Fracture detection using crosswell and single well surveys

Journal Article · Sat Mar 01 04:00:00 EST 1997 · Geophysics

DOI:https://doi.org/10.1190/1.1444160· OSTI ID:483824

Majer, E L; Peterson, J E; Daley, T; Kaelin, B; Myer, L ^[1]; Queen, J; D`Onfro, P; Rizer, W ^[2]

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1. Lawrence Berkeley National Lab., CA (United States)
2. Conoco Inc., Ponca City, OK (United States)

The authors recorded high-resolution (1 to 10 kHz), crosswell and single well seismic data in a shallow (15 to 35 m), water-saturated, fractured limestone sequence at Conoco`s borehole test facility near Newkirk, Oklahoma. The objective was to develop seismic methodologies for imaging gas-filled fractures in naturally fractured gas reservoirs. The crosswell (1/4 m receiver spacing, 50 to 100 m well separation) surveys used a piezoelectric source and hydrophones before, during, and after an air injection that the authors designed to displace water from a fracture zone. The intent was to increase the visibility of the fracture zone to seismic imaging and to confirm previous hydrologic data that indicated a preferred pathway. For the single well seismic imaging (a piezoelectric source and an eight-element hydrophone array at 1/4 m spacing), the authors also recorded data before and after the air injection. The crosswell results indicate that the air did follow a preferred pathway that was predicted by hydrologic modeling. In addition, the single well seismic imaging using vertical common depth-point (CDP) gathers indicated an anomaly consistent with the anomaly location of crosswell and hydrologic inversion results. Following the field tests, a slant well was drilled and cored to confirm the existence and nature of the rock associated with the seismic anomalies. A vertical fracture was intersected within less than 1 m of where the seismic results had predicted.

• Sponsoring Organization: USDOE Assistant Secretary for Fossil Energy, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 483824
• Journal Information: Geophysics, Journal Name: Geophysics Journal Issue: 2 Vol. 62; ISSN GPYSA7; ISSN 0016-8033
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
DATA ANALYSIS
EXPLORATORY WELLS
FRACTURED RESERVOIRS
GEOLOGIC FRACTURES
LIMESTONE
NATURAL GAS DEPOSITS
OKLAHOMA
SEISMIC SURVEYS
TEST FACILITIES
WELL DRILLING