Effect of carboxymethylcellulose on the rheological and filtration properties of bentonite clay samples determined by experimental planning and statistical analysis

Abstract

Over the past few years, considerable research has been conducted using the techniques of mixture delineation and statistical modeling. Through this methodology, applications in various technological fields have been found/optimized, especially in clay technology, leading to greater efficiency and reliability. This work studied the influence of carboxymethylcellulose on the rheological and filtration properties of bentonite dispersions to be applied in water-based drilling fluids using experimental planning and statistical analysis for clay mixtures. The dispersions were prepared according to Petrobras standard EP-1EP-00011-A, which deals with the testing of water-based drilling fluid viscosifiers for oil prospecting. The clay mixtures were transformed into sodic compounds, and carboxymethylcellulose additives of high and low molar mass were added, in order to improve their rheology and filtrate volume. Experimental planning and statistical analysis were used to verify the effect. The regression models were calculated for the relation between the compositions and the following rheological properties: apparent viscosity, plastic viscosity, and filtrate volume. The significance and validity of the models were confirmed. The results showed that the 3D response surfaces of the compositions with high molecular weight carboxymethylcellulose added were the ones that most contributed to the rise in apparent viscosity and plastic viscosity, and that those with low molecular weight were the ones that most helped in the reduction of the filtrate volume. Another important observation is that the experimental planning and statistical analysis can be used as an important auxiliary tool to optimize the rheological properties and filtrate volume of bentonite clay dispersions for use in drilling fluids when carboxymethylcellulose is added.

Comparative Analysis of Carboxymethyl Cellulose and Partially Hydrolyzed Polyacrylamide – Low-Solid Nondispersed Drilling Mud With Respect to Proper-Ty Enhancement and Shale Inhibition

“…Variations in the filtration properties, including the filtrate loss and mud cake thickness, are shown in Figures 15-18. Both the filtrate loss [17] and mud cake thickness show the desired decreasing trend as the CMC [22] and PHPA [12] concentrations increase. The PHPA mud shows a greater decrease in mud cake thickness, providing a thin mud cake, which is desirable and essential for a stable wellbore.…”

“…The densities of the prepared CMC and PHPA muds with increasing concentration are shown in Figures 1 and 2. Figures 1 and 2 show that the density increases slightly, from 1018.52 to 1024.52 kg/m 3 , with increasing CMC concentration [17]; for PHPA, the density increases from 1020.92 to 1025.71 kg/m 3 . This result indicates that as the formation pressure increases, higher concentrations of CMC and PHPA can aid in maintaining the required safety allowance for hydrostatic pressure.…”

Influence of MgO and CaCl2 on the rheological properties of bentonitic clays from the new Paraíba-Brazil deposits using experimental planning and statistical analysis

“…In this study, Olivedos clays were also investigated individually, which did not produce satisfactory results, driving the decision to use secondary additives with these samples. The physical, chemical and mineralogical characterizations of the used clay samples are described in [12], which shows that they had clay minerals from the smectite group with kaolinite and mica, and quartz as a non-clay mineral. These clays were transformed with a sodium compound through the classic process with the addition of sodium carbonate at a ratio of 125 meq/100 g of dry clay.…”

“…These systems have been shown to have satisfactory rheological property values at intermediate points, where traditional techniques do not indicate adequate results. Some researchers [12][13][14] have used statistical and mathematical techniques to study the effect of clay compositions and additives on the rheological properties of clay-water systems. This methodology has found application in a number of technological areas [13][14][15][16][17].…”

Stabilization of the swelling soil for earth construction

“…The carboxymethyl cellulose is a cellulose ether composed of sodium cellulose glycolate, also known as cellulose gum [40][41][42][43][44][45]…”