摘要
川西坳陷合兴场气田须二段地层埋藏深度大,经历的成岩作用复杂多样,导致储层致密化严重,仅局部发育相对优质储层,而该储层具有极强的非均质性,这对气田的勘探开发具有重要影响。综合运用薄片鉴定、扫描电镜、物性测试、XRD矿物分析以及电子探针等实验方法,系统表征了研究区须二段致密砂岩储层的基本特征,厘清了储层发育的主控因素。结果表明,合兴场气田须二段约有71.6%的样品岩性为岩屑砂岩,储集空间按产状和成因分为残余原生孔、粒内溶孔和微裂缝等。孔隙度主要为2%~4%,平均孔隙度为3.45%,中值为3.27%;渗透率主要为0.01~0.10 mD,渗透率几何平均值为0.054 mD,中值为0.045 mD;整体属于特低孔、超低渗致密储层,储层孔渗关系一般,可以划分为孔隙型储层和裂缝-孔隙型储层2类。沉积作用为储层的形成提供先决条件,含量较高的长石矿物组分为溶蚀作用提供物质基础。储层经历的破坏性成岩作用主要有压实压溶作用、硅质胶结作用和碳酸盐(方解石和白云石)胶结作用,而建设性成岩作用主要为溶蚀作用、岩石破裂作用以及发生在较早成岩阶段的绿泥石和菱铁矿胶结作用。
The Xu2 Member of Hexingchang Gas Field in the western Sichuan Depression is deep and has undergone a complex diagenetic process,resulting in significant densification of reservoirs.Relatively high-quality reservoirs are only locally well-developed,and these reservoirs exhibit extreme heterogeneity,significantly influencing the gas field’s exploration and development.This study systematically characterizes the basic properties of tight sandstone reservoirs of the Xu2 Member in the study area and clarifies the primary controlling factors based on data of thin section,scanning electron microscopy,physical property testing,XRD mineral analysis,and electron microprobe.The results show that the lithology of about 71.6%of the samples is litharenite in the Xu2 Member of Hexingchang Gas Field.The reservoir space is classified as residual primary pores,intragranular dissolution pores,and microcracks according to the occurrence and genesis.The porosity is mainly distributed between 2%to 4%,with an average porosity of 3.45%and a median of 3.27%.The permeability primarily ranges from 0.01 mD to 0.10 mD,with a geometric average permeability of 0.054 mD and a median of 0.045 mD.The reservoirs are characterized by extremely low porosity and permeability,which belong to tight reservoirs.The reservoirs have a general relationship between porosity and permeability and can be divided into pore type and fracture-pore type.Sedimentary processes provide the prerequisite conditions for reservoir formation,while the relatively high content of feldspar mineral components offers a material basis for subsequent dissolution processes.Most reservoirs have undergone destructive diagenetic processes,including compaction and pressure dissolution,siliceous cementation,and carbonate cementation(calcite and dolomite).In contrast,the constructive diagenetic processes are primarily dissolution,rock fracturing,and early-stage diagenetic cementation by chlorite and siderite.
作者
赵诗红
朱丽
张玲
ZHAO Shihong;ZHU Li;ZHANG Ling(Exploration and Development Research Institute,Southwest Oil and Gas Company,SINOPEC,Chengdu 610041,China)
出处
《非常规油气》
2025年第4期13-22,共10页
Unconventional Oil & Gas
基金
中国石化科技项目“川西须二气藏裂缝欠发育区储层综合评价”(P21040-4)。
关键词
川西坳陷
合兴场气田
须二段
致密砂岩
储层特征
主控因素
成岩作用
western Sichuan Depression
Hexingchang Gas Field
Xu2 Member
tight sandstone
reservoir characteristics
main controlling factors
diagenesis
