Optimal Nanosilica Concentration in Synthetic-Based Mud for HP/HT Wells

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 176036, “Optimal Nanosilica Concentration in Synthetic-Based Muds for High-Pressure/High-Temperature Wells,” by Norazwan Wahid and Muhammad Aslam Md. Yusof, Petronas, and Nor Hazimastura Hanafi, Scomi Oiltools, prepared for the 2015 SPE Asia Pacific Oil and Gas Conference and Exhibition, Bali, Indonesia, 20–22 October. The paper has not been peer reviewed. At certain conditions, the good performance of synthetic-based mud (SBM) will degrade, particularly because of the effect of chemical instability under high temperature. The study of nanoparticles in smart fluids in drilling operations has been gaining attention worldwide. This study intends to describe the improvement in performance of SBM with silicon dioxide (SiO2) nanopowder (nanosilica) at different concentrations. Introduction Recently, research into the use of nanotechnology to design smart fluids containing nanoparticles has been conducted. This enhanced formulation with nanoparticles is intended to become a system optimizer, particularly with an aim toward enhancing filtration performance and providing better rheological behavior. The use of nanoparticles as a system optimizer corresponds with the fact that nanoparticles have better thermal stability [good for high-pressure/ high-temperature (HP/HT) conditions], are able to serve as bridging agents in fluid-loss systems to control lost circulation, and form Pickering emulsions for stabilizer systems. Although this research began almost a decade ago, there is no consensus about what percentage of nanoparticles must be added to a system to achieve optimal performance of the drilling fluid in reducing the drilling-fluid cost in total. Therefore, this study intends to investigate the role of nanosilica in improving SBM rheological properties and to identify the optimal concentration of nanosilica in SBM formulations. Experimental Approach The first part of this study focuses on the performance of nanosilica in the base-mud system, where the testing temperature is 275°F, to understand its behavior at normal drilling temperatures. The second part of this study focuses on evaluating the performance of enhanced SBM formulations with nanosilica at the onset of HP/HT conditions (350°F). The concentration of nanosilica became the modifying parameter in the analysis, and it varies from 20 to 60% of the commercial-fluid-loss-control-additive weight [0.16 to 1.05% of total mud weight (MW)]. Overall, the study focuses on mud properties such as MW, plastic viscosity (PV), yield point (YP), gel strength, electrical stability, and HP/HT fluid-loss volume. A process flow chart, as well as a discussion of testing equipment, is provided in the complete paper.