Activation of Local Bentonite for Oil and Gas Industry Application

Magzoub, et al 20171 have proposed a method of converting calcium bentonite to sodium bentonite. The method will require a reactor for upscaling. The method involves preparation of soda ash solution, heating, mixing for at least 24 hours and finally removing impurities and drying out. Besun et al. 19972 have proposed a method that will require also a reactor facility to upscale. Starch has to be added in water then bentonite is added in a separate water solution. Both were mixed and heated to form a structure of bentonite-starch gel. The formed gel has 20% starch and 80% bentonite. Bentonite is used in different applications such as drilling fluid, leaching earth, and animal feed additive.3 Sodium bentonite is more attractive in applications such as drilling due to its high swelling and good fluid loss control which makes it always in high demand. 4 & 5 The objectives of this study are to investigate and characterize local calcium bentonite in Saudi Arabia and to find optimum method to activate it for application in drilling fluids and cementing. The characterization performed utilized XRF, XRD, and ESEM backscattered electron images along with EDS spectra for samples collected from different depths (5 meter and 7-meter samples). API testing including viscosity and fluid loss measurements were also conducted in the characterization phase. Activation was done utilizing cost effective additives such as soda ash. The activated bentonite was testing using standard testing procedures for drilling fluids and cementing such as rheology, fluid loss control, settling, compressive strength and thickening time tests. The characterization concluded that the samples consisted mainly of Na-montmorillonite with appreciable amounts of impurities of quartz, kaolinite, illite, albite, calcite, and hematite. Compared to API reference sample, the local bentonite samples had less Na-montmorillonite contents, which probably needs some treatments to improve their quality. From this characterization, we can tell that activation of the 7 meter will be easier than the 5-meter bentonite because the Sodium Montmorillonite content is higher. The activation effort was focused on the 7-meter local bentonite sample since it showed better properties in terms of viscosity build up and fluid loss control. A new cost-effective activation method was conducted compared to the previous methods in the literature. Soda ash is an important step to convert or to increase the Na/Ca ratio to ensure higher swelling capacity.