Temperature logging is an efficient technique to locate inflow intervals in the reservoir, evaluate inflow rates in them and the drawdown pressure that creates temperature disturbance, detect cross-flows in the wellbore and/or behind casing and check for casing, tubing and the bottom-hole leakages. Temperature logging can detect wellbore flows with rates way below the mechanical spinner's threshold. Another impressive application of temperature logging is picking flow zones behind unperforated casing that develop through behind-casing channelling. Such findings can be verified or discarded through numerical simulation of temperature logs. This paper presents the TSMp solver module of the TERMOSIM simulator that can reproduce complex hydrodynamic flow patterns and the associated thermodynamic effects, taking place during fluid flows through a multi-layer reservoir towards the wellbore and their blending in it, including heat exchange between reservoir and wellbore flows and the surrounding rocks.
The TSMp solver takes into account possible inter-reservoir communications both inside and outside casing caused by the pressure difference between formation units, as well as short-term and long-term lateral flows that can disturb the temperature at any depth, and calculates fluid rates for each formation unit and temperature profiles for the wellbore and for any distance from it.
This paper describes the general physical and mathematical models and user interface of the TERMOSIM TSMp simulator for producers and presents modelling results for two production wells of Oman. For each well, the TSMp simulator has been employed to create a best-fit individual thermohydrodynamic model and match downhole pressure and temperature records for different production rates. The well log analyses based on temperature modelling presented in these case studies open the way to (a) identify actual reservoir inflow intervals, (b) evaluate formation pressure in flowing units, (c) evaluate inflow rate from each flowing unit and (d) distinguish between wellbore cross-flows and behind-casing channelling.
The case studies presented in this paper are focused on low-compressible, mostly single-phase fluids with high water or oil and low free-gas contents (while multiphase flows with abundant free gas will be covered in a separate paper).