鄂尔多斯盆地岩溶古地貌恢复与天然气富集关系——以高桥地区奥陶系马家沟组马五段为例

The Relationship between Karst Palaeogeomorphology Recovery and Gas Enrichment in Ordos Basin:Example from Mawu Section of Ordovician Majiagou Formation in Gaoqiao Area

以鄂尔多斯盆地高桥地区SA79井区奥陶系马家沟组马五段为例,利用钻井、岩心、测井、地震和分析化验等资料,通过地质分析法、印模法及残厚法对岩溶古地貌进行了恢复,分析鄂尔多斯盆地奥陶系岩溶古地貌特征及其对天然气分布的控制作用,预测有利勘探区。根据研究结果,表明SA79井区主体位于岩溶古地貌斜坡位置,呈现西高东低的形态;局部发育岩溶残丘;东部发育岩溶洼地(凹地)。岩溶古地貌对天然富集有明显的控制作用,天然气主要富集于岩溶洼地上方的斜坡、残丘带和洼地之间的残丘。

Taking the Mawu section of Ordovician Majiagou Formation in SA79 oil well region of Gaoqiao area,Ordos Basin as an example,after analyzing the drilling,comprehensively cores,well logging,seismic and analysis assay data,the karst palaeogeomorphology has been recovered by the traditional geological analytic method,impression method and residual thickness method,the controlling action of Ordovician karst palaeogeomorphology on gas distribution in Ordos Basin has analyzed,and the favorable exploration region has been predicted.The results show that the SA79 oil well region is located in the slope position of karst palaeogeomorphology,with the morphology of west high and east low;The karst monadnock was partially developed,and the karst depression was occurred in the eastern part.The karst palaeogeomorphology is obviously controlled the enrichment of gas,and the gas was mainly enriched in the slope position at the front end of depression and monadnock between monadnock belt and depression.