一种延缓交联凝胶的长岩心物模性能评价

Performance Evaluation on Physical Model of Long Core forA Delayed Crosslinking Gel

针对目前油田深部调剖的需要,研制出一种延缓交联的凝胶调剖剂体系,通过长岩心物模实验对其性能进行评价。研究结果表明:该凝胶调剖剂体系初始黏度低,在40mPa·s以内;低黏度周期长, 10天内黏度在250mPa·s以内;25天后体系成胶强度2400mPa·s以上,且65天内基本保持不变,热稳定性良好。该凝胶调剖剂体系经1. 2m长岩心两次剪切后,最终成胶强度可以达到1500mPa·s以上,且65天内强度基本不变,黏度损失率仅为37. 5%,具有较好的深部调剖能力;该凝胶调剖剂体系经长岩心两次反复剪切后的凝胶蠕变恢复率为80%,且恢复应力百分比最低为5%,依然具有一定的形变恢复和抗压能力,说明该延缓交联的凝胶体系注入性能良好;该凝胶调剖剂体系经长岩心剪切后成胶强度大小是由Cr3+的岩心吸附和聚合物剪切双方共同作用所决定的,虽然成胶强度有一定的损失,但依然可以保证成胶,且强度较强;体系的岩心封堵率达到96%以上,可以满足现场的封堵要求,为油田深部调剖提供了有效的技术保障。

According to the needs of deep profile control in oilfield presently,a delayed crosslinking gel profile control agent system has been developed,whose performance was evaluated by testing a long core physical model experiment.Research results showed that the gel control agent system has low initial viscosity of less than 40mPa·s.The low viscosity cycle was long,remaining within 250mPa·s in 10 days,and the gel strength reached higher than 2400mPa·s after 25 days,which kept constant basically in 65 days with good thermal stability.After twice shearing in 1.2m long core,the final gel strength could still be higher than 1500mPa·s with unchanged strength in 65 days,and the viscosity loss rate was only 37.5%with favorable deep profile control ability.Gel creep recovery rate of the gel profile control agent system was 80%after twice shearing,and the lowest recovery stress percentage rate was 5%with a certain deformation recovery and compressive capacity.It is indicated that the delayed crosslinking gel system has a good injection performance.The gel strength value of the gel profile control agent system after shearing in long core is dependent on the combined action of both the adsorption on the core of Cr3+and shear force of polymer,although a certain loss in the gel strength,which still has gelling action with relatively strong gel strength.The core plugging rate of the gel system is above 96%,which can meet the requirement of plugging operation in the field application.The system provides effective technical supports for deep profile control in oilfield.