Abstract

Microseismic logging technology was applied to a Devonian Shale well in the Appalachian Basin to evaluate the height and orientation of a hydraulic fracture. The technique was used in the Sterling Drilling and Production Company Jarvis No. 1143, which is the Gas Research Institute's (GRI) Comprehensive Study Well No, 2 (CSW 2). The well, completed in the Devonian Shales, is located in Calhoun County, WV. This was the first application of the fracture mapping procedure in the Appalachian Basin; it was performed as part of GRI's efforts to understand fracture growth and orientation part of GRI's efforts to understand fracture growth and orientation in the Devonian Shales. The procedure was also unique in that it was the first time the seismic data were collected in a gas-filled wellbore and after a well had been produced for an extended period of two years. The microseismic logging analysis results on CSW 2 indicate a 200-ft fracture height with an orientation trending N34 degrees E. Also presented in this paper are the results obtained from a series of hydraulic fracture diagnostic tests performed on the CSW 2 prior to the microseismic logging experiment.

Introduction

Among the objectives of the Gas Research Institute (GRI) is the increase of the available gas supply. Two of GRI's major research programs have been in Tight Gas Sands and in the Devonian Shales programs have been in Tight Gas Sands and in the Devonian Shales of the Appalachian Basin. The Tight Gas Sands research has featured technology for improving hydraulic fracture treatments and evaluation techniques in low permeability sandstones. Research has been conducted in four wells as Stage Field Experiments (SFE) in the Travis Peak and Cotton Valley formations of east Texas and the Frontier formation of Wyoming. GRI has cofunded additional research related to understanding hydraulic fracture growth and geometry in the Canyon Sandstone of south Texas. The Devonian Shales research is directed at identifying geologic and reservoir production controls, refining formation evaluation tools, and production controls, refining formation evaluation tools, and improving stimulation practices. In conjunction with industry partners, the Shales research has participated in Comprehensive partners, the Shales research has participated in Comprehensive Study Wells throughout the Appalachian Basin to characterize the reservoir, to improve stimulation practices, and to better understand production from the Devonian Shales. production from the Devonian Shales. This paper describes a combination of these two programs in that the microseismic logging technique developed in the GRI Tight Gas Sands research was applied to a well in the Devonian Shales research program. Unique to the work reported here is that (1) this was the program. Unique to the work reported here is that (1) this was the first application of microseismic logging technology to obtain fracture height and orientation in the Appalachian Basin; (2) this was the first time that microseismic logging technology was used in a gas-filled wellbore; and (3) this was the first time that microseismic logging technology was used in a well that had been fractured two years before the survey.

The microseismic logging survey was performed as one of several post-stimulation diagnostic tests on CSW 2 in 1990. This paper also post-stimulation diagnostic tests on CSW 2 in 1990. This paper also presents a summary of the qualitative results of the other diagnostic presents a summary of the qualitative results of the other diagnostic tests and provides a comparison to the microseismic logging results. The objectives of the diagnostic tests were to determine the location and geometry of the propped hydraulic fracture and to provide a more detailed reservoir description. Previous field research 1 in the Shales, conducted by GRI, indicates that fracture treatments pumped into large perforated intervals may not stimulate all portions of the treatment interval equally. This paper presents our qualitative observations regarding the hydraulic fracture, while a future SPE paper will address the quantitative study results pertaining to the paper will address the quantitative study results pertaining to the detailed reservoir description. The post-stimulation diagnostics tests performed on CSW 2 included zone isolation/communication tests, performed on CSW 2 included zone isolation/communication tests, individual zone nitrogen injection/falloff tests, individual zone and total well flow/buildup tests, and the microseismic logging survey.

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