Abstract Temporary-plugging-and-diverting fracturing (TPD fracturing) is widely used to enhance hydrocarbon recovery from unconventional reservoirs. During TPD fracturing, diverters are injected to prevent the propagation of the previously formed fractures, then divert the fracturing fluid into the unstimulated zones. However, the influence of the fracture morphology on the diversion remains unknown. This study examined the characteristics of diversion under the influence of fracture undulation and roughness. The fracture surface was represented through the application of the 3D scanning and printing method. The digitized scan data is used to characterize the roughness and undulation of the fracture surface. Moreover, the width in the normal direction (normal width) of the fracture surface is used to measure the width of the flow channel in the fracture. A new method for describing the characteristics of fracture plugging location based on the normal width of the fracture is established. Besides, we chose a combination of particles with a diameter of 1 mm and fibers and studied its plugging behavior in a fracture with a width of 2 mm under the carrying of cross-linked guar fracturing fluid. Parallel experimental results suggest the presence of the characteristic plugging position, which is the narrow area inside the fracture. A fracture shape parameter quantitatively describing the characteristics of the region was established. It can be used to predict the inflection point in the pressure response of the diversion process. The research results show that the shape and distribution of the narrow areas in the fracture have a great impact on the plugging behavior. Even with similar average fracture width or the degree of normal width variation, there are significant differences in plugging efficiency. This study deepens the understanding of the plugging behavior of diverters in rough fractures.

中文翻译：

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暂堵分流压裂裂缝表面形态对封堵效率影响的试验研究

摘要 临时堵漏压裂（TPD 压裂）被广泛用于提高非常规油气藏的油气采收率。在 TPD 压裂过程中，注入转向器以防止先前形成的裂缝扩展，然后将压裂液转向未增产区。然而，裂缝形态对分流的影响仍然未知。本研究考察了裂缝起伏和粗糙度影响下的导流特性。通过应用3D扫描和打印方法来表示断口表面。数字化扫描数据用于表征断裂表面的粗糙度和起伏。而且，裂缝面法线方向的宽度（normal width）用于衡量裂缝中流道的宽度。建立了一种基于裂缝法向宽度描述裂缝封堵位置特征的新方法。此外，我们选择了直径为1 mm的颗粒和纤维的组合，研究了其在交联瓜尔胶压裂液携带下在宽度为2 mm的裂缝中的封堵行为。平行实验结果表明存在特征堵塞位置，即裂缝内部的狭窄区域。建立了定量描述该区域特征的裂缝形状参数。可用于预测导流过程压力响应的拐点。研究结果表明，裂缝中狭窄区域的形状和分布对封堵行为有很大影响。即使平均裂缝宽度或正常宽度变化程度相近，封堵效率也存在显着差异。本研究加深了对粗糙裂缝分流器封堵行为的理解。