by us. In certain geographic areas, the price
reference and benchmark prices may be defined by contractual arrangements.



The
product prices which were actually used by OOGC to determine the future gross revenue for each property reviewed by us reflect
adjustments to the benchmark prices for gravity, quality, local conditions, gathering and transportation fees and/or distance
from market, referred to herein as “differentials.” The differentials used by OOGC were accepted as factual data and
reviewed by us for their reasonableness; however, we have not conducted an independent verification of the data used by OOGC.



The
table below summarizes OOGC’s net volume weighted benchmark prices adjusted for differentials for the properties reviewed
by us and referred to herein as OOGC’s “average realized prices.” The average realized prices shown in the table
below were determined from OOGC’s estimate of the total future gross revenue before production taxes for the properties
reviewed by us and OOGC’s estimate of the total net reserves for the properties reviewed by us for the geographic area.



RYDER SCOTT COMPANY PETROLEUM CONSULTANTS


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|GeographicArea | Product        | Price Reference         | Average
        
        Benchmark
        
        Prices | Average
        
        Prices Net of Marketing, Transmission,
        
        and
        
        Processing | Average
        
        Realized
        
        Prices at Point
        
        of Sale
|-------------- | -------------- | ----------------------- | ---------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------
|               | North America 
|United States  | Oil/Condensate | West Texas Intermediate | $42.75/Bbl                                                 | $35.63/Bbl                                                                                                       | $39.80/Bbl                                                                                 
|NGLs*          | Mt Belvieu     | $18.52/Bbl              | $10.13/Bbl**                                               | $16.81/Bbl                                                                                                      
|Gas            | Henry Hub      | $2.46/MMBTU             | $(2.30)/Mcf**                                              | $2.45/Mcf                                                                                                       





*
NGL price was based upon the Mt. Belvieu benchmarks for each NGL constituent multiplied by fractional contribution



**
Includes certain gas gathering and related services fees









The
effects of derivative instruments designated as price hedges of oil and gas quantities are not reflected in OOGC’s individual
property evaluations.



Accumulated
gas production imbalances, if any, were not taken into account in the proved gas reserve estimates reviewed. The proved gas volumes
presented herein do not include volumes of gas consumed in operations as reserves.



Operating
costs furnished by OOGC are based on the operating expense reports of OOGC and include only those costs directly applicable to
the leases or wells for the properties reviewed by us. The operating costs include a portion of general and administrative costs
allocated directly to the leases and wells. The operating costs for non-operated properties include the COPAS overhead costs that
are allocated directly to the leases and wells under terms of operating agreements. The operating costs furnished by OOGC were
accepted as factual data and reviewed by us for their reasonableness; however, we have not conducted an independent verification
of the data used by OOGC. No deduction was made for loan repayments, interest expenses, or exploration and development prepayments
that were not charged directly to the leases or wells.



Development
costs furnished by OOGC are based on authorizations for expenditure for the proposed work or actual costs for similar projects.
The development costs furnished by OOGC were accepted as factual data and reviewed by us for their reasonableness; however, we
have not conducted an independent verification of the data used by OOGC. The estimated net cost of abandonment after salvage was
included by OOGC for properties where abandonment costs net of salvage were significant. OOGC’s estimates of the net abandonment
costs were accepted without independent verification.



The
proved developed non-producing and undeveloped reserves for the properties reviewed by us have been incorporated herein in accordance
with the operator’s plans to develop these reserves as of December 31, 2016. The implementation of the development plans
as presented to us is subject to the approval process adopted by OOGC’s management. As the result of our inquiries during
the course of our review, OOGC has informed us that the development activities for the properties reviewed by us have been subjected
to and received the internal approvals required by OOGC’s management at the appropriate local, regional and/or corporate
level. In addition to the internal approvals as noted, certain development activities may still be subject to specific partner
AFE



RYDER SCOTT COMPANY PETROLEUM CONSULTANTS


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processes,
Joint Operating Agreement (JOA) requirements or other administrative approvals external to OOGC. Additionally, OOGC has informed
us that they are not aware of any legal, regulatory, or political obstacles that would significantly alter their plans. While
these plans could change from those under existing economic conditions as of December 31, 2016, such changes were, in accordance
with rules adopted by the SEC, omitted from consideration in making this evaluation.



Current
costs used by OOGC were held constant throughout the life of the properties.



OOGC’s
forecasts of future production rates are based on historical performance from wells currently on production. If no production
decline trend has been established, future production rates were held constant, or adjusted for the effects of curtailment where
appropriate, until a decline in ability to produce was anticipated. An estimated rate of decline was then applied to depletion
of the reserves. If a decline trend has been established, this trend was used as the basis for estimating future production rates.



Test
data and other related information were used by OOGC to estimate the anticipated initial production rates for those wells or locations
that are not currently producing. For reserves not yet on production, sales were estimated to commence at an anticipated date
furnished by OOGC. Wells or locations that are not currently producing may start producing earlier or later than anticipated in
OOGC’s estimates due to unforeseen factors causing a change in the timing to initiate production. Such factors may include
delays due to weather, the availability of rigs, the sequence of drilling, completing and/or recompleting wells and/or constraints
set by regulatory bodies.



The
future production rates from wells currently on production or wells or locations that are not currently producing may be more
or less than estimated because of changes including, but not limited to, reservoir performance, operating conditions related to
surface facilities, compression and artificial lift, pipeline capacity and/or operating conditions, producing market demand and/or
allowables or other constraints set by regulatory bodies.



OOGC’s
operations may be subject to various levels of governmental controls and regulations. These controls and regulations may include,
but may not be limited to, matters relating to land tenure and leasing, the legal rights to produce hydrocarbons, drilling and
production practices, environmental protection, marketing and pricing policies, royalties, various taxes and levies including
income tax and are subject to change from time to time. Such changes in governmental regulations and policies may cause volumes
of proved reserves actually recovered and amounts of proved income actually received to differ significantly from the estimated
quantities.



The
estimates of proved reserves presented herein were based upon a review of the properties in which OOGC owns an interest; however,
we have not made any field examination of the properties. No consideration was given in this report to potential environmental
liabilities that may exist nor were any costs included by OOGC for potential liabilities to restore and clean up damages, if any,
caused by past operating practices.



Certain
technical personnel of OOGC are responsible for the preparation of reserve estimates on new properties and for the preparation
of revised estimates, when necessary, on old properties. These personnel assembled the necessary data and maintained the data
and workpapers in an orderly manner. We consulted with these technical personnel and had access to their workpapers and supporting
data in the course of our audit.



OOGC
has informed us that they have furnished us all of the material accounts, records, geological and engineering data, and reports
and other data required for this investigation. In



RYDER SCOTT COMPANY PETROLEUM CONSULTANTS


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performing
our audit of OOGC’s forecast of future proved production, we have relied upon data furnished by OOGC with respect to property
interests owned, production and well tests from examined wells, normal direct costs of operating the wells or leases, other costs
such as transportation and/or processing fees, ad valorem and production taxes, recompletion and development costs, development
plans, abandonment costs after salvage, product prices based on the SEC regulations, adjustments or differentials to product prices,
geological structural and isochore maps, well logs, core analyses, and pressure measurements. Ryder Scott reviewed such factual
data for its reasonableness; however, we have not conducted an independent verification of the data furnished by OOGC. We consider
the factual data furnished to us by OOGC to be appropriate and sufficient for the purpose of our review of OOGC’s estimates
of reserves. In summary, we consider the assumptions, data, methods and analytical procedures used by OOGC and as reviewed by
us appropriate for the purpose hereof, and we have used all such methods and procedures that we consider necessary and appropriate
under the circumstances to render the conclusions set forth herein.



Audit
Opinion



Based
on our review, including the data, technical processes and interpretations presented by OOGC, it is our opinion that the overall
procedures and methodologies utilized by OOGC in preparing their estimates of the proved reserves as of December 31, 2016 comply
with the current SEC regulations and that the overall proved reserves for the reviewed properties as estimated by OOGC are, in
the aggregate, reasonable within the established audit tolerance guidelines of 10 percent as set forth in the SPE auditing standards.



We
were in reasonable agreement with OOGC's estimates of proved reserves for the properties which we reviewed; although in certain
cases there was more than an acceptable variance between OOGC's estimates and our estimates due to a difference in interpretation
of data or due to our having access to data which were not available to OOGC when its reserve estimates were prepared. However
not withstanding, it is our opinion that on an aggregate basis the data presented herein for the properties that we reviewed fairly
reflects the estimated net reserves owned by OOGC.



Standards
of Independence and Professional Qualification



Ryder
Scott is an independent petroleum engineering consulting firm that has been providing petroleum consulting services throughout
the world since 1937. Ryder Scott is employee-owned and maintains offices in Houston, Texas; Denver, Colorado; and Calgary, Alberta,
Canada. We have over eighty engineers and geoscientists on our permanent staff. By virtue of the size of our firm and the large
number of clients for which we provide services, no single client or job represents a material portion of our annual revenue.
We do not serve as officers or directors of any privately-owned or publicly-traded oil and gas company and are separate and independent
from the operating and investment decision-making process of our clients. This allows us to bring the highest level of independence
and objectivity to each engagement for our services.



Ryder
Scott actively participates in industry-related professional societies and organizes an annual public forum focused on the subject
of reserves evaluations and SEC regulations. Many of our staff have authored or co-authored technical papers on the subject of
reserves related topics. We encourage our staff to maintain and enhance their professional skills by actively participating in
ongoing continuing education.



RYDER SCOTT COMPANY PETROLEUM CONSULTANTS


CNOOC Limited – OOGC America, LLC January 20, 2017 Page 9


Prior
to becoming an officer of the Company, Ryder Scott requires that staff engineers and geoscientists have received professional
accreditation in the form of a registered or certified professional engineer’s license or a registered or certified professional
geoscientist’s license, or the equivalent thereof, from an appropriate governmental authority or a recognized self-regulating
professional organization.



We
are independent petroleum engineers with respect to OOGC. Neither we nor any of our employees have any financial interest in the
subject properties, and neither the employment to do this work nor the compensation is contingent on our estimates of reserves
for the properties which were reviewed.



The
results of this audit, presented herein, are based on technical analysis conducted by teams of geoscientists and engineers from
Ryder Scott. The professional qualifications of the undersigned, the technical person primarily responsible for overseeing, reviewing
and approving the review of the reserves information discussed in this report, are included as an attachment to this letter.



Terms
of Usage



The
results of our third party audit, presented in report form herein, were prepared in accordance with the disclosure requirements
set forth in the SEC regulations and intended for public disclosure as an exhibit in filings made with the SEC by CNOOC Limited.



CNOOC
makes periodic filings on Form 20-F with the SEC under the 1934 Exchange Act. Furthermore, CNOOC has certain registration statements
filed with the SEC under the 1933 Securities Act into which any subsequently filed Form 20-F is incorporated by reference. We
have consented to the incorporation by reference in the registration statements on Form F-3 of CNOOC of the references to our
name as well as to the references to our third party report for CNOOC, which appears in the December 31, 2016 annual report on
Form 20-F of CNOOC. Our written consent for such use is included as a separate exhibit to the filings made with the SEC by CNOOC.



We
have provided OOGC with a digital version of the original signed copy of this report letter. In the event there are any differences
between the digital version included in filings made by CNOOC and the original signed report letter, the original signed report
letter shall control and supersede the digital version.











RYDER SCOTT COMPANY PETROLEUM CONSULTANTS


CNOOC Limited – OOGC America, LLC January 20, 2017 Page 10


The
data and work papers used in the preparation of this report are available for examination by authorized parties in our offices.
Please contact us if we can be of further service.







| | Very truly yours,                
| | ---------------------------------
| |                                  
| | RYDER SCOTT COMPANY, L.P.        
| | TBPE Firm Registration No. F-1580
| |                                  
| |                                  
| | /s/ Val Rick Robinson            
| |                                  
| |                                  
| | Val Rick Robinson, P.E.          
| | TBPE License No. 105137          
| | Managing Senior Vice President   



[SEAL]



VRR (DPR)/pl





|cc: | Mr. Yong Wang, OOGC
    Reserves Engineer    
|--- | ---------------------------------------------
|    | Mr. Lichuan Lan,
    Eagle Ford Asset Manager
|    | Mr. Todd Nicol, Rockies
    Asset Manager    
|    | Terrance Kryschuk, Deloitte LLP              
|    | Jenny Yang, Deloitte
    LLP                 





RYDER SCOTT COMPANY PETROLEUM CONSULTANTS





Professional
Qualifications of Primary Technical Engineer



The conclusions
presented in this report are the result of technical analysis conducted by teams of geoscientists and engineers from Ryder Scott
Company, L.P. Mr. Val Rick Robinson was the primary technical person responsible for the estimate of the reserves, future production
and income presented herein.



Mr. Robinson,
an employee of Ryder Scott Company, L.P. (Ryder Scott) since 2006, is a Managing Senior Vice President responsible for coordinating
and supervising staff and consulting engineers of the company in ongoing reservoir evaluation studies worldwide. Before joining
Ryder Scott, Mr. Robinson served in a number of engineering positions with ExxonMobil Corporation. For more information regarding
Mr. Robinson’s geographic and job specific experience, please refer to the Ryder Scott Company website at www.ryderscott.com/Company/Employees.



Mr. Robinson
earned a Bachelor of Science degree in Chemical Engineering from Brigham Young University in 2003 and is a licensed Professional
Engineer in the State of Texas. He is also a member of the Society of Petroleum Engineers.



In addition
to gaining experience and competency through prior work experience, the Texas Board of Professional Engineers requires a minimum
of fifteen hours of continuing education annually, including at least one hour in the area of professional ethics, which Mr. Robinson
fulfills. As part of his 2016 continuing education hours, Mr. Robinson attended 23 hours of formalized training including the
2016 RSC Reserves Conference and various professional society presentations covering such topics as the definitions and disclosure
guidelines contained in the United States Securities and Exchange Commission Title 17, Code of Federal Regulations, Modernization
of Oil and Gas Reporting, Final Rule released January 14, 2009 in the Federal Register, the SPE/WPC/AAPG/SPEE Petroleum Resources
Management System, reservoir engineering, overviews of the various productive basins of North America, computer software, and
professional ethics.



Based on
his educational background, professional training and more than 13 years of practical experience in the estimation and evaluation
of petroleum reserves, Mr. Robinson has attained the professional qualifications as a Reserves Estimator set forth in Article
III of the “Standards Pertaining to the Estimating and Auditing of Oil and Gas Reserves Information” promulgated by
the Society of Petroleum Engineers as of February 19, 2007.



RYDER SCOTT COMPANY PETROLEUM CONSULTANTS





PETROLEUM
RESERVES DEFINITIONS



As Adapted
From:



RULE 4-10(a)
of REGULATION S-X PART 210



UNITED
STATES SECURITIES AND EXCHANGE COMMISSION (SEC)



PREAMBLE



On
January 14, 2009, the United States Securities and Exchange Commission (SEC) published the “Modernization of Oil and Gas
Reporting; Final Rule” in the Federal Register of National Archives and Records Administration (NARA). The “Modernization
of Oil and Gas Reporting; Final Rule” includes revisions and additions to the definition section in Rule 4-10 of Regulation
S-X, revisions and additions to the oil and gas reporting requirements in Regulation S-K, and amends and codifies Industry Guide
2 in Regulation S-K. The “Modernization of Oil and Gas Reporting; Final Rule”, including all references to Regulation
S-X and Regulation S-K, shall be referred to herein collectively as the “SEC regulations”. The SEC regulations take
effect for all filings made with the United States Securities and Exchange Commission as of December 31, 2009, or after January
1, 2010. Reference should be made to the full text under Title 17, Code of Federal Regulations, Regulation S-X Part 210, Rule
4-10(a) for the complete definitions (direct passages excerpted in part or wholly from the aforementioned SEC document are denoted
in italics herein).



Reserves
are estimated remaining quantities of oil and gas and related substances anticipated to be economically producible, as of a given
date, by application of development projects to known accumulations. All reserve estimates involve an assessment of the uncertainty
relating the likelihood that the actual remaining quantities recovered will be greater or less than the estimated quantities determined
as of the date the estimate is made. The uncertainty depends chiefly on the amount of reliable geologic and engineering data available
at the time of the estimate and the interpretation of these data. The relative degree of uncertainty may be conveyed by placing
reserves into one of two principal classifications, either proved or unproved. Unproved reserves are less certain to be recovered
than proved reserves and may be further sub-classified as probable and possible reserves to denote progressively increasing uncertainty
in their recoverability. Under the SEC regulations as of December 31, 2009, or after January 1, 2010, a company may optionally
disclose estimated quantities of probable or possible oil and gas reserves in documents publicly filed with the SEC. The SEC regulations
continue to prohibit disclosure of estimates of oil and gas resources other than reserves and any estimated values of such resources
in any document publicly filed with the SEC unless such information is required to be disclosed in the document by foreign or
state law as noted in §229.1202 Instruction to Item 1202.



Reserves
estimates will generally be revised only as additional geologic or engineering data become available or as economic conditions
change.



Reserves
may be attributed to either natural energy or improved recovery methods. Improved recovery methods include all methods for supplementing
natural energy or altering natural forces in the reservoir to increase ultimate recovery. Examples of such methods are pressure
maintenance, natural gas cycling, waterflooding, thermal methods, chemical flooding, and the use of miscible and immiscible displacement
fluids. Other improved recovery methods may be developed in the future as petroleum technology continues to evolve.



Reserves
may be attributed to either conventional or unconventional petroleum accumulations. Petroleum accumulations are considered as
either conventional or unconventional based on the nature of their in-place characteristics, extraction method applied, or degree
of processing prior to sale.



RYDER SCOTT COMPANY PETROLEUM CONSULTANTS


PETROLEUM RESERVES STATUS DEFINITIONS AND GUIDELINES  Page 2


Examples
of unconventional petroleum accumulations include coalbed or coalseam methane (CBM/CSM), basin-centered gas, shale gas, gas hydrates,
natural bitumen and oil shale deposits. These unconventional accumulations may require specialized extraction technology and/or
significant processing prior to sale.



Reserves
do not include quantities of petroleum being held in inventory.



Because
of the differences in uncertainty, caution should be exercised when aggregating quantities of petroleum from different reserves
categories.



RESERVES
(SEC DEFINITIONS)



Securities
and Exchange Commission Regulation S-X §210.4-10(a)(26) defines reserves as follows:



Reserves.Reserves are estimated remaining quantities of oil and gas and related substances anticipated to be economically producible,
as of a given date, by application of development projects to known accumulations. In addition, there must exist, or there must
be a reasonable expectation that there will exist, the legal right to produce or a revenue interest in the production, installed
means of delivering oil and gas or related substances to market, and all permits and financing required to implement the project.



Note
to paragraph (a)(26): Reserves should not be assigned to adjacent reservoirs isolated by major, potentially sealing, faults
until those reservoirs are penetrated and evaluated as economically producible. Reserves should not be assigned to areas that
are clearly separated from a known accumulation by a non-productive reservoir (i.e., absence of reservoir, structurally
low reservoir, or negative test results). Such areas may contain prospective resources (i.e., potentially recoverable resources
from undiscovered accumulations).



PROVED
RESERVES (SEC DEFINITIONS)



Securities
and Exchange Commission Regulation S-X §210.4-10(a)(22) defines proved oil and gas reserves as follows:



Proved
oil and gas reserves.Proved oil and gas reserves are those quantities of oil and gas, which, by analysis of geoscience
and engineering data, can be estimated with reasonable certainty to be economically producible—from a given date forward,
from known reservoirs, and under existing economic conditions, operating methods, and government regulations—prior to the
time at which contracts providing the right to operate expire, unless evidence indicates that renewal is reasonably certain, regardless
of whether deterministic or probabilistic methods are used for the estimation. The project to extract the hydrocarbons must have
commenced or the operator must be reasonably certain that it will commence the project within a reasonable time.



(i)
The area of the reservoir considered as proved includes:



(A)
The area identified by drilling and limited by fluid contacts, if any, and



(B)
Adjacent undrilled portions of the reservoir that can, with reasonable certainty, be judged to be continuous with it and to contain
economically producible oil or gas on the basis of available geoscience and engineering data.



RYDER SCOTT COMPANY PETROLEUM CONSULTANTS


PETROLEUM RESERVES STATUS DEFINITIONS AND GUIDELINES  Page 3


PROVED
RESERVES (SEC DEFINITIONS) CONTINUED



(ii)
In the absence of data on fluid contacts, proved quantities in a reservoir are limited by the lowest known hydrocarbons (LKH)
as seen in a well penetration unless geoscience, engineering, or performance data and reliable technology establishes a lower
contact with reasonable certainty.



(iii)
Where direct observation from well penetrations has defined a highest known oil (HKO) elevation and the potential exists for an
associated gas cap, proved oil reserves may be assigned in the structurally higher portions of the reservoir only if geoscience,
engineering, or performance data and reliable technology establish the higher contact with reasonable certainty.



(iv)
Reserves which can be produced economically through application of improved recovery techniques (including, but not limited to,
fluid injection) are included in the proved classification when:



(A)
Successful testing by a pilot project in an area of the reservoir with properties no more favorable than in the reservoir as a
whole, the operation of an installed program in the reservoir or an analogous reservoir, or other evidence using reliable technology
establishes the reasonable certainty of the engineering analysis on which the project or program was based; and



(B)
The project has been approved for development by all necessary parties and entities, including governmental entities.



(v)
Existing economic conditions include prices and costs at which economic producibility from a reservoir is to be determined. The
price shall be the average price during the 12-month period prior to the ending date of the period covered by the report, determined
as an unweighted arithmetic average of the first-day-of-the-month price for each month within such period, unless prices are defined
by contractual arrangements, excluding escalations based upon future conditions.



RYDER SCOTT COMPANY PETROLEUM CONSULTANTS





PETROLEUM
RESERVES STATUS DEFINITIONS AND GUIDELINES



As Adapted
From:



RULE 4-10(a)
of REGULATION S-X PART 210



UNITED
STATES SECURITIES AND EXCHANGE COMMISSION (SEC)



and



PETROLEUM
RESOURCES MANAGEMENT SYSTEM (SPE-PRMS)



Sponsored
and Approved by:



SOCIETY
OF PETROLEUM ENGINEERS (SPE)



WORLD PETROLEUM
COUNCIL (WPC)



AMERICAN
ASSOCIATION OF PETROLEUM GEOLOGISTS (AAPG)



SOCIETY
OF PETROLEUM EVALUATION ENGINEERS (SPEE)



Reserves
status categories define the development and producing status of wells and reservoirs. Reference should be made to Title 17, Code
of Federal Regulations, Regulation S-X Part 210, Rule 4-10(a) and the SPE-PRMS as the following reserves status definitions are
based on excerpts from the original documents (direct passages excerpted from the aforementioned SEC and SPE-PRMS documents are
denoted in italics herein).



DEVELOPED
RESERVES (SEC DEFINITIONS)



Securities
and Exchange Commission Regulation S-X §210.4-10(a)(6) defines developed oil and gas reserves as follows:



Developed
oil and gas reserves are reserves of any category that can be expected to be recovered:



(i)
Through existing wells with existing equipment and operating methods or in which the cost of the required equipment is relatively
minor compared to the cost of a new well; and



(ii)
Through installed extraction equipment and infrastructure operational at the time of the reserves estimate if the extraction is
by means not involving a well.



Developed
Producing (SPE-PRMS Definitions)



While
not a requirement for disclosure under the SEC regulations, developed oil and gas reserves may be further sub-classified according
to the guidance contained in the SPE-PRMS as Producing or Non-Producing.



Developed
Producing Reserves



Developed
Producing Reserves are expected to be recovered from completion intervals that are open and producing at the time of the estimate.



Improved
recovery reserves are considered producing only after the improved recovery project is in operation.



RYDER SCOTT COMPANY PETROLEUM CONSULTANTS


PETROLEUM RESERVES STATUS DEFINITIONS AND GUIDELINES Page 2


Developed
Non-Producing



Developed
Non-Producing Reserves include shut-in and behind-pipe reserves.



Shut-In



Shut-in
Reserves are expected to be recovered from:



| | (1) | completion
                                         intervals which are open at the time of the estimate, but which have not started producing;
| | --- | -----------------------------------------------------------------------------------------------------------------------------------------------



| | (2) | wells
                                         which were shut-in for market conditions or pipeline connections; or
| | --- | -------------------------------------------------------------------------------------------------------------------



| | (3) | wells
                                         not capable of production for mechanical reasons.
| | --- | ------------------------------------------------------------------------------------------------



Behind-Pipe



Behind-pipe
Reserves are expected to be recovered from zones in existing wells, which will require additional completion work or future re-completion
prior to start of production.



In
all cases, production can be initiated or restored with relatively low expenditure compared to the cost of drilling a new well.



UNDEVELOPED
RESERVES (SEC DEFINITIONS)



Securities
and Exchange Commission Regulation S-X §210.4-10(a)(31) defines undeveloped oil and gas reserves as follows:



Undeveloped
oil and gas reserves are reserves of any category that are expected to be recovered from new wells on undrilled acreage, or from
existing wells where a relatively major expenditure is required for recompletion.



(i)
Reserves on undrilled acreage shall be limited to those directly offsetting development spacing areas that are reasonably certain
of production when drilled, unless evidence using reliable technology exists that establishes reasonable certainty of economic
producibility at greater distances.



(ii)
Undrilled locations can be classified as having undeveloped reserves only if a development plan has been adopted indicating that
they are scheduled to be drilled within five years, unless the specific circumstances, justify a longer time.



(iii)
Under no circumstances shall estimates for undeveloped reserves be attributable to any acreage for which an application of fluid
injection or other improved recovery technique is contemplated, unless such techniques have been proved effective by actual projects
in the same reservoir or an analogous reservoir, as defined in paragraph (a)(2) of this section, or by other evidence using reliable
technology establishing reasonable certainty.



RYDER SCOTT COMPANY PETROLEUM CONSULTANTS