Exhibit 99.1



|                                        |                          
|--------------------------------------- | -------------------------
|TBPE REGISTERED ENGINEERING FIRM F-1580 | FAX (713) 651-0849       
|1100 LOUISIANA    SUITE 4600            | HOUSTON, TEXAS 77002-5294



| | February 19, 2018
| | -----------------



Ecopetrol

Cra. 13 No. 36-24

Edificio Principal, Piso 7

Bogotá, D.C., Colombia



Gentlemen:



At the request of Ecopetrol,
Ryder Scott Company, L.P. (Ryder Scott) has prepared an estimate of the proved reserves attributable to certain properties of Ecopetrol,
as of December 31, 2017. The subject properties are located in the country of Colombia and the United States of America. Ryder
Scott estimated the reserves 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). Our third party study, completed on January 20, 2018 and presented herein, was
prepared for public disclosure by Ecopetrol in filings made with the SEC in accordance with the disclosure requirements set forth
in the SEC regulations.



The properties evaluated
by Ryder Scott account for a portion of Ecopetrol’s total net proved reserves as of December 31, 2017. Based on information
provided by Ecopetrol, the third party estimate conducted by Ryder Scott addresses 67 percent of the total proved developed net
liquid hydrocarbon reserves and 75 percent of the total proved undeveloped net liquid hydrocarbon reserves, of Ecopetrol. The Ryder
Scott review also addresses 80 percent of the total proved developed net gas reserves and 75 percent of the total proved undeveloped
net gas reserves, of Ecopetrol.



The estimated reserve
amounts presented in this report, as of December 31, 2017, are related to hydrocarbon prices. The hydrocarbon prices used in the
preparation of this report are based on 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, 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 may differ
significantly from the estimated quantities presented in this report. The results of Ryder Scott’s estimates are summarized
as follows.



|SUITE  600,  1015  4TH  STREET,
S.W.   CALGARY, ALBERTA T2R 1J4 | TEL (403) 262-2799          | FAX (403) 262-2790
|--------------------------------------------------------------- | --------------------------- | ------------------
|621  17TH STREET, SUITE 1550                                    | DENVER, COLORADO 80293-1501 | TEL (303) 623-9147











Ecopetrol

February 19, 2018

Page 2



SEC PARAMETERS

Estimated Net Reserves

Certain Interests of

ECOPETROL

|As of December 31, 2017
|-----------------------



|                          |  | Proved    |          
|------------------------- |  | --------- | ---------
|                          |  |           |          
|                          |  | Developed |          
|Net Remaining Reserves    |  |           |          
|Oil/Condensate - MBarrels |  |           | 497,019  
|Plant Products - MBarrels |  |           | 49,483   
|Sales Gas - MMCF          |  |           | 2,304,998
|Fuel Gas - MMCF           |  |           | 220,191  



Liquid hydrocarbons
are expressed in thousand standard 42 gallon barrels. 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.
Further, they include Ecopetrol’s participation interest in properties operated by Ecopetrol America Incorporated, Equion
Energía Ltd. and Hocol Petroleum Ltd. The proved liquid hydrocarbon reserves volumes are exclusive of royalties. The net
gas reserves volumes include certain gas royalty volumes paid in cash.



Reserves Included in This Report



The proved reserves
included herein conform to the definition as set forth in the Securities and Exchange Commission’s Regulations Part 210.4-10(a).
An abridged version of 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.



No attempt was made
to quantify or otherwise account for any accumulated gas production imbalances that may exist. The proved gas volumes included
herein do not attribute gas consumed in operations as reserves. Non-hydrocarbon or inert gas volumes have been excluded from the
reserves reported herein.



Reserves are those
estimated remaining quantities of petroleum that are anticipated to be economically producible, as of a given date, from known
accumulations under defined conditions. 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 Ecopetrol’s request, this report addresses only the proved reserves attributable to the properties
evaluated herein.



RYDER SCOTT COMPANY   PETROLEUM CONSULTANTS







Ecopetrol

February 19, 2018

Page 3



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. If deterministic methods are used, the SEC has defined reasonable certainty for proved reserves 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,
the revenues therefrom, and the actual costs related thereto, could be more or less than the estimated amounts.



The proved reserves
reported herein are limited to the period prior to expiration of current contracts providing the legal rights to produce, or a
revenue interest in such production, unless evidence indicates that contract renewal is reasonably certain. Furthermore, properties
in the different countries may be subjected to significantly varying contractual fiscal terms that affect the net revenue to Ecopetrol
for the production of these volumes. The prices and economic return received for these net volumes can vary significantly based
on the terms of these contracts. Therefore, when applicable, Ryder Scott reviewed the fiscal terms of such contracts and discussed
with Ecopetrol the net economic benefit attributed to such operations for the determination of the net hydrocarbon volumes and
income thereof. Ryder Scott has not conducted an exhaustive audit or verification of such contractual information. Neither our
review of such contractual information nor our acceptance of Ecopetrol’s representations regarding such contractual information
should be construed as a legal opinion on this matter.



Ryder Scott did not
evaluate the country and geopolitical risks in the countries where Ecopetrol operates or has interests. Ecopetrol’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 including the granting,
extension or termination of production sharing contracts, the fiscal terms of various production sharing contracts, drilling and
production practices, environmental protection, marketing and pricing policies, royalties, various taxes and levies including income
tax, and foreign trade and investment 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 detailed study of the properties in which Ecopetrol 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 for potential liabilities to restore and clean up damages, if any, caused by past operating
practices.





RYDER SCOTT COMPANY   PETROLEUM CONSULTANTS







Ecopetrol

February 19, 2018

Page 4



Estimates of Reserves



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 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 economic risks as previously noted herein.



The proved reserves
for the properties included herein were estimated by performance methods, the volumetric method, or a combination of performance
and volumetric methods. The following table summarizes the approximate percent of reserves estimated by each of these methods.



|Approximate Percent Proved Reserves Estimated by the Various Methods
|--------------------------------------------------------------------
|                                                                    
|                                                                    
|Method                                                              
|Volumetric                                                          
|Performance                                                         
|Analogy                                                             
|Combination                                                         



RYDER SCOTT COMPANY   PETROLEUM CONSULTANTS







Ecopetrol

February 19, 2018

Page 5



These performance methods
include, but may not be limited to, decline curve analysis and analogy which utilized extrapolations of historical production and
pressure data available through November 2017 in those cases where such data were considered to be definitive. The data utilized
in this analysis were supplied to Ryder Scott by Ecopetrol and were considered sufficient for the purpose thereof. The volumetric
method was used where there were inadequate historical performance data to establish a definitive trend and where the use of production
performance data as a basis for the reserve estimates was considered to be inappropriate. The volumetric analysis utilized pertinent
well and seismic data supplied to Ryder Scott by Ecopetrol that were available through November 2017. The data utilized from the
well and seismic data incorporated into our volumetric analysis were considered sufficient for the purpose thereof.



To estimate economically
recoverable proved oil and gas reserves and related future net cash flows, we consider many factors and assumptions including,
but not limited to, the use of reservoir parameters derived from geological, geophysical and engineering data that 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 making this evaluation.



Ecopetrol 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 preparing our forecast of future proved production and income, we have relied upon data furnished
by Ecopetrol 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 Ecopetrol. We consider the factual data used in this report appropriate and sufficient for the purpose of preparing
the estimates of reserves herein.



In summary, we consider
the assumptions, data, methods and analytical procedures used in this report appropriate for the purpose hereof, and we have used
all such methods and procedures that we consider necessary and appropriate to prepare the estimates of reserves herein. The proved
reserves included herein were determined in conformance with the United States Securities and Exchange Commission (SEC) Modernization
of Oil and Gas Reporting; Final Rule, including all references to Regulation S-X and Regulation S-K, referred to herein collectively
as the “SEC Regulations.” In our opinion, the proved reserves presented in this report comply with the definitions,
guidelines and disclosure requirements as required by the SEC regulations.



Future Production Rates



For wells currently
on production, our forecasts of future production rates are based on historical performance data. 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.



RYDER SCOTT COMPANY   PETROLEUM CONSULTANTS







Ecopetrol

February 19, 2018

Page 6



Test data and other
related information were used 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 Ecopetrol.
Wells or locations that are not currently producing may start producing earlier or later than anticipated in our 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.



Hydrocarbon Prices



The hydrocarbon prices
used herein are based on SEC price parameters using the average prices during the 12-month period prior to the “as of date”
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.



Ecopetrol furnished
us with the above mentioned average prices in effect on December 31, 2017. These initial SEC hydrocarbon prices 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 for the geographic area included in the report. In certain
geographic areas, the price reference and benchmark prices may be defined by contractual arrangements. In cases where there are
numerous contracts or price references within the same geographic area, the benchmark price is represented by the unweighted arithmetic
average of the initial 12-month average first-day-of-the-month benchmark prices used.



The product prices
that were actually used to determine the future gross revenue for each property reflect adjustments to the benchmark prices for
gravity, quality, local conditions and/or distance from market, referred to herein as “differentials.” The differentials
used in the preparation of this report were furnished to us by Ecopetrol. The differentials furnished to us 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
Ecopetrol to determine these differentials.



In addition, the following
table summarizes the net volume weighted benchmark prices adjusted for differentials and referred to herein as the “average
realized prices.” The average realized prices shown in the table below were determined from the total future gross revenue
before production taxes and the total net reserves for the geographic area and presented in accordance with SEC disclosure requirements
for each of the geographic areas included in the report.



RYDER SCOTT COMPANY   PETROLEUM CONSULTANTS







Ecopetrol

February 19, 2018

Page 7



|Geographic Area         |  | Product        |  | Price Reference |  | Average Benchmark Prices |          |      | Average Realized Prices |  
|----------------------- |  | -------------- |  | --------------- |  | ------------------------ | -------- | ---- | ----------------------- | -
|                        |  | Oil/Condensate |  | Brent           |  | $                        | 54.93    | /Bbl |                         | $
|North and South America |  | NGLs           |  | Brent           |  | $                        | 54.93    | /Bbl |                         | $
|                        |  | Gas            |  | Contract        |  |                          | Contract |      |                         | $



The liquid prices above,
as provided by Ecopetrol, used the ICE Brent published by Bloomberg as reference. The effects of derivative instruments designated
as price hedges of oil and gas quantities are not reflected in our individual property evaluations. For the properties reviewed
by Ryder Scott, approximately 75 percent of the future gross income is derived from the sale of liquid hydrocarbons and 25 percent
from gas sales.



Costs



Operating costs used
in our evaluation were based on the operating expense reports of Ecopetrol and include only those costs directly applicable to
the evaluated assets. The operating costs include a portion of general and administrative costs allocated directly to the leases
and wells. The operating costs furnished to us were accepted as factual data and reviewed by us for their reasonableness; however,
we have not conducted an independent verification of the operating cost data used by Ecopetrol. No deduction was made for loan
repayments, interest expenses, or exploration and development prepayments that were not charged directly to the assets.



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



The proved developed
and undeveloped reserves in this report have been incorporated herein in accordance with Ecopetrol’s plans to develop these
reserves as of December 31, 2017. The implementation of Ecopetrol’s development plans as presented to us and incorporated
herein is subject to the approval process adopted by Ecopetrol’s management. As the result of our inquires during the course
of preparing this report, Ecopetrol has informed us that the development activities included herein have been subjected to and
received the internal approvals required by Ecopetrol’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 processes,
Joint Operating Agreement (JOA) requirements or other administrative approvals external to Ecopetrol. Additionally, Ecopetrol 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, 2017, such changes were, in accordance
with rules adopted by the SEC, omitted from consideration in making this evaluation.



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



RYDER SCOTT COMPANY   PETROLEUM CONSULTANTS







Ecopetrol

February 19, 2018

Page 8



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.



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 Ecopetrol. 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
study, 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 evaluation 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 study, 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 Ecopetrol.



We have provided Ecopetrol
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 Ecopetrol and the original signed report letter, the original signed report letter shall control
and supersede the digital version.



RYDER SCOTT COMPANY   PETROLEUM CONSULTANTS







Ecopetrol

February 19, 2018

Page 9



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/ Mario A. Ballesteros, P.E.   
|             |                                  
|             | Mario A. Ballesteros, P.E.       
|             | TBPE License No. 107132          
|             | Managing Senior Vice President   
|             |                                   | 
|MAB (DPR)/pl |                                   | 



RYDER SCOTT COMPANY   PETROLEUM CONSULTANTS







Professional Qualifications of Primary
Technical Person



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. Mario A.
Ballesteros was the primary technical person responsible for overseeing the independent estimation of reserves, future production
and income to render the audit conclusions of the report presented herein.



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



Mr. Ballesteros earned a Bachelor of Science
degree in Mechanical Engineering in 1991 and a Masters of Petroleum Engineering degree in 1993 from the University of Tulsa. He
also earned a Masters in Finance in 2000 from the Meta University in Colombia. He is a registered Professional Engineer in the
State of Texas.



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. Ballesteros fulfills. Mr. Ballesteros has attended
formalized training and conferences including dedicated to the subject of 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.



Based on his educational background, professional
training and more than 21 years of practical experience in the estimation and evaluation of petroleum reserves, Mr. Ballesteros
has attained the professional qualifications as a Reserves Estimator and Reserves Auditor 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, as the following
definitions, descriptions and explanations rely wholly or in part on excerpts from the original document (direct passages excerpted
from the aforementioned SEC document are denoted in italics herein).



Reserves are those
estimated remaining quantities of petroleum which are anticipated to be economically producible, as of a given date, from known
accumulations under defined conditions. All reserve estimates involve some degree of uncertainty. 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 Commission. 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 Commission
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 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.



RYDER SCOTT COMPANY   PETROLEUM CONSULTANTS







PETROLEUM
RESERVES DEFINITIONS

Page 2



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. 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 producible3⁄4from
a given date forward, from known reservoirs, and under existing economic conditions, operating methods, and government regulations3⁄4prior
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.



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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 further conditions.



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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 EV

ALUATION 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 extracting 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.



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PETROLEUM RESERVES STATUS DEFINITIONS AND
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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 yet 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.
| | ----- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



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