Modified Rectorite Provides Reliable Rheology and Suspendability in Biodiesel-Based Fluids

Abstract

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 189310, “Novel Modified Rectorite Provides Reliable Rheology and Suspendability for Biodiesel-Based Drilling Fluid,” by Wai Li, SPE, Beijing Oilchemleader Science and Technology Development Company; Jishan Liu, The University of Western Australia; Xionghu Zhao, Jian Zhang, and Jiwei Jiang, SPE, China University of Petroleum; Tao He, GWDC Drilling Fluid Company; Liu Liu and Peiyuan Shen, The University of Western Australia; and Min Zhang, Sinopec, prepared for the 2018 SPE/IADC Middle East Drilling Technology Conference and Exhibition, Abu Dhabi, 29–31 January. The paper has not been peer reviewed. The use of organophilic clays as additives to provide proper rheological and filtration properties in nonaqueous drilling fluids (NADFs) has long been a topic of study. Currently, most of these clays are based on the modification of bentonite with quaternary ammonium salts. As new NADF systems emerge, novel clay-modification technologies are needed to obtain more-effective organophilic clays for specific drilling fluids. This paper introduced a modified rectorite designed for biodiesel-based drilling fluid (BBDF). Introduction Biodiesel has drawn a great deal of attention from petroleum scientists and drilling engineers who are seeking environmentally friendly, high-performance, low-cost drilling fluids. The advantageous properties of biodiesel—such as a high flash point (for fire safety), sufficient viscosity (to carry cuttings to the surface during drilling), low eco-toxicity, excellent biodegradability, and good lubricity—make it suitable as a base oil for drilling fluid. Biodiesel also is relatively inexpensive in many situations. Many investigations and trials are being con-ducted on BBDF, suggesting some exciting results. A general necessity for new drilling-fluid techniques is to customize a series of corresponding chemical additives; BBDF is no exception. Preliminary experience has shown that an additive used in traditional oil-based drilling fluids (OBDFs) may be unable to perform well in a BBDF system. Consequently, new additives should be developed for BBDF in order to obtain the optimal operational and environmental properties. Traditionally, most organophilic clays for drilling fluids are based on the intercalating reaction between bentonite and quaternary ammonium salts, which are classified as cationic surfactants. However, this type of organobentonite (OB) still has some disadvantages, such as eco- toxicity and high resistance to degradation when discarded in the environment. Inexpensive rectorite has been selected to replace the commonly used bentonite as the raw clay to produce organophilic clay through a modification reaction with nonionic surfactants. Crucial properties, including swelling index, viscosity, yield point, gel strength, and suspendability, were evaluated.