To Determination of Formation Equilibrium Temperature from Temperature Measurements in Production Wells

The knowledge of the equilibrium formation temperature, geothermal gradient and heat flow is important for basin modeling and production logging in quantitative interpretation using simulators. Several approaches to determine the parameters of geothermal field according to the temperature measured in the wellbore are known. One of them is the measurement of temperature along special wells (scientific, control, piezometric). There is a way based on the registration of non-stationary temperature in the borehole after drilling. All these methods have well known disadvantages and they can be used only in a small number of wells of the interested oil fields.

We have proposed a method of determining the equilibrium formation temperature and geothermal gradient from thermal logs measured in producing wells. These measurements are carried out in large numbers of wells in oil and gas fields being developed. If the well has a sufficiently long sump (for producers it is more than 10 meters), then there is a zone near the bottom with undisturbed geotherm.

CFD modeling and analysis of downhole measurements made it possible to investigate the influence of confounding factors on the distribution of temperature in the sump: conductive heat transfer from the reservoir and metal casing, free heat convection.