柴达木盆地西部地区古近系湖相碳酸盐岩储层特征  

Reservoir characteristics of Paleogene lacustrine carbonate rocks in western Qaidam Basin

作　　者：崔俊[1] 毛建英[1] 陈登钱[1] 施奇 李雅楠 夏晓敏[1] CUI Jun;MAO Jianying;CHEN Dengqian;SHI Qi;LI Yanan;XIA Xiaomin(Research Institute of Exploration and Development,PetroChina Qinghai Oilfield Company,Dunhuang 736202,Gansu,China)

机构地区：[1]中国石油青海油田公司勘探开发研究院,甘肃敦煌736202

出　　处：《岩性油气藏》2022年第2期45-53,共9页Lithologic Reservoirs

基　　金：中国石油天然气股份有限公司重大科技专项“柴达木盆地建设高原大油气田勘探开发关键技术研究与应用”(编号:2016E-01)资助。

摘　　要：柴达木盆地西部地区古近系下干柴沟组上段(E_(3)^(2))至上油砂山组(N_(2)^(2))广泛发育湖相碳酸盐岩。为研究其分布及储层发育特征,开展岩心观察、薄片鉴定、扫描电镜及X射线衍射分析等工作。结果表明:①研究区湖相碳酸盐岩具有岩石类型多、相变快、陆源碎屑发育、普遍白云石化等特点;主要岩石类型有块状碳酸盐岩、纹层状碳酸盐岩、藻灰岩、颗粒碳酸盐岩,其分布与沉积微相及古环境密切相关。②研究区块状碳酸盐岩储集空间以晶间孔为主,局部发育裂缝,纹层状碳酸盐岩顺层微裂缝发育,藻灰岩储集空间以藻格架孔为主,非均质性强,颗粒碳酸盐岩受胶结作用影响显著。③块状碳酸盐岩平均孔隙度为10.6%,平均基质渗透率为0.03 mD,排驱压力为10.0 MPa,平均孔喉半径为0.038μm;纹层状碳酸盐岩平均孔隙度为7.4%,平均渗透率为0.76 mD,排驱压力为11.5 MPa,平均孔喉半径为0.071μm;藻灰岩平均孔隙度为10.1%,平均渗透率为9.09 mD,排驱压力为3.2 MPa,平均孔喉半径为0.117μm;颗粒碳酸盐岩平均孔隙度为7.1%,平均渗透率为0.01 mD,排驱压力为15.0 MPa,平均孔喉半径为0.026μm。④尕斯地区古近系优质储层以藻灰岩为主,英西—干柴沟地区的碳酸盐岩发育裂缝系统,为高产“甜点”区;茫崖凹陷为勘探潜力区。该成果对柴达木盆地古近系湖相碳酸盐岩油气勘探具有借鉴作用。Lacustrine carbonate rocks are widely developed in the upper member of Xiaganchaigou Formation(E_(3)^(2))and upper Youshashan Formation(N_(2)^(2))of Paleogene in the western Qaidam Basin.In order to study its distribution and reservoir development characteristics,core observation,thin section identification,scanning electron microscope analysis and X-ray diffraction analysis were carried out.The results show that:(1)The lacustrine carbonate rocks in the study area have the characteristics of many rock types,rapid phase transformation,terrigenous clastic development and general dolomitization.The rocks are mainly composed of massive carbonate rocks,laminar carbonate rocks,algal limestones and granular carbonate rocks,which are closely related to sedimen-tary microfacies and paleoenvironment.(2)The massive carbonate reservoir space in the study area is mainly composed of intergranular pores,and fractures are locally developed.The bedding microfractures of laminar carbonate rocks are developed,the algal limestone reservoir space is mainly composed of algal framework pores with strong heterogeneity,and the granular carbonate rocks are significantly affected by cementation.(3)The average porosity of massive carbonate rocks is 10.6%,the average matrix permeability is 0.03 mD,the displacement pressure is 10.0 MPa,and the average pore throat radius is 0.038μm.The average porosity of laminar carbonate rocks is 7.4%,the average permeability is 0.76 mD,the displacement pressure is 11.5 MPa,and the average pore throat radius is 0.071μm.The average porosity of algal limestones is 10.1%,the average permeability is 9.09 mD,the displacement pressure is 3.2 MPa,and the average pore throat radius is 0.117μm.The average porosity of granular carbonate rocks is 7.1%,the average permeability is 0.01 mD,the displacement pressure is 15.0 MPa,and the average pore throat radius is 0.026μm.(4)The Paleogene high-quality reservoirs in Gasi area are mainly algal limestones,the carbonate rocks in Yingxi-Ganchaigou area develop fracture sys

关 键 词：孔隙结构 储层特征 晶间孔 白云石化 湖相碳酸盐岩 古近系 柴达木盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]