X油田Aradeiba和Bentiu储层所含粘土矿物以高岭石为主,不含蒙脱石等膨胀性粘土矿物。应用岩心流动实验对Aradeba和Bentiu储层进行了水敏性实验研究,结果表明储层具有强水敏性。水敏机理分析表明,储层内流体矿化度的大幅度降低将减弱颗粒与高岭石间的结构力而产生水敏效应。通过对储层岩石成分和微观结构的分析,高岭石在岩石中存在两种水敏机理,或分散、移动并堵塞喉道,或使胶结的矿物颗粒分解、移动,造成储层渗透率下降。研究表明储层水敏性强弱与各类岩性特征有直接关系,并在此基础上提出了相应的开发对策。
The clay minerals in Aradeiba and Bentiu reservoirs of X oilfield are mainly made up of kaolinite and no expansive clay, such as montmorillonite. This paper studies the water sensitivity through core flow experiment. The results show that reservoirs possess strong water sensitivity. Precipitous decrease of fluid salinity has weakened the attraction between grains and kaolinite and leads to water sensitivity effect. Analysis of core composition and microstrueture indicates that kaolinite has two different water sensitivity mechanisms: one is directly dispersing and blocking throat, the other is detaching rock particles. Above two mechanisms have been proved to be the decrease reason of the reservoir permeability. The study proves that various lithological characteristics have intimate relations to the intensity of water sensitivity. And furthermore ,on the basis of the above study results, the corresponding development measures have been carried out.