True Triaxial Laboratory Study of the Strain Patterns Measured by Distributed Fiber Optics for Hydraulic Fracturing of Multilevel Horizontal Wells

Summary As the exploitation of oil and natural gas has progressed, hydraulic fracturing has become a primary method for increasing oilfield production. Simultaneous hydraulic fracturing of several perforation clusters, by employing limited-entry methods, has become standard in horizontal well stimulation. However, challenges such as unclear fracture identification and limited monitoring methods persist in hydraulic fracturing. This study integrates an optical frequency domain reflector with true triaxial fracturing of multilevel horizontal wells to develop a physical simulation system for monitoring fractures in a laboratory setting via distributed fiber optics. By employing fiber optics, dynamic monitoring of fractures during the fracturing process of multilevel horizontal wells can be achieved. The results indicate that monitoring with distributed fiber optics can clearly record data and accurately determine the initiation points of fractures. The strain data induced by the fractures on the fibers can be interpreted to deduce the fracture width. If a fracture deflects upon encountering a fiber, the fiber will exhibit tensile strain within an abnormal range. When using distributed fiber optics for monitoring fractures in multilevel horizontal wells, it is crucial to optimize the placement of fractures to ensure that the signals detected by the fibers are complete and avoid signal loss. In this paper, we demonstrate the feasibility of using distributed fiber optics for fracture monitoring in multilevel horizontal well fracturing experiments, overcoming the limitations of current single-method approaches to monitoring laboratory true triaxial hydraulic fractures.