砂砾岩储层水力裂缝扩展规律试验研究

发布时间：2018-05-26 17:18

本文选题：岩石力学 + 砂砾岩　；参考：《岩石力学与工程学报》2017年10期

【摘要】：由于砂砾岩储层中砾石的存在,导致压裂工程中水力裂缝扩展形态复杂,施工难度大。为了研究砂砾岩储层水力裂缝扩展规律,采用真三轴压裂模拟试验系统对天然砂砾岩露头岩样开展试验研究,分析水平应力差、砾石粒径和分布规律以及压裂液黏度和排量对水力裂缝扩展形态的影响。研究表明:砂砾岩储层的压裂裂缝形态由应力状态和砾石特征共同决定。以小粒径砾石为主的岩样中,砾石对裂缝扩展形态的影响较小,形成单一主裂缝,裂缝面平直;大粒径砾石为主的岩样中,水力裂缝沿着砾石界面偏转并形成分支裂缝,裂缝面扭曲。水平应力差较低、砾石无规则杂乱排布的情况下,分支裂缝的偏转更加明显,裂缝形态更加复杂。同时,水力裂缝由砾石内部起裂时的破裂压力更高。分支裂缝的产生以及裂缝的转向扩展导致裂缝宽度变窄;采用高黏度的胍胶压裂液能够有效增加裂缝宽度,有助于加砂和避免砂堵。
[Abstract]:Because of the existence of gravel in sand and gravel reservoir, the hydraulic fracture extension form is complicated and the construction is difficult in fracturing engineering. In order to study the rule of hydraulic fracture propagation in sandy gravel reservoir, the true triaxial fracturing simulation test system is used to study the outcrop rock samples of natural sand and gravel rock, and the horizontal stress difference is analyzed. The influence of gravel particle size and distribution law and fracturing fluid viscosity and displacement on hydraulic fracture propagation morphology. The results show that the fracturing fracture morphology of sand and gravel reservoir is determined by the stress state and gravel characteristics. In rock samples with small gravels, the influence of gravel on fracture propagation morphology is small, and the single main fracture is formed, the fracture surface is straight, and the hydraulic fracture deflects along the gravel interface and forms a branch fracture in the large gravel-dominated rock sample. The crack face is twisted. Under the condition of low horizontal stress difference and irregular arrangement of gravel, the deflection of branch cracks is more obvious and the fracture morphology is more complex. At the same time, the fracture pressure is higher when the hydraulic fracture starts from the gravel. The formation of branching fractures and the expansion of fractures make the width of fractures narrow, and the use of guanidine gel fracturing fluid with high viscosity can effectively increase the width of fractures and help to add sand and avoid sand plugging.
【作者单位】：中国石油大学(北京)石油工程学院;
【基金】：国家重点基础研究计划项目(2015CB250903) 中国石油大学(北京)科研启动基金项目(ZX20160022)~~
【分类号】：TU45

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