Effective Modified Xanthan Gum Fluid Loss Agent for High-Temperature Water-Based Drilling Fluid and the Filtration Control Mechanism

Abstract

Xanthan gum (XG) was widely used as an oilfield chemical treatment agent because of its environmental protection and diverse functions. With the increased drilling depth and formation complexity, the shortcomings such as poor solubility and low resistance to temperature were gradually exposed. In this study, a modified XG derivative XG-g-AAA was synthesized by grafting XG with acrylic acid (AA), acrylamide (AM), and 2-acrylamido-2-methylpropane sulfonic acid (AMPS). The chemical structure of XG-g-AAA was determined by Fourier transform infrared spectroscopy and nuclear magnetic resonance ( 1 H NMR). Then, the solubility, high-temperature rheology and filtration properties, resistance to Na + /Ca 2+ , and compatibility were investigated. Results show that (1) both in aqueous and salt solutions, XG-g-AAA can completely be dissolved within 15 min. The significant improvement of the solubility of XG-g-AAA makes it more suitable for field use. ( 2) XG-g-AAA is less sensitive to high temperatures, and the viscosity decay decreased by 23.3 and 21.3% than XG at 150 and 180 °C, respectively. XG-g-AAA-based drilling fluid is a high-quality drilling fluid with significant shear thinning behavior, and the power-law model is the optimal model to describe its high-temperature rheology. Within 150 °C, 1.5% XG-g-AAA can maintain a reasonable value of the flow behavior index (n) (0.55−0.69), filtration volume (<11.6 mL), and sufficient gel strength (GS). At 150−200 °C, 3% XG-g-AAA is recommended. The value of n was in the range of 0.45−0.62, and the fluid loss was within 10 mL. However, 3% XG-g-AAA cannot provide enough GS at 200 °C; thus, a shear strength-improving agent is recommended to be added. (3) XG-g-AAA showed excellent contamination tolerance and compatibility. It could resist 2 wt % CaCl 2 and 35 wt % NaCl at room temperature and 0.75% CaCl 2 and 5% NaCl after 150 °C aging. (4) XG-g-AAA showed compatibility with sulfonated drilling fluids and could replace commercial fluid loss agents in the formula. Furthermore, the high-temperature fluid loss control mechanism was discussed by analyzing the effects of XG-g-AAA on the bentonite layer spacing, particle size distribution, stability of the colloidal system, and mud cakes.

Investigation on Filtration Control of Zwitterionic Polymer AADN in High Temperature High Pressure Water-Based Drilling Fluids

“…The interlayer distance (d 001 ) can effectively characterize the hydration dispersion effect of BT particles [ 42 ]. The interlayer distance of BT particles was analyzed by XRD, as shown in Figure 7 .…”

Deep Eutectic Solvents for Enhancing the Rheological Behavior of Polymers and Clays in Polymeric Water-Based Drilling Fluids

“…Natural biopolymers include xanthan gum, guar gum, starch, and cellulose and their modified products. ,− Synthetic polymers are mainly acrylamide synthetic polymers. Various acrylamide-based polymers have been developed through the optimization of molecular monomers and molecular structures, and they have been widely used in drilling fluids. − In contrast, natural biopolymers have a stronger ability to improve drilling fluid rheology and are environmentally friendly, but the disadvantage is insufficient temperature resistance. ,− Whether it is a natural, modified, or synthetic polymer, most polymeric rheological modifiers often improve the suspension and rock-carrying ability of drilling fluids by way of viscosification. The molecular structure chain of the polymer is stretched and intertwined with each other, which greatly increases the apparent viscosity of the drilling fluid, thereby improving the suspending ability of the system.…”

Nano-Grafted Acrylamide Copolymer as an Anti-Temperature and Anti-Calcium Fluid Loss Agent for Water-Based Drilling Fluids

“…Drilling fluids are essential to drilling operations in the same way as blood is to the human body. − Water-based drilling fluids (WBDFs) are prioritized despite the fact that oil-based drilling fluids perform better than they do in terms of performance because of the high cost of oil-based drilling fluids and their poor environmental performance. − Water, bentonite, and other treatment agents are the main ingredients of WBDFs, which are still the most frequently used drilling fluids in drilling operations. , Free water in the drilling fluid intrudes into the formation as a result of the pressure differential between the formation and the borehole . Yet, significant water loss results in drilling that is extremely stuck, wellbore collapses, damages to the formation, and even reduces drilling efficiency. , …”