Earthquakes induced by hydrocarbon production
- Stanford Univ., CA (USA)
Seismicity has been associated with oil and gas production in a number of areas. Earthquakes related to fluid injection for secondary oil recovery were documented over 20 yr ago. These earthquakes are understood to be caused by decreasing effective normal stress resulting from increased pore-fluid pressures. The reduced frictional resistance allows faults to slip in response to preexisting tectonic shear stress. Seismic activity bas also been associated with hydrocarbon fields in which no fluid injection has taken place and in which measured pore-fluid pressures have declined. It is now understood that, in some circumstances, pore-fluid production itself can induce earthquakes. Production decreases pore pressures in the reservoir, and this causes the reservoir rocks to contract slightly. This volumetric contraction leads to marked subsidence in some fields. Strata above and below the reservoir do not experience the same pore-pressure decline and thus do not contract. The difference in volumetric strain between the reservoir rocks and the surrounding rocks leads to a strain mismatch that generates elastic stresses. These stresses may cause earthquakes, depending on the preexisting tectonic stress state and the mechanical properties of the rocks. The theory used to calculate stress changes resulting from hydrocarbon production can be readily tested. The mathematical models used to compute stress change predict horizontal as well as vertical deformation at the earth's surface. These deformations can be measured using a variety of geodetic techniques. The degree to which the theoretical predictions match observed surface strains and replacement, serves as a check on the theory. These results have significant implications for petroleum production. The importance of the state of stress on fracture permeability is widely recognized. Production alters the state of stress in the reservoir and its surroundings.
- OSTI ID:
- 6633770
- Report Number(s):
- CONF-900605--
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (USA), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (USA) Vol. 74:5; ISSN AABUD; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020300* -- Petroleum-- Drilling & Production
58 GEOSCIENCES
580000 -- Geosciences
EARTHQUAKES
ENVIRONMENTAL EFFECTS
FLUID INJECTION
GEOLOGIC DEPOSITS
INDUSTRY
MINERAL RESOURCES
NATURAL GAS DEPOSITS
ORIGIN
PETROLEUM DEPOSITS
PETROLEUM INDUSTRY
RESERVOIR ROCK
RESOURCES
SEISMIC EVENTS
SEISMICITY
TECTONICS