(An assessment of borehole seismic fracture diagnostics)

Conference · Fri Jan 01 00:00:00 EST 1988

OSTI ID:6883934

A five year effort to apply triaxial borehole seismometer technology to mapping hydraulic fractures by detecting microseismic events associated with the fracturing process has been completed. During this time, a number of evolutionary improvements to thee borehole receiver have lead to a unique sensor array geometry consisting of four geophone axes, positioned so that each axis makes the same angle with both the horizontal plane and the plane of the clamp are. The receiver includes downhole amplifiers which provides two gains, 112 dB for weak seismic sources and 100 dB to avoid saturation from strong seismic sources. The amplified seismic signals from the eight data channels are frequency division multiplexed onto frequency modulation subcarriers for transmission to the surface through a single conductor wire line. This combination of multi-geophone reception, downhole amplification and frequency modulation data transmission results in a very sensitive receiver, almost completely free of electric noise. The data from two downhole receivers in offset wells are recorded on tape to provide a continuous record of all signals. An event location scheme, based on primary wave polarization and using directional statistics, computes the location of microseismic events with error estimates. Over 700 microseismic events were digitized during a recent stimulation experiment. Analysis of these data resulted in 160 microseismic event locations, some as far as 450 ft. (137 m) from the receiver. The azimuth determined from event locations agrees reasonably well with the predicted fracture azimuth, the head agrees with temperature log tops, and fracture height is in good agreement with fracture model calculations. Wrong lengths are less than fracture model predictions unless fracture width is larger than expected. 9 refs., 5 figs., 2 tabs.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6883934
• Report Number(s): SAND-88-1869C; CONF-881012-2; ON: DE88012958
• Resource Relation: Conference: 63. Society of Petroleum Engineers (SPE) annual technical conference and exhibition: reservoir engineering, Houston, TX, USA, 2 Oct 1988; Other Information: Portions of this document are illegible in microfiche products
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
HYDRAULIC FRACTURES
MAPPING
HYDRAULIC FRACTURING
SEISMIC NOISE
NATURAL GAS DEPOSITS
ACOUSTIC MONITORING
BOREHOLES
DATA ANALYSIS
NATURAL GAS WELLS
SANDSTONES
SEISMIC DETECTORS
SEISMIC P WAVES
SEISMIC S WAVES
SEISMIC SURVEYS
CAVITIES
COMMINUTION
FAILURES
FRACTURES
FRACTURING
GEOLOGIC DEPOSITS
GEOPHYSICAL SURVEYS
MEASURING INSTRUMENTS
MINERAL RESOURCES
MONITORING
NOISE
RESOURCES
ROCKS
SEDIMENTARY ROCKS
SEISMIC ARRAYS
SEISMIC WAVES
SURVEYS
WELLS
030900* - Natural Gas- Artificial Stimulation
Plowshare- (-1989)