Research on Numerical Simulation and Interpretation Method of Water Injection Well Temperature Field Based on DTS

Traditional water injection profile monitoring primarily relies on methods such as isotope tracers and oxygen activation. Conventional resistive temperature instruments, which are drag-measured, are highly sensitive to production interference and can only capture the transient temperature response of the wellbore at a single depth. As a result, the temperature data obtained from well temperature logging has certain limitations. Using DTS (Distributed Temperature Sensing) for pre-and post-well opening and shut-in water injection profile testing, along with quantitative analysis of water absorption, addresses the limitations of traditional well temperature logging, which typically offers only qualitative insights. However, the interpretation of DTS data still requires further refinement to improve its alignment with actual conditions. In this study, COMSOL software 6.1 was used to simulate the temperature distribution within the downhole temperature field, both spatially and temporally. The Sobol method was employed to analyze the influence of fluid flow rate and rock thermal conductivity on the temperature field. The results indicated that the fluid flow rate in the wellbore has a more significant impact and is the primary controlling factor of the downhole temperature field. Based on actual field conditions and the forward simulation results, the differential evolution algorithm was applied to invert and interpret the water injection profile. The inversion results showed minimal error, confirming the feasibility of this approach. It is helpful to interpret the well temperature profile measured by the distributed fiber optic temperature sensor, which is helpful to improve the ability of well temperature logging to identify the output profile, which has important academic value and practical significance for the development of water injection wells.