Experimental Effect of Biopolymers, Synthetic and Modified Polymers on Western Pakistan Shale (GHAZIJ) Stability

Several wellbore instabilities issues arise when drilling into any reactive shale formation. These problems affect the drilling activity seriously which eventually results in non-productive time events. This article primarily focuses on the reduction in filtration loss volume and increased wellbore stability in shale by making it hydrophobic in nature upon its contact with industrial polymers classified as biopolymers, synthetic polymer, and modified polymer. The comparison is performed to highlight the advantages of ecofriendly biopolymers over other classes of polymeric systems. The result of the study reveals significant reduction in filtrate loss volume with the use of biopolymers. Their polymeric chain entangled with the hydrogen bonding in xanthan gum and decreased the loss of filtrate volume. Moreover, biopolymers also formed thin, smooth, and denser mud cake. On the other hand, the presence of monovalent cations in the base mud system reduced the performance of modified polymer and caused them to dehydrate. These mud systems were also tested on Ghazij shale obtained from the western part of Pakistan. The cutting disintegration test after 24 h revealed the efficacy of biopolymers with 100% and shale cutting recovery of 95%. The encapsulation of the shale cutting was the reason behind the higher recovery percentage. This result was also validated by the linear dynamic swell meter test. In addition, the contact angle measurement revealed that biopolymers were capable of increasing the hydrophobicity of shale formation, preventing the migration of water molecules and increasing the overall shale stability.