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脉动水力压裂技术是一项具有广阔前景的增渗新技术。当前脉动压裂过程中传播机理研究较少,为更好地研究脉动压裂增压效果与裂缝中传播机理,指导脉动水力压裂施工。该文基于波动方程和湍流模型,编制计算程序,建立模拟井下压力传播物理模型和类地层边界条件,研究了脉动压裂传播机理。计算结果表明:该模拟条件下,脉动波传播特征与实验结果具有较高吻合度,得出以下三个结论:(1)脉动压裂能够获得比静载压裂更高压力,提高压力值约30%;矩形脉动波比正弦脉动波与锯齿脉动波能够获得更高压力,提高压力约20%。(2)矩形脉动波压力值从波谷阶跃到波峰产生“水锤效应”明显,利于提高流体压力。(3)脉动压裂压力波衰减满足线性对数关系:y=-A·ln(x)+B,y为压力值,x为传播距离,A和B为常数系数;传播过程中脉动水力能量主要消耗在近井壁地带。研究成果有利于指导优化脉动水力压裂工艺参数。
The pulsating hydraulic fracturing technology is a new prospect of infiltration technology. At present, there are few researches on the propagation mechanism in the pulsating fracturing. In order to better study the effect of the pulsating fracturing and the propagating mechanism in the fractures, we should guide the pulsating hydraulic fracturing construction. Based on the wave equation and the turbulence model, a program is developed to simulate the pressure propagation physics model and the boundary conditions of the formation-like formation. The propagation mechanism of the pulsating fracturing is studied. The calculation results show that under the simulation conditions, the propagation characteristics of pulsating wave have good agreement with the experimental results, and the following three conclusions are obtained: (1) pulsatile fracturing can obtain higher pressure than static pressure fracturing and increase the pressure about 30%; Rectangle ripple than sinusoidal ripple and sawtooth ripple wave to obtain higher pressure, increase the pressure of about 20%. (2) Rectangular ripple wave pressure value from trough step to wave crest “water hammer effect ” obvious, help to improve fluid pressure. (3) The pressure wave attenuation of pulsatile fracturing satisfies the linear logarithm relationship: y = -A · ln (x) + B, where y is the pressure value, x is the propagation distance and A and B are constant coefficients. The fluctuating hydraulic energy Mainly consumed near the wellbore. The research results are helpful to guide the optimization of fluctuating hydraulic fracturing parameters.