凝析气顶油藏开发过程中原油性质变化

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...

Oil property changes during waterflooding for reservoirs with condensate gas cap

Zanarol oil field is a giant carbonate reservoir with condensate cap, weakly volatile oil, and bioclastic limestone of low porosity and permeability. During the waterflooding stage, formation pressure decreased step by step resulting from the former depleting development and the strong heterogeneity of carbonate reservoirs. The gas cap spread outwards with the formation pressure dropping, causing gas breakthrough in production wells near the oil and gas contact, GOR increased and oil density decreased. In the internal oil region far from the oil-gas contact, the dropping reservoir pressure led to dissolved gas separating out from oil, making crude oil change to black oil from weak volatile oil. With the separated solution gas, the oil density, produced gas oil ratio and oil viscosity increased, the oil well productivity decreased, all these make waterflooding more difficult. The main method for improving development response is to keep formation pressure and improve the utilization factor of water injection.