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Reservoir Characteristics of Lower Silurian Shale in Sichuan Basin, China

Jinliang Huang, Caineng Zou, Jianzhong Li, Dazhong Dong, and Yuman Wang
RIPED, PetroChina, Beijing, China

Based on analysis of single well geology and research results of other drillings, outcrops and predecessors, it analyzed the reservoir characteristic of Longmaxi shale Formation of lower Silurian in Sichuan Basin, including depositional environment and black shale distribution, mineral composition, reservoir pore types, store-permeability conditions, and mechanical properties. It is initially confirmed that Longmaxi shale is similar to the main producing gas shales in United States with four significant reservoir features: Black shale is deep-water shelf facies, thick, stable distribution, widely distributed in Sichuan Basin and surroundings, therein organic-rich shale interval has a high gamma log response and is generally 20~135m thick in the depocenter area; The content of three brittle minerals which are quartz, feldspar and calcareous is higher than 40%. There is no montmorillonite in clay minerals. The formations are rigid and brittle, characterized by relative high elastic modulus and low Poisson’s ratio; There exists four kinds of matrix porosity including residual primary pore, organic pore, interlayer micropore in clay minerals and dissolution pore in unstable minerals, and a large amount of fractures. Organic micropore and interlayer micropore in clay minerals are the main constituents of shale matrix pore; Geophysical, re-examination of previous data and laboratory analysis are utilized to approve initially that Lomgmaxi shale has the character of abnormal high pressure gas reservoir and that physical properties of the shale are better than anticipation. It is considered that Longmaxi shale of Lower Silurian is in good reservoir condition for shale gas exploration and production in Sichuan Basin.

AAPG Search and Discovery Article #90175©2013 AAPG Hedberg Conference, Beijing, China, April 21-24, 2013