ATP负载杂环两性共聚物型超高温降失水剂的合成与性能评价

The Synthesis of ATP Loaded Heterocyclic Amphoteric Copolymer and Its Performance and Mechanisms of Reducing Filtration Rate under Ultra-High Temperatures

现有AMPS共聚物类降失水剂高温稀释降黏作用明显,对固井水泥浆的超高温沉降稳定性尤其不利。对此,合成了一种凹凸棒土(ATP)负载杂环两性共聚物型超高温固井降失水剂ATP-FLA以减弱共聚物的高温分散副作用。对负载前后的产品进行了综合性能对比,结果表明,在150~240℃范围内,加有4.0%~6.0%负载型降失水剂ATP-FLA、2.0%~4.0%悬浮剂的水泥浆API失水量不大于40 mL,沉降密度差不大于0.03 g/cm^(3),超高温稳定性良好。在240℃、120 MPa下养护后的水泥浆流性指数达到0.8976,浆体高温稠度高,剪切阻力大。同时,利用超高温固井现场水泥浆对ATPFLA进行了适应性评价,结果表明其能够在有效控制API失水量的同时不影响水泥浆的其他性能。此外,利用分子动力学模拟研究了杂环两性共聚物FLA的作用机理。模拟分析结果表明,杂环两性共聚物FLA相比于常规阴离子型共聚物的优势在于其减弱了自身分子链受环境中金属离子的“去水化”效应干扰,更耐金属离子进攻,使其更加适应水泥浆体系的碱金属离子溶液环境。

The AMPS copolymer filter loss reducers have obvious thinning effect which is detrimental to the ultra-high temperature settling stability cement slurries.To solve this problem,an ultra-high temperature cement slurry filter loss reducer ATP-FLA is developed for use at elevated temperatures to weaken the high temperature dispersion side-effect of pure copolymers.ATP-FLA is synthesized as an attapulgite(ATP)loaded heterocyclic amphoteric copolymer.Comparison of the copolymer with and without ATP loading shows that in a temperature range of 150-240℃,a cement slurry treated with 4.0%-6.0%ATP-FLA and 2.0%-4.0%suspending agent has API filtration rate of less than 40 mL and density difference from settlement of the cement slurry of not greater than 0.03 g/cm^(3).After aging at 240℃and 120 MPa,the cement slurry has flow index of 0.897,6 as well as high thickness and shear resistance at high temperatures.To evaluate the compatibility of the filter loss reducer ATP-FLA,ultra-high temperature cement slurry samples were taken from several wellsites.The evaluation test results show that the ATP-FLA can control the filtration rate without affecting the other properties of the cement slurries.Study on the working mechanisms of ATP-FLA using molecular dynamics shows that ATP-FLA has advantages over conventional ionic copolymers in that the disturbances to the molecular chains of ATP-FLA from the“dehydration”effect of metal ions in the environment are weakened,and the ATP-FLA molecules are therefore resistant to the attack of the metal ions,and this is why,on the basis of mechanisms,the ATP-FLA filter loss reducer is more adaptable to the metal ion environment prevailing in cement slurries.