【摘要】 埕海潜山位于歧口凹陷南缘,是覆盖巨厚中生界、上古生界的内幕型潜山构造,近期勘探在远离基岩风化壳的奥陶系发现高产天然气.为明确奥陶系碳酸盐岩潜山形成演化、内幕缝洞储层发育及天然气成藏的关系,在新的三维地震资料解释基础上,解剖内幕潜山地质结构.结果表明:埕海潜山经历3期构造变形,即印支期逆冲褶皱、盐山期走滑断陷及喜山期反转构造.中生代早期逆冲推覆、新生代构造负反转对潜山内幕圈闭形成和缝洞储层展布最为重要.埕海潜山天然气源自上古生界煤系,新近纪构造深埋促进煤系源岩二次生烃,并沿负反转断裂系充注于奥陶系内幕成藏.由于高角度裂缝切割奥陶系含石膏地层,促进大规模TSR反应,导致天然气藏富集硫化氢.更多还原

【Abstract】 Chenghai buried-hill located in the southern margin of Qikou sag is an interior buried-hill structure overlain by thick Mesozoic and upper Palaeozoic.Recently,high production gas has been found in Ordovician reservoir far away from weathering crust in Chenghai buried-hill.In order to clarify the controlling factors for buried-hill evolution and interior fracture reservoir formation and their influence in natural gas accumulation,the detailed structure style inner Ordovician reservoir and evolution history were investigated based on new 3Dseismic data in this paper.The author proposed that Chenghai buried-hill experienced three stages of tectonic deformation,that is:thrust fold stage in Indosinian,strikeslip fault stage during Yanshanian and negative inversion stage during Himalayan.The thrust deformation in early Mesozoic and negative inversion tectonic evolution were most important events to formation of interior buried-hill traps and the distribution of fracture cave reservoirs.Natural gas in Chenghai buried-hill was generated from the upper palaeozoic coal measure source rocks which enter the threshold of secondary hydrocarbon generation stage by deep burial process during Neogene era,and migrated along the fracture system of negative inversion structures into Ordovician reservoir.Due to high angle fractures cutting the Ordovician gypsum formation,hydrocarbon and sulfate minerals contacted and largescale TSR reaction was promoted,leading to the enrichment of sulfide and carbon dioxide in natural gas in Chenghai buried-hill.更多还原