Use of distributed temperature sensors is becoming increasingly common for monitoring producing sections of horizontal wells through a real-time measurement of a temperature profile. This information can potentially be inverted to infer the types and amounts of fluid entering along the wellbore. This information is essential for reservoir management to identify excessive water or gas influx, to guide the action of sliding sleeves or other downhole flow control devices, and to decide if reservoir stimulation is needed in a particular horizontal section.
The inferences described above require a model to translate temperature information into flow information. This paper presents a model for predicting the temperature profile in a nominally horizontal well during normal production (steady-state flow). A forward model of the temperature profile caused by given flow conditions can be the basis of the inverse model needed to determine flow profiles
Prediction of the wellbore temperature profile requires models of all of the often-subtle thermal effects occurring in the reservoir and in the wellbore itself. For the reservoir temperature model, we couple mass and energy balances of fluid flow in a permeable media in a box-shaped homogeneous reservoir with a wellbore temperature model using a multisegment technique. Similarly for the wellbore, we couple mass, momentum, and energy balances to model pressure and temperature behavior. The models presented in this paper account for Joule-Thomson effects, and convective and conductive heat transfer. The primary results of the model are estimates of the extent of temperature change from geothermal temperature during flow. Results show that temperature changes of a few degrees are possible; temperature changes of this magnitude are certainly detectable with current technology. A second result is a demonstration of the inference of single phase and multiphase flow profiles from a synthetic case. Sensitivity studies with the model illustrate the flow conditions that cause measurable temperature changes or anomalies that could be recognized in an analysis of distributed temperature measurements.