Preparation and investigation of self-healing gel for mitigating circulation loss

Abstract

Lost circulation is a common and complex downhole accident in the process of oil and gas drilling. Traditional bridge plugging material has the limitation of poor adaptability to lost formations. Therefore, this study synthesized a new self-healing plugging material to improve the plugging success rate; specifically, the hydrophobic association polymer lauryl methlacrylate-acrylamide-acrylic acid containing Fe 3+ was modified via curdlan to form a composite gel with high strength and self-healing properties. The self-healing time, mechanicalness and rheological properties of the self-healing gel were systematically evaluated. The results showed that the modification of curdlan could significantly improve the mechanical properties and rheological strength of self-healing gel, and the chelating structure formed by Fe 3+ and carboxyl groups could further enhance the mechanical properties of the self-healing gel. Toughness and storage modulus of the LF 0.15 C 2 selfhealing gel with the introduction of curdlan and Fe 3+ could reach 30.2 kJ/m 3 and 3,458 Pa, respectively. Compared with conventional gel materials, composite gels with self-healing properties exhibited better pressure-bearing capacity of 2.5 MPa, and could effectively avoid causing plugging at the entrance of the fractures by high-concentration inert material and improve the pressure-bearing capacity. In addition, the plugging mechanism of the self-healing gel modified via curdlan in formation fractures was analysed in detail. The self-healing gel modified via curdlan prepared in this work has application potential as a lost circulation material in the field of oil and gas drilling.

Review of the Perspectives and Study of Thermo-Responsive Polymer Gels and Applications in Oil-Based Drilling Fluids

“…As oil and gas extraction moves towards increasingly complex and variable reservoir environments, the demand for high-quality oilfield chemicals continues to rise. Researchers have drawn on previous successes and advancements with thermo-responsive polymers in other fields to develop intelligent materials for oil and gas extraction [66][67][68][69][70][71][72], as shown in Figure 6. These materials display the advantageous properties of thermo-responsive polymers, resulting in high efficiency and environmental friendliness.…”

Nanolaponite/Comb Polymer Composite as a Rheological Modifier for Water-Based Drilling Fluids

“…The drilling workload and drilling difficulty continue to increase. Drilling fluid with excellent performance is the key to safe, efficient, economical, and green drilling . The drilling fluid rheology is the core parameter used to evaluate the performance of the drilling fluid system, which plays a decisive role in the ability of the drilling fluid to suspend cuttings and clean the wellbore. − However, under ultrahigh temperatures and high salt conditions in deep wells, drilling fluid additives are greatly affected by degradation, flocculation, and instability, resulting in out-of-control rheological properties of the drilling fluid, which can lead to sticking, wellbore instability and leakage, and other complex downhole accidents.…”