Zhao Chunhua, Zhang Jian, Lv Jianrong, Huang Bo, Yang Guang, Tang Engao, Chen Minggui, Xu Chenyu, Ge Yizhuo
. . State Key Laboratory of Offshore Oil Exploitation, CNOOC, Beijing 100028, PR China.
. . Research Institute of Exploration and Development, Xinjiang Oilfield Company, Petro China, Karamay 834000, PR China.
ACS Omega. 2023 Dec 19;9(1):422-436. doi: 10.1021/acsomega.3c05875. eCollection 2024 Jan 9.
Injecting water with chemicals to generate emulsions in the reservoir is a promising method for enhancing heavy oil recovery because oil-in-water (O/W) emulsions significantly reduce oil viscosity. To enhance heavy oil recovery efficiency, we developed new star-like branched AM-SSS copolymers (SB-PAMs) with reduction in the viscosity of the heavy oil emulsion, which was synthesized by reversible addition-fragmentation chain transfer (RAFT) controlled radical polymerization. The core structure of the branched polymer was RAFT polymerization of acrylamide (AM) and ,'-methylene bis-acrylamide (BisAM), in the presence of 3-(((benzylthio)carbonothioyl)thio)propanoic acid as a chain transfer agent, followed by chain extension with AM and SSS. The core structures were achieved by incorporation of total monomer ratios [BisAM]/[AM] of 1:11. The expansion of the core structures by copolymerization of AM and SSS resulted in star-like branched polymer SB-PAM--SSS with apparent molecular weights ranging from 240 to 2381 kDa. H-nuclear magnetic resonance (H NMR) and Fourier transform infrared (FTIR) confirmed the synthesized polymer structure. The molecular weight was determined by gel permeation chromatography (GPC). The polydispersity coefficient was between 1 and 7, which has a broad molecular weight distribution. The polymer dissolves only 0.75 h in deionized water, faster than conventional polyacrylamide. At 50 °C, the viscosity of the 1000 mg/L SB-polymer solution can reach up to 45 mPa·s. First, heavy oil viscosity reduction by 800 mg/L SB polymer can reach 91.7%, at a water dehydration rate of 90.4%; second, with 0.6 PV injection, 800 mg/L SB polymer improved oil recovery up to 23.66% after water flooding; and third, SB-polymer-assisted hot water flooding shows that heavy oil recovery improved by 19.46% at 110 °C with 0.6 pore volume (PV) SB-polymer injection. This novel branched chain polymer with heavy oil emulsion capability will shed light on high-temperature polymer flooding and the development of a new candidate structure for heavy oil viscosity reduction.
向油藏中注入含化学剂的水以生成乳液是提高稠油采收率的一种很有前景的方法，因为水包油（O/W）乳液能显著降低原油粘度。为提高稠油采收效率，我们通过可逆加成-断裂链转移（RAFT）可控自由基聚合反应合成了新型星状支化AM-SSS共聚物（SB-PAMs），该共聚物能降低稠油乳液的粘度。支化聚合物的核心结构是在3-(((苄硫基)羰基硫基)硫代)丙酸作为链转移剂的存在下，丙烯酰胺（AM）和N,N'-亚甲基双丙烯酰胺（BisAM）进行RAFT聚合，随后用AM和SSS进行扩链。通过加入总单体比例为[BisAM]/[AM] 1:11来实现核心结构。AM和SSS的共聚使核心结构扩展，得到了表观分子量范围为240至2381 kDa的星状支化聚合物SB-PAM-SSS。氢核磁共振（H NMR）和傅里叶变换红外光谱（FTIR）证实了合成聚合物的结构。分子量通过凝胶渗透色谱（GPC）测定。多分散系数在1到7之间，具有较宽的分子量分布。该聚合物在去离子水中仅0.75小时即可溶解，比传统聚丙烯酰胺更快。在50℃下，1000 mg/L SB聚合物溶液的粘度可达45 mPa·s。首先，800 mg/L SB聚合物使稠油粘度降低91.7%，脱水率达90.4%；其次，注入0.6孔隙体积（PV）后，800 mg/L SB聚合物在水驱后提高采收率达23.66%；第三，SB聚合物辅助热水驱表明，在110℃注入0.6孔隙体积（PV）的SB聚合物时，稠油采收率提高了19.46%。这种具有稠油乳化能力的新型支链聚合物将为高温聚合物驱以及开发新的稠油降粘候选结构提供思路。
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