Water‐free synthesis of temperature‐sensitive polyacrylamide microgels and pore modeled oil recovery performance

Abstract

Polymer gel treatments can improve sweep efficiency and reduce water production during oil recovery operations. In this article, a novel suspension polymerization method was developed to synthesize a temperature-sensitive microgel. The microgel was prepared by suspension polymerization above the melting point of the monomer in a nonpolar solvent without water. Dry microspheres were obtained, which can be readily used without post-treatment. Two different crosslinkers were employed in the suspension polymerization synthesis to give the particles thermally responsive aqueous swelling properties. After entering pore channels, gel particles expand to engineered size to realize flow profile changes within in a reservoir formation. When dispersed into water under lower temperatures (ambient to 40 8C), the original dry particles can swell about 18 times their original size. Exposure to a harsher environment (e.g., 80 8C) resulted in cleavage of the labile crosslinking agent and some chain cleavage gave a further size expansion. A Millipore film filtration model system was adopted to evaluate pore occlusion performance of the gel particles. It was found that the nuclear pores were effectively sealed by swollen microgels only when gel particle sizes were similar to or smaller than the membrane pores and interpore separation distance.

Fabrication and characteristics of self‐aggregation nanoparticles used for conformance control treatment

“…Therefore, the thermal stability of the nanoparticles is higher than those of the conventional HPAM and polymer nanoparticles with single organic cross‐linked structure 31,32 . According to thermogravimetric analysis, we can infer that these nanoparticles are heterogeneous, which also agrees with the TEM observation and elements analysis results.…”

“…It shows that the weight loss of the nanoparticles can be divided into three stages, which are 0 C to 360 C, from 360 C to 480 C, from 480 C to 610 C. Therefore, the thermal stability of the nanoparticles is higher than those of the conventional HPAM and polymer nanoparticles with single organic cross-linked structure. 31,32 According to thermogravimetric analysis, we can infer that these nanoparticles are heterogeneous, which also agrees with the TEM observation and elements analysis results. The mechanical shear resistance of CSA nanoparticles were introduced in the case of 6000 rpm and 10,000 rpm, respectively.…”

Development of Thermotransformable Controlled Hydrogel for Enhancing Oil Recovery

“…Inventive tPPG serves as a plugging agent for a designed and controlled period to improve the conformance control, so that more oil may be swept out of the low-permeability formation pores to the production well. Meanwhile, depending on the stimuli-like reservoir temperature (main factor), pH value, and/or formation water salinity, the labile (temperature-sensitive) cross-linker disintegrates, − resulting in the formation of a viscous polymer solution. Viscous polymer solution from the “smart” degradation of tPPG moves into the deep regions of the reservoir formation to increase water viscosity and, hence, boost polymer flooding.…”

Water Control with Gels Based on Synthetic Polymers under Extreme Conditions in Oil Wells

“…The particle size can be well controlled during synthesis and the softness of the particles can penetrate reservoir rock without mechanical trapping [41,47]. The microgels can swell by absorbing water, pH changing, temperature or CO 2 stimulation in such a way that they can expand many times their diameter and occlude the rock pores and stimulate the oil production; plugging efficiencies up to 97 % can be obtained [66][67][68]. Microgels are made up of anionic or cationic polymers.…”