东海盆地西湖凹陷X油田辫状河三角洲隔夹层成因与分布

Genisis and Distribution of Braided River Delta Interlayer inX Oilfield of Xihu Sag, East China Sea Basin

海上油田稀井区隔夹层刻画是储层表征中的一个难点问题。以东海盆地西湖凹陷X油田H3砂层组为例,在隔夹层成因类型分析的基础上建立了隔夹层电性特征识别标准,并通过地质与地震相耦合的方法对隔夹层空间分布进行了半定量刻画。研究结果表明,H3砂层组发育洪泛型、废弃河道型、落淤泥型、河道滞留型、细粒沉积型和成岩型等六种隔夹层。依据隔夹层渗透率性将洪泛型、废弃河道型和落淤泥归为泥质隔夹层,河道滞留型和细粒沉积型归为物性夹层,成因型归为钙质隔夹层;H3砂层组内部H3a与H3b小层间隔夹层非常发育,厚度大,连续性好,全区稳定分布,起到较好封隔作用;H3b与H3c间隔夹层发育不均匀,在X10井北、X7-X8井西、X4-X5井区、X1井西南等区域厚度较薄,导致H3b与H3c砂体间存在弱连通。研究结果较好表征了H3砂层组内隔夹层分布,为后续剩余油分析提供了地质基础。通过地质、地震相耦合的方法能够有效进行海上油田稀井网区隔夹层刻画,对类似地区储层精细刻画具有重要的借鉴意义。

Interlayer characterization in sparse well area of offshore oilfield is a difficult problem in reservoir characterization.Taking the H3 sand group of X oilfield in Xihu sag,East China Sea Basin as an example.Based on the analysis of the genetic type of the interlayer,the identification standard of the electrical characteristics of the interlayer was established,and the spatial distribution of the interlayer was semi-quantitatively characterized by the method of geological and seismic coupling.The results show that the H3 sand group develops six interlayers:flood type,abandoned channel type,silt type,channel retention type,fine-grained sedimentary type and diagenesis type.According to the permeability of the interlayer,the flood type,the abandoned channel type and the silt fall are classified as the muddy interlayer,the channel retention type and the fine-grained sedimentary type are classified as the physical interlayer,and the gene-tic type is classified as the calcareous interlayer.The interlayer between H3a and H3b in H3 sand group is very developed,with large thickness,good continuity,stable distribution in the whole area and good sealing effect.the interlayer between H3b and H3c is unevenly developed,and the thickness is thin in the north of X10,west of X7-X8,X4-X5 area and the southwest of X1,resulting in weak connectivity between H3b and H3c sand bodies.The research results better characterize the distribution of interlayers in the H3 sand group,and provide a geological basis for remaining oil analysis.The method of geological and seismic coupling can effectively describe the interlayers in the thin well pattern area of offshore oilfield,which has a good reference for the fine characterization of reservoirs in similar areas.