致密砂岩气层毛细管自吸水锁损害及控制因素

Damage of water blocking by spontaneous imbibition in tight sandstone gas reservoir and its controlling factors

王俊杰 胡勇 刘义成 张连进 兰雪梅 何溥为1

中国石油西南油气田分公司勘探开发研究院，四川 成都 610000 中国石油西南油气田分公司，四川 成都 610000）

Exploration and Development Research Institute, Southwest Oil & Gas Field Company, PetroChina, Chengdu 610000, China Southwest Oil & Gasfield Company, PetroChina, Chengdu 610000, China

致密砂岩气层具有特殊的微观储层地质特征，在开发过程中极易形成水锁损害，而目前水锁损害主要通过检测宏观物性参数的变化来表征，未能刻画微观机理及控制因素。文中基于核磁共振T2谱、核磁成像等手段，建立了一套致密砂岩毛细管自吸水锁损害定量、可视化表征方法。研究表明：物性较好的岩心孔喉半径大、迂曲程度低，岩心自吸强度大于扩散强度；初始含水饱和度越低，毛细管自吸强度越大，流体主要分布在半径0.01 μm以下的小孔隙内；裂缝可以降低孔隙迂曲程度，扩大流体与基质的接触面，加速毛细管自吸水锁损害的形成；毛细管半径越小对应的自吸毛细管力越强，流体优先通过自吸进入半径0.01 μm以下的孔隙。孔喉半径和孔隙迂曲程度是影响致密砂岩气层自吸水锁损害形成的重要因素。

The tight sandstone gas reservoir has special micro?鄄reservoir geological characteristics, which makes it easy to form water blocking damage in the development process. At present, the characterization of water blocking damage mainly depends on the change of physical parameters, which fails to describe the micro?鄄mechanism and controlling factors. Based on NMR T2 spectroscopy and imaging, this study establishes a set of quantitative and visual characterization methods for capillary self?鄄suction blocking damage in tight sandstone. The results show that the core with good physical properties has large pore throat radius and low tortuosity. The self?鄄priming strength of core is greater than the diffusion strength. The lower the initial water saturation is, the greater the capillary self?鄄priming strength is. The fluid in the initial state is mainly distributed in the small pore with radius less than 0.01 μm. Fractures reduce the degree of pore tortuosity. Fracture surface enlarges the contact area between fluid and matrix, and accelerates the formation of capillary self?鄄suction locking damage. The smaller the capillary radius is, the stronger the self?鄄priming capillary force is. The fluid preferentially enters the pore with radius less than 0.01 μm through self?鄄priming. The radius of pore throat and the degree of pore tortuosity are important factors affecting the formation of self?鄄absorbent blocking damage in tight sandstone.

10.6056/dkyqt201905018