西湖凹陷深层致密砂岩裂缝控制因素及发育模式——以中部洼陷带中南部W构造为例  

Controlling factors and development patterns of fractures in deep tight sandstone in Xihu Sag,East China Sea Shelf Basin:a case study from W Structure in south central region of Central Depression Belt

作　　者：李宁 徐振中 钟荣全 姜勇 赵军 张武 俞伟哲 LI Ning;XU Zhenzhong;ZHONG rongquan;JIANG Yong;ZHAO Jun;ZHANG Wu;YU Weizhe(Shanghai Branch of CNOOC(China)Ltd.,Shanghai 200335,China)

机构地区：[1]中海石油(中国)有限公司上海分公司,上海200335

出　　处：《海洋地质前沿》2024年第10期19-28,共10页Marine Geology Frontiers

基　　金：中海石油(中国)有限公司重大科技专项“东海西湖凹陷大中型气田勘探方向及关键技术研究”(KJZX-2023-0101)。

摘　　要：西湖凹陷大部分油气资源量集中在3500 m之下的深层低孔渗储层中,前人对该区深层裂缝型“甜点”储层的研究相对较少。以中部洼陷带W构造为重点研究靶区,总结裂缝预测方法,研究深层裂缝形成的控制因素及发育模式。研究结果表明,按裂缝成因类型划分,W构造深层低孔渗砂岩储层裂缝包括成岩缝、剪切缝和张裂缝。其中,成岩缝的发育受沉积层理与压力释放的共同控制;剪切缝受地层变形强弱的控制,主要发育于花港组地层变形较强的部位;张裂缝与地层上隆后产生的水平伸展应力有关。结合储层物性条件分析认为,深层裂缝发育是控制致密砂岩气藏“甜点”储层的重要因素之一。通过构造应力场模拟研究并结合单井岩芯及薄片综合分析,可有效预测裂缝的集中发育区,为深层裂缝型“甜点”储层的预测提供依据。Most of the oil and gas resources in the Xihu Sag are concentrated in deep low-porosity and permeability reservoirs below 3500 m.Previous studies on deep fractured"sweet spot"reservoirs in this area are relatively rare.Taking the W structure in the central depression belt as the research target area,the fracture prediction method is summarized,and the controlling factors and development patterns of deep fracture formation are studied.Results show that the fractures in the deep tight sandstone reservoir of the W structure could be classified into diagenetic fractures,shear fractures,and tension fractures in fracture genesis type.Among them,the diagenetic fractures is controlled by sedimentary bedding and pressure release.The shear fractures are controlled by the intensity of stratum deformation and are mainly developed in the parts with strong deformation of the Huagang Formation.The tension fractures are related to the horizontal extension stress generated after the stratum uplift.After analyzing the reservoir physical properties,we believe that the development of deep fractures is one of the important factors controlling the"sweet spot"reservoirs of tight sandstone gas reservoirs.Through tectonic stress field simulation combined with single well core and thin section analysis,the concentrated development area of fractures can be effectively predicted,providing a basis for the prediction of deep fractured"sweet spot"reservoirs.

关 键 词：深层低渗储层 裂缝发育模式 裂缝类型 西湖凹陷 低幅背斜 

分 类 号：P744.4[天文地球—海洋科学] P618.13