低渗透储层特征研究

LOW PERMEABILITY FORMATION CHARACTERS

不同低渗透储层特征差异大,储层特征对渗流能力和开发效果有重要影响。通过对大庆和长庆低渗透储层岩芯恒速压汞、核磁共振、启动压力梯度、粘土类型与含量分析测试,对比研究了低渗透储层特征。研究结果表明主流喉道半径是渗流能力的主控因素,粘土类型及含量和可动流体饱和度进一步减小了储层的有效渗流空间,特别是大庆低渗透储层粘土含量高,以伊利石和蒙脱石为主,对渗流空间影响很大。气测渗透率相近的储层,长庆低渗透储层与大庆低渗透储层相比,主流喉道半径大、可动流体饱和度高以及启动压力梯度小。这些特征参数揭示了大庆和长庆低渗透油藏开发难度差异的原因。

The low permeability formation characters of different oil fields are much different,which affects the ability flowing through porous media and development effect.Constant rate Hg injection test,NMR test,threshold pressure gradient to flow test and clay analysis are carried out on low permeability cores from Daqing and Changqing Oilfields to study their formation properties and characters of flow through porous media.Research results indicate that the main flow throat is the main controlling factor for ability flowing through porous media.The amount and types of clay minerals and movable fluid saturation decrease the effective size of flow channels especially for Daqing low permeability formation with high amount of clay.For Changqing and Daqing Oilfields,even with the same gas permeability,the main flow radium and movable fluid saturation of low permeability reservoirs in Changqing are much bigger than those in Daqing,while the threshold pressure gradient of low permeability reservoirs in Changqing is much lower than that in Daqing,which indicates why it is easier to develop low permeability reservoirs in Changqing than to develop the low permeability reservoirs in Daqing.