基于仿生技术的泥页岩井壁稳定处理液研究

Bionic Technique-Based Treatment Fluid for Wellbore Stability in Drilling through Shale Formations

为解决气体钻井钻遇地层出水引发的泥页岩井壁失稳问题,根据植物叶面的"荷叶效应",优选了仿生处理剂,研制了泥页岩仿生处理液,并进行了室内性能评价试验。试验结果表明,该仿生处理液能有效降低泥页岩表面的表面能,形成类似于荷叶或芋叶表面的微米—纳米突起结构,实现泥页岩表面从亲水向疏水转变(清水接触角大于120°),从而达到阻止泥页岩自吸水的作用,提高泥页岩在水溶液中的强度,维持泥页岩井壁稳定;同时,该仿生处理液形成的疏水表面具有一定耐磨性和热稳定性,不受地层水矿化度的影响,适用于中性或碱性条件,但地层温度不宜高于80℃。研究表明,利用仿生学原理,通过控制泥页岩的自吸水作用避免泥页岩黏土水化,可作为一种解决气体钻井地层出水导致井壁失稳问题的有效途径。

Using bionic treatment fluid while drilling through shale formations was developed by optimization of bionic treatment agents based on the ＂lotus effect＂ of plant leaves. The goal was to solve wellbore instability issues due to water production while drilling through shale gas formations. Experimental tests were used to evaluate the performance of such bionic treatment fluid. The tests results showed that the bionic treatment fluid could effectively reduce surface energy of shales and form bump structures at a micro or nano scale in the same way that those on lotus or taro leaves convert the shale surface from hydrophilic to hydrophobic （the contact angle of fresh water is larger than 120°） which prevents shales from absorbing water and to enhance shale strength while in water solution. In addition, hydrophobic surfaces generated by the bionic treatment fluid have certain abrasion resistance and thermal stability, and are not affected by the salinity of formation water. The bionic treatment fluid is applicable to neutral or alkaline formations with temperatures under 80 ℃. In summary,it is an effective measure for solving wellbore instability issues in drilling through shale gas formations because, based on the bionic theory, it is possible to prevent clay hydration through water adsorption.