Microseismic activity observed during depressurization of an oil storage cavern in rock salt

Conference · Thu Jan 01 04:00:00 EST 1981

OSTI ID:6175946

Albright, J; Pearson, C

In November 1978, the Los Alamos National Laboratory installed a triaxial downhole geophone package at the Bryan Mound Strategic Petroleum Reserve, a salt dome near Freeport, Texas. Monitoring was for the purpose of detecting microseismic activity during the depressurization of one of the oil storage caverns. Seismic activity started soon after the start of depressurization, reached a peak 5 days later, and rapidly died off. Nineteen locatable microearthquakes with magnitudes between -1 and -2 were observed during and after depressurization. All but two of these events were located near the side of the oil storage cavern. Because the shear-wave spectra of these events were characterized by well-defined corner frequencies we were able to calculate the radius of the rupture surface, the seismic moment, and the stress drop from the source spectra. Estimates of the source radius vary from 15 to 100 m, stress drops range from 0.3 to 0.01 bar, and seismic moments range from 3 x 10/sup 14/ to 3 x 10/sup 15/ dyne/cm. Important conclusions from this study are that comparatively small changes in the internal pressure of oil storage caverns may be enough to cause failure in the salt near the cavern walls and that downhole microseismic surveys can locate zones near large underground excavations that are undergoing rock failure.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6175946
• Report Number(s): LA-UR-81-2622; CONF-811036-1; ON: DE81030237
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
024000* -- Petroleum-- Storage-- (-1989)
CAVITIES
DEPRESSURIZATION
DETECTION
ENERGY SOURCES
FAILURES
FOSSIL FUELS
FUELS
MONITORING
NORTH AMERICA
PETROLEUM
PRESSURE DEPENDENCE
RESERVES
RESOURCES
SALT CAVERNS
SEISMIC DETECTION
SOUTHWEST REGION
STORAGE
STORAGE FACILITIES
STRATEGIC PETROLEUM RESERVE
TEXAS
UNDERGROUND STORAGE
USA