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Title: Diagenesis of sandstone reservoirs of Pattani basin, Gulf of Thailand

Abstract

Miocene sandstones from gas fields in the Gulf of Thailand's Pattani basin provide an example of rapid decline in porosity and permeability with increasing burial depth. This decline results from rapid burial diagenesis that is related to very high geothermal gradients in the basin. Porosity loss with depth in these subquartzose sandstones results from mechanical compaction and from progressive cementation by quartz overgrowths, kaolinite, and illite. Quartz overgrowths increase with depth, indicating continuous or episodic silica cementation. Kaolinite occurs as a pore-filling cement and is abundant between the depths of 1980 and 3050 m (6500 and 10,000 ft). Minor cements include calcite, ankerite, mixed-layer illite-smectite, siderite, pyrite, chlorite, and barite. The best porosity and permeability in Pattani basin reservoirs are generally associated with large intergranular pores in sandstones between 915 and 1980 m (3000 and 6500 ft). At greater depths most interparticle pores have been occluded, and porosity is mainly secondary in origin. Skeletonized feldspars indicate progressive dissolution with increasing burial depth. In low-permeability sandstones from deeper zones (2285-3050 m or 7500-10,000 ft), porosity is mainly restricted to dissolution voids within detrital feldspars. These secondary pores are usually partly filled by authigenic kaolinite and illite, and their pore apertures aremore » generally smaller (1-15 ..mu..m) than intergranular pore aperatures (10-75 ..mu..m). However, favorable reservoir properties may occur locally at depth where large feldspars have been leached from coarse-grained sandstones. 14 figures, 1 table.« less

Authors:
;
Publication Date:
Research Org.:
Unocal Corp., Brea, California
OSTI Identifier:
6884152
Resource Type:
Journal Article
Journal Name:
Am. Assoc. Pet. Geol., Bull.; (United States)
Additional Journal Information:
Journal Volume: 70:3
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; NATURAL GAS DEPOSITS; RESERVOIR ROCK; DIAGENESIS; PERMEABILITY; POROSITY; THAILAND; CLAYS; QUARTZ; SANDSTONES; ASIA; CHALCOGENIDES; DEVELOPING COUNTRIES; GEOLOGIC DEPOSITS; MINERAL RESOURCES; MINERALS; OXIDE MINERALS; OXIDES; OXYGEN COMPOUNDS; RESOURCES; ROCKS; SEDIMENTARY ROCKS; SILICON COMPOUNDS; SILICON OXIDES; 030200* - Natural Gas- Reserves, Geology, & Exploration

Citation Formats

Trevena, A S, and Clark, R A. Diagenesis of sandstone reservoirs of Pattani basin, Gulf of Thailand. United States: N. p., 1986. Web.
Trevena, A S, & Clark, R A. Diagenesis of sandstone reservoirs of Pattani basin, Gulf of Thailand. United States.
Trevena, A S, and Clark, R A. 1986. "Diagenesis of sandstone reservoirs of Pattani basin, Gulf of Thailand". United States.
@article{osti_6884152,
title = {Diagenesis of sandstone reservoirs of Pattani basin, Gulf of Thailand},
author = {Trevena, A S and Clark, R A},
abstractNote = {Miocene sandstones from gas fields in the Gulf of Thailand's Pattani basin provide an example of rapid decline in porosity and permeability with increasing burial depth. This decline results from rapid burial diagenesis that is related to very high geothermal gradients in the basin. Porosity loss with depth in these subquartzose sandstones results from mechanical compaction and from progressive cementation by quartz overgrowths, kaolinite, and illite. Quartz overgrowths increase with depth, indicating continuous or episodic silica cementation. Kaolinite occurs as a pore-filling cement and is abundant between the depths of 1980 and 3050 m (6500 and 10,000 ft). Minor cements include calcite, ankerite, mixed-layer illite-smectite, siderite, pyrite, chlorite, and barite. The best porosity and permeability in Pattani basin reservoirs are generally associated with large intergranular pores in sandstones between 915 and 1980 m (3000 and 6500 ft). At greater depths most interparticle pores have been occluded, and porosity is mainly secondary in origin. Skeletonized feldspars indicate progressive dissolution with increasing burial depth. In low-permeability sandstones from deeper zones (2285-3050 m or 7500-10,000 ft), porosity is mainly restricted to dissolution voids within detrital feldspars. These secondary pores are usually partly filled by authigenic kaolinite and illite, and their pore apertures are generally smaller (1-15 ..mu..m) than intergranular pore aperatures (10-75 ..mu..m). However, favorable reservoir properties may occur locally at depth where large feldspars have been leached from coarse-grained sandstones. 14 figures, 1 table.},
doi = {},
url = {https://www.osti.gov/biblio/6884152}, journal = {Am. Assoc. Pet. Geol., Bull.; (United States)},
number = ,
volume = 70:3,
place = {United States},
year = {Sat Mar 01 00:00:00 EST 1986},
month = {Sat Mar 01 00:00:00 EST 1986}
}