Preparation of MOF-Based Core-Shell Gel Particles with Catalytic Activity and Their Plugging Performance

Abstract

Drilling fluid systems for deep and ultra-deep wells are hampered by both high-temperature downhole environments and lengthy cycle periods. Suppose that the gel particle-plugging agent, the primary treatment agent in the system, fails to offer durable and stable plugging performance. In such a scenario, the borehole wall is susceptible to instability and landslide after prolonged immersion, leading to downhole accidents. In this study, novel core-shell gel particles (modified ZIF) with ZIF particles employed as the core material and organosilicon-modified polyethylene polyamine (PEPA) as the polymer shell were fabricated using PEPA, in-house synthesized (3-aminopropyl) triethoxysilane (APTS), and the ZIF-8 metal-organic framework (MOF) as the raw materials to enhance the long-term plugging performance of gel plugging agents. The modified ZIF particles are nanoscale polygonal crystals and differ from conventional core-shell gel particles in that they feature high molecular sieve catalytic activity due to the presence of numerous interior micropores and mesopores. As a result, modified ZIF exhibits the performance characteristics of both rigid and flexible plugging agents and has an excellent catalytic cross-linking effect on the sulfonated phenolic resin (SMP-3) and sulfonated lignite resin (SPNH) in drilling fluids. Consequently, a cross-linking reaction occurs when SMP-3 and SPNH flow through the spacings in the plugging layer formed by the modified ZIF particles. This increases the viscosity of the liquid phase and simultaneously generates an insoluble gel, forming a particle-gel composite plugging structure with the modified ZIF and significantly enhancing the long-term plugging performance of the drilling fluid.

Application and Research Prospect of Functional Polymer Gels in Oil and Gas Drilling and Development Engineering

“…Fan et al [68] developed a fractured-formation polymer plugging gel particle; the covalent bonding of the reactive carboxylate and hydroxylate monomers used as raw materials improves the physical properties of the gel. The gel also has good deformation capacity; with a pressure-bearing capacity of up to 21 MPa and counterpressure capacity of up to 20 MPa, it is more than twice as strong as conventional polymer buffer gels and can significantly improve formation pressure capacity and well control (team of academic Sun [69]). A new type of core-shell gel particle (modified ZIF) was prepared (Figure 10) that possessed both rigid and flexible sealing properties and crosslinks with sulfonated phenolic resin (SMP-3) and sulfonated lignite resin (SPNH) in drilling fluids to increase the viscosity of the fluid as it passes through the gaps in the barrier layer formed by the modified ZIF particles, preparing insoluble gels and gel complexes of modified ZIF particles to increase the long-term thickening properties of the drilling fluid, successfully adjusting the rheological properties of the drilling fluid and optimizing the efficiency of reducing seepage losses.…”