带气顶裂缝性碳酸盐岩油藏开发特征及技术政策

哈萨克斯坦让纳若尔油田为带凝析气顶的大型复杂碳酸盐岩油田.Г北油藏是让纳若尔油田的主力油藏,油藏具有孔隙一裂缝双重介质渗流特征,且平面上不同区域的裂缝发育程度具有较大差别.由于油藏早期注水不足,地层压力持续下降,导致自然递减一直处于较高水平.研究不同裂缝发育程度储集层的开发特点以及合理开发技术政策发现,裂缝发育区与不发育区的开发技术政策存在明显的差别:裂缝发育区合理压力保持水平为25～27 MPa.以1.1的注采比恢复压力,可以获得更高采出程度;裂缝不发育区合理压力保持水平为32 MPa,合理注采比1.3.屏障注水与面积注水注水量比例为2:8时,能实现既合理利用气顶能量,又提高面积注水效果的目的.图9参10

Development of complex carbonate reservoir with condensate gas cap

Zanarol Oilfield in Kazakstan is a big carbonate reservoir with condensate gas cap. Г North reservoir is the major reservoir of the field. The reservoir has a dual-porosity character. Fracture distribution changes on plane. Insufficient previous water injection results in decrease of formation pressure and increase of natural declining rate. The study of the developing characteristics and reasonable development technique policies for reservoirs with differently developed fractures reveals that development policies are different depending on the distribution of fractures. Sound formation pressure maintenance for reservoirs with well-developed fractures is 25-27 MPa, and the reasonable injection-withdrawal ratio is 1.1. Sound formation pressure maintenance for reservoirs with undeveloped fractures is 32 MPa, and the sound injection-withdrawal ratio is 1.3. When the flooding ratio of gas cap to oil rim is 2 to 8, energy of gas cap can be utilized well and the water flooding in oil rim can act more effectively.