An Interpretation Method for a Gas Production Profile Based on the Temperature and Pressure Behavior of Low-Permeability Gas Reservoirs

摘要

This study aims to interpret the temperature and pressure behavior of an open-hole horizontal gas well (OHHGW) in a lowpermeability gas reservoir in order to obtain the permeability and production profile of the OHHGW. First, the mathematical model, which is comprised of viscous dissipation, friction, the Joule–Thomson effect, and several other micro-thermal effects, was developed under a single-phase condition. Second, during the process of solving the numerical model, the drilling skin, heterogeneity, and non-Darcy effect were taken into consideration. In addition, the reservoir and wellbore models were coupled. Third, the testing temperature and pressure data were inverted using the Levenberg–Marquardt (LM) or Markov Chain simulated annealing algorithms, and the permeability and production profiles of the wellbore were obtained. The synthetic cases demonstrate the models’ ability to predict the temperature profile, and the results show the following: (a) The inversion results are in good agreement with the actual data, that is, the model can provide effective guidance for horizontal well development. (b) The wellbore temperature is lower than that of the reservoir boundary, so the micro-thermal effects for the horizontal gas well cannot be ignored during production. (c) As the gas production, the relative density of the gas, and the drilling skin factor increase, the wellbore temperature profile gradually decreases. The wellbore temperature increases with increasing horizontal permeability. (d) The trend of the temperature profile is contrary to the flow path of the wellbore fluid. (e) Reservoir heterogeneity has a significant influence on the temperature profile.