A method for correcting log-derived temperatures in deep wells, calibrated in the Gulf of Mexico

Abstract

A method for correcting log-derived temperatures in deep wells (3500–6500 m) has been developed by comparing log temperatures from the Gulf of Campeche (Mexican Gulf of Mexico) with DST temperatures in the same wells. The equations developed in this study are modified slightly from those of Waples & Mahadir Ramly (2001) , which were calibrated using data from depths <3500 m in Malaysia. The correction depends strongly on time since end of mud circulation ( TSC ) and, to a much lesser degree, on depth. In this study the true subsurface temperature (Celsius) is given by \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} T_{true}=T_{surf}+f{\cdot}\left(T_{meas}{-}T_{surf}\right){-}0.001391\left(Z{-}4498\right)\end{document} where f =1.32866 −0.005289 TSC , T surf is the seafloor or land-surface temperature (°C), T meas is the measured log temperature (°C), TSC is in hours and Z is depth below seafloor in metres. If TSC is unknown, it can be estimated from the trend of TSC with depth. An estimate of the uncertainty in the corrected temperature is obtained from the equation: \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} {\sigma}=0.10842^{{-}0.029TSC}\end{document} where σ is the standard deviation of the correction factor f . The uncertainty in the correction factor f can be expressed as ±2 σ .

The contribution of gravity method in geothermal exploration of southern part of the Gulf of Suez–Sinai region, Egypt

“…Several methods have been used to correct the logged BHT to real formation temperatures. BHT were corrected by using two methods Waples et al (2004) and Horner methods (1951), to obtain the true Formation Temperature (FT), which is an essential parameter to determine the temperature gradient and heat flow. Horner method (1951) is recommended if three of more self-consistent BHT from a given depth are available.…”

“…3). Waples et al (2004) method is used for correcting logderived temperatures in deep wells (3500-6500 m) by comparing log temperatures from the Gulf of Campeche (Mexican Gulf of Mexico) with Drill Stem Test (DST) temperatures in the same wells. The equations developed are modified slightly from those of Waples and Mahadir (2001), which were calibrated using data from depths less than 3500 m in Malaysia.…”

Integration of Well Logging and Remote Sensing Data for Detecting Potential Geothermal Sites along the Gulf of Suez, Egypt

“…These temperature measurements are collected at the time of active drilling or shortly after drilling circulation has ceased. Due to the convective cooling effect of fluid introduction in the mechanical drilling process, the temperatures measured with this procedure are reduced in comparison to their baseline temperatures [36][37][38]. After the drilling process concludes and no further cooling fluids are added, the borehole steadily returns to a less altered formation temperature.…”

“…After the drilling process concludes and no further cooling fluids are added, the borehole steadily returns to a less altered formation temperature. The temperature measurements collected are reflective of the equilibrium formed between the thermally cool drill fluid and the high temperature of the underlying formation-notably, raw BHT measurements reflect temperatures that are cooler than actual formation temperatures [36,37,39,40]. Corrections for the raw BHT can be made when the BHT measurement, time since circulation, and/or depth of measurement are known.…”

“…In order to address the temperature differentials between the logged BHT measurements and the real formation temperature, various correction methods have been utilized [36][37][38][39][40][41][42][43]. In this study, BHT data were corrected by applying the widely used Horner, and Gulf of Mexico correction methods to obtain the actual formation temperatures.…”