一种具有“盐响应”特性的两性离子聚合物增黏降滤失剂

A novel salt-responsive zwitterion polymer tackifying-fluid loss additive

随着深层、超深层及非常规油气开采的不断深入,钻井过程中盐污染已成为水基钻井液在极端盐度和高温条件下面临的严峻挑战,盐污染会导致钻井液流变性和滤失性能的急速恶化。为避免上述问题发生,通过自由基聚合反应研发了一种具有“盐响应”特性的两性离子聚合物增黏降滤失剂(PAMN),并利用红外光谱分析(FT-IR)、核磁共振氢谱分析(1H-NMR)、热重分析(TGA)、分子模拟技术(MS)、扫描电镜(SEM)及钻井液流变和滤失分析等实验方法,表征了PAMN的分子结构、热稳定性及增黏降滤失性能,并揭示了PAMN的“盐响应”机理。研究结果表明:①合成的PAMN热降解温度高达285℃,PAMN分子链在饱和盐水中的均方位移、扩散系数及回转半径远大于其在纯水中,其回转半径分别为12.5Å和3.8Å;②当氯化钠含量为0时,PAMN分子链内或分子链间正负离子基团通过静电吸引力形成空间网络形态而卷曲成类球状结构,随着氯化钠含量增加,其分子链逐渐转变为溶解性更好的柔性链状结构,对氯化钠表现出正响应性;③PAMN可将饱和盐水钻井液表观黏度增加542.9%,滤失量从194 mL降低至4.8 mL,具有良好的增黏和降滤失性能。结论认为,PAMN的研发成功从根本上实现了传统钻井液处理剂从“抗盐”到“盐响应”的转变,该产品在含盐膏的深层、超深层油气开发工程中具有广阔的应用前景。

As deep,ultra-deep and unconventional oil and gas production advances continuously,salt contamination in the process of well drilling has brought a serious challenge to water-based drilling fluids under the conditions of extreme salinity and high temperature,and it can deteriorate the rheology and filtration performance of drilling fluid rapidly.In this paper,a novel zwitterion polymer tackifyingfluid loss additive(PAMN)with"salt-responsive"characteristics is synthesized through free radical polymerization reaction.In addition,its molecular structure,thermal stability and viscosity increasing and filtration reducing performance are characterized by infrared spectroscopy(FT-IR),nuclear magnetic resonance hydrogen spectroscopy analysis(1H-NMR),thermogravimetric analysis(TGA),molecular simulation technology(MS),scanning electron microscopy(SEM),and drilling fluid rheological and filtration analysis,and its"salt-responsive"mechanism is revealed.And the following research results are obtained.First,the PAMN synthesized in this paper has a thermal degradation temperature of 285℃,and its molecular chains have much larger mean square displacement,diffusion coefficient and gyration radius in saturated saline than in pure water.The gyration radius in saturated saline and pure water are 12.5Åand 3.8Å,respectively.Second,when the sodium chloride content is 0,the positive and negative ion groups within or between PAMN molecular chains form a spatial network shape through electrostatic attraction and curl into the spherical structure.As the sodium chloride content increases,the molecular chains gradually transform into more soluble flexible chain structures,exhibiting positive responsiveness to sodium chloride.Third,PAMN can increase the apparent viscosity of saturated-saline drilling fluid by 542.9%,and reduce the fluid loss from 194 mL to 4.8 mL,which indicates its good performance in tackifying and fluid-loss reducing.In conclusion,the successful development of PAMN has fundamentally transformed the traditional drilling fluid treatment agent from"salt-resistant"to"salt-responsive",and this product has promising application prospects in the oil and gas developmentof salt-gypsum-bearing deep and ultra-deep strata.