Abstract

Oil well cement additives applied in high-temperature environments play an increasingly important role in well cementing work. In this study, a ternary copolymer LNS-1 consisting of sodium styrene sulfonate (SSS), maleic acid (MA), and N-vinylcaprolactam (NVCL) was designed and synthesized using potassium persulfate as an initiator via free radical aqueous solution copolymerization, which was then used as a retarder additive for oil well cement under high-temperature conditions. The structure and performance of copolymer LNS-1 was assessed via gel permeation chromatography, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance hydrogen spectrum, Thermogravimetric analysis, and scanning electron microscopy analysis. To study the effect of the retarder on cement slurry properties, the performance of the slurry with LNS-1 was tested. The experimental results demonstrate that LNS-1 was successfully synthesized with excellent retarding ability, thermal resistance, and outstanding suspension; thus, the copolymer can serve as an excellent retarder for oil well cement. Through exploration, it is found that the mechanism of the retarder mainly includes adsorption – membrane layer mechanism and chelation – covering mechanism. NVCL exhibits good complexation, adsorption, hydrolysis stability, and thermal stability. It contains three lone pairs of electrons, which allow the NVCL to chelate Ca²⁺ that in the liquid phase of the cement. The number of calcium ions is therefore reduced in the cement liquid phase, and cement hydration is inhibited to a certain extent, contributing to a longer hydration process.

摘要

应用于高温环境的油井水泥添加剂在固井工作中发挥着越来越重要的作用。本研究以过硫酸钾为引发剂，通过自由基水溶液共聚，设计合成了苯乙烯磺酸钠（SSS）、马来酸（MA）和N-乙烯基己内酰胺（NVCL）三元共聚物LNS-1。随后被用作高温条件下油井水泥的缓凝剂。通过凝胶渗透色谱、X射线光电子能谱、傅里叶变换红外光谱、核磁共振氢谱、热重分析和扫描电子显微镜分析对共聚物LNS-1的结构和性能进行了评估。研究缓凝剂对水泥浆性能的影响，测试了含有 LNS-1 的浆料的性能。实验结果表明，LNS-1成功合成，具有优异的缓凝性、耐热性和优异的悬浮性；因此，该共聚物可作为油井水泥的优良缓凝剂。通过探索发现缓凝剂的作用机理主要包括吸附-膜层机理和螯合-覆盖机理。NVCL表现出良好的络合、吸附、水解稳定性和热稳定性。它包含三个孤对电子，使 NVCL 能够螯合 Ca 该共聚物可作为油井水泥的优良缓凝剂。通过探索发现缓凝剂的作用机理主要包括吸附-膜层机理和螯合-覆盖机理。NVCL表现出良好的络合、吸附、水解稳定性和热稳定性。它包含三个孤对电子，使 NVCL 能够螯合 Ca 该共聚物可作为油井水泥的优良缓凝剂。通过探索发现缓凝剂的作用机理主要包括吸附-膜层机理和螯合-覆盖机理。NVCL表现出良好的络合、吸附、水解稳定性和热稳定性。它包含三个孤对电子，使 NVCL 能够螯合 Ca²⁺在水泥的液相中。因此水泥液相中钙离子的数量减少，水泥水化受到一定程度的抑制，有助于延长水化过程。