鄂尔多斯盆地苏39区块致密气藏气水分布及其主控因素

Gas-water distribution and main controlling factors of tight gas reservoir in block Su 39,Ordos Basin

鄂尔多斯盆地苏里格气田发育典型的致密砂岩油气藏,其中苏39区块位于伊陕斜坡和天环坳陷交界部位的气水过渡带上,气水关系复杂,深入探索苏39区块的气水分布关系,对致密砂岩气藏的有效开发具有重要意义。综合试产、测井、储层以及地质背景等资料,系统研究了苏39区块致密砂岩气藏太原组(P_(1)t)—盒8段(P_(2)h_(8))气水分布关系,总结了气水分布关系的主控因素,划分了气水分布模式。研究结果表明:根据含气水特征、气水分布产状、储层物性特征、测井解释以及产能情况,可以将研究区气水分布关系划分为纯气型、气水同层型、上气下水正常型、上水下气倒置型和纯水无气型5种。研究区气水分布关系主要受生烃强度、源储距离、局部构造、断层以及储层物性和非均质性的影响。生烃强度控制了气水分布的范围,源储距离影响气水的纵向分布;断层沟通了烃源岩和储层,对于气水有一定的调整作用;区域构造起伏对气水分异有一定的影响;储层物性控制储层局部的气水分布,储层非均质性影响着气水纵向分布关系。根据不同源储组合的差异,分别建立了源储一体(源内)型和源储相邻(近源)型2种致密砂岩气水分布模式。

Tight gas reservoir is the main hydrocarbon accumulation type in the Sulige Gas Field.Block Su 39 is one of the most important exploration zones in the gas-water transition zone of the Sulige Gas Field.Based on the data of trial production,well logging,reservoir,and geological setting,the gas-water distribution pattern of Taiyuan Formation(P_(1)t)-H8 member(P_(2)h_(8))in block Su 39 is systematically studied.The research results showed that the gas-water distribution can be divided into five types,including pure gas type,same-layer gas-water type,upper gas-lower water type,upper water-lower gas type,and pure water type.The distribution range is regulated by hydrocarbon generation intensity,while the distance between source and reservoir influences the longitudinal distribution.Local structure,faults,reservoir physical properties,and reservoir heterogeneity affect the vertical distribution of gas and water.Two distinct tight sandstone gas and water distribution models are established due to the difference of different source-reservoir combinations.