Study of Rheological Characteristics of a Water-Based Drilling Fluid in Presence of Biopolymers, Synthetic Polymer, and Modified Natural Polymer

Abstract

The major contemplation in the recent decades is to minimize the operational difficulties during any drilling activity by improving the characteristics of water-based drilling fluids (WBDF). Such problem as a poor hole-cleaning because of settling of drill cutting and debris are extremely common. This problem will eventually convert into a serious non-productive time event in the form of pipe sticking. The most common additives added in the mud system to improve its rheological properties and tackle sedimentation issues are polymeric materials. During this study, four different polymers including sodium alginate and pure-bore as biopolymers, PHPA as a synthetic polymer, and the L-grade polyanionic cellulose (PAC-L) as a modified natural polymer have been used to improve rheological characteristics of WBDF. Laboratory measurements have indicated no considerable changes in the mud weight in the case of addition of these polymers. Moreover, these results reveal that all the systems behave as shear thinning fluid (flow index 1). A decrease in the dynamic viscosity with an increase in the shear rate has been observed for all samples. The disentangling of polymeric chains occurring at high shear rate eventually reduces the viscosity of these systems. In addition, samples that comprised of pure-bore and sodium alginate exhibit the desired operating magnitude of rheology (PV, YP, GS, AV, and YP/PV). These results show such particles minimize operational problems arising because of a poor hole-cleaning. In contrast, a system with PHPA and PAC-L has shown detrimental rheological characteristics. The high molecular weight of PHPA and the hydration of PAC-L in the presence of potassium chloride decrease their performance.