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Title: Reservoir compaction of the Belridge Diatomite and surface subsidence, south Belridge field, Kern County, California

Abstract

Surface subsidence due to reservoir compaction during production has been observed in many large oil fields. Subsidence is most obvious in coastal and offshore fields where inundation by the sea occurs. Well-known examples are Wilmington field in California and Ekofisk field in the North Sea. In South Belridge field, the Belridge Diatomite member of the late Miocene Reef Ridge Shale has proven prone to compaction during production. The reservoir, a high-porosity, low-permeability, highly compressive rock composed largely of diatomite and mudstone, is about 1,000 ft thick and lies at an average depth of 1,600 ft. Within the Belridge Diatomite, reservoir compaction due to withdrawal of oil and water in Sec. 12, T28S, R20E, MDB and M, was noticed after casing failures in producing wells began occurring and tension cracks, enlarged by hydrocompaction after a heavy rainstorm were observed. Surface subsidence in Sec. 12 has been monitored since April 1987, through the surveying of benchmark monuments. The average annualized subsidence rate during 1987 was {minus}1.86 ft/yr, {minus}0.92 ft/yr during 1988, and {minus}0.65 ft/yr during 1989; the estimated peak subsidence rate reached {minus}7.50 ft/yr in July 1985, after 1.5 yrs of production from the Belridge Diatomite reservoir. Since production from the Belridgemore » Diatomite reservoir commenced in February 1984, the surface of the 160-ac producing area has subsided about 12.5 ft. This equates to an estimated reservoir compaction of 30 ft in the Belridge Diatomite and an average loss of reservoir porosity of 2.4% from 55.2 to 52.8%. Injection of water for reservoir pressure maintenance in the Belridge diatomite began in June 1987, and has been effective in mitigating subsidence to current rates and repressurizing the reservoir to near-initial pressure. An added benefit of water injection has been improved recovery of oil from the Belridge Diatomite by waterflood.« less

Authors:
;  [1]
  1. Mission Resources, Inc., Bakersfield, CA (USA)
Publication Date:
OSTI Identifier:
7032942
Report Number(s):
CONF-900605-
Journal ID: ISSN 0149-1423; CODEN: AABUD
Resource Type:
Conference
Journal Name:
AAPG Bulletin (American Association of Petroleum Geologists); (USA)
Additional Journal Information:
Journal Volume: 74:5; Conference: Annual convention and exposition of the American Association of Petroleum Geologists, San Francisco, CA (USA), 3-6 Jun 1990; Journal ID: ISSN 0149-1423
Country of Publication:
United States
Language:
English
Subject:
02 PETROLEUM; 58 GEOSCIENCES; CALIFORNIA; PETROLEUM DEPOSITS; RESERVOIR ROCK; FORMATION DAMAGE; ENHANCED RECOVERY; GEOLOGIC FORMATIONS; NORTH SEA; PETROLEUM; SHALES; TERTIARY PERIOD; WATERFLOODING; ATLANTIC OCEAN; CENOZOIC ERA; ENERGY SOURCES; FEDERAL REGION IX; FLUID INJECTION; FOSSIL FUELS; FUELS; GEOLOGIC AGES; GEOLOGIC DEPOSITS; MINERAL RESOURCES; NORTH AMERICA; RECOVERY; RESOURCES; ROCKS; SEAS; SEDIMENTARY ROCKS; SURFACE WATERS; USA; 020300* - Petroleum- Drilling & Production; 580000 - Geosciences

Citation Formats

Bowersox, J R, and Shore, R A. Reservoir compaction of the Belridge Diatomite and surface subsidence, south Belridge field, Kern County, California. United States: N. p., 1990. Web.
Bowersox, J R, & Shore, R A. Reservoir compaction of the Belridge Diatomite and surface subsidence, south Belridge field, Kern County, California. United States.
Bowersox, J R, and Shore, R A. 1990. "Reservoir compaction of the Belridge Diatomite and surface subsidence, south Belridge field, Kern County, California". United States.
@article{osti_7032942,
title = {Reservoir compaction of the Belridge Diatomite and surface subsidence, south Belridge field, Kern County, California},
author = {Bowersox, J R and Shore, R A},
abstractNote = {Surface subsidence due to reservoir compaction during production has been observed in many large oil fields. Subsidence is most obvious in coastal and offshore fields where inundation by the sea occurs. Well-known examples are Wilmington field in California and Ekofisk field in the North Sea. In South Belridge field, the Belridge Diatomite member of the late Miocene Reef Ridge Shale has proven prone to compaction during production. The reservoir, a high-porosity, low-permeability, highly compressive rock composed largely of diatomite and mudstone, is about 1,000 ft thick and lies at an average depth of 1,600 ft. Within the Belridge Diatomite, reservoir compaction due to withdrawal of oil and water in Sec. 12, T28S, R20E, MDB and M, was noticed after casing failures in producing wells began occurring and tension cracks, enlarged by hydrocompaction after a heavy rainstorm were observed. Surface subsidence in Sec. 12 has been monitored since April 1987, through the surveying of benchmark monuments. The average annualized subsidence rate during 1987 was {minus}1.86 ft/yr, {minus}0.92 ft/yr during 1988, and {minus}0.65 ft/yr during 1989; the estimated peak subsidence rate reached {minus}7.50 ft/yr in July 1985, after 1.5 yrs of production from the Belridge Diatomite reservoir. Since production from the Belridge Diatomite reservoir commenced in February 1984, the surface of the 160-ac producing area has subsided about 12.5 ft. This equates to an estimated reservoir compaction of 30 ft in the Belridge Diatomite and an average loss of reservoir porosity of 2.4% from 55.2 to 52.8%. Injection of water for reservoir pressure maintenance in the Belridge diatomite began in June 1987, and has been effective in mitigating subsidence to current rates and repressurizing the reservoir to near-initial pressure. An added benefit of water injection has been improved recovery of oil from the Belridge Diatomite by waterflood.},
doi = {},
url = {https://www.osti.gov/biblio/7032942}, journal = {AAPG Bulletin (American Association of Petroleum Geologists); (USA)},
issn = {0149-1423},
number = ,
volume = 74:5,
place = {United States},
year = {Tue May 01 00:00:00 EDT 1990},
month = {Tue May 01 00:00:00 EDT 1990}
}

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