对中原油田开发几个问题的思考

Discussion on some development problems in Zhangyuan Oilfield

20世纪70年代以前,国内发现的油田多为陆相沉积,多油层储层,非均质性严重;原油性质多属中高黏度,油水黏度比一般高于20,在注水开发中形成较强的非均质性和水驱油的非活塞现象。注水开发的基本规律是:注水开发早、中期含水上升速度快,采出程度低,相当多的水驱可采储量要在高含水期采出。70年代末发现的中原油田,储层比较均匀,特别是原油性质好,低密度、低黏度,油水黏度比小,和其他开发油田有很大不同,避免了注水开发过程中的非均质性和注入水的非活塞现象,其基本规律是:注水开发的早、中期含水上升速度慢,采出程度高,相当多的水驱可采储量在中、低含水期就可采出,中原油田濮城沙一段油藏的开发实践就证明了这一点。中原油田的储层具有小孔隙、细喉道、低渗透的特点,和大孔隙、粗喉道、高渗透油田有很大的不同,开发中必须区别对待,特别是保护油气层不受污染,要形成大思路、大政策,贯彻到油田开发的始终,实现注水开发的高水平、高效益。

The oilfields discovered before the 1970s in our country mostly belongs to the continental deposit and they have multioil layer reservoirs with strong heterogeneity. Oil property mainly belong to middle-high viscosity and oil-water viscosity ratio is high than 20. During the injection development, the strong heterogeneity and displacement of oil by water are formed. The basic law of injection development is the injection development at the early stage, fast water-cut rising and low recovery degree at middle stage. Quite a number of water flooding recoverable reserves can be recovered at the high water-cut stage. The reservoirs discovered at the end of the 70s in Zhongyuan Oilfield are relatively homogenous and the oil property is good with low viscosity, low density and low oil-water viscosity, which is different from the above developed oilfields. Therefore, the heterogeneity and non-piston phenomenon can be avoided. At the early and middle stages of injection development, the water-cut rises fast and the oil recovery degree is high. Quite a number of water flooding recoverable reserves can be recovered at the middle to low water-cut stages, which are proved by development practices of S1 reservoir in Pucheng of Zhongyuan Oilfield. The reservoirs in Zhongyuan Oilfield have the characteristics of small pores, small throats and low permeability, which is greatly different from the oilfields with big pores, big throats and high permeability. Development must be treated differently in order to protect reservoir and realize high-efficiency injection development.