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Abstract
Production from over 500 Devonian Shale wells has been analyzed. Permeability-thickness, kh, determined from potential test and production data has been found to correlate with well performance. Empirical performance equations, production type curves, and a dual-porosity model with automatic history-matching scheme were developed for the Devonian Shale.
Introduction
Thousands of wells have been completed in the Devonian Gas Shales of the Appalachian Basin. Although a wealth of historical production data exists for these wells, these data have never been systematically studied on a large scale. The purpose of our work was to gather and analyze as purpose of our work was to gather and analyze as much of these data as possible with the following objectives in mind:Analyze Devonian Shale production data to determine reservoir characteristics;Identify those reservoir characteristics which correlate with superior well quality;Assess the potential of exploring for reservoirs with "superior" characteristics; andDetermine the effects of various completion and stimulation techniques on well performance.
Production data and other pertinent well Production data and other pertinent well information have been gathered for over 1000 Devonian Shale wells in Kentucky, Ohio, and West Virginia. We first conducted a pilot data analysis study on wells located in southwestern West Virginia and eastern Kentucky (Area I in Figure 1) to insure that Devonian Shale production data could be analyzed logically and systematically. Upon successful completion of the pilot study, we selected four areas (Figure 1) for study and added the objective of finding an optimal method for analyzing and predicting Devonian Shale well performance for use by the practicing engineer. performance for use by the practicing engineer. During the course of this work we have done the following:Developed an analytical dual-porosity reservoir model for analyzing and predicting Devonian Shale production;Analyzed flow test and/or production data on over 1000 wells;Correlated permeability-thickness product with observed well performance;Developed a family of type curves for analyzing and predicting Devonian Shale production;Developed empirical equations for predicting Devonian Shale production; andStudied the theoretical effect of various stimulation methods on Devonian Shale production.
We have not yet completed our study of stimulation methods and exploration applications. Nor have we completed our production data analysis in that we cannot vet establish uniquely important reservoir properties such as size and fracture pore volume. We believe, however, it will be possible to determine these properties. When they are determined, we can improve our empirical model for performance predictions so it includes variables performance predictions so it includes variables other than permeability-thickness product.
DATA ACQUISITION
Data have been gathered from four areas in Kentucky, Ohio, and West Virginia (Figure 1). Area 1 is often referred to as the "Big Sandy" area and contains a large number of wells with long producing histories. This area includes most of the best producing histories. This area includes most of the best shale gas wells and produces chiefly dry gas. Area II is in central West Virginia and contains many wells of average quality which produce mainly dry gas.
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