针对SZ36-1油田的堵漏返排型修井液体系研究

Research on the Loss Control and Flow-back Workover Fluid Used in Block SZ36-1

在SZ36—1油田修井作业过程中易发生修井液大量漏失，而导致黏土膨胀、速敏、微粒运移以及润湿性的改变等问题，从而引起储层损害。针对SZ36—1油田绪层岩性和储层孔隙、孔喉以及渗透率特点，研究开发出了堵漏返排型修井液体系，并利用离心法、页岩防膨法和API堵漏模拟实验评价法以及沉降稳定评价等实验方法，依据防膨理论和1／2～2／3架桥规则、1／4～1／2充填规则，优选出了适合于SZ36-1油田堵漏返排型修井液体系的黏土稳定剂、堵漏荆和悬浮增黏剂的类型、粒径和加量，确定出了具体配方。性能评价结果表明，该堵漏返排型修井液具有良好的泵送性、封堵性和自行解堵性，解堵后在2h内岩心渗透率恢复值均能达到92％以上。

In the workover jobs in block SZ36-1,large amount of workover fluids were lost into the porous formations leading to problems such as clay swelling,flow velocity sensitivity,particle migration and wettability reversion etc which may imposed permeability impairment to the reservoir formations.A flow-back workover fluid which was able to control the mud loss was developed,based on the understanding of the lithology,reservoir pore characteristics,pore throats and permeability of the reservoir formations in Block SZ36-1.The additives of this workover fluid,such as clay stabilizer,lost circulation materials,and the viscosifiers,were optimized using centrifuge experiment,shale swelling tests,API mud loss evaluation method,and sedimentary stability test,and the so-called 1/2-1/3 bridging rule and the 1/4-1/2 packing rule.Laboratory studies showed that this workover fluid had good pumpability,sealing capacity and can be removed very easily.The permeability return of a core tested using this workover fluid were as high as 92% in 2 hours.