Hydroxyethyl cellulose as a rheology modifier for water-based drilling fluids formulated with Algerian bentonite

Abstract

Under the different geological conditions of wells and during the drilling operation, some of the water-based drilling fluid compositions are sometimes not efficient for the drilling success of the oil and gas wells (case of the Algerian oil and gas wells). In the use of bentonite in drilling fluid applications, the addition of hydroxyethyl cellulose (HEC) is recommended to obtain good rheological properties of the fluid. In this research, we investigate the rheological behaviour in steady state, and dynamic shear rheology of drilling fluids formulated based on an Algerian bentonite with a fixed concentration of 3 wt% and a water-soluble polymer HEC of high molecular weight (~ 9.5 × 10 5 g/mol) at different concentrations ranged from 0.02 to 0.2%. All the results obtained by a controlled stress rheometer have been commented by taking the interaction between the clay and the polymer molecules into consideration, to highlight the effect of HEC on the rheological properties of bentonite suspensions. Herschel-Bulkley (H-B) model was used to fit and interpret the experimental data. A significant increase in the rheological properties of the mixture bentonite-HEC with the increase in HEC concentration has been shown. These properties reached the maximum at HEC concentration of 0.1 wt%; beyond this value, they decreased. X-ray diffraction test performed on the different samples also allowed understanding the rheological behaviour of the system bentonite-HEC. Indeed, the HEC could intercalate the bentonite interlayer and formed link bridges between bentonite particles below a critical concentration of 0.1 wt%. Based on the results of the study, it is recommended to choose the optimum concentration of HEC to be added to the bentonite suspension to ensure the optimum rheological characteristics of the drilling fluids. Keywords Water-based mud • HEC • Algerian bentonite • Rheological properties • X-ray diffraction List of symbols Roman symbols G′ Storage modulus (Pa) G″ Loss modulus (Pa) G 0 Elastic modulus (Pa) k Consistency index (Pa s n) n Flow index w Pulsation (rad/s) Greek symbols α Time constant (s) Shear rate (s −1) λ X-ray wavelength (Å) 2θ Scattering angle Viscosity of the polymer solution (Pa s) 0 Zero shear rate viscosity (Pa s) ∞ Infinite shear rate viscosity (Pa s) τ Shear stress (Pa) τ c Yield stress (Pa)

Gel Stability of Calcium Bentonite Suspension in Brine and Its Application in Water-Based Drilling Fluids

“…The treatment agents used to prepare drilling fluids directly with seawater can be divided into two categories: organic treatment agents and inorganic treatment agents. Inorganic treatment agents are usually sodium carbonate, sodium hydroxide, potassium hydroxide, etc., used to adjust the pH of the drilling fluid; commonly used organic treatment agents are polyacrylamide (PAM), hydrolyzed sodium polyacrylonitrile (NaPAN), carboxymethyl cellulose sodium (CMC) [ 16 , 17 ], hydroxyethyl cellulose (HEC), polyanionic cellulose (PAC), xanthan gum biopolymer (XC) [ 18 , 19 , 20 ], sulfomethylated phenolic resin (SMP) and other salt-resistant water-soluble polymers [ 21 , 22 , 23 , 24 , 25 , 26 , 27 ].…”

Optimizing the impact of rheological properties on bentonite pre-hydrated based drilling mud through the utilization of pre-hydration

“…Excessive bentonite addition can lead to excessively high viscosity, which may hinder drilling progress and increase pumping requirements. Therefore, the optimal concentration of bentonite should be determined based on factors such as the specific drilling conditions, desired mud properties, and the characteristics of the formation being drilled [15] and completion [16][17][18].…”

Rheological Properties of Bentonite/Polymer Based Drilling Fluid Under Different pH Conditions

“…To produce valuable and good results, before starting the rheological tests, the samples were softly agitated for 20 min, thereafter, the mud was closely loaded to the measuring geometry of the rheometer. Samples were also exposed to a preshear of 1000 s −1 , and afterwards, they were left at rest prior to the measurements for 60 s to have the identical structural state of reference [18,19].…”