A new method for correcting temperature log profiles in low-enthalpy plays

Sandra Schumacher,Inga Moeck

doi:10.1186/s40517-020-00181-w

Abstract

Temperature logs recorded shortly after drilling operations can be the only temperature information from deep wells. However, these measurements are still influenced by the thermal disturbance caused by drilling and therefore do not represent true rock temperatures. The magnitude of the thermal disturbance is dependent on many factors such as drilling time, logging procedure or mud temperature. However, often old well reports lack this crucial information so that conventional corrections on temperature logs cannot be performed. This impedes the re-evaluation of well data for new exploration purposes, e.g. for geothermal resources. This study presents a new method to correct log temperatures in low-enthalpy play types which only requires a knowledge of the final depth of the well as an input parameter. The method was developed and verified using existing well data from an intracratonic sedimentary basin, the eastern part of the North German Basin. It can be transferred to other basins with little or no adjustment.

Highlights

A knowledge of the correct subsurface temperature regime in a well is important for the hydrocarbon industry, and for geothermal purposes (e.g. Ganz 2015; Schumacher et al 2020), as well as for modelling of the thermal state in a particular region (e.g. Norden et al 2012) or of the crust (e.g. Bonté et al 2012; Agemar et al 2012) or even the entire lithosphere (e.g. Bayer et al 1997; Norden et al 2008; Freymark et al 2017; Przybycin et al 2017).Temperature measurements in boreholes have been carried out for more than 100 years
The analyses showed that there exists a depth-point in each of these wells at which the thermal disturbance due to mud circulation is zero
Of the three temperature methods newly developed for correcting temperature log profiles for wells in the eastern part of the North German Basin, method B shows the best match between the corrected log temperatures and temperatures measured during production tests

Summary

Introduction

A knowledge of the correct subsurface temperature regime in a well is important for the hydrocarbon industry, and for geothermal purposes Temperature measurements in boreholes have been carried out for more than 100 years. Researchers have struggled to obtain accurate formation temperature measurements which can be used to understand the thermal regime in the subsurface Thermal disturbance Temperature data can be recorded directly after the end of drilling operations or after a gap of some time. Mud is circulated in the borehole to cool the drill bit and remove cuttings. The temperature within the borehole deviates from

Methods

Results

Conclusion