Search citation statements
Paper Sections
Citation Types
Year Published
Publication Types
Relationship
Authors
Journals
The flocculation of aqueous-based drilling fluid, particularly at high temperature or in a high-salinity environment, is a common problem. The aggregation and settling of solid particles (e.g. manganese tetraoxide) causes operational problems, such as stuck pipe, well control, false bit gain, and scale problems. The flocculation of manganese tetraoxide particles becomes more severe at high density with the presence of clays such as bentonite and common fluid contaminants, such as cement and divalent salts. This affects the rheological behavior and sagging tendency of the drilling fluid adversely. Dispersants called deflocculants, thinner or dispersing agents, are used in drilling fluids to prevent solid flocculation. To minimize such flocculation problems, a thorough study was undertaken to identify aggregation of Mn3O4 particles and appropriate dispersants for water–based fluids weighted with Mn3O4. The dispersion of Mn3O4 particles in aqueous solutions was evaluated through visual transparency testing and a PC-2200 Spectrek laser particle analyzer. A Mastersizer 2000 was used to obtain the particle size distribution and specific surface area of Mn3O4 particles. A TGA was used to assess the thermal stability. The compatibility of over 50 dispersants with aqueous solutions was examined using a variable speed mixer. Viscosity and sagging tendency were evaluated using a Fan 35A viscometer and density variation measurements. The effect of CaCl2 was considered in the experimental study. The drilling fluids were aged using a hot rolling oven up to 400°F. Linear and other structures of particle aggregations were identified in Mn3O4-based filter cake. Dispersants examined were categorized into groups A, B, and C. Groups A and B dispersants showed settling times of 24 hours and 1–3 hours, respectively. More than 25 dispersants were assigned to groups A and B. Laser particle analysis showed that aggregation of particles was reduced in the presence of a lignosulfonate-based dispersant. Lignosulfonate and acrylate-based dispersants were compatible with water-based fluids and thermally stable up to 400°F and in the presence of CaCl2. Both dispersants reduced the sag factor and fluid loss for the drilling fluids in the presence of cement contamination. The shear stress/rate relationship and viscosity measurements showed that the rheological behavior of drilling fluids dispersed with either dispersants was improved. The dispersants chosen were non-toxic to aquatic organisms and biodegradable. The examined drilling fluids were high-density fluids up to 20 lbm/gal appropriate for deep drilling.
The flocculation of aqueous-based drilling fluid, particularly at high temperature or in a high-salinity environment, is a common problem. The aggregation and settling of solid particles (e.g. manganese tetraoxide) causes operational problems, such as stuck pipe, well control, false bit gain, and scale problems. The flocculation of manganese tetraoxide particles becomes more severe at high density with the presence of clays such as bentonite and common fluid contaminants, such as cement and divalent salts. This affects the rheological behavior and sagging tendency of the drilling fluid adversely. Dispersants called deflocculants, thinner or dispersing agents, are used in drilling fluids to prevent solid flocculation. To minimize such flocculation problems, a thorough study was undertaken to identify aggregation of Mn3O4 particles and appropriate dispersants for water–based fluids weighted with Mn3O4. The dispersion of Mn3O4 particles in aqueous solutions was evaluated through visual transparency testing and a PC-2200 Spectrek laser particle analyzer. A Mastersizer 2000 was used to obtain the particle size distribution and specific surface area of Mn3O4 particles. A TGA was used to assess the thermal stability. The compatibility of over 50 dispersants with aqueous solutions was examined using a variable speed mixer. Viscosity and sagging tendency were evaluated using a Fan 35A viscometer and density variation measurements. The effect of CaCl2 was considered in the experimental study. The drilling fluids were aged using a hot rolling oven up to 400°F. Linear and other structures of particle aggregations were identified in Mn3O4-based filter cake. Dispersants examined were categorized into groups A, B, and C. Groups A and B dispersants showed settling times of 24 hours and 1–3 hours, respectively. More than 25 dispersants were assigned to groups A and B. Laser particle analysis showed that aggregation of particles was reduced in the presence of a lignosulfonate-based dispersant. Lignosulfonate and acrylate-based dispersants were compatible with water-based fluids and thermally stable up to 400°F and in the presence of CaCl2. Both dispersants reduced the sag factor and fluid loss for the drilling fluids in the presence of cement contamination. The shear stress/rate relationship and viscosity measurements showed that the rheological behavior of drilling fluids dispersed with either dispersants was improved. The dispersants chosen were non-toxic to aquatic organisms and biodegradable. The examined drilling fluids were high-density fluids up to 20 lbm/gal appropriate for deep drilling.
Managing the solid flocculation in high-density drilling fluids is a challenge in drilling operations. A weighting material such as manganese tetroxide is used to formulate drilling fluids at density requirements for deep drilling because of its high specific gravity (i.e. 4.8). However, the microsized particles, surface charge, and presence of biopolymers increase the tendency to agglomerate and, thus, promote sagging. Developing a good dispersant is critical for a successful drilling operation, especially in HP/HT conditions. The dispersion of Mn3O4 particles in aqueous solutions was evaluated through visual transparency testing and a PC-2200 Spectrek laser particle analyzer. A Mastersizer 2000 was used to obtain the particle size distribution and specific surface area of Mn3O4 particles. TGA and variable speed mixers were used to assess the thermal stability and compatibility. Rheology and sagging tendency were evaluated using a Fan 35A viscometer and density variation measurements. The microstructure of Mn3O4-based filter cake was interpreted through SEM to identify the aggregation of solid particles. The effect of CaCl2 on the solubility and dispersion of Mn3O4 particles in aqueous dispersant solutions was considered in the experimental study. The drilling fluids were aged at 400°F. Several dispersants showed high potential to disperse manganese tetroxide particles in water-based drilling fluids. The dispersants examined showed particle settling times from 0.03 to 24 hours. Zeta potential measurements showed a region of dispersion stability at a pH from 6 to 11 for lignosulfonate and sulfonic acid-based dispersants. Zeta potential and particle settling tests indicated that dispersion with sulfonic based copolymer is more effective than that of benzene sulfonic acid. Zeta potential values increased with temperature in sulfonic acid-based dispersant (i.e., 77 and 120°F). Zeta potential and transparency experiments showed that the optimum dispersant concentration was below 1 wt% and nearly 0.5 wt%. TGA analysis showed that the acrylates- and lignosulfonate-based dispersants were thermally stable between 300 and 500°F. SEM images of filter cake showed that aggregation of particles was reduced when acrylic based dispersant was used in clay contaminated drilling fluid. In most cases, the rheological behavior (i.e, shear stresses and viscosities) of clay contaminated and non-contaminated drilling fluids (17.5 and 20 lbm/gal) before/after heat aging at 400°F was lower in the presence of dispersants. Dispersant solutions with NaCl had varying compatibilities and particle settling interactions. The settling times of manganese tetroxide particles were lower, higher, or did not change for several dispersant solutions at 5 and 10 wt% NaCl. The sagging tendency of clay contaminated and non-contaminated drilling fluids was improved in the presence of dispersants. For instance, the sag factor was reduced from 0.55 to 0.51 in clay and rock salt contaminated drilling fluids when acrylic based copolymer was used.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.