大庆外围低渗透油田直井多分支缝压裂提产技术

大庆外围低渗透油田常规压裂形成小规模双翼缝，缝控体积小、增产效果差，增加缝长不仅易沟通邻井，还不能改善井排间砂体控制程度，且成本较高。直井多分支缝压裂技术，在井网条件下，通过在主缝两侧形成多条分支缝，有效增大缝控体积，改善井排间砂体控制程度，提高增产效果。通过物模及数模实验，明确了分支缝形成机制；基于岩石力学参数变化规律和分支缝起裂特征，形成了集地应力演变计算、裂缝参数优化的完整优化设计方法。研究评价优选了纤维缝内暂堵剂，形成了“纤维+支撑剂”缝内暂堵工艺，配套了现场诊断控制方法。现场累计应用310口井，初期单井日增油1.9～4.8 t，达到常规压裂的2.1～4.0倍，投入产出比达1∶2.5，为大庆油田低渗透储层的高效开发提供技术支撑。

Technology of production enhancement by fracturing of multiple branch fracture in vertical well in low permeability oilfields in the periphery of Daqing

Conventional fracturing in low-permeability oilfields in the periphery of Daqing creates the small scale double-wing fracture, and the small fracture controlled volume and the poor stimulation effect were obtained. Increasing the fracture length promotes communication with offset wells and fails in improving the controlling degree of sand body between well arrays, and the development cost increases. The fracturing technology of multiple branch fractures in the vertical well creates multiple branch fractures on both sides of the major fracture under the condition of well pattern, increases the fracture controlled volume, improves the controlling degree of sand body between well arrays, and enhances the stimulation effect. Through physical and numerical simulation, the formation mechanism of branch fractures was obtained. Based on variation of rock mechanical parameters and the characteristics of branch fracture initiation, an optimization design method integrating computation of in-situ stress evolution and optimization of fracture parameters was formed. The fiber temporary plugging agent inside the fracture was optimized, the temporary plugging process of fiber + proppant in the fracture was formed, and the field diagnosis and control method was developed. The technology has been applied in 310 wells. The increase in daily oil production per well at the initial stage is 1.9-4.8 t, which is 2.1-4.0 times that of conventional fracturing, and the return on investment is 1:2.5, providing technical support for efficient development of low-permeability reservoirs in Daqing Oilfield.