Reservoir characteristics and distribution of lacustrine fine-grained sedimentary rocks:a case study from Zhanhua sag,Bohai Bay Basin,China
In order to deepen the understanding of lacustrine fine-grained sedimentary rock reser-voirs,this paper takes the Lower Sub-member of Third Member of Shahejie Formation(Es3L)of Bonan subsag in Zhanhua sag,Jiyang depression,Bohai Bay Basin as the research object,and uses core de-scription,thin section identification,scanning electron microscope observation,physical property analy-sis and logging curve to reveal the reservoir characteristics,main controlling factors and distribution pat-terns.Based on mineral composition,sedimentary structure and organic matter content,fine-grained sedi-mentary rocks in Es3L are divided into six lithofacies:organic-rich laminated gray fine-grained mixed rock(LF1),organic-rich laminated felsic fine-grained carbonate rock(LF2),organic-rich layered gray fine-grained mixed rock(LF3),organic-rich layered/massive felsic fine-grained carbonate rock(LF4),or-ganic-rich layered felsic fine-grained carbonate rock(LF5),organic-rich massive felsic fine-grained car-bonate rock(LF6).The main reservoir spaces of the reservoir are intergranular pores,intergranular pores,dissolution pores,and interlayer micro-fractures.The reservoir porosity mainly ranges from 0.67％to 5.56％,with an average of 4.93％.The permeability mainly ranges from 0.02× 10-3 μm2 to 4.87 × 10-3 μm2(average of 0.59× 10-3 μm2).The dominant control factors for the distribution of the Es3L fine-grained reservoir development include lithofacies,sedimentary environment,diagenesis and thermal evo-lution of organic matter.In the middle and lower part of the Lower Sub-member of Third Member of Shahe-jie Formation,the amount of terrestrial input is low,the water salinity is high,and the water stratification is strong.The main lithofacies area LF2 and LF4,which are prone to the development of Class Ⅰ and ClassⅡ high-quality reservoirs.The fine-grained reservoirs in Es3L are in the intermediate diagenetic stage A.The transformation of clay minerals,dissolution,recrystallization and dolomitization,as well as the ther-mal evolution of organic matter produce secondary pores and fractures,which improve the physical pro-perties of the reservoir.
Bonan subsagthe Lower Sub-member of Third Member of Shahejie Formationlacus-trine fine-grained sedimentary rockshigh quality reservoirmain controlling factorsregularity of distri-bution
万方数据
维普
