Multi-Level Detachment Structural Deformation Systems and Its Controls Upon Hydrocarbon Accumulation in East Sichuan Basin

Abstract

East Sichuan Basin is one of the large gas province in the extensive intra-continental deformation setting, and boasts for its series of discoveries both the conventional gas and shale-gas in the recent years. To disclose the characteristics of large hydrocarbon accumulation in a relatively stable area under complex tectonic zone is not only an important reference to petroleum exploration in China, and but also a key basis for addressing the deformation mechanism of South China continent. Guided by the new advances of continental dynamics and rheology, and based upon the large quantities of exploratory wells, geophysical data and geological surveys, systematic rock mechanic tests and seismic interpretation, the paper utilizes the methods of analogue modeling and mathematical modeling, firstly to explore the distribution of detachment zone and its deformation mechanism, and chiefly to study the formation and evolution of the multi-level detachment structural deformation system (MDS), and successively to analyze its controls upon the geological conditions for the oil and gas, and to explore the rules for the multi-layer and poly-type hydrocarbon accumulations. To establish a series of structural cross sections covering the whole East Sichuan Basin, the paper constructs the geometrical and kinematic models, and discusses the mechanics of the deformation. It also reconstructs the temperature field, the fluid pressure field, and the stress field during the geological history, analyzes the fluid migration, especially of the migration crossing the detachment-zone boundaries, locates the oil and gas preserving units, and explore the accumulation mechanisms in the different stratigraphic layers in the MDSs.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015