Inversion of distributed temperature measurements to interpret the flow profile for a multistage fractured horizontal well in low-permeability gas reservoir

Distributed temperature sensors (DT%) are gradually being used to monitor downhole conditions for multistage fractured horizontal wells (MFHWs) during production. However, significant challenges exist with respect to translating the downhole DTS data to flow profiles of MFHWs, especially for low-permeability gas reservoirs (LPGRs). This study aims to interpret the flow profiles for an MFHW in LPGR through the inversion of downhole distributed temperature measurements. Firstly, a comprehensive inversion procedure combined with forward and inversion models is developed. The forward temperature prediction model is used to simulate the temperature distributions of an MFHW in each inversion iteration. Based on the Levenberg-Marquart (L-M) algorithm, an inversion model is proposed to decrease the differences between the simulated temperature data and the observed temperature data. Subsequently, a sensitivity study using an orthogonal design table L-18 (3(7)) is performed to determine the inversion parameters (fracture half-length and reservoir permeability). Then, an original case demonstrates the direct translation of the observed temperature to the flow profile. Finally, two more cases are presented to illustrate how to interpret the flow profiles based on the inversion results of the two aforementioned inversion parameters respectively. The satisfactory inversion results validate the accuracy and feasibility of the proposed inversion approach to predict flow profiles or diagnose fracture parameters from the DTS data of an MFHW in LPGR theoretically. (C) 2019 Elsevier Inc. All rights reserved.