侧链对油井水泥降失水剂性能的影响及机理研究

Effects of Polymer Sidechains on Performance of Oil Well Cement Filter Loss Reducers and Studies on Mechanisms of the Effects

为明确共聚物型油井水泥浆降失水剂的构效关系以及指导新型抗超高温耐盐降失水剂的分子结构设计,通过分子动力学模拟和实验相结合的方法研究了侧链结构对共聚物型降失水剂性能的影响及其抗温耐盐作用机理。实验结果表明,刚性苯环侧基的引入降低了240℃养护后淡水/饱和盐水水泥浆的API失水量,表现出优异的抗超高温耐盐性能。通过分子动力学模拟结果表明,刚性苯环侧基的引入增大了共聚物链段的回转半径,并减弱大量反离子(Na^(+)和Ca^(2+))存在时对共聚物功能基团的去水化作用。这有利于降失水剂在水泥颗粒表面的吸附和水化,并充分发挥其原有使用效能。

To understand the relationship between the molecular structure and the performance of copolymers used as oil well cement filter loss reducers,as well as to guide the molecular structure design of new ultra-high temperature and salt resistant filter loss reducers,the effects of polymer sidechains on the filtration control performance of the copolymer filter loss reducer were studied through molecular kinetics simulation and laboratory experiment.The mechanisms of the copolymer’s ability to resist high temperature and salt contamination were also investigated.Laboratory experimental results show that the introduction of rigid benzene side groups into the final copolymer reduces the API filtration rate of a fresh water and a saturated saltwater cement slurry after being aged at 240℃,meaning that the copolymer has excellent ultra-high temperature and salt-resistant performance.Molecular kinetics simulation results show that the introduction of the rigid benzene side groups increases the gyration radius of the copolymer segments,weakens the dehydration effect of the large amount of counterions(Na^(+)and Ca^(2+))on the functional groups of the copolymer.This is beneficial to the adsorption and hydration of the filter loss reducer molecules on the surfaces of the cement particles,and gives full play to its original use efficiency.