全油气系统动力场成藏背景下的火山岩富油气甜点预测:方法、原理及实际应用OA

The source rocks of the Permian Fengcheng Formation in the Junggar Basin possess considerable hydrocarbon exploration potential.However,the hydrocarbon sources and main factors controlling hydrocarbon enrichment in volcanic rock reservoirs along the northwestern margin of the basin have long remained unclear,resulting in a low success rate of sweet-spot drilling and limited reserve expansion,thereby constraining further exploration in the region.This study investigated the dynamic mechanisms of hydrocarbon accumulation and conducted quantitative evaluation of the volcanic rock reservoirs in the JL2 well block on the northwestern margin of the Junggar Basin,with the aim of precisely addressing key exploration challenges and identifying favorable exploration targets and their productivity potential.The investigation was based on the dynamic field-controlled accumulation theory of the whole petroleum system and incorporated 47 sets of geochemical data from the study area and well-test data from multiple high-yield wells.As indicated by the research results,(1)the critical thresholds defining the lower limit of buoyancy-driven hydrocarbon accumulation for local volcanic rocks stand at porosity of 9%and permeability of 1×10⁻³ µm².These two core parameters enable reliable classification of two major hydrocarbon accumulation domains—the free dynamic field and the confined dynamic field.(2)Quantitative characterization of four functional elements for primary accumulation(i.e.,source,facies,potential energy,and cap rock)confirms buoyancy as the dominant migration force within the free dynamic field,and a hydrocarbon-rich accumulation model was constructed based on the spatiotemporal configuration of these functional elements.(3)The dynamic field threshold of the facies-potential-source index(FPSI)served as a benchmark to quantitatively map hydrocarbon-rich sweet spots and precisely delineate potential exploration zones in the study area.(4)A quantitative dynamic-field model delivered calibrated productivity estimates for proposed drilling prospects.One new wildcat well location was prioritized and re-evaluation schemes covering eight prospective intervals across five existing wells were formulated.These findings clarify the hydrocarbon accumulation patterns and enrichment mechanisms of volcanic rock reservoirs in the study area.Its theoretical framework lays a solid foundation for refined exploration,efficient development,and reserve upgrading of volcanic hydrocarbon resources in the study area.