摘要
堵漏颗粒在裂缝内架桥封堵过程与颗粒紧密堆积现象相类似,因此可参考颗粒紧密堆积Fuller曲线来确定封堵颗粒粒径分布。利用三轴承压堵漏实验装置可模拟漏失地层裂缝和三轴地应力状态,对比岩样破裂压力、重张压力和堵漏承压压力,开展2 mm裂缝下颗粒粒径分布对堵漏效果影响的堵漏模拟实验。结果表明,承压封堵裂缝的各级别颗粒粒径B、C、D、E所占百分比约为1.25∶1∶1.25∶1.5,而且粒径累积分布曲线与Fuller曲线相近,表明Fuller曲线可作为选择堵漏颗粒粒径分布的参考依据;实验后缝内堵漏颗粒只在裂缝内某些部位堆积分布,在裂缝面扭曲变形部位颗粒堆积更为明显;随着细颗粒百分比的增加,缝内封堵逐渐由缝口向裂尖过渡。
The process of bridging formed by lost circulation materials during plugging fractures is similar to the phenomenon of dense packing by particles. Consequently,the Fuller Curve of particle packing theory can be used to determine the particle size distribution of lost circulation materials. In this paper,a true tri-axial plugging experimental set-up was used to simulate the fractures in thief zone and the in-situ stresses in three different directions. It was developed to carry out a series of plugging experiments for evaluating the fracture breakdown pressure,the fracture re-open pressure and the fracture bearing pressure after plugged by lost circulation materials,and tests were made on the effects of particle size distribution on the plugging. The experimental results show that the percentage of particle grade B,C,D and E is 1.25∶1 ∶1.25∶1.5,and the particle size distribution cumulative curve is similar to the Fuller curve,which means that the Fuller Curve can be used to determine the particle size distribution of particles. The distribution of particles in fractures after the plugging experiments indicates that the lost circulation materials accumulate only in some areas in fractures. Particularly,the particles are prone to accumulate at the position where the fracture bifurcates or distorts. As the percentage of fine particles increase,the plugging locations are prone to be formed at the fracture inner part or the fracture tip instead of at the fracture mouth.
出处
《钻采工艺》
CAS
北大核心
2017年第1期14-17,共4页
Drilling & Production Technology
关键词
井漏
模拟实验
堵漏材料
颗粒紧密堆积
封堵区域
lost circulation
simulated experiment
lost circulation materials
particle packing
plugging area
