鄂尔多斯盆地甘泉-志丹地区上古生界致密砂岩气藏特征及类型

摘要

Based on an extensive investigation and a comprehensive study of gas reservoir characteristics,reservoir-seal assemblage,temperature and pressure characteristics and gas-water distribution by thin section,physical prop-erty ,mercury injection,well logging data and gas production test data,the reservoir types in Ganquan-Zhidan area was determined.The results showed that reservoir was mainly composed of medium and fine grain quartz sandstone, lithic quartz sandstone and lithic sandstone,and porosity was between 2.0%~10.0% and permeability was be-tween 0.01 ~0.60 mD,so it belonged to low porosity and low permeability reservoir.The natural gas was accumula-ted in unconventional lithologic trap which was the lithologic trap group formed by contraposed of multiple adjacent small and medium-sized lithologic trap.The gas reservoir were in quasi -continuous pervasive distribution,and mainly controlled by source rock and reservoir conditions.Although there were several wells produce water,but gas and water contact was complex and no regional updip water present.Comprehensive analysis showed that the study area is a typical quasi-continuous gas reservoir.%为了搞清甘泉—志丹区块上古生界气藏特征及类型，实验根据铸体薄片、物性、压汞、重矿物等测试分析资料和测井资料，结合现场试气资料，对上古生界储层及储盖组合特征、气藏温压特征和气水分布特征进行了分析，并对该区气藏类型进行探讨。研究表明，研究区储层主要为中粒、细粒石英砂岩、岩屑石英砂岩和岩屑砂岩。储层孔隙度主体介于2.0％～10.0％，渗透率在0.01～0.60×10－3μm2之间，属特低孔、特低渗致密储集层。气藏圈闭类型主要为非常规岩性圈闭，是海相－海陆过渡相和河流－三角洲相沉积形成的多个相互邻近的中小型岩性圈闭叠置所构成的岩性圈闭群。上古生界气藏呈大面积准连续分布，天然气的分布主要受烃源岩和储层控制，气藏内虽多口井产水，但纯水井很少，主要表现为气水同储同出，未发现边底水，更无气水倒置。综合分析表明研究区为典型的准连续型气藏。