Overpressure fluid flow and rapid accumulation of natural gas in Yinggehai Basin
HAO Fang DONG Wei-Hang ZOU Hua-yao YANG Xu-sheng (School of Resource and Information Technology, University of Petroleum , Beijing 102249, China ; Petroleum Research Center, China National Offshore Oil Corporation , Beijing 100027, China )
A new style of overpressure fluid flow,namely late-stage overpressure fluid flow, was found and verified in Yinggehai Basin on the basis of comprehensive study of the formation pressure structure, distribution and development mechanism of diapers, and the effects of overpressure fluid flow. Different from the overpressure fluid flow model of Cartwright, the overpressure fluid flow in Yinggehai Basin was in a closed system in the early stage and expulsed in a focused manner through diapers in the late stage. The focused flow of overpressure fluids resulted in the late-stage, episodic and rapid accumulation of natural gases. The trap of DFl-1 gas field was formed in the Quaternary, and the minimum average injection rate of the DFl-1 gas field was estimated to be up to 140 cubic meters per day. The inter-reservoir compositional heterogeneities,the transient state thermal effects resulted from fluid activities and the strong migration fractionation reflected the non-continuous fluid flows,rapid changes in temperature-pressure conditions during fluid migration and inter-action of multi-stage injected fluids, which could become the effective parameters for identifying episodic fluid migration.