深生浅储天然气封盖保存模式及能力评价——以大庆长垣南部黑帝庙油层为例

Sealing and Preservation Pattern and Its Ability Evaluation of Shallow Gas Reservoirs Come from Deep Source—A Case Study of Heidimiao Oil Bed in the South of Changhuan,Daqing

通过统计钻井数据得到,大庆长垣南部黑帝庙油层泥岩盖层主要发育于H16、H15、H14小层,其底部分别发育的3套区域分布的泥岩盖层是其天然气的主要封盖层。由盖层厚度与源断裂断距大小比较可以得到,3套区域分布的泥岩盖层多处被错开,形成多处逸散窗口,天然气只能在源断裂之间未被错开的H16、H15和H14三套泥岩盖层之下被保存下来,如果圈闭发育便可以聚集成藏,否则天然气将会继续沿逸散窗口运移散失。通过比较盖层所能封闭住的最大气柱高度与圈闭幅度大小可以得到,3套区域分布的泥岩盖层所能封闭住的最大气柱高度远大于圈闭构造幅度,可以封盖住进入圈闭中的天然气。通过目前天然气显示井与盖层之间时空分布关系研究得到,3套区域分布的泥岩盖层空间分布控制着天然气聚集层位和平面上的分布部位,其形成时期与嫩一、二段源岩大量排气期较好地匹配,有利于天然气在黑帝庙油层中聚集成藏。

By the statistics of drilling data, the mudstone covers of Heidimiao Oil Bed in the south of Changhuan, Daqing mainly developed in H1^6 , H1^5 and H1^4 layers, and the 3 sets of regional mudstone covers respectively developed at the bot- tom of each small layer were main covers of gas. By the comparisons of cover thickness and fault throws of source faults, it concluded that the 3 sets of regional mudstone covers were staggered in many places which became dissipation windows, and the gas could be only sealed by the 3 covers distributed between faults connecting source rocks and formed gas reservoirs if traps developed. By the comparisons of the maximum gas column heights sealed by covers and the size of trap region, it showed that the maximum gas column height sealed by the 3 sets of regional mudstone covers was much greater than struc- tural magnitude of the trap, and the gas migrated into traps could he sealed. By the research on space-time relation between displaying wells of gas and covers, it showed that the spatial distribution of 3 sets of regional mudstone covers of Heidimiao Oil Bed in the south of Changhuan, Daqing had controlled the accumulation horizons of gas and the distribution sites in the plane, and gas formation periods were well matched with the main degassing periods, which was favorable for gas accumu- lation in Heidimiao Oil Bed.