薄层低品位油藏孔隙结构及渗流特征

Study on pore structure and percolation characteristics of thin zone and lean reservoir

薄层低品位油藏的油层厚度比较薄、埋藏比较深、渗透率比较低、储量丰度低、开采难度大。通过物理模拟实验研究了薄层低品位油藏的孔隙结构特征、两相渗流规律、启动压力梯度和岩石压缩性的变化规律,重点分析了不同渗透率毛管压力曲线的变化、不同渗透率相对渗透率曲线的变化规律、启动压力梯度对储层物性的影响、流动系数之间的关系、围压与渗透率之间的变化规律等。结果表明,薄层低品位油藏的孔隙结构及渗流特征与中高渗油藏有很大不同,启动压力梯度和压力敏感性影响很大,必须选择合理的注采压差和注采井距,建立有效的驱替压差,才能克服启动压力梯度和压力敏感性的不利影响,改善开发效果。

Thin effective thickness, deeply buried, low permeability, low abundance of reserve, and more difficult exploitation are the traits of the thin zone and lean reservoir. This paper studies the pore structure, two-phase fluid flow rule, starting pressure gradient and rock compression of the thin zone and lean reservoir by the physical simulation experiment. It emphatically analyzes the capillary pressure curve of different permeabilities, the relative permeability curve of different permeabilities, the impaction of starting pressure gradient on the reservoir physical property, the relationship between transmissibility coefficient and starting pressure gradient, and the relationship between confining pressure and permeability. The result indicates that the pore structure and percolation characteristics of the thin zone and lean reservoir are very different from the middle and high permeability reservoirs. The starting pressure gradient and the pressure sensitivity have great influence on the thin zone and lean reservoir. Only the rational injector producer pressure difference and injector produce distance are chosen and the effective displacement pressure difference is established, the harmful influences of starting pressure gradient and pressure sensitivity can be overcome and the development effect can he improved.