多尺寸封堵微球在压力穿透试验下的封堵性能对比分析

Comparative Analysis on Plugging Performance of Multi-size Plugging Microspheres under Pressure Penetration Test

中国页岩油气资源潜力巨大,而硬脆性泥页岩中微裂缝发育丰富,钻采过程中裂缝扩张,无有效封堵的情况下,流体顺沿裂缝进入页岩深部,导致了井壁失稳及深层应力变化问题。常规高分子封堵材料无法应对页岩裂缝多尺度变化,从而封堵效率低,并且在岩层各项应力作用下,高分子链段发生断裂,以至于材料失效进而影响其对页岩深层裂缝的封堵能力。该文针对页岩裂缝的多尺度特点,研究了不同微球体系与封堵性能的关系。通过对比分析(丙烯酰胺/丙烯酸/2-丙烯酰胺-2-甲基丙磺酸)共聚微球及其蒙脱土纳米复合微球体系[(AM/AA/AMPS)/I-MMT]和(丙烯酰胺/丙烯酸/4-丙烯酰吗啉)共聚微球及其石墨烯纳米复合微球体系[(AM/AA/ACMO)/GMASG]的PPT封堵率(95.57%vs. 85.00%),可知(AM/AA/AMPS)三元共聚微球体系更适配页岩储层的复杂地势条件。且通过分析封堵率提高率,可以发现(AM/AA/ACMO)/GMASG体系高达13.84%,比(AM/AA/AMPS)/I-MMT体系高出7.88%。这表明纳米复合微球可以抵抗岩层应力从而形成较为稳定的封堵层,且石墨烯保护和增效聚合物微球的效果显著。

Shale oil and gas resources in China show great potential and micro-fractures are abundant in hard and brittle shale.In the process of drilling and production,fractures expand without effective plugging and the fluid extends fractures into the deep shale,leading to wellbore instability and deep stress changes.Conventional polymer plugging materials are unable to cope with the multiscale changes of shale fractures,resulting in low plugging efficiency.Moreover,under the action of various rock stress,polymer chain segments may be broken,so that the material ability may become poor,which affects its sealing ability of deep shale fractures.According to the multi-scale characteristics of shale fractures,the relationship between different microsphere systems and plugging performance was studied in this paper.Through the comparison and analysis of the PPT plugging rate between(AM/AA/AMPS)/I-MMT and(AM/AA/ACMO)/GMASG microsphere system,it can be seen that(AM/AA/AMPS)terpolymer microsphere system has better adaptability to shale formations with multi-scale fractures.Through the comparison and analysis of the increasing plugging rate,it can be found that the increasing value of(AM/AA/ACMO)/GMASG system is 13.84%which is 7.88%higher than that of(AM/AA/AMPS)/I-MMT system,which means nanocomposite microspheres can resist rock stress and form a relatively stable plugging layer.Moreover,graphene has a significant effect on protecting and enhancing polymer microspheres.