准噶尔盆地中拐地区致密砂岩气成藏特征及富集规律

Accumulation Characteristics and Enrichment Regularity of Tight Sandstone Gas Reservoirs in Zhongguai Area,Junggar Basin

致密砂岩气作为一种清洁高效的低碳能源,对能源消费结构转型升级和实现“双碳”目标具有重要意义。准噶尔盆地西北缘中拐地区二叠系佳木河组致密砂岩气的成藏特征及富集规律认识不清。基于钻井、测井、三维地震、岩心和实验分析测试资料,综合分析研究区致密砂岩气成藏地质特征、富集规律及高产主控因素。研究结果表明:中拐地区二叠系佳木河组致密砂岩气类型主要由油型气、煤型气及混合气组成,气源主要来自沙湾凹陷风城组及下乌尔禾组烃源岩,佳木河组烃源岩可能供烃,具有多源供烃特征;气藏类型为岩性-地层圈闭型,具有远源运移,多期次聚集成藏特征;致密储层受浊沸石矿物等溶蚀作用在局部地区形成物性相对较好的储层“甜点”,其主要分布在研究区东部,纵向上主要发育在4320~4640 m和4830~4900 m深度段,高产层段主要集中在上部“甜点”带。致密砂岩气藏的富集及高产受控于有利成岩相带上的储层“甜点”和局部发育的古凸起及构造裂缝。

As a kind of clean and efficient low-carbon energy,ight sandstone gas is of great significance to the transformation and upgrading of energy consumption structure and the realization of the goal of“carbon peaking and carbon neutrality”.The formation characteristics and enrichment laws of tight sandstone gas in the Permian Jiamuhe Formation in Zhongguai area,northwest margin of the Junggar basin,are unclear.Based on drilling,logging,3D seismic,core and experimental analysis and testing data,the geological characteristics,enrichment laws and main controlling factors for high production of tight sandstone gas reservoirs in the study area are comprehensively analyzed.The research results show that the tight sandstone gas type of the Permian Jiamuhe Formation in Zhongguai area is mainly composed of oil type gas,coal type gas and mixed gas.The gas source is mainly from the source rock of Fengcheng Formation and Lower Wuerhe Formation in Shawan Sag.The source rock of the Jiamuhe Formation may supply hydrocarbon,which has the characteristics of multisource hydrocarbon supply;The gas reservoir type is a lithologic stratigraphic trap type,with characteristics of distant source migration and multi-stage accumulation and accumulation;The dense reservoir is eroded by turbidite minerals and other minerals,forming relatively good physical properties in local areas as reservoir“sweet spots”.They are mainly distributed in the eastern part of the study area,and vertically,they mainly develop in the depths of 4320~4640 m and 4830~4900 m,with high yield layers mainly concentrated in the upper“sweet spots”zone.The enrichment and high production of tight sandstone gas reservoirs are controlled by the favorable diagenetic facies zones of reservoir“sweet spots”and locally developed paleo-uplift and structural fractures.