Well Test Analysis

eP has a wide range of experience in well test analysis, related to the development of the company's software development, consulting, and training services.

eP has the foremost experts in well test analysis in the industry, with many years of practical experience in the analysis and interpretation of well tests. Our consultancy expertise has been enhanced by the parallel development of the PanSystem well test analysis package, which is the world's market leader, and by giving many training courses all over the world. In addition, eP engineers have substantial practical experience in the acquisition of well test data, having worked for some of the leading data acquisition companies throughout the world and supervised many tests. In-house expertise in the associated areas of production log analysis, PVT studies, core analysis, and geomechanics allows a depth of understanding in well performance to an unparalleled level. Some of the areas in which eP has a unique level of expertise include:

Multi-Layered Testing

The design and supervision of multi-layered well tests are crucial to the understanding of complex layered reservoirs. Many sedimentary reservoirs are the result of paleoenvironments of deposition which result in vertically limited bodies separated by lower permeability horizons. The determination and analysis of connectivity between each layer is paramount to understanding reservoir production. Our engineers have a proven expertise in this field and have assisted in the development of eP PanSystem software to aid the interpretation of production log tool data.

Production Log and Analysis Interface

Decisions on workovers and production optimization are invariably based on the analysis of production logs and well tests. Combining many years of practical experience gained in production log acquisition and interpretation, and expertise using eP WellFlo, a production optimization software package, our engineers are well placed to analyze even the most difficult problems. In addition, PLOG, a production log analysis software package, is available for in-house use.

Gas Condensates

The methodology for prediction of gas condensate deliverability using steady state, two phase pseudo-pressures and PVT is based on Equations of State (EoS) recently developed by eP engineers. These analyses allow gas condensate well tests to be interpreted, taking into account liquid dropout, over a wide range of pressures and temperatures, therefore better predicting fluid behavior and allowing production modeling.

Compartmentalized Reservoirs

Reservoirs which are composed of a number of blocks separated by partially communicating barriers are a very important feature of reservoir descriptions, especially in faulted traps. eP pioneered the identification of compartmentalized reservoirs using well tests and material balance calculations and have a proven track record in this area accumulated while successfully completing a number of volumetric studies.

Complex Geological Environments

The interaction between core analysis and well test analysis allows eP to effectively describe complex reservoirs. Vertical (fault planes) and horizontal (shales) barriers often combine to produce a geologically intricate body which cannot be satisfactorily analyzed using conventional well test techniques. The integration of validated laboratory core data permits eP engineers to confirm possible interpretations and establish suitable reservoir models and optimum production profiles.

Horizontal Wells

The importance of effective flow length and formation thickness is recognized in horizontal well test analysis and has been incorporated into PanSystem. The determination of both permeability and skin has allowed the precise identification of horizontal well performance based on compartmentalized reservoirs and sweet spots, available in PanSystem and WellFlo: both of which are frequently used by our engineers while determining horizontal DSTs.

Numerous well tests have been investigated during the PanSystem development program and as a result of our software support services. In addition, eP engineers have presented special horizontal well test analysis seminars worldwide.

Extended Well Tests

The evaluation of variable rate production well test data is a much neglected area of analysis. eP has developed new methods which allow real extended drawdown tests to be adequately interpreted.

Injection Well Tests

The effects of thermal fracturing and variable wellbore storage make the interpretation of injection well tests difficult. Special techniques have been developed to allow the proper understanding of these tests and they have been extended into slug test analysis and the interpretation of coal bed methane projects. The latter is potentially an important area of hydrocarbon exploration and production and offers considerable scope for the integrated skills within eP.

Typical Well Test Analysis Activities

• Two major field studies have been carried out to identify interblock communication as a precursor to reservoir simulation.
• Studies carried out on South American fluvial reservoirs resulted in a clearer understanding of the connectivity of channel sand bodies.
• Well test design of a high temperature/pressure gas condensate reservoir.
• An EoS model was tuned to a gas condensate well and successfully used to accurately predict top hole conditions from measured bottom hole data
• Numerous horizontal well test interpretations.
• Well test analysis for UK and US nuclear waste disposal programs.
• Tests of 10 days to 2 years duration, exhibiting significant rate changes have been deconvolved.
• Extensive software and engineering support through maintenance contracts for PanSystem.
• Industry training in well test analysis encompassing both basic and advanced interpretation techniques, well test analysis in horizontal wells, and PanSystem user courses. Over 1000 engineers have passed through schools run by eP in Edinburgh, and in-house throughout the world since 1985.