Development of a polyacrylamide-based mud formulation for loss circulation treatments

Loss circulation materials in the last two decades have witnessed a lot of developments and implementations. New technologies and materials are introduced to treat various types of loss zones. However, the success rate is still very low due to many uncertainties in the selection of types and particle size of the bridging materials. In addition, there are many operational restrictions such as the risk of plugging and pumping difficulties when large size of particle is needed, especially in deep-water drilling. In this study, polyacrylamide (PAM) crosslinked with polyethylenimine (PEI) is introduced as polymer-based mud for loss circulation treatment. The PAM/PEI systems have wide applications in water shutoff for high water production zones and are known for their strong gel and exceptional rheological properties. This study provides a rheological method for screening of PAM/PEI-based drilling formulation with optimized molecular weight and concentrations. Comparative analysis of rheology of non-crosslinked and crosslinked polyacrylamide with other drilling fluids additives as well as proper mixing procedures are provided. The results achieved in this study are used as a strong tool to design a polymer-based mud with competitive rheological properties which achieved an 80% reduction in fluid loss when compared with other conventional loss circulation materials.