The BST oilfield in the northwestern Taklamakan Desert is a fractured carbonate reservoir, but issues of water breakthrough are becoming increasingly severe with the development of water flooding. Unfortunately, the high-temperature and high-salt conditions (130 °C, 71695 mg/L) of the BST oilfield pose challenges for the development of plugging agents. In this study, the effects of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) content on AM/AMPS copolymers and gels were studied through viscosity measurements, nuclear magnetic resonance (NMR), and cryo-scanning electron microscope (Cryo-SEM). Moreover, the AMPS stabilization mechanism of the polymers and gels was explained. Heat-resistant and salt-tolerant gel systems were developed, and their gelation properties, thermal stability, injection capacity, and plugging ability were evaluated. Experimental results showed inconsistencies between the effects of AMPS content on the polymers and gels. For the polymers, the thermal stability increased with increased AMPS content in the polymer. However, excessive AMPS content resulted in poor gelation and low strength. The developed gel systems with S30 polymer (AMPS content is approximately 26%) exhibited excellent thermal stability, controllable gelation time, good injection capacity, and plugging ability. The field application results indicated that most production wells had a positive response, with reduced water-cut and increased daily oil production.
Pan Xiong,Yanyan Niu,Fanjun Meng,Qinglin Ma,Cui Song,Qian Zhang,Yuju Che
The conventional acrylamide-based polymers are greatly restricted under the reservoir conditions of high temperature and high salt due to their linear molecular structures. In this article, a grafted water-soluble copolymer based on hydroxypropyl methyl cellulose (HPMC) with excellent thermal viscosifying and salt-tolerant properties at low concentration was prepared via the “graft from” method, with acrylamide (AM) and methyl allyl polyoxyethylene ether (HPEG) as grafted monomers . The structure of the copolymer was identified by 1 H nuclear magnetic resonance spectroscopy ( 1 H NMR), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The basic displacement properties of the copolymers under extreme conditions were systematically studied. The results showed that due to the symbiotic effects of the rigid heterocyclic structure of HPMC and the hydrophobic inter-molecular aggregation of thermosensitive HPEG units in the copolymer chain, the copolymer exhibited better thermal thickening ability (the viscosity enhancements changes from 7.1 to 19.9 times from 25 °C to 95 °C in brine solution with total salinity 9350.08 mg.L −1 ), salt resistance (the viscosity enhancements changes from 1.13 to 2.29 times with salts concentration from 0.0 wt% to 2.0 wt% at 85 °C), shear tolerance (the viscosity retention rate was from 18.6% to 24.2% at 1000s −1 ) and anti-aging properties (the viscosity retention rate up to 73.7% at 65 °C for three weeks) than polyacrylamide at low concentration (0.2 wt%). Furthermore, the polymer flooding test showed that the copolymer yielded a higher recovery rate of 23.2% higher than that yielded by polyacrylamide (14.5%), elucidating that the copolymer synthesized herein was suitable for enhanced oil recovery in reservoirs with severe conditions.
危险品化学品经营许可证（带存储）