Services | CGA

Cawley, Gillespie & Associates




• Regional & field level geologic studies

• Exploration & exploitation studies

• Seismic interpretations / integration of geophysical studies

• Structural & stratigraphic interpretation and mapping

• Well log analysis & core studies

• Reservoir description & determination of rock properties

• Geostatistical (stochastic) analysis & reservoir description’

• Volumetric analysis

• Probabilistic risk assessment

• 3D visualization

• Reserves and resources determination & certification

• Economic evaluations for sales, acquisitions, mergers, estate & ad valorem taxes

• Stock exchange filings (e.g. SEC filings & IPO evaluations, Canadian NI 51-101)

• Fair market value determinations

• Unproven property evaluation

• Probabilistic evaluations

• Data room preparation

• Comprehensive field studies

• Reservoir management studies

• Drilling & development program studies

• Gas deliverability & forecasting

• Wellhead & pipeline compression studies

• Underground gas storage studies

• Economic, feasibility & uncertainty analyses

• Production performance studies

• Coalbed methane, oil shales & gas shales

• Gas storage selection, design & monitoring

• Gas plant & pipeline feasibility

• Reservoir modeling & simulation

• In-house custom, industry-standard software & graphics support

• Waterflooding

• Gas injection, gas cycling

• Miscible injection

• Carbon dioxide (CO2) flooding

• Steam flooding, cycling

• Water drive

• Depletion drive

• Coalbed methane or gas shale

• Tight (low permeability) formations

• Condensate or retrograde

• Overpressured or low pressure

• Deliverability

• Gas storage selection, design & monitoring

• Gas plant & pipeline feasibility

• Type curve preparation

• Reservoir characterization

• Performance evaluation

• Gas-in-place estimates

• Log analysis

• Reserve & economic evaluation

• Drainage studies

• Planning for drilling & completion

• Acquisition

• Expert opinion (negotiation, litigation, arbitration, regulatory hearings)

• Litigation support

• Litigation graphics

Reserve Reporting

CG&A’s main line of business relates to classifying and quantifying reserves and determining the associated net present values. The result of our efforts is usually a formal bound Reserve Report which can be used for a variety of purposes. Since 1960, CG&A has published over 10,000 formal reserve evaluations.

Regardless of the use of the report, CG&A applies the same level of expert analysis in reaching conclusions. In the case of a reserve appraisal, CG&A performs an independent technical analysis, including production performance analysis and/or all other analyses necessary to comprehend and securely quantify the remaining reserves.

Combining the technical analyses with analyses of costs and prices, CG&A forecasts these figures into the future and performs a cash flow analysis. In cases where CG&A does not perform the analysis, we are available to audit the work of another firm or client and comment on its merits in an audit letter.

Our reports are prepared in accordance with the most appropriate industry reserve and resource definitions, shown below in the order of most widely used for reporting:


(1) SPE-PRMS– 2007 Petroleum Resources Management System (PRMS) approved by the Society of Petroleum Engineers (SPE)

(2) SEC– U.S. Securities and Exchange Commission (SEC) Regulation S-X Rule 4-10(a)

(3) COGEH NI 51-101 – Canadian Oil and Gas Evaluation Handbook (COGEH), as prepared by the Society of Petroleum Evaluation Engineers (SPEE, Calgary Chapter) and Canadian Institute of Mining, Metallurgy & Petroleum (Petroleum Society).

A & D

Clients frequently rely on CG&A reserve evaluations for transactions such as acquisitions, divestitures and mergers. Our wide experience and independence make our opinions useful as an unbiased measure of value. In particular, our reports are being requested and utilized more often by 3rd party marketers that realize the value of having a reasonable, independent reserve report to support divestiture efforts.

Each year, CG&A evaluates billions of dollars in potential transactions. Working closely with clients, CG&A performs the technical analysis required to accurately predict reservoir performance. We also thoroughly investigate the economic parameters to prepare the best possible cash flow analysis.

A&D projects often require CG&A to quickly assemble a team of professionals and travel to the data room of a seller or marketer. This is one of our core services that we provide to our clients, and we do it often. Our clients call on us for these transactions because they know we are reliable, reasonable, and will often bend over backwards to accommodate a very tight schedule. Often, the acquisition evaluation process will involve the following:

• Travel to data room and gather pertinent details from the seller’s technical staff
• Prepare detailed data requests for critical data not supplied
• Provide early commentary to our clients on project viability and evaluation plans
• Prepare an independent reserves and economics evaluation, with varying levels of effort
     o Full-scale evaluation with extensive geosciences and engineering efforts
     o Scaled-down evaluation, auditing seller work product for reasonableness
• Prepare sensitivity evaluations as per client requirements
     o Pricing and escalation sensitivities
     o Probabilistic reserve estimations
     o Re-schedules of capital expenditure timing
• Assist client with bid price and due diligence as needed

Success Stories:

• A pair of major oil companies considering consolidating operations in California hired CG&A to determine the value of the contribution from each company. A team of 10 CG&A professionals and staff members was relocated to California, where, for several weeks, they worked day and night to provide the clients with the answer they required by the time they needed it.

• One of CG&A’s largest public clients invests hundreds of millions of dollars annually acquiring interests in oil and gas properties. To help this client evaluate the downside risk of its purchases, CG&A performs a probabilistic analysis on all potential acquisitions. CG&A has also created a web-based system for interaction with the operators of the properties to permit real-time monitoring of the production and economic performance of the projects.


CG&A has an experienced staff of reservoir engineers that regularly assist clients with a wide range of reservoir engineering services. We set ourselves apart from our larger competition because we are able to mobilize our staff very quickly and get your project completed quickly. Let us show you how we can help you with your engineering needs. A brief list of the reservoir engineering services we provide are:

• Estimation of petroleum reserves and resources
• Economic evaluations of prices, revenues, expenses and cash flows
• Fair market and estate valuations
• Comprehensive field and/or basin studies
• Pipeline and gathering system studies
• Enhanced recovery studies – secondary & tertiary
• Equity determinations/redeterminations
• Reservoir modeling and simulation
• Reservoir management studies
• Probabilistic reserve modeling
• Operations and surface facility analysis
• Litigation support and expert testimony

Success Stories:

• CG&A co-operated with a major exploration and production company to evaluate an enhanced oil recovery project on a giant oil field in North America. CG&A prepared a sophisticated partial field model and history-matched that model at an individual well level. We used the model to find and evaluate optimum waterflood and water-alternating-gas (WAG) scenarios. From this study, the client justified the drilling of additional development wells and the implementation of a limited WAG project.

• The operator of a 14,000 acre sandstone reservoir with 105 wells engaged CG&A to determine the economics for varied depletion plans. From aerial simulation studies we designed a waterflood pattern which increased unit rates from 4, 500 BPD to 22,000 BPD with individual wells responding in excess of 1,000 BPD.


CG&A has an experienced staff of geoscientists that regularly evaluate both conventional and unconventional reservoirs and fields throughout the world. This work includes understanding and mapping complex stratigraphic and/or structural reservoirs, as well as unconventional reservoirs such as coalbed methane, oil shales, gas shales and tight gas. We also have extensive experience in most producing basins of the world, including a variety of depositional environments ranging from continental to deepwater. Our geoscientists work hand-in-hand with our reservoir engineers to seamlessly incorporate the geological, geophysical and petrophysical attributes with the engineering analyses to arrive at the best possible reserve estimates. Our geoscience services include:

• Analyzing wireline logs, mud & drilling logs, cores & core data
• Subsurface interpretation and mapping
    o Structure, isopach and pore volume maps
    o Stratigraphic and structural cross-sections
    o Lithologic interpretation and facies distribution
• Seismic interpretation and mapping
• Reservoir characterization & geostatistical analysis
• Volumetric reserves estimation
• Basin and/or field geological studies
• Unconventional reservoirs (coalbed, shale, tight sand, heavy oil)

Success Stories:

• CG&A was asked to study a severely faulted reservoir located beneath the overhang of a salt dome and to predict primary and expected secondary recovery. From detailed geological and simulation studies, initial volumetric calculations of oil in place were increased almost 30%, and a depletion scheme was designed to optimize recovery and value.

• CG&A investigated the effects of reservoir heterogeneity on the variability of production of wells from the Austin Chalk formation of Texas. We used GSLIB to create hundreds of realizations from a single variogram without constraining the realizations to known data. We then simulated production from each of the realizations and compared production characteristics to actual field production.

• Sand reservoir in New Mexico is extremely complex and heterogeneous. Initial fluid saturations were characterized as an oil-water transition zone extending over the entire pay section. CG&A evaluated core analysis, correlated to wireline logs and compared to the results of transient tests. A detailed simulation of the field confirmed the presence of a sealing horizontal shale barrier that was effectively breached in some wells. Sensitivity runs were made to investigate the impact of producing gas-oil ratio on ultimate recovery to allow the operator to produce the field in the most economic manner.

Field Basin Studies

Choosing how to develop and produce a field can make an enormous difference to the bottom line. CG&A’s multidisciplinary teams are expert in conducting reservoir studies to optimize production and value, thus allowing clients to make better reservoir management decisions.

CG&A has also successfully assisted pipeline companies with field studies that help estimate potential volumes of hydrocarbons that may impact their pipeline systems. CG&A regularly studies localized regions or entire basins for clients that want to understand drilling trends, average well type curves, economic break-even analysis, and future volumes. CG&A has the tools in place to efficiently and accurately make these predictions.