--> ABSTRACT: Exploration Models for Tertiary Lacustrine Carbonates, Liaodong Bay, People's Republic of China, by A. J. Lomando; #91019 (1996)

Datapages, Inc.Print this page

Exploration Models for Tertiary Lacustrine Carbonates, Liaodong Bay, People's Republic of China

A. J. Lomando

Lacustrine carbonates are a significant reservoir target in the basins of eastern China. Difficulty in seismically imaging this play type generates the need for accurate exploration models to define geometries for lead and prospect identification.

Rifted and karsted Cambro-Ordovician carbonates form the base of the section which is overlain by thick Tertiary lacustrine deposits. Two types of lacustrine carbonate plays have been identified. Carbonate alluvial fans developed from the erosion of Cambro-Ordovician dolomites and limestones in places along the banks of tilted fault block ridges. During lake formation and expansion, these fans formed small shelves along the lake margins which became the sites of active carbonate production and winnowing. This play type forms discontinuous trends of lacustrine shoreline skeletal grainstones which mimic the underlying fan geometries.

A second play type was identified in the JZ-20/JZ-9 trend. Stacked, shoaling upward cycles of skeletal grainstones occur on the gentle ramp sides of tilted fault blocks. In contrast, a different style of lake margin accumulation occurs on the bounding fault side of these blocks. Blocks with single major bounding faults have narrow shelves prohibiting accumulation of carbonate, whereas structures with sets of subsidiary faults form perched platforms ideal for the accumulation of thick lacustrine carbonate sections. Both of these play types have good modern analogues from the Great Salt Lake in Utah and the East African Rift System.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California