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

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.