Effect of Crosslinker Types on Temporary Plugging Performance of Degradable Preformed Particle Gels for Unconventional Petroleum Reservoir Development

Abstract

Temporary plugging agents (TPAs) have been widely used in unconventional petroleum reservoirs to increase the stimulated reservoir volume and generate an easier flow of oil and gas into the production well. The properties of particle-gel-based TPAs include a straightforward injection procedure, excellent deformation, strong plugging strength, and total self-degradation. This study prepared degradable preformed particle gel (DPPG) samples polymerized by two types of crosslinkers (i.e., alcohol ester and alkenoic acid ester) for low-temperature (less than 40 °C) reservoirs. The effects of different crosslinkers in the DPPG compositions on the temporary plugging performance were investigated. Infrared spectrum analysis, differential calorimetry scanning evaluation, static particle gel swelling and degradation performance assessment experiments, and dynamic temporary plugging performance tests were all employed. The results showed that the swelling ratio of DPPGs prepared by the crosslinker containing alcohol ester was larger than that of alkenoate acid ester, but the degradation rate was slower. Among them, when the amount of crosslinker was 0.01 g, the swelling ratio of DPPG prepared using the alcohol ester crosslinker was as high as 40 times, and the complete degradation time could be regulated between 80 and 360 h. When the type of crosslinker was the same, the influence of its molecular weight also significantly affected the performance of the particle gel. The plugging strength of DPPG prepared by different crosslinkers in cores was as high as 20 MPa. The DPPG prepared from the alcohol ester crosslinker caused less damage to the core after being self-degraded and was used as an ideal crosslinker. Infrared spectroscopy and differential scanning calorimetry analysis at the molecular level verified that different types of crosslinkers had apparent effects on the chemical structure stability of the DPPG. In this paper, the influence of the type of crosslinker on the performance of the DPPG was studied, which provides a new idea and theoretical basis for developing a particle gel-based TPA system with programmed self-degradation time at low temperatures.

Synthesis and Performance Study of Self-Degradable Gel Plugging Agents Suitable for Medium- and Low-Temperature Reservoirs

“…Since the Tuha Engineering Institute proposed the gel plugging technology under pressure in 2007, many scholars have carried out research on this technology, and the feasibility of this technology has been verified through field experiments. − With the rise of polymer chemistry, polymer gel technology has achieved long-term development, giving birth to hydrogel materials with good pregelling rheological properties, characterized by easy injection, postgelling deformability, and adjustable plugging strength. − Therefore, polymer gels boast unique advantages in plugging operations. − Due to its high deformability, it is not restricted by the leakage channel. After injection, it can be cross-linked and copolymerized from an easy-flowing polymer or monomer solution to form immobile jelly or gel, which can produce a plugging effect in extremely small pores.…”