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Title: Mixing of biogenic siliceous and terrigenous clastic sediments: South Belridge field and Beta field, California

Abstract

The intermixing and interbedding of biogenically derived siliceous sediment with terrigenous clastic sediment in reservoirs of upper Miocene age provides both reservoir rock and seal and influences productivity by affecting porosity and permeability. Miocene reservoirs commonly contain either biogenic-dominated cyclic diatomite, porcelanite, or chert (classic Monterey Formation) or clastic-dominated submarine fan sequences with interbedded or intermixed siliceous members of biogenic origin. Biogenic-clastic cycles, 30-180 ft thick, at South Belridge field were formed by episodic influx of clastic sediment from distant submarine fans mixing with slowly accumulating diatomaceous ooze. The cycles consist of basal silt and pelletized massive diatomaceous mudstone, overlain by burrowed, faintly bedded clayey diatomite and topped by laminated diatomite. Cycle tops have higher porosity and permeability, lower grain density, and higher oil saturation than clay and silt-rich portions of the cycles. Submarine fan sediments forming reservoirs at the Beta field are comprised of interbedded sands and silts deposited in a channelized middle fan to outer fan setting. Individual turbidites display fining-upward sequences, with oil-bearing sands capped by wet micaceous silts. Average sands are moderately to poorly sorted, fine- to medium-grained arkosic arenites. Sands contain pore-filling carbonate and porcelaneous cements. Porcelaneous cement consists of a mixture of opal-A, opal-CT,more » and chert with montmorillonite and minor zeolite. This cement is an authigenic material precipitated in intergranular pore space. The origin of the opal is biogenic, with recrystallization of diatom frustules (opal-A) into opal-CT lepispheres and quartz crystals. Porcelaneous cement comprises 4-21% of the bulk volume of the rock. Seventy percent of the bulk volume of the cement is micropore space.« less

Authors:
 [1]
  1. (Shell Western Exploration and Production, Inc., Bakersfield, CA (USA))
Publication Date:
OSTI Identifier:
6634883
Alternate Identifier(s):
OSTI ID: 6634883
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; OIL FIELDS; RESERVOIR ROCK; GEOLOGIC FORMATIONS; MONTMORILLONITE; PERMEABILITY; POROSITY; SILTSTONES; SOURCE ROCKS; TERTIARY PERIOD; CENOZOIC ERA; CLAYS; FEDERAL REGION IX; GEOLOGIC AGES; GEOLOGIC DEPOSITS; INORGANIC ION EXCHANGERS; ION EXCHANGE MATERIALS; MATERIALS; MINERAL RESOURCES; NORTH AMERICA; PETROLEUM DEPOSITS; RESOURCES; ROCKS; SEDIMENTARY ROCKS; USA 020200* -- Petroleum-- Reserves, Geology, & Exploration; 580000 -- Geosciences

Citation Formats

Schwartz, D.E. Mixing of biogenic siliceous and terrigenous clastic sediments: South Belridge field and Beta field, California. United States: N. p., 1990. Web.
Schwartz, D.E. Mixing of biogenic siliceous and terrigenous clastic sediments: South Belridge field and Beta field, California. United States.
Schwartz, D.E. Tue . "Mixing of biogenic siliceous and terrigenous clastic sediments: South Belridge field and Beta field, California". United States.
@article{osti_6634883,
title = {Mixing of biogenic siliceous and terrigenous clastic sediments: South Belridge field and Beta field, California},
author = {Schwartz, D.E.},
abstractNote = {The intermixing and interbedding of biogenically derived siliceous sediment with terrigenous clastic sediment in reservoirs of upper Miocene age provides both reservoir rock and seal and influences productivity by affecting porosity and permeability. Miocene reservoirs commonly contain either biogenic-dominated cyclic diatomite, porcelanite, or chert (classic Monterey Formation) or clastic-dominated submarine fan sequences with interbedded or intermixed siliceous members of biogenic origin. Biogenic-clastic cycles, 30-180 ft thick, at South Belridge field were formed by episodic influx of clastic sediment from distant submarine fans mixing with slowly accumulating diatomaceous ooze. The cycles consist of basal silt and pelletized massive diatomaceous mudstone, overlain by burrowed, faintly bedded clayey diatomite and topped by laminated diatomite. Cycle tops have higher porosity and permeability, lower grain density, and higher oil saturation than clay and silt-rich portions of the cycles. Submarine fan sediments forming reservoirs at the Beta field are comprised of interbedded sands and silts deposited in a channelized middle fan to outer fan setting. Individual turbidites display fining-upward sequences, with oil-bearing sands capped by wet micaceous silts. Average sands are moderately to poorly sorted, fine- to medium-grained arkosic arenites. Sands contain pore-filling carbonate and porcelaneous cements. Porcelaneous cement consists of a mixture of opal-A, opal-CT, and chert with montmorillonite and minor zeolite. This cement is an authigenic material precipitated in intergranular pore space. The origin of the opal is biogenic, with recrystallization of diatom frustules (opal-A) into opal-CT lepispheres and quartz crystals. Porcelaneous cement comprises 4-21% of the bulk volume of the rock. Seventy percent of the bulk volume of the cement is micropore space.},
doi = {},
journal = {AAPG Bulletin (American Association of Petroleum Geologists); (USA)},
issn = {0149-1423},
number = ,
volume = 74:5,
place = {United States},
year = {1990},
month = {5}
}

Conference:
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