缝洞型底水油藏油井底水突破时间预测方法——以塔河油田4区S48井为例

Bottom water breakthrough prediction in fractured-vuggy reservoirs with bottom water——an example from the well S48 in Block 4 of Tahe oilfield

陈朝晖 邓勇 许博 董建新

Chen Zhaohui Deng Yong Xu Bo Dong Jianxin

底水锥进是降低底水油藏单井产量和采收率的重要原因。塔河油田奥陶系发育缝洞型底水油藏,该类型油藏与孔隙型和裂缝性油气藏具有较大的差别,储层中孔、缝、洞共存,其中大型的古溶洞系统是其主要的储集空间。由于储层尺度在空间上变化较大,储集空间分布不连续,该类型底水油藏的底水锥进机理与常规底水油藏存在明显差异。考虑塔河油田储层缝洞分布不均、非均质性较强的特点,将该类型储层抽象成为渗透率变异的概念地质模型,定义渗透率变异系数和泄油半径比来表征储层缝洞的发育程度,在此基础上推导出缝洞型底水油藏油井底水突破时间的预测公式。以塔河油田4区S48井为例开展实例计算,对比预测效果并分析缝洞发育程度(渗透率变异系数和泄油半径比)、单井产量和射孔程度对该类型底水油藏油井底水突破时间的影响。

Bottom water coning is a major reason reducing production and recovery factor of single well in reservoirs with bottom water.The Ordovician of the Tahe oilfield has well-developed fractured-vuggy reservoirs with bottom water,which are different from conventional porous reservoirs and fractured reservoirs in many ways.Pores,fractures and vugs coexist and large cavern system dominates the reservoir spaces in this type of reservoirs.Due to spatial diversification of reservoir scale and discontinuous distribution of reservoir space,the fractured-vuggy reservoirs have a water coning mechanism significantly different from that of a regular reservoir with bottom water.Considering its uneven distribution of vugs and strong heterogeneity,we established a conceptual geological model with permeability variation to describe the reservoirs and derived a prediction formula for the bottom water breakthrough by defining permeability variation coefficient and the drainage radius ratio to characterize the development of fractures and vugs.We applied the formula to the calculation of bottom water breakthrough time in the well S48 in Block 4 of the Tahe oilfield.Through the comparison of the results with the actual data,we tried to determine the effectiveness of the formula and analyze the influences of fracture and vug deve-lopment(represented by permeability variation coefficient and drainage radius ratio),single well production and perforation upon the time of bottom-water breakthrough.

10.11743/ogg20120517