Modeling and interpreting transient wellbore temperature behaviors in wellbores under nonisothermal single-phase liquid flow conditions in oil reservoirs

Currently, the transient temperature data can be useful to predict reservoir and wellbore parameters. With developing technology, temperature sensors can recognize small temperature changes like 0.01 K or less; thus, resarchers use transient temperature data for parameter estimation in reservoir or wellbore. Near wellbore zone, parameter estimation from the transient pressure data is difficult because the pressure changes hastily near wellbore zone. Generally, it is assumed that fluid flow is isothermal in the reservoir although it is nonisothermal. There are some factors which cause thermal changes in reservoir as J-T coefficient, adiabatic expansion or compression, convection and conduction. So, the heat flow model should be used to model and interprete wellbore temperature data. In this work, the transient wellbore temperature distrubitions in wellbores are modeled and interpreted under nonisothermal single-phase liquid flow conditions for oil reservoirs. By using mass, momentum and energy balance equations, the temperature behaviors are obtained for transient and steady state conditions in drawdown and buildup periods. Then, the analytical solutions are coupled with sandface pressure and temperature solutions derived by Kocak (2017) in Laplace space. Derived equations in the solution of analytical model are conventional wellbore storage (WBS) model equation by using mass balance, momentum equation, and heat flow model equation. These equations provide transient and steady state wellbore temperature distrubitions in drawdown and buildup. With these distrubitions, the effects of various parameters on sandface and wellbore temperature can be investigated. Also, the parameters such as permeability, skin, J-T coefficient, earth thermal conductivity can be estimated from transient wellbore temperatures along with transient wellbore pressure data. All of equations derived in this work provide transient temperature data for single phase and slightly compressible fluid for a vertical wellbore in drawdown and buildup periods, for nonisothermal conditions. These data can be used to estimate reservoir and fluid properties, but drawdown temperature data is more crucial due to exhibiting discernable flow regimes. Also, we can not see any distinguishable flow regimes in buildup temperature behaviors.