致密油碎屑岩储层分类方法探讨

Discussion on the Classification Method of Tight Oil Clastic Rock Reservoirs

中国石油行业常规碎屑岩储层分类是按孔隙度的倍数分类,而致密油等非常规油气藏还没有一个统一的致密储层分类行业标准。一般来说,石油对于碎屑岩具有非润湿性,水对于碎屑岩具有润湿性,因此,油、水在致密储层孔喉与外界间会产生毛细管压力,推动油、水的相互流动,流动量的大小与孔喉直径、毛细管压力高低以及浮力大小有较大关系,由此产生油饱和度和水饱和度随孔隙度起伏变化,在变化的拐点、极值点或突变点可作为致密油储层的分类界点。因此,把常规储层分类中的特低孔隙度特低渗透率储层作为致密储层重新调整分类界点,并进一步细分为流体束缚、毛细管和油水平衡三类致密储层。

The classification of conventional pyroclastic rocks in Chinese oil industry is often classified by the multiples of porosity.But unconventional oil and gas reservoirs, such as tight oil, have no uniform industry standard for tight reservoir classification.Generally speaking, oil has non-wettability and water has wettability for pyroclastic rocks.Therefore, oil and water will produce capillary pressure between the pore throat of tight reservoir and external environment which will promote oil and water flow.The flow rate is related to pore throat diameter, capillary pressure and buoyancy, which will cause the variation of oil and water saturation with porosity.The inflection point, extreme point or mutation point can be used as the boundary point of tight oil reservoir classification.Thus, the tight oil reservoir in the Sichuan basin can be divided into three kinds of tight reservoirs： fluid binding, capillary and oil-water balance.