东濮凹陷马寨油田卫95块扇三角洲沉积特征及沉积模式

Sedimentary characteristics and sedimentary model of Wei95 block in Mazhai oilfield,Dongpu depression

沙三下亚段是马寨油田卫95块的主要含油层系,钻井资料显示储层厚度大、砂体成因复杂、相带认识难度大.为了研究卫95块沙三下亚段的沉积特征及沉积模式,根据地质学及沉积学理论,分析其泥岩颜色、岩石类型及组合、粒度特征、构造特征及沉积相.结果表明:位于东濮凹陷西北端第三断阶带的马寨油田卫95块发育扇三角洲前缘亚相,物源主要来自于西部的内黄隆起;该亚相又进一步识别出水下分流河道、水下分流河道侧翼、席状砂和水下分流河道间等4种微相,各主力砂组发育多期扇三角洲沉积,各扇体相互叠置,呈北西—南东向展布;亚相以水下分流河道和席状砂微相为主,其余微相次之.在区域构造背景的基础上,结合扇体的物源方向及时空展布特征,总结卫95块的沉积微相模式,为油田开发提供参考.

Es3 subinterval is the main oil-bearing horizon of Wei95 block in Mazhai oilfield.Reservoir is very thick,genesis of sand is very complicated and consequently it is hard to cognize the facies zone.The article analyzed sedimentary characteristic and sedimentology pattern of Es3 low sub-member of Wei95 block.Under the guide of geology and sedimentology,we analyzed the color of mudstone of target zone,rock type and combination,fineness and structure characteristic comprehensively to study the deposition facies.It is concluded that fan-dealta subfacies distributed widely there and the source is from Neihuang uplift in the west.The subfacies is divided into 4microfacies:underwater distributary channel,channel flanking,sheet sand and inter-channel and we summarized well-log respond mode of each type.From the single-well facies and planar facies of main sand group,we found that multistage fan-delta distributed from northwest to southeast and overlapped mutually.Underwater distributary channel and sheet sand took the majority.Based on the analysis of structure of target area,sedimentary mode of Wei95 block was summarized according to the source direction and distribution characteristic.The result could provide geological reference for further development of the oilfield.