Evaluating initial fracture effectiveness and optimizing energy replenishment in Ordos Basin shale oil horizontal wells using distributed fiber optic sensing

The Fiber Optic Sensing has been adopted to support shale oil development since last century. However, tackling the noise of Fiber Optic Sensing signals is the key to the success of enhancing the precision of energy replenishment process in the pressure declining stage of shale oil development. Distributed Acoustic Sensing (DAS) and Distributed Temperature Sensing (DTS) of optical fiber systems are used in a Shan 156 Area in the Ordos Basin. The prececision of the fiber optic sensing test was established by building a temperature profile prediction model for horizontal water injection wells and a water intake profile interpretation model. DAS signal denoising system and DTS data processing are typical Fiber-Optic Data Processing Techniques for Shale Oil Horizontal Well Monitoring. The Well SP with 10 initial stimulated fractures in Shan 156 area was in low production and high-water saturation for a long period. Coiled Tubing-Conveyed Fiber-Optic Injection Profile Monitoring (DTS + DAS) was successfully conducted, and its results demonstrated the that segments 3 and 8 are high water-intake zones. In the energy replenishment design before refracturing, the injection fluid volume to segments 3 and 8 was increased to achieve a balanced pressure rise within the fractures across all segments of the horizontal section.