多层段水力压裂压后统一返排模型

Unified backflow model after multilayer hydraulic fracturing

陈昱辛 曲占庆 丁云宏 郭天魁 白羽 王继伟2

中国石油勘探开发研究院，北京 100083 中国石油大学（华东）石油工程学院，山东 青岛 266580

Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China School of Petroleum Engineering, China University of Petroleum, Qingdao 266580, China

压裂液返排是水力压裂施工的重要工序，是影响压后效果的因素之一，但目前压后返排模型大多考虑单层段压裂压后返排情形，未对现场更为常见的多层段压裂统一返排情形给出具体的计算方法。为此，建立了单层段压裂裂缝自然闭合与强制闭合2种模式下的返排模型，并研究了多层段统一返排情形的具体计算方法，进而建立了多层段压后统一返排模型。该模型可对统一返排过程中井口压力、返排流量等参数进行计算，并据此编制了计算程序。现场实例计算表明，该模型具有较好的计算精度，可准确预测多层段统一返排过程中各项参数的变化，为现场制定返排工作制度提供了理论依据，有利于返排施工的科学化。

Fracturing fluid backflow, as an important process in hydraulic fracturing operation, is one of the factors that affect the fracturing effect. However, at present, only the single layer post?鄄fracturing backflow model is considered mostly, the multilayer fracturing unified backflow, which is more common in the field, is not given specific consideration. For this reason, the backflow model of single layer fracture under two conditions, natural closure of fracture and forced closure of fracture, is established. In addition, the specific method of unified backflow after multilayer fracturing is studied. Then the unified backflow model after multilayer fracturing is established, which can calculate the changes of wellhead pressure, the flowback rate and other parameters in the process of unified backflow. Besides, the calculation procedure is compiled based on the model. Field example calculations show that the model has good calculation accuracy, can accurately predict the parameters change in the process of unified backflow. The model can provide theoretical basis for establishing the backflow working system, and is conducive to the scientific and theoretical backflow operation.

10.6056/dkyqt202004015