Discussion on characteristics and accumulation mechanisms of "proximal-generation and proximal-storage" type tight sandstone gas accumulations in Shuixigou Group, Turpan-Hami Basin

Key words:  tight sandstone  source rocks of coal series  crevasse splay  proximal-generation and proximal-storage  accumulation mechanism

Abstract:

Based on field outcrops and fine core observations, as well as contrasting regional sedimentary profiles, a sedimentary model was summarized in the Shuixigou Group, Turpan-Hami Basin by combining a series of analyses of a variety of geochemical indexes, the statistics and contrast of the relationship between the gas layer and the coal strata, and the survey of reservoir physical properties. With examples of gas accumulation profiles, the tight sandstone gas accumulations in the Shuixigou Group were studied. The results show that there are genetic relationships between the Jurassic gas and the coal series source rock in the Shuixigou Group. The favorable accumulation factors of the Jurassic tight sandstone strata in Turpan-Hami Basin mainly include the direct contact of the sandstones with the coal layers in large areas, as well as so-called “chimney-like” channels as crevasse splay bodies and structural fractures serving as an effective connecting medium between sources and reservoirs. Tight sandstone gas accumulations of Shuixigou Group in Turpan-Hami Basin is a "proximal-generation and proximal-storage" type in nature whose generation, migration and accumulation are all confined to the Shuixigou Group itself.