--> Abstract: Organic Facies Analysis of Cretaceous Petroleum Source Rocks, Southern Indus Basin, Pakistan, by M. A. Smith, K. W. Schwab, and K. K. Bissada; #91015 (1992).

Datapages, Inc.Print this page

ABSTRACT: Organic Facies Analysis of Cretaceous Petroleum Source Rocks, Southern Indus Basin, Pakistan

SMITH, MICHAEL A., Texaco EPTD, Houston, TX, KARL W. SCHWAB, Geo-Stat, Inc., Houston, TX, and K. K. BISSADA, Texaco EPTD, Houston, TX

New geochemical data for well samples from the southern Indus basin in Pakistan allow definition of the organic facies and oil-generation potential of Cretaceous source rocks. The terrestrial gas-prone Tertiary section thickens to the north, but marine Cretaceous rocks are either thermally immature or within the oil window in much of the southern part of the basin. Rock-Eval pyrolysis, visual kerogen assessment, and evaluation with other geochemical techniques provided a sapropel index that measures oil-generation potential. Cyclic variations in kerogen type define repeated transgressive sequences, 40 to 165 m thick, that contain both oil and gas source rocks. Oil-prone organic facies contain predominantly fluorescent, Type-I amorphous kerogen deposited in relatively deep water. Kerog n in individual sequences grades upward through a facies of mixed organic-matter types into a shallow-water, oxidized, gas-prone organic facies.

Variation in geochemical parameters that indicate kerogen type and liquid hydrocarbon source quality can be used to delineate these shallowing-upward sequences by means of a geochemical well log. Lithologic changes identified in seismic data can also be used to map major cycles. Regional data suggest that these organic facies may be limited to the trailing edge of the Cretaceous Indian Continent, and that a possible control on the water depth on this margin was the velocity of its northward drift.

 

AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)