Study On Characteristics And Controlling Factors Of The Second Member Of Shahejie Formation In Bonan Sag

According to the environment of Continental rift lake in Es-2 of Bonan sag, through stratum comparison between closed lateral section and lake basin filling mode, the complete stratum comparison on the target stratum of Bonan Sub-Sag is made; based on the analyses on the regional sediment environment and integrating core observation, log information and logging information, sedimentary facies of the sandy dam, of which the sedimentary facies of delta can be classified into microfacies such as front subfacies of fan delta, the delta-front subfacies can be classified into underwater distributary channel, distributary channel, estuary dam, far sand dam, sill-like sand and so on.The diagenetic evolution stage was divided and on the basis of these, the diagenetic facies types and their distribution law were summarized. The results indicated that the reservoir rocks in the subsag consist mostly quartz sandstone, with mainly lithic arkose near the platfood, and the heterogeneity of reservoir is strong. The porosity and permeability distributed with a strong heterogeneity in the surface. Reservoir physical property reduced generally with the increase of clay mineral and cement. The four main diagenesis types which the Second Member of Shahejie Formation developed were compaction, cementation, metasomatism and dissolution. Compaction and cementation were the main reasons for the poor reservoir quality, particularly the influence of the cementation of clay mineral and carbonate.Based on the sequence of authigenic mineral, rock structure characteristics, clay mineral composition and illite-smectite mixed-layer mineral(I/S) transformation etc., the Second Member of Shahejie Formation in Bonan Subsag was mainly in the middle diagenesis phase A1. Based on logging interpretation technology and coring well data, the Second Member of Shahejie Formation was divided into five types of diagenetic facies, including diagenetic facies of compaction density, carbonate cementation, argillaceous cementation, argillic-carbonate mixed cementation and dissolution.on the basis of diagenesis and diagenetic facies analysis, combined with logging facies and seismic facies, through the formation mechanism of diagenesis and diagenetic facies establish the correspondence between the sand Sec diagenetic facies conventional logging response characteristics, and then apply to the study area, divided by logging interpretation techniques diagenetic facies types found in the general vicinity of the projection with diagenetic dissolution developmental phase, usually in sag internal phase cementation, compaction diagenetic phases.