Regained Gas Permeability - An Aid To Improved Hydraulic Fracture Design
Authors: Derby J.A. , Smith P.L. 
Published: December 2007

The search for oil and gas has progressed throughout the years at a continually progressed throughout the years at a continually increasing pace. Each year has seen additional technology added to the preceding fund of knowledge in an effort to more efficiently produce formations that could not be produce formations that could not be economically considered 20 years ago.

These same economics, now, in conjunction with the law of supply and demand, make it imperative that every formation be given the best preliminary evaluation prior to stimulation. Formation fluids, if available, should be tested for its various characteristics and compatibility with proposed treatment solutions. The formation itself should be evaluated not only for all the usual properties but also for its ability to regain its properties but also for its ability to regain its original productivity or permeability after being subjected to the proposed treatment fluids during fluid loss testing, etc.

Regain gas permeability tests, as shown in this paper, are designed to help select the optimum treatment fluid for any given formation with respect to fluid, fluid loss and time to regain 70 to 80 percent of the initial undamaged permeability.

Introduction

Thirty years ago commercial hydraulic fracturing was initiated. The first two oil wells stimulated that day, March 17, by hydraulic pressure were very small volume treatments: less than 1700 gal. (6.43 m3) total fluid for both wells.

The demand for fuel has intensified the pace of production and search for new pace of production and search for new reserves. Along with this expansion came more technology related to stimulation due to the type of new reservoirs being located. New reserves are ever deeper, hotter and less permeable. Production intervals cored permeable. Production intervals cored during drilling to obtain representative samples are evaluated in laboratories throughout the industry. These samples of the producing formation are used to replace No. 50 Whatman filter paper commonly used in the early 50's for test purposes to determine fluid parameters for optimum treatments.

Laboratory studies of representative core plugs from candidate formations to be stimulated by hydraulic fracturing are continually being evaluated and the test techniques refined and upgraded.

The concept of regained gas permeability is designed to evaluate the effect permeability is designed to evaluate the effect of hydraulic fracturing fluids contemplated for use in treating any given producing gas formation. Samples of core are used to simulate an incremental area of formation to be treated by establishing a production direction and treatment or injection direction of flow.

Direct comparison of several different incremental areas of formations and fracturing fluids will yield a set of relative data from which one can select the better treating fluid in terms of the least amount of time required to return production to any predetermined level of initial undamaged flow. predetermined level of initial undamaged flow. PROCEDURE PROCEDURE Cores obtained in the process of drilling wells throughout the world are obtained for test purposes.

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