超深致密砂岩储层特征及影响因素——以库车坳陷阳霞凹陷侏罗系为例

Features and influence factors of ultra-deep tight sandstone reservoirs: a case study of Jurassic in Yangxia Sag, Kuqa Depression

宋金鹏,郇志鹏,田盼盼,杨连刚,代俊杰,王珠峰,邱升梁

中国石油塔里木油田分公司勘探事业部，新疆 库尔勒 841000 中国石油塔里木油田分公司克拉油气开发部，新疆 库尔勒 841000 中国石油塔里木油田分公司安全环保与工程监督中心，新疆 库尔勒 841000

Exploration Department, Tarim Oilfield Branch, PetroChina, Korla 841000, China Kela Oil and Gas Development Department, Tarim Oilfield Branch, PetroChina, Korla 841000, China Safety, Environment Protection and Engineering Supervision Center, Tarim Oilfield Branch, PetroChina, Korla 841000, China

库车坳陷北部致密砂岩储层是塔里木盆地油气勘探重要接替领域。扫描电镜、激光共聚焦、岩心CT扫描等资料显示，阳霞凹陷侏罗系储层以粒内溶孔、微裂缝等次生孔隙为主，属孔隙￣裂缝双孔介质储层，主要受沉积相带、成岩作用、构造运动及上覆巨厚膏盐岩等因素控制。其中：沉积作用决定了储层原始物性，影响后期成岩作用类型及强度，是形成超深有效储层的基本条件；压实、胶结、溶蚀等成岩作用控制了超深致密储层当前孔渗大小和有效性，大幅减少原生孔35.48%，并形成大量次生孔隙，增孔率6.11%；同时，新近系巨厚膏盐岩大幅降低盐下地层温度，形成异常高压，有利于储层物性保存。后期构造挤压减孔率6.67%，但伴生的裂缝与各种微裂缝组合形成缝网系统，有效沟通了孤立状次生溶孔，极大地改善了储层渗透性。

Tight sandstone reservoirs of Jurassic in northern Kuqa Depression are the significant succession area of exploration in Tarim Basin. Data from SEM, LCS and CT scanning show that reservoirs of Jurassic in Yangxia Sag are dominated by secondary porosity such as intragranular dissolved pore and micro-cracks, which belong to pore-fracture dual porosity reservoir. The reservoir is controlled by sedimentary facies belt, diagenesis, tectonic movement and the overlying ultra-thick gypsum-salt rock. Sedimentation dominates the original physical properties, and affects type and intensity of late diagenesis, which is the basic for the formation of ultra-deep effective reservoirs. Diagenesis including compaction, cementation and dissolution controls the size and effectiveness of current porosity and permeability in ultra-deep tight reservoirs, greatly reducing primary pores by 35.48% and forming abundant secondary porosities, increasing pores by 6.11%. At the same time, ultra-thick gypsum-salt rock of Neogene greatly reduces the sub-salt formation temperature and forms overpressure, which is positive for preserving physical properties. Late tectonic compression reduces pores by 6.67%, while the combination of associated fractures and various micro-cracks make up a fracture network, which effectively connect isolated secondary dissolved pores and greatly improve reservoir permeability. 

10.6056/dkyqt202105003