小气顶底水薄层油藏开发规律及技术政策

Development rules and technical policies of thin-layer reservoir with small gas cap and bottom water

小气顶底水驱薄层油藏开发过程中,受气顶与底水的同时作用,油气水互窜,采油井生产气油比高、含水上升快,开发难度较大。文中借助油藏数值模拟技术,建立了此类油藏的机理模型,探究其生产规律与最优开发方式,并对气顶指数、底水倍数、油柱高度、垂向布井位置等参数进行敏感性分析。研究认为:小气顶底水薄层油藏在开发过程中气窜是无法避免的,其日产油量变化曲线表现出三段式特征,反映了气窜、油气互侵、底水侵入3个过程;此类油藏的最优开发方式为油气同采,在小气顶布井可以缩短油气互侵的时间,并在原油侵入气顶后采油;在较小气顶和较强底水的情况下,排气采油方式开发效果更好。

Thin-layer reservoir with small gas cap and bottom water is affected by the gas cap and bottom water drive at the same time during the development process,which leads to the situation that the oil and gas are mutually turbulent,resulting in high production gas-oil ratio,high water content in the production well and difficult development of this kind of reservoir.The mechanism model of such reservoirs was established by means of reservoir numerical simulation to explore the production law and optimal development of such reservoirs,and the sensitivity of gas cap index,bottom water multiple,oil column height,vertical well placement and other parameters were analyzed.According to the research,it is believed that gas channeling is unavoidable during the development process in the thin-layer reservoir with gas cap and bottom water.The daily oil production curve shows three-stage characteristics,and reflects the three processes of gas channeling,oil and gas intrusion and the intrusion of bottom water.Commingled production of oil and water is the optimal development method for such reservoirs,where well spacing in the gas cap can shorten the time of oil and gas intrusion and recover oil after oil intrusion into the gas cap.Under the circumstance of smaller gas cap and stronger bottom water,the theory of oil production with exhausting gas has a better development effect.