致密油藏不同沉积岩人工裂缝导流能力实验

人工压裂是致密油藏增产提液的重要手段，准确评价人工裂缝导流能力是进一步开展产能预测的基础。常规室内实验采用均匀铺砂方式无法准确模拟实际储层人工裂缝从井底到远端支撑剂浓度逐渐降低的分布特征，通过开展5种类型沉积岩岩板(滩坝砂、砂砾岩、浊积岩和2种露头岩心)多段非均匀铺砂导流能力测试实验，测试了主裂缝非均匀铺砂模式下的导流能力，并从岩石成分和粒度组成的角度分析了不同沉积岩导流能力产生差异的原因。实验结果表明，非均匀铺砂方式相比于均匀铺砂平均导流能力低4.7~8.5个百分点；当闭合应力为60 MPa时，滩坝砂储层导流能力损失最小，浊积岩储层居中，砂砾岩储层损失最大，导流能力损失率为38.9%~53.7%；其原因是不同沉积岩的抗压能力不同，导致支撑剂嵌入深度不同，从而引起导流能力差异，这为不同类型致密储层保持合理地层压力提供了依据。

Experimental study on the flow conductivity of hydraulic fractures in different sedimentary rocks of tight oil reservoirs

Hydraulic fracturing is one important technology for the production increase and liquid level lifting of tight sandstone oil reservoirs, and evaluating the flow conductivity of hydraulic fractures accurately is the foundation of further productivity prediction. The uniform sanding mode is adopted in conventional laboratory experiments, but it cannot accurately simulate the gradual decline characteristics of proppant concentration in hydraulic fractures of actual reservoirs from the bottom hole to the distant end. To this end, this paper tested the flow conductivity of main fractures in the mode of nonuniform sanding by carrying out the flow conductivity testing experiment of multi-section nonuniform sanding on five types of sedimentary rock plates (beach bar sandstone, glutenite, turbidite and two types of outcrop cores). In addition, the reasons for the different flow conductivities of different sedimentary rocks were analyzed from the aspects of rock composition and size composition. The experimental results show that the average flow conductivity in the mode of nonuniform sanding is 4.7%~8.5% lower than that in the mode of uniform sanding. At the closure stress of 60 MPa, the lost flow conductivity of beach bar sandstone reservoir is the least, that of turbidite reservoir is moderate and that of glutenite reservoir is the largest, whose flow conductivity loss ratio is 38.9%~53.7%. That is because different sedimentary rocks are different in compression strength, which leads to different proppant embedment depths and consequently results in different flow conductivities. The research results provide a basis for maintaining the reasonable reservoir pressure of different types of tight reservoirs.