Analysis of Effects of Foreign Clay and Local Clay Additives on Viscosity of Water Based Drilling Mud

Abstract

This research compared the viscosity and other allied rheological properties of formulated water based drilling mud using local clay (that is modified with cheap and available additives) and foreign clay. These additives (such as xanthum gum, high viscosity polyanionic cellulose (PAC-R), modified natural polyanionic cellulose (PAC-L), potassium hydroxide (KOH), sodium carbonate (Na2CO3), and barite) are added to enhance/control the rheological properties (such as density, viscosity, yield point and gel strength) of the drilling mud. In this work, the viscosity and other allied rheological properties of water based mud were improved by the use of locally sourced clay from Awgu in Enugu State. The local clay was beneficiated/treated with hydrochloric acid (HCl) and characterized using x-ray fluorescence (XRF) spectrometer. The results of the characterization revealed that the local clay is more of silica which is typical of a kaolinitic clay. Local clay was examined as a possible replacement for foreign bentonite by comparing the rheological properties of water based mud (WBM) with bentonite and WBM with clay. Plastic viscosities (PV) of WBM with bentonite and WBM with clay were found to be 11.7 and 12.3 cP respectively. Other allied properties such as yield point, gel strength, pH and mud weight of WBM with bentonite and WBM with clay adequately compared closely. Laboratory analyses on the effects of three process variables (such as temperature, aging time and dosage of clay/bentonite) on the viscosity of the formulated muds were investigated. The laboratory results show that the readily available additives added to the local clay improved its viscosity and other allied rheological properties for effective drilling of oil and gas well when compared with foreign bentonite.