Fault structure characteristics and its control action on oil and gas in Kuinan-Longwangmiao region,Liaohe offshore

Kuinan-Longwangmiao region has limited seismic and geologic data,very complex fault development and evolution process,and uncertain fault association and structure formation mechanism.In 2008,fine structure interpretation and comprehensive geological study were conducted based on new seismic data.The NE-trending Yannan and Gaizhoutan faults are defined as the main faults,showing en-echelon distribution.The Yannan fault appears as normal fault in the upper section and reverse fault in the lower section.Longbei fault is composed by intersection with a number of secondary faults formed in a later period,showing splays distribution in general.It is also defined that the Gainan structure is a fault nose;the Longwangmiao structure is an incomplete faulted anticline structure of negative flower-shape;the Kuidong Ⅱ structure appears as fault nose in shallow and medium formation,and as fault block controlled by thrust fault in deep formation.Hydrocarbon accumulation and distribution were controlled by structure type,structural high and faulting movement.It is predicted that Gainan,Longbei-Longwangmiao and Kuidong Ⅱ structures are possible zones of oil and gas accumulation.