Method of determining reservoir pressure

Abstract

A well test method for use in tight gas reservoirs prior to hydraulic fracture stimulation. The method can use injection of water using low-rate surface pumps into the reservoir below parting pressure. The measured rates and pressures are converted to sandface rate and pressure datasets for each stage. The technique can utilize either surface or bottom-hole pressure sensors. The resulting sandface datasets are analyzed using the baseline / calibration method or other analysis appropriate to stage data to determine reservoir flow properties. The small-volume, staged well test enables estimation of the flow properties of reservoir, including pressure and permeability, in hours rather than days.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation-in-part under 35 U.S.C. §120 of pending U.S. patent application Ser. No. 13 / 327,182, filed Dec. 15, 2011, entitled “Method of Determining Reservoir Pressure,” which claims priority from U.S. Provisional Application Ser. No. 61 / 423,692, filed Dec. 16, 2010. The disclosures of said applications are hereby incorporated herein by reference in their entireties.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]Not applicable.BACKGROUND[0003]1. Field of the Invention[0004]This invention relates generally to the field of exploration and production of hydrocarbons. More specifically, the invention relates to a method of determining reservoir properties in hydrocarbon reservoirs.[0005]2. Background of the Invention[0006]Increasingly, hydrocarbon resource is being developed in low permeability reservoirs. For example, more than 50% of the currently identified gas resources in the United States is...

AI Technical Summary

Benefits of technology

The patent describes a method for estimating the pressure of a gas well by injecting fluid into the reservoir and measuring the parameters that indicate reservoir pressure over time. The method can be used in different types of gas reservoirs, including tight gas and shale reservoirs, and can also be used in conventional reservoirs, oil, and coalbed methane reservoirs. The method involves injecting fluid at different rates or pressures to create baseline and calibration trends, which are then compared to determine if the reservoir pressure value is correct. The method can be implemented using bottom-hole gauges, surface gauges, or level gauges with properly designed instrumentation. The patent also describes a system for carrying out the method and a computer program for implementing it. The technical effect of the invention is to provide a reliable and accurate method for estimating reservoir pressure in gas wells, which can aid in the evaluation and development of oil and gas reservoirs.

Problems solved by technology

A small amount of fluid may injected to ensure perforations are open, but careful measurement of volumes pumped and injection rates / volumes are limited to minimize the creation of any hydraulic fracture length during the test.

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