Did Devonian Shale Wells Drilled During the 1980's and Early 1990's in West Virginia Measure Up to Expectations?: ABSTRACT

Abstract

In the mid-1980`s, a model of future Devonian shale drilling and production was prepared for the Gas Research Institute (GRI). In late 1995, the West Virginia Geological and Economic Survey (WVGES) was contracted by GRI to evaluate actual drilling and production in the 1980`s and early 1990`s and compare these data to the predictions made in the existing model. Drilling activity data were compiled for the years 1979-1993 for all wells drilled, and for all Devonian shale wells drilled. Monthly and annual production data were summarized for both categories. The Devonian shale wells were subdivided into two subsets: (1) the western black shales trend and (2) the eastern black and gray shales and siltstones trend, according to the play definitions used in the {open_quotes}Atlas of Major Appalachian Gas Reservoirs{close_quotes}. Devonian shale wells were subdivided into vintages by completion year. Finally, each Devonian shale well was assigned to a 30 minute geographic grid or {open_quotes}cell{close_quotes} and production data were compiled and compared between cells. Analysis of the data led to the following conclusions: fewer shale wells were being drilled in the early 1990s, but these wells had better recoveries than the wells drilled in the 1980s. Some grid cells showed highermore » recoveries for the black and gray shales and siltstones play than in cells with black shale reservoirs alone. These higher recoveries perhaps can be attributed to the common practice of completing and producing shallower zones (i.e. Mississippian sandstones) in addition to the Devonian shales.« less