黑云母水化机理及对注水开发影响

BIOTITE HYDRATION MECHANISM AND THE INFLUENCE ON WATER INJECTION PRODUCTION

从黑云母的化学结构和结晶形态出发,本质上分析了黑云母的水化机理,黑云母水化的实质是层间域中K+被其他大分子或离子替换,是一个释放K+的过程。水化过程可分为解理缝裂开、边缘断裂分散为特征的边缘水化阶段和解理缝消失、颗粒呈鳞片状为特征的完全水化阶段。黑云母一旦在储层中水化,晶体结构膨胀,部分边缘颗粒逐渐脱落,随水动力分散运移,堵塞孔喉,易造成储层损害。含黑云母储层在注水开发中应该提高K+浓度,防止云母水化产物产生的水敏和速敏损害,以保护储集层。

Biotite is a common rock-forming mineral and widely exists in reservoir,it is stable in solution rich in K+ and easy to hydrate in solution poor in K+,biotite hydration may transform into hydrobiotite,vermiculite,montmorillonite,chlorite,kaolinite and so on.Based on chemical structure and crystal form of biotite,the authors of this paper analyze mechanism of biotite hydration,biotite hydration in essence is a procedure of releasing K+ interlayer.Hydration falls into edge stage with the characters of cleavage dehiscence and complete stage with features of cleavage disappearance.Once biotite hydrate occurs in reservoir,crystal structure will swell,particles on the edge will gradually drop off,migrate with hydrodynamic dispersion,block the throat and damage reservoir.Thus,water injection in reservoir with biotite minerals is suggested to boost concentration of K+,avoid water and flow velocity sensitivity due to generation of biotite hydration and protect reservoir.