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让纳若尔油田是一个带凝析气顶的大型碳酸盐岩油藏,原油为弱挥发性原油,储集层为低孔低渗生物碎屑灰岩。由于早期衰竭式开发和碳酸盐岩储集层的强非均质性,在注水开发过程中,油藏地层压力逐渐下降。随着地层压力的下降,凝析气顶向外扩大,导致油气界面附近的生产井发生气窜,气油比上升,原油密度降低;同时,在远离油气界面的油环内部,由于地层压力下降,大量溶解气析出,地层原油性质发生变化,由弱挥发性原油逐渐转变成普通黑油,原油密度增大,地层原油黏度增大,油井生产气油比升高,油井产能降低,油藏水驱开发难度增大。保持一定的地层压力水平,提高注水利用率是进一步改善和提高该油田注水开发效果的主要手段。
The Najauar field is a large carbonate reservoir with a condensate gas roof. The crude oil is a weak volatile oil and the reservoir is a low-porosity, low-permeability bioclastic limestone. Due to the early depletion development and the strong heterogeneity of carbonate reservoirs, reservoir pressure gradually decreases during waterflood development. As the pressure of the formation decreases, the top of the condensate gas expands outward, resulting in gas channeling in the production wells near the interface of the oil and gas, increasing the gas-oil ratio and decreasing the density of the crude oil. At the same time, due to the decrease of formation pressure in the oil ring far away from the oil- , A large amount of dissolved gas is precipitated, and the formation crude oil properties change from weak volatile crude oil to ordinary black oil. The density of crude oil increases, the viscosity of formation crude oil increases, the gas-oil ratio of oil wells increases, the well productivity decreases, and the reservoir water Drive development more difficult. Maintaining a certain level of formation pressure and improving water injection utilization rate are the main means to further improve and enhance the water injection development effect in this field.