涠洲F4油田流沙港组储层微观结构及两相渗流特征

 涠洲F4 油田位于南海北部湾地区，包含涠洲组和流沙港组两套含油层，其中涠洲组属于高渗油藏，已经全面开发，测井解释结果显示流沙港组储量可观，但低渗透储量高达82%，涠洲组的开发经验不适用于流沙港组。针对流沙港组非均质性强、微观孔隙结构复杂及注水难度大等问题，利用恒速压汞、核磁共振和油水驱替物理模拟等实验技术，对储层微观孔隙结构及油水驱替规律等进行系统研究。研究表明，涠洲F4 油田流沙港组需要技术攻关的储层渗透率是1×10^-3~5×10^-3 μm²，且储层渗透率低于2×10^-3μm²时，以小于1 μm 的喉道为主，渗流阻力大，水驱开发难度大；低渗透油藏，前期保持较高地层压力能明显提高驱替效率，残余油状态水相渗透率低于0.2，注水压力高，后期采用小排量温和注水既有利于有效注水，又能保持较高渗吸效率，以此提高储层采收率。

Microscopic Structural and Seepage Characteristics of Reservoirs in the Group of L WZF4 Oilfield

WZF4 oilfield is located in the Beibu Gulf in the South China Sea area, including the oil-bearing formation for the group of WZ and the group of L. The group of WZ contains high permeability reservoirs, and is fully developed. The logging interpretation results show considerable reserves for the group of L, with the low permeability reserves up to 82%. The development experience for the group of WZ is not applicable to the group of L. The group of L has the problems of heterogeneity, complicated micro pore structure and difficult water injection. The microscopic pore structure and the distribution of the oil-water displacement of reservoirs are obtained by the experiment technologies of the constant rate mercury, the NMR and the physical simulation of the oil-water displacement. It is shown that the reservoir permeability is 1×10^-3-5×10^-3μm² for the group of L. When the reservoir permeability is below 2×10^-3μm², most throats are less than 1 μm, the filtration resistance is high and the water flooding development is difficult. For the low permeability reservoir, the high formation pressure can significantly improve the displacement efficiency. The residual oil phase permeability is lower than 0.2, the water injection pressure is high, and the small moderate injection is conducive to the effective injection, and keeps a high imbibition efficiency, to improve the reservoir recovery.