Abstract
Static formation temperature (SFT) is required to determine the thermophysical properties and production parameters in geothermal and oil reservoirs. However, it is not easy to determine SFT by both experimental and physical methods. In this paper, a mathematical approach to predicting SFT, based on a new model describing the relationship between bottom hole temperature (BHT) and shut-in time, has been proposed. The unknown coefficients of the model were derived from the least squares fit by the particle swarm optimization (PSO) algorithm. Additionally, the ability to predict SFT using a few BHT data points (such as the first three, four, or five points of a data set) was evaluated. The accuracy of the proposed method to predict SFT was confirmed by a deviation percentage less than ±4% and a high regression coefficient R2 (>0.98). The proposed method could be used as a practical tool to predict SFT in both geothermal and oil wells.
Highlights
Deep drilling is necessary for the exploitation of deep geothermal reservoirs [1]
Borehole drilling is a complicated process in which a constant thermal anomaly affects the static formation temperature (SFT) around the borehole [2]
In this case such errors may arise from various sources, including unrealistic models proposed to describe the drilling process, heat transfer models based on simple assumptions, measurement errors in the bottom-hole temperature (BHT) data, and total uncertainties in SFT estimation [17]
Summary
Deep drilling is necessary for the exploitation of deep geothermal reservoirs [1]. In this case, borehole drilling is a complicated process in which a constant thermal anomaly (in addition to the circulating drilling mud) affects the static formation temperature (SFT) around the borehole [2].Determining SFT at any depth demands a lot of time to measure the bottom-hole temperature (BHT)and shut-in time [3]. Deep drilling is necessary for the exploitation of deep geothermal reservoirs [1]. In this case, borehole drilling is a complicated process in which a constant thermal anomaly (in addition to the circulating drilling mud) affects the static formation temperature (SFT) around the borehole [2]. Determining SFT at any depth demands a lot of time to measure the bottom-hole temperature (BHT). Measuring BHT can be costly due to the usage of sophisticated logging equipment and the necessity to temporarily stop the wellbore drilling [4]. Estimation of SFT is usually achieved by analytical and numerical simulation methods. Most of the analytical methods are based on the constant linear and cylindrical heat source models
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