Evolution mechanism of optical fiber strain induced by multi-fracture growth during fracturing in horizontal wells

Petroleum Exploration and Development

Yun XU¹  Shicheng ZHANG²  Ming CHEN³  Tong ZHOU³  Tiankui GUO³  Yunpeng WANG⁴  Zhanqing QU⁵ 

[1] Corresponding author;Development, Beijing 100083, China;College of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China;College of Petroleum Engineering, China University of Petroleum, Beijing 102249, China;;PetroChina Research Institute of Petroleum Exploration &

关键词: horizontal well;    multi-stage fracturing;    optical fiber strain;    strain distribution;    forward model;    identification of multi-fracture growth;   

DOI  :  

来源: DOAJ

【 摘 要 】

A forward model for optical fiber strain was established based on a planar 3D multi-fracture model. Then the forward method calculating distributed fiber strain induced by multi-fracture growth was proposed. Based on this method, fiber strain evolution during fracturing of the horizontal well was numerically simulated. Fiber strain evolution induced by fracture growth can be divided into three stages: strain increasing, shrinkage convergence, and straight-line convergence, whereas the evolution of fiber strain rate has four stages: strain rate increasing, shrinkage convergence, straight-line convergence, and strain rate reversal after pumping stops. Fiber strain does not flip after pumping stop, while the strain rate flips after pumping stop so that strain rate can reflect injection dynamics. The time when the fracture extends to the fiber and inter-well pressure channeling can be identified by the straight-line convergence band of distributed fiber strain or strain rate, and the non-uniform growth of multiple fractures can be evaluated by using the instants of fractures reaching the fiber monitoring well. When the horizontal section of the fiber monitoring well is within the height range of a hydraulic fracture, the instant of the fracture reaching the fiber can be identified; otherwise, the converging band is not apparent. In multi-stage fracturing, under the influence of stress shadow from previous fracturing stages, the tensile region of fiber strain may not appear, but the fiber strain rate can effectively show the fracture growth behavior in each stage. The evolution law of fiber strain rate in single-stage fracturing can be applied to multi-stage fracturing.

【 授权许可】

Unknown