Crosswell logging for acoustic impedance

Journal Article · Fri Jan 01 00:00:00 EST 1988 · J. Pet. Technol.; (United States)

DOI:https://doi.org/10.2118/15543-PA· OSTI ID:5324803

Iverson, W P

Crosswell seismic data are recorded by placing the seismic source in one well and receivers in a second well to measure physical properties between the two wells. When reflected seismic energy is extracted from the recorded seismograms, the resultant picture is a function of acoustic impedance (density times velocity) between the wells. Previous crosswell seismic studies have predominantly used direct waves and measure only seismic velocities by tomographic techniques. Synthetic crosswell seismic data are generated by a computer to illustrate the concepts and procedures used for crosswell impedance logging in this study. Such synthetics are useful for investigating how the experiment should work, but real data reveal how the experiment does work. Crosswell seismic data recorded at the Multiwell Experiment (MWX) site in western Colorado revealed a few surprises when compared with synthetic data. Real data consist of a lot more than simple direct arrivals and reflections. There are numerous converted waves, borehole (tube) waves, and general noise. Source directivity proves to be a very limiting problem, because energy is concentrated in a horizontal plane perpendicular to the borehole. The final product of crosswell logging for acoustic impedance is a seismogram similar to the classic CDP seismogram recorded on the surface for exploration. The crosswell data in this paper are in the kilohertz range as opposed to surface data, which are generally below 100 cycles/sec (100 Hz). Seismic data in the kilohertz range can theoretically resolve layers as thin as 2 ft (0.6 m) vertically. Actual resolution indicated is about 5 to 10 ft (1.5 to 3 m).

• Research Organization: Univ. of Wyoming (USA)
• OSTI ID: 5324803
• Journal Information: J. Pet. Technol.; (United States), Vol. 40:1
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
EXPLORATORY WELLS
ACOUSTICS
SEISMIC DETECTION
SONIC LOGGING
COLORADO
DATA PROCESSING
EXPLORATION
LAYERS
NATURAL GAS DEPOSITS
NOISE
PETROLEUM DEPOSITS
SEISMIC DETECTORS
SEISMIC SOURCES
SOUND WAVES
DETECTION
FEDERAL REGION VIII
GEOLOGIC DEPOSITS
MEASURING INSTRUMENTS
MINERAL RESOURCES
NORTH AMERICA
PROCESSING
RESOURCES
SEISMIC ARRAYS
USA
WELL LOGGING
WELLS
020200* - Petroleum- Reserves
Geology
& Exploration
030200 - Natural Gas- Reserves
Geology
& Exploration