含离子液体链段抗高温高盐钙降滤失剂可控聚合方法及作用机理研究

The performance of filtration control additives in drilling fluid affects the quality of filtration control and wall building and directly relates to the success of well drilling. As the exploration and exploitation level of hydrocarbon reservoir in complicated geological conditions strengthens, higher requirements of temperature-, salt- and calcium-resistant properties have been presented for filtration control additives. However, almost all of the filtration control additives in water-based drilling fluids used currently are prepared by conventional methods, the calcium-resistance of which is not sufficient at high temperature. Therefore, only researching with new methods and developing novel filtration control additives with excellent temperature-, salt- and calcium-resistance can we guarantee the safety and high efficiency of drilling operation..On the basis of the relevant research in laboratory, we first proposed a brand-new design of filtration control additive by introducing ionic liquid segments into the molecular structure with reversible addition–fragmentation chain transfer (RAFT) polymerization method, and then would reveal the mechanism of anti-temperature, salt and calcium. The main work is as follows: optimizing the formula of ionic liquid; exploring RAFT “living” polymerization method for copolymers; preparing copolymers with different compositions, molecular weights and structures; systematically assess the filtration control ability of the copolymers with different structures, molecular weights and compositions, mainly in order to obtain temperature-, salt- and calcium-resistant filtration control additives with low molecular weight; revealing the interactions between copolymers containing ionic liquid segment and clay, and clearly demonstrating the mechanism of filtration control on the foundation of the DLVO theory..Finally, a set of controlled polymerization method and technology will be established for fabricating filtration control additives with high-performance of temperature-, salt- and calcium-resistance, which would show great theoretical and practical significance for promoting the drilling fluids applications.

钻井液用降滤失剂性能好坏影响滤失造壁性，并直接关系钻井成败。随着勘探开发复杂地质条件油气藏力度的加大，对降滤失剂的抗高温高盐钙能力提出了更高要求，而目前水基钻井液降滤失剂几乎都是按照传统方法研发，高温下抗盐钙能力不足。创建新的研发思路，开发新型抗高温高盐钙降滤失剂是保证我国钻井作业安全高效进行的重要保障。申请人在实验室研究基础上，首次采用可控聚合方法研发性能优异的含离子液体链段聚合物降滤失剂，并揭示抗高温高盐钙和降滤失机理。主要包括：优选离子液体种类；探索共聚物的RAFT“活性”聚合方法，研发组成、分子量和结构可控的聚合物；系统评价聚合物降滤失剂性能与组成、分子量及结构的关系，制备低分子量抗高温高盐钙降滤失剂；结合DLVO理论，揭示高温高盐钙条件下聚合物与粘土之间作用行为和降滤失机理。从而创建抗高温高盐钙聚合物降滤失剂的可控聚合方法和技术，对推动我国钻井液技术发展具有重要的理论和现实意义。

离子液体具有良好的热稳定性和化学稳定性，已在绿色反应化学、生物质催化、萃取分离和电化学等领域发挥了重要作用。本研究利用离子液体天然阳离子及抗高温的特点，制备了钻井液用抗高温高钙降滤失剂和抗高温抑制剂，并对机理进行深入分析，能够为钻井作业安全高效进行提供重要保障。.首先，优选1-乙烯基-3-乙基咪唑溴盐离子液体（VeiBr），与AMPS和AM进行聚合，合成一种共聚物PASV。实验表明PASV表现良好的抗高温高钙降滤失性；此外，探究了PASV的降滤失机理，发现它能够通过氢键与离子键吸附在黏土颗粒上，阻止Ca2+与粘土结合，降低Ca2+对黏土的电荷中和作用，促进黏土颗粒的分散，改善滤饼质量，从而形成致密的滤饼，降低滤失量。.然后，采用RAFT聚合方法，实现VeiBr、AMPS和AM三种单体的活性聚合，制备了一系列不同分子量的聚合物。实验发现聚合物的分子量及结构均对其降滤失性产生影响。分子量越大，降滤失性越好；与嵌段共聚物相比，无规共聚有利于降滤失性的提高。.实验还发现，离子液体可以作为高效页岩抑制剂应用于钻井液中。离子液体的阳离子和阴离子均可以对其抑制性产生影响。无论阴离子还是阳离子，尺寸越小、亲水性越好的组成，有利于其抑制性能的提高，但作用机理有很大区别。其中阳离子的大小及亲疏水性能够影响其进入层间减小层间距的能力影响抑制性；阴离子能够影响离子液体的稳定粘土胶体的能力而影响其抑制性。.综合以上几个方面，本研究主要针对离子液体在钻井液中应用的可行性，展开了大量研究，并进行深入分析，能够为抗高温钻井液处理剂的研发打下坚实基础。