水力压力波动注入压裂增产工艺的力学原理

Mechanical principles of hydraulic pressure fluctuation injection based on fracturing technology

仝少凯 高德利

TONG Shaokai GAO Deli

中国石油大学（北京）石油工程教育部重点实验室 油气资源与工程国家重点实验室

Key Laboratory of Petroleum Engineering Education Ministry, China University of Petroleum (Beijing), Beijing 102249, China State Key Laboratory of Petroleum Resource and Engineering, Beijing 102249, China

为了提高水力压裂的改造增产效果, 解决连续油管环空水力压裂作业中高泵压的难题, 提出了一种新的水力压力波动注入压裂增产工艺。基于水力压裂原理, 解释了水力压力波动注入条件下井筒压力系统变化规律; 根据流体力学、弹性力学及波动力学理论, 建立了水力压力波动注入压裂增产工艺的基础力学原理。分析结果表明, 水力压力波动注入条件下, 井筒内流动流体发生了能量转换, 在井底附近产生了不稳定的压力波动, 这种由于不稳定注入排量产生的不稳定的压力波动在储层裂缝内以压力波的形式传播; 水力压力振动波沿缝长方向传播时并不是以恒定压力振幅传播, 而是呈现压力振幅衰减的规律; 水力裂缝的长度和宽度随着压裂泵工作转速的增大而增加。研究结果表明, 水力压力波动注入压裂增产工艺可以提高水力压裂的改造效果和油气井的产量, 建议将该工艺方法应用到现场水力压裂作业中。

A new hydraulic pressure fluctuation injection method based on fracturing technology was proposed to improve the stimulation effect of hydraulic fracturing and solve the high pump pressure during the hydraulic fracturing of coiled tubing annulus. The change laws of borehole pressure system under hydraulic pressure fluctuation injection were illustrated according to the principle of hydraulic fracturing. Moreover, the basic mechanical principles of hydraulic pressure fluctuation injection based on fracturing technology were established according to the theories of fluid mechanics, elasticity and wave mechanics. It indicates that the flowing fluid in the borehole undergoes energy transfer and unstable pressure fluctuation occurs near the bottom hole under hydraulic pressure fluctuation injection. And this kind of unstable pressure fluctuation generated by unstable injection flow rate is propagated in the form of pressure wave in reservoir fractures. When the hydraulic pressure vibration wave propagates along the direction of fracture length, it doesn't propagate at the constant pressure amplitude and the propagation presents the law of pressure amplitude depletion. The length and width of hydraulic fractures increase with the running rotation speed of fracturing pump. In conclusion, hydraulic pressure fluctuation injection based on fracturing technology can improve the stimulation effect of hydraulic fracturing and increase the production rate of oil and gas wells. It is recommended to apply this technology to the field hydraulic fracturing. The results provide the new method and theoretical basis for improving the stimulation effect of hydraulic fracturing.

10.13639/j.odpt.2018.02.021