skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Fracture detection, mapping, and analysis of naturally fractured gas reservoirs using seismic technology. Final report, November 1995

Abstract

Many basins in the Rocky Mountains contain naturally fractured gas reservoirs. Production from these reservoirs is controlled primarily by the shape, orientation and concentration of the natural fractures. The detection of gas filled fractures prior to drilling can, therefore, greatly benefit the field development of the reservoirs. The objective of this project was to test and verify specific seismic methods to detect and characterize fractures in a naturally fractured reservoir. The Upper Green River tight gas reservoir in the Uinta Basin, Northeast Utah was chosen for the project as a suitable reservoir to test the seismic technologies. Knowledge of the structural and stratigraphic geologic setting, the fracture azimuths, and estimates of the local in-situ stress field, were used to guide the acquisition and processing of approximately ten miles of nine-component seismic reflection data and a nine-component Vertical Seismic Profile (VSP). Three sources (compressional P-wave, inline shear S-wave, and cross-line, shear S-wave) were each recorded by 3-component (3C) geophones, to yield a nine-component data set. Evidence of fractures from cores, borehole image logs, outcrop studies, and production data, were integrated with the geophysical data to develop an understanding of how the seismic data relate to the fracture network, individual well production,more » and ultimately the preferred flow direction in the reservoir. The multi-disciplinary approach employed in this project is viewed as essential to the overall reservoir characterization, due to the interdependency of the above factors.« less

Publication Date:
Research Org.:
Coleman Research Corp., Golden, CO (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
390643
Report Number(s):
DOE/MC/28135-5258
ON: DE96011352; TRN: 96:005958
DOE Contract Number:
AC21-92MC28135
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Oct 1995
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; FRACTURED RESERVOIRS; SEISMIC SURVEYS; NATURAL GAS DEPOSITS; MAPPING; DRILLING; ROCKY MOUNTAINS; UINTA BASIN; SHEAR; GREEN RIVER FORMATION; SEISMIC WAVES; SEISMIC S WAVES; STRATIGRAPHY; GEOLOGY; SEISMIC P WAVES

Citation Formats

NONE. Fracture detection, mapping, and analysis of naturally fractured gas reservoirs using seismic technology. Final report, November 1995. United States: N. p., 1995. Web. doi:10.2172/390643.
NONE. Fracture detection, mapping, and analysis of naturally fractured gas reservoirs using seismic technology. Final report, November 1995. United States. doi:10.2172/390643.
NONE. 1995. "Fracture detection, mapping, and analysis of naturally fractured gas reservoirs using seismic technology. Final report, November 1995". United States. doi:10.2172/390643. https://www.osti.gov/servlets/purl/390643.
@article{osti_390643,
title = {Fracture detection, mapping, and analysis of naturally fractured gas reservoirs using seismic technology. Final report, November 1995},
author = {NONE},
abstractNote = {Many basins in the Rocky Mountains contain naturally fractured gas reservoirs. Production from these reservoirs is controlled primarily by the shape, orientation and concentration of the natural fractures. The detection of gas filled fractures prior to drilling can, therefore, greatly benefit the field development of the reservoirs. The objective of this project was to test and verify specific seismic methods to detect and characterize fractures in a naturally fractured reservoir. The Upper Green River tight gas reservoir in the Uinta Basin, Northeast Utah was chosen for the project as a suitable reservoir to test the seismic technologies. Knowledge of the structural and stratigraphic geologic setting, the fracture azimuths, and estimates of the local in-situ stress field, were used to guide the acquisition and processing of approximately ten miles of nine-component seismic reflection data and a nine-component Vertical Seismic Profile (VSP). Three sources (compressional P-wave, inline shear S-wave, and cross-line, shear S-wave) were each recorded by 3-component (3C) geophones, to yield a nine-component data set. Evidence of fractures from cores, borehole image logs, outcrop studies, and production data, were integrated with the geophysical data to develop an understanding of how the seismic data relate to the fracture network, individual well production, and ultimately the preferred flow direction in the reservoir. The multi-disciplinary approach employed in this project is viewed as essential to the overall reservoir characterization, due to the interdependency of the above factors.},
doi = {10.2172/390643},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1995,
month =
}

Technical Report:

Save / Share:
  • There are a number of producing gas fields in the United States where production is controlled by natural fractures. The host rock may consist of low porosity, low permeability formations, and wells completed in the unfractured rock have low productivity. On the other hand, wells intercepting fractured rocks may show good production. The objective of the research under this contract is to improve the technology for detecting fractures by surface geophysical methods. This remote detection of fractures will allow optimum placement of vertical or horizontal wells. The critical components of the project are: (1) Selection of a gas field withmore » known production from naturally occurring fractures. The project scope does not allow for drilling of wells, so that evidence for occurrence of fractures and gas production from fractures must be obtained from existing wells` field production history, and other data. (2) Acquisition of both surface and downhole seismic P-wave and S-wave data. The project will acquire one 9-component (9-C) VSP. In a 9-C VSP survey, seismic events are recorded by 3-C geophones from one P-wave, and two perpendicular oriented S-wave sources (SH and SV). Also, approximately 12 miles of 9-C surface seismic data will be acquired. (3) Processing and interpretation of 9-C VSP and 9-C surface seismic data, and correlating the seismic anomalies observed to all available geologic and production information to show how the variations in seismic response is related to fracture density, fracture orientation, lithology, structure, and production history.« less
  • The approach in this project has been to integrate the principles of rock physics into a quantitative processing and interpretation scheme that exploits, where possible, the broader spectrum of fracture zone signatures: (1) anomalous compressional and shear wave velocity; (2) Q and velocity dispersion; (3) increased velocity anisotropy; (4) amplitude vs. offset (AVO) response, and (5) variations in frequency content. As part of this the authors have attempted to refine some of the theoretical rock physics tools that should be applied in any field study to link the observed seismic signatures to the physical/geologic description of the fractured rock. Themore » project had 3 key elements: (1) rock physics studies of the anisotropic viscoelastic signatures of fractured rocks, (2) acquisition and processing of seismic reflection field data, and (3) interpretation of seismic and well log data. The study site is in a producing field operated by Amoco and Arco at the southern boundary of the Powder River basin in Wyoming. During the winter of 1992--1993 the authors collected about 50 km of 9-component reflection seismic data and obtained existing log data from several wells in the vicinity. The paper gives background information on laboratory studies, seismic field studies of fracture anisotropy, and the problem of upscaling from the laboratory to the field. It discusses fluid effects on seismic anisotropy and a method for predicting stress-induced seismic anisotropy. Then results from the field experiment are presented and discussed: regional geologic framework and site description; seismic data acquisition; shear wave data and validation; and P-wave data analysis. 106 refs., 52 figs.« less
  • Major accomplishments of this project occurred in three primary categories: (1) fractured reservoir location and characteristics prediction for exploration and production planning; (2) implications of geologic data analysis and synthesis for exploration and development programs; and (3) fractured reservoir production modeling. The results in each category will be discussed in turn. Seven detailed reports have been processed separately.
  • High skins in naturally-fractured formations may require stimulation where a natural completion would otherwise suffice. We measured flow through the fracture before and after perforating and observe a general decrease in fracture conductivity. Performation flow is also uniformly lower than expected even based on measured post-shot fracture flow rates. We have used X-ray CT and visual examination to observe flow restrictions. Shock stresses from the shaped charge jet cause deformation of the rock, sealing the fracture where it intersects the perforation. Jet metal can also invade the fracture if the intersection is near the tip of performation. This shortens themore » usable penetration depth. These effects will be present despite efforts to ensure adequate penetration and fluid loss protection.« less
  • Analysis of conventional 2D and 3D seismic data from Devonian-shale gas fields in West Virginia indicate that seismic data can be used to map stratigraphic variations within a shale sequence. Seismic evidence also reveals the presence of syndepositional and post-depositional structural controls in both fields. The occurrence of local stratigraphic variations and the anomalous intensely fractured areas observed in the seismic data are not confined to the highly productive areas within these fields. However, the active influence of deeper basement structures during and after the deposition of the producing shale intervals appears to be a controlling element in the developmentmore » of both fields. A Kalman/Mendel deconvolution algorithm was developed that yields a better estimate of the reflectivity sequence than the conventional Weiner filter. A reduced-order solution to the estimation problem was also developed to reduce computation time. Comparative analysis of structure and isopotential maps in the Eastern Kentucky field shows that wells with high gas flows follow basement fault zones that are occasionally expressed as surface lineaments. Regional-fracture permeability occurs in organic shales that are decollement zones in the adjacent Appalachian foreland.« less