Quantitative Evaluation Technology of Sandstone Reservoir Connectivity in Dense Well Pattern Area

Abstract

Daqing Changyuan Oilfield is in the stage of extra high recovery degree and extra high water cut. The remaining oil distribution is scattered and the potential for tapping is difficult. The difference of sand body connectivity has a great influence on the remaining oil adjustment. Using the core data to optimize the evaluation index of sand body connectivity, the principal component principle is used to establish the quantitative evaluation model of sand body connectivity. According to the co-kriging algorithm, the sandstone thickness based on seismic attributes is predicted and the channel boundary is predicted and the distribution characteristics of reservoir parameters are predicted accurately. On this basis the sand body connectivity between wells is described quantitative. The results show that the three principal components of the study area have clear geological meanings, which represent the factors affecting sand body connectivity such as sand body size, heterogeneity and interlayer condition. Principal component analysis can reduce the dimensionality of connectivity evaluation indicators and objectively determine its weight. The quantitative evaluation results are highly correlated with oil displacement efficiency. Quantitative description of sand body connectivity combing seismic data with well logging data is beneficial to accurately analyzing the affected condition of injection-production well. There are four types of remaining oil tapping potential combining the allocation of well network such as “partial occlusion type” and “incompleted injection-production” and “uncontrolled by well pattern type” and “river internal weak water drive type”, which provide a reliable geological basis for accurate potential tapping of remaining oil in water-flooding and polymer-flooding.