EXHIBIT 99.1

March 26, 2002

Carrizo Oil & Gas, Inc.
14701 St. Mary's Lane, Suite 800
Houston, Texas 77079

Gentlemen:

At your request, we have prepared an estimate of the reserves, future
production, and income attributable to certain leasehold and royalty interests
of Carrizo Oil & Gas, Inc. (Carrizo) as of December 31, 2001. The subject
properties are located in the states of Louisiana and Texas. The income data
were estimated using the Securities and Exchange Commission (SEC) guidelines for
future price and cost parameters.

The estimated reserves and future income amounts presented in this
report are related to hydrocarbon prices. December 31, 2001 hydrocarbon prices
were used in the preparation of this report as required by SEC guidelines;
however, actual future prices may vary significantly from December 31, 2001
prices. Therefore, volumes of reserves actually recovered and amounts of income
actually received may differ significantly from the estimated quantities
presented in this report. The results of this study are summarized below.

SEC PARAMETERS
Estimated Net Reserves and Income Data
Certain Leasehold and Royalty Interests of
CARRIZO OIL & GAS, INC.
As of December 31, 2001
----------------------------------------------------------------------

<Table>
<Caption>
Proved
----------------------------------------------------------------
Developed
------------------------------ Total
Producing Non-Producing Undeveloped Proved
------------ ------------- ------------ ------------

NET REMAINING RESERVES
Oil/Condensate - Barrels 132,491 253,839 260,544 646,874
Plant Products - Barrels 30,080 79,804 0 109,884
Gas - MMCF 5,714 7,381 4,104 17,199

INCOME DATA
Future Gross Revenue $ 16,572,129 $ 23,592,894 $ 14,547,940 $ 54,712,963
Deductions 3,381,584 5,484,871 3,446,736 12,313,191
------------ ------------- ------------ ------------
Future Net Income (FNI) $ 13,190,545 $ 18,108,023 $ 11,101,204 $ 42,399,772

Discounted FNI @ 10% $ 11,590,322 $ 13,573,392 $ 8,940,400 $ 34,104,114
</Table>

Liquid hydrocarbons are expressed in standard 42 gallon barrels. All
gas volumes are sales gas expressed in millions of cubic feet (MMCF) at the
official temperature and pressure bases of the areas in which the gas reserves
are located.

Carrizo Oil & Gas, Inc.
March 26, 2002
Page 2

The future gross revenue is after the deduction of production taxes.
The deductions are comprised of the normal direct costs of operating the wells,
ad valorem taxes, recompletion costs, development costs, and certain abandonment
costs net of salvage. The future net income is before the deduction of state and
federal income taxes and general administrative overhead, and has not been
adjusted for outstanding loans that may exist nor does it include any adjustment
for cash on hand or undistributed income. No attempt was made to quantify or
otherwise account for any accumulated gas production imbalances that may exist.
Gas reserves account for approximately 80 percent and liquid hydrocarbon
reserves account for the remaining 20 percent of total future gross revenue from
proved reserves.

RESERVES INCLUDED IN THIS REPORT

The proved reserves included herein conform to the definition as set
forth in the Securities and Exchange Commission's Regulation S-X Part 210.4-10
(a) as clarified by subsequent Commission Staff Accounting Bulletins. The
probable reserves and possible reserves included herein conform to definitions
of probable and possible reserves approved by the SPE/WPC using the
deterministic methodology. The definitions of proved, probable, and possible
reserves are included in the section entitled "Reserve Definitions" which is
attached with this report.

Because of the direct relationship between volumes of proved
undeveloped reserves and development plans, we include in the proved undeveloped
category only reserves assigned to undeveloped locations that we have been
assured will definitely be drilled, and reserves assigned to the undeveloped
portions of secondary or tertiary projects which we have been assured will
definitely be developed.

The proved and probable developed non-producing reserves included
herein are comprised of shut-in and behind pipe categories. The various reserve
status categories are defined in the section entitled "Reserve Definitions "
which is attached with this report.

ESTIMATES OF RESERVES

In general, the reserves included herein were estimated by performance
methods or the volumetric method; however, other methods were used in certain
cases where characteristics of the data indicated such other methods were more
appropriate in our opinion. The reserves estimated by the performance method
utilized extrapolations of various historical data in those cases where such
data were definitive. Reserves were estimated by the volumetric method in those
cases where there were inadequate historical performance data to establish a
definitive trend or where the use of production performance data as a basis for
the reserve estimates was considered to be inappropriate.

The reserves included in this report are estimates only and should not
be construed as being exact quantities. They may or may not be actually
recovered, and if recovered, the revenues therefrom and the actual costs related
thereto could be more or less than the estimated amounts. Moreover, estimates of
reserves may increase or decrease as a result of future operations.

FUTURE PRODUCTION RATES

Initial production rates are based on the current producing rates for
those wells now on production. Test data and other related information were used
to estimate the anticipated initial production rates for those wells or
locations which are not currently producing. 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

Carrizo Oil & Gas, Inc.
March 26, 2002
Page 3

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. For reserves not yet on production, sales were estimated to
commence at an anticipated date furnished by Carrizo.

In general, we estimate that future gas production rates limited by
allowables or marketing conditions will continue to be the same as the average
rate for the latest available 12 months of actual production until such time
that the well or wells are incapable of producing at this rate. The well or
wells were then projected to decline at their decreasing delivery capacity rate.
Our general policy on estimates of future gas production rates is adjusted when
necessary to reflect actual gas market conditions in specific cases.

The future production rates from wells now on production may be more or
less than estimated because of changes in market demand or allowables set by
regulatory bodies. Wells or locations which are not currently producing may
start producing earlier or later than anticipated in our estimates of their
future production rates.

HYDROCARBON PRICES

Carrizo furnished us with hydrocarbon prices in effect at December 31,
2001 and with its forecasts of future prices which take into account SEC and
Financial Accounting Standards Board (FASB) rules, current market prices,
contract prices, and fixed and determinable price escalations where applicable.

In accordance with FASB Statement No. 69, December 31, 2001 market
prices were determined using the daily oil price or daily gas sales price ("spot
price") adjusted for oilfield or gas gathering hub and wellhead price
differences (e.g. grade, transportation, gravity, sulfur and BS&W) as
appropriate. Also in accordance with SEC and FASB specifications, changes in
market prices subsequent to December 31, 2001 were not considered in this
report.

For hydrocarbon products sold under contract, the contract price
including fixed and determinable escalations, exclusive of inflation
adjustments, was used until expiration of the contract. Upon contract
expiration, the price was adjusted to the current market price for the area and
held at this adjusted price to depletion of the reserves.

COSTS

Operating costs for the leases and wells in this report are based on
information provided by Carrizo and include only those costs directly applicable
to the leases or wells. When applicable, the operating costs include a portion
of general and administrative costs allocated directly to the leases and wells
under terms of operating agreements. No deduction was made for indirect costs
such as general administration and overhead expenses, loan repayments, interest
expenses, and exploration and development prepayments that are not charged
directly to the leases or wells.

Development costs were furnished to us by Carrizo and are based on
authorizations for expenditure for the proposed work or actual costs for similar
projects. The estimated net cost of abandonment after salvage was included for
properties where abandonment costs net of salvage are significant. At the
request of Carrizo, their estimate of zero abandonment costs after salvage value
for onshore properties was used in this report. Ryder Scott has not performed a
detailed study of the abandonment costs nor the salvage value and makes no
warranty for Carrizo's estimate.

Current costs were held constant throughout the life of the properties.

Carrizo Oil & Gas, Inc.
March 26, 2002
Page 4

GENERAL

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 also increase or decrease from existing levels, such changes
were, in accordance with rules adopted by the SEC, omitted from consideration in
making this evaluation.

The estimates of reserves presented herein were based upon a detailed
study of the properties in which Carrizo 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 which may exist nor were any costs
included for potential liability to restore and clean up damages, if any, caused
by past operating practices. Carrizo has informed us that they have furnished us
all of the accounts, records, geological and engineering data, and reports and
other data required for this investigation. The ownership interests, prices, and
other factual data furnished by Carrizo were accepted without independent
verification. The estimates presented in this report are based on data available
through December 2001.

Carrizo has assured us of their intent and ability to proceed with the
development activities included in this report, and that they are not aware of
any legal, regulatory or political obstacles that would significantly alter
their plans.

Neither we nor any of our employees have any interest in the subject
properties and neither the employment to make this study nor the compensation is
contingent on our estimates of reserves and future income for the subject
properties.

This report was prepared for the exclusive use and sole benefit of
Carrizo Oil & Gas, Inc. The data, work papers, and maps used in 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.

Michael F. Stell, P.E.
Vice President
MFS/sw

PETROLEUM RESERVES DEFINITIONS

SECURITIES AND EXCHANGE COMMISSION

INTRODUCTION

Reserves are those quantities of petroleum which are anticipated to be
commercially recovered from known accumulations from a given date forward. 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. It should be noted that Securities and Exchange Commission
Regulation S-K prohibits the disclosure of estimated quantities of probable or
possible reserves of oil and gas and any estimated value thereof in any
documents publicly filed with the Commission.

Reserves estimates will generally be revised as additional geologic or
engineering data become available or as economic conditions change. Reserves do
not include quantities of petroleum being held in inventory, and may be reduced
for usage or processing losses if required for financial reporting.

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,
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.

PROVED RESERVES (SEC DEFINITIONS)

Securities and Exchange Commission Regulation S-X Rule 4-10 paragraph
(a) defines proved reserves as follows:

PROVED OIL AND GAS RESERVES. Proved oil and gas reserves are the estimated
quantities of crude oil, natural gas, and natural gas liquids which geological
and engineering data demonstrate with reasonable certainty to be recoverable in
future years from known reservoirs under existing economic and operating
conditions, i.e., prices and costs as of the date the estimate is made. Prices
include consideration of changes in existing prices provided only by contractual
arrangements, but not on escalations based upon future conditions.

(i) Reservoirs are considered proved if economic producibility is
supported by either actual production or conclusive formation test. The
area of a reservoir considered proved includes:

(A) that portion delineated by drilling and defined by gas-oil
and/or oil-water contacts, if any; and

(B) the immediately adjoining portions not yet drilled, but which
can be reasonably judged as economically productive on the basis
of available geological and engineering data. In the absence of
information on fluid contacts, the lowest known structural
occurrence of hydrocarbons controls the lower proved limit of the
reservoir.

PETROLEUM RESERVES DEFINITIONS
Page 2

(ii) Reserves which can be produced economically through application of
improved recovery techniques (such as fluid injection) are included in
the "proved" classification when successful testing by a pilot project,
or the operation of an installed program in the reservoir, provides
support for the engineering analysis on which the project or program was
based.

(iii) Estimates of proved reserves do not include the following:

(A) oil that may become available from known reservoirs but is
classified separately as "indicated additional reserves";

(B) crude oil, natural gas, and natural gas liquids, the recovery
of which is subject to reasonable doubt because of uncertainty as
to geology, reservoir characteristics, or economic factors;

(D) crude oil, natural gas, and natural gas liquids, that may be
recovered from oil shales, coal, gilsonite and other such sources.

PROVED DEVELOPED OIL AND GAS RESERVES. Proved developed oil and gas reserves are
reserves that can be expected to be recovered through existing wells with
existing equipment and operating methods. Additional oil and gas expected to be
obtained through the application of fluid injection or other improved recovery
techniques for supplementing the natural forces and mechanisms of primary
recovery should be included as "proved developed reserves" only after testing by
a pilot project or after the operation of an installed program has confirmed
through production response that increased recovery will be achieved.

PROVED UNDEVELOPED RESERVES. Proved undeveloped oil and gas reserves are
reserves 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. Reserves on undrilled acreage shall be limited to those drilling
units offsetting productive units that are reasonably certain of production when
drilled. Proved reserves for other undrilled units can be claimed only where it
can be demonstrated with certainty that there is continuity of production from
the existing productive formation. Under no circumstances should estimates for
proved 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 tests
in the area and in the same reservoir.

Certain Staff Accounting Bulletins published subsequent to the
promulgation of Regulation S-X have dealt with matters relating to the
application of financial accounting and disclosure rules for oil and gas
producing activities. In particular, the following interpretations extracted
from Staff Accounting Bulletins set forth the Commission staff's view on
specific questions pertaining to proved oil and gas reserves.

Economic producibility of estimated proved reserves can be supported to
the satisfaction of the Office of Engineering if geological and engineering data
demonstrate with reasonable certainty that those reserves can be recovered in
future years under existing economic and operating conditions. The relative
importance of the many pieces of geological and engineering data which should be
evaluated when classifying reserves cannot be identified in advance. In certain
instances, proved reserves may be assigned to reservoirs on the basis of a
combination of electrical and other type logs and core analyses which indicate
the reservoirs are analogous to similar reservoirs in the same field which are
producing or have demonstrated the ability to produce on a formation test.
(extracted from SAB-35)

PETROLEUM RESERVES DEFINITIONS
Page 3

In determining whether "proved undeveloped reserves" encompass acreage
on which fluid injection (or other improved recovery technique) is contemplated,
is it appropriate to distinguish between (i) fluid injection used for pressure
maintenance during the early life of a field and (ii) fluid injection used to
effect secondary recovery when a field is in the late stages of depletion? ...
The Office of Engineering believes that the distinction identified in the above
question may be appropriate in a few limited circumstances, such as in the case
of certain fields in the North Sea. The staff will review estimates of proved
reserves attributable to fluid injection in the light of the strength of the
evidence presented by the registrant in support of a contention that enhanced
recovery will be achieved. (extracted from SAB-35)

Companies should report reserves of natural gas liquids which are net
to their leasehold interest, i.e., that portion recovered in a processing plant
and allocated to the leasehold interest. It may be appropriate in the case of
natural gas liquids not clearly attributable to leasehold interests ownership to
follow instruction (b) of Item 2(b)(3) of Regulation S-K and report such
reserves separately and describe the nature of the ownership. (extracted from
SAB-35)

The staff believes that since coalbed methane gas can be recovered from
coal in its natural and original location, it should be included in proved
reserves, provided that it complies in all other respects with the definition of
proved oil and gas reserves as specified in Rule 4-10(a)(2) including the
requirement that methane production be economical at current prices, costs, (net
of the tax credit) and existing operating conditions.
(extracted from SAB-85)

Statements in Staff Accounting Bulletins are not rules or
interpretations of the Commission nor are they published as bearing the
Commission's official approval; they represent interpretations and practices
followed by the Division of Corporation Finance and the Office of the Chief
Accountant in administering the disclosure requirements of the Federal
securities laws.

SUB-CATEGORIZATION OF DEVELOPED RESERVES (SPE/WPC DEFINITIONS)

In accordance with guidelines adopted by the Society of Petroleum
Engineers (SPE) and the World Petroleum Congress (WPC), developed reserves may
be sub-categorized as producing or non-producing.

PRODUCING. Reserves sub-categorized as producing are expected to be recovered
from completion intervals which 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.

NON-PRODUCING. Reserves sub-categorized as non-producing include shut-in and
behind pipe reserves. 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 awaiting pipeline
connections or as a result of a market interruption, or (3) wells not capable of
production for mechanical reasons. Behind pipe reserves are expected to be
recovered from zones in existing wells, which will require additional completion
work or future recompletion prior to the start of production.