姬塬油田吴433油藏长6₁亚段单砂体识别及刻画

Identification and Characterization of Single Sand Body in Chang 6₁ Submember of Wu 433 Reservoir in Jiyuan Oilfield

摘要: 姬塬油田吴433油藏属于鄂尔多斯盆地典型特低渗透油藏，目前已进入高含水开发阶段，受隔夹层分布复杂、单砂体识别精度不足制约，储层非均质性造成剩余油分布零散，制约油藏挖潜效果。以岩心、录井、测井资料为基础，开展沉积微相解析、隔夹层识别、单砂体划分，剖析砂体空间叠置接触关系与储层连通特征，形成单砂体精细刻画成果并指导现场开发调整。研究表明：研究区长6₁亚段属于三角洲前缘亚相，发育水下分流河道、河口坝、分流间湾沉积微相；依据隔夹层垂向、侧向识别标志，将长6₁亚段划分为11套单砂体；垂向砂体接触样式包含孤立式、侧叠式、叠加式，以叠加式占比最高；侧向发育分离式、对接式、侧切式，侧切式为主要接触类型；不同单砂体连通能力差异显著，长6₁^2-2-2单砂体连通率可达87.43%。基于砂体连通性认识，针对低连通井组实施重复压裂、暂堵压裂与暂堵酸化工艺，为高含水特低渗透油藏剩余油挖潜提供地质依据。

Abstract: Wu 433 reservoir in Jiyuan Oilfield is a typical ultra-low permeability reservoir in Ordos Basin. At present, it has entered the stage of high water cut development. Due to the complex distribution of interlayer and insufficient accuracy of single sand body identification, reservoir heterogeneity causes a scattered distribution of remaining oil, which restricts the potential tapping effect of the reservoir. Based on core, mud logging and logging data, sedimentary microfacies analysis, interlayer identification and single sand body division are carried out, and the spatial overlapping contact relationship of sand bodies and reservoir connectivity characteristics are analyzed, forming fine characterization results of single sand bodies and guiding field development and adjustment. The research shows that Chang 6 submember belongs to delta front subfacies, and the sedimentary microfacies of underwater distributary channel, estuary bar and distributary bay are developed. According to the vertical and lateral identification marks of interlayer, Chang 6 submember is divided into 11 sets of single sand bodies; Vertical sand body contact styles include isolated, side-stacked and superimposed, with superimposed accounting for the highest proportion; Lateral contact styles include separation, docking, lateral cutting, with lateral cutting as the main contact type; The connectivity of different single sand bodies is significantly different, and the connectivity of Chang 6₁^2-2-2 single sand body can reach 87.43%. Based on the understanding of sand body connectivity, the technologies of repeated fracturing, temporary plugging fracturing and temporary plugging acidification are implemented for low-connected well groups, which provide geological basis for tapping the potential of remaining oil in ultra-low permeability reservoirs with high water cut.