致密砂岩含气区成藏条件与模式研究

Analysis on Characteristics of Tight Sandstone Gas Regions in China

在大量资料调研的基础上,总结出致密砂岩气藏(田)具有低孔隙度、低渗透率、高含水饱和度、复杂气水关系、地层压力异常、砂体多呈透镜状等一般特征;对鄂尔多斯盆地上古生界致密砂岩含气区、川西坳陷超致密砂岩含气区及准噶尔盆地南缘高丰度致密砂岩含气区的成藏条件、成藏机理及成藏模式进行了系统对比分析。认为我国不同致密砂岩含气区的地质条件、成藏机理均有较大不同:鄂尔多斯盆地致密砂岩含气区构造平缓,储层的致密化程度中等,气藏具有明显的气水倒置关系;川西坳陷致密砂岩含气区的突出特点是储层超致密化,由于受喜马拉雅运动及超压的影响,形成大量的断裂和裂缝,气体沿裂缝运移至圈闭聚集成藏;准噶尔盆地南缘高丰度致密砂岩含气区超压产生的裂缝是气体运移的主要通道,气藏的分布主要受背斜构造带及优质盖层分布的控制。

Based on investigating a large amount of iMormation, and then we sum - med up the general characteris- tics of tight sandstone gas reservoir （field） , which is low porosity, low permeability, high water saturation, complex relationship of gas and water, abnormal form - ation pressure, and lenticular shapes sand body, et al. This paper sys- tematically compared and analyzed accumulation conditions, accumulation mechanism and reservoir pattern of the tight sandstone gas reservoirs of Upper Paleosoic in Ordos basin, the regions of super tight sandstone gas in west Si- ehuan and the high abundance tight sandstone gas reservoirs in the southern edge of Junggar Basin. The tight sand- stone gas reservoirs of our country mainly distributed across the foreland basins, the rift basins and the relatively sta- ble platforms. The structure of the tight sandstone gas regions in Ordos basin is gentle, the tight degree of reservoir is medium, and the gas reservoirs are the clearly inverted gas - water position. The salient characteristic of the super tight sandstone gas reservoirs in west Sichuan is the over tight degree of reservoirs. And on the influence of Himalay- an orogeny and overpressure, the reservoirs formed a large of fracture and fault;the gas migrated along the fault to trap and formed gas reservoirs. The main channels of gas migration are overpressure cracks in the southern edge of Junggar Basin. The distribution of gas reservoirs are mainly controlled by anticline structural belt and the distribution of good cap rocks.