Experimental Study on Response of Deviated Well Fiber-optic Strain Induced by Fracture Propagation in Hydraulic Fracturing

ABSTRACT: Distributed optical fiber in adjacent wells can clearly reflect the fracture propagation of hydraulic fracturing. Some oil fields on site today use deviated well optical fibers instead of horizontal adjacent well optical fibers for monitoring. In response to the problem of unclear understanding of the mechanism of fiber-optic monitoring for hydraulic fracturing in deviated well, this paper designs a real tri-axial hydraulic fracturing indoor physical simulation experiment for fiber-optic strain evolution of deviated well induced by single fracture propagation in hydraulic fracturing. By analyzing the fracture propagation and distributed fiber-optic strain data of the real tri-axial hydraulic fracturing physical simulation experiment, the evolution mechanism of fiber-optic strain induced by hydraulic fracturing single fracture propagation in deviated well is obtained. The analysis of experimental results shows that the fiber-optic strain evolution caused by single fracture propagation in deviated well can be divided into 3 stages: strain enhancement, strain convergence, and linear strain convergence. When the inclination angle is 60°, the strain response characteristics of the deviated well fiber-optic are mainly controlled by the expansion of the fracture-width. When the inclination angle is 30°, the strain response characteristics of the deviated well fiber optic are mainly controlled by the expansion of the fracture-height. When the inclination angle is 45°, the deviated well fiber optic data can simultaneously reflect both of the expansion of the fracture-width and fracture-height.