Abstract
In this paper, a method for determining the thermal conductivity of in situ formation rock, which combines experimental measurements, theoretical model predictions, and geophysical logging of formation porosity, is presented to predict the thermal conductivity of in situ formation rocks (this method effectively combines experimental measurements, theoretical model, and geological conditions, referred to as “ETG,” where E is for experimental measurements, T is for the theoretical model, and G is for geological conditions). 24 drilling cuttings samples from rocks down to a depth of 2000 m were selected for transient plane source thermal conductivity tests, and an effective thermal conductivity method was used to predict the thermal conductivity of rocks corresponding to each formation. The predicted thermal conductivity of mudstone was 2.31–3.27 W/(m K), and that of sandstone was 2.40–3.69 W/(m K). An independent-samples t test was carried out between the thermal conductivity results from the ETG prediction method and those from a diagenetic mineral-theory model. The results showed that there were no statistically significant differences between the two groups (P > 0.05) and that the fitting degree was high. The mean-square error in the solid thermal conductivities determined by the two methods was about 0.3, which indirectly demonstrates that the ETG method has high accuracy for predicting the thermal conductivity of in situ formation rock. Therefore, this method is likely to become popular in engineering practice.
Highlights
Disastrous events brought about by global warming are increasing year by year
Using the principle of unsteady heat transfer, Kämmlein and Stollhofen6 employed a probe method to calculate the thermal conductivities of materials by measuring the temperature change with time when a linear heat source is acting on a quasi-infinite uniform medium. They applied this technique to measuring the thermal conductivity of drilling cuttings and found that the particle size distribution was the main factor affecting the porosity of the rock, while the particle size had little influence on the thermal conductivity, and the mineral composition was the main factor affecting the thermal conductivity of rock powder
The thermal conductivity values of the saturated drilling cuttings powder samples, measured according to the method described in Sec
Summary
Disastrous events brought about by global warming are increasing year by year. The process of replacing traditional fossil-fuel energy with clean and renewable energy is accelerating continuously. Using the principle of unsteady heat transfer, Kämmlein and Stollhofen employed a probe method to calculate the thermal conductivities of materials by measuring the temperature change with time when a linear heat source is acting on a quasi-infinite uniform medium They applied this technique to measuring the thermal conductivity of drilling cuttings and found that the particle size distribution was the main factor affecting the porosity of the rock, while the particle size had little influence on the thermal conductivity, and the mineral composition was the main factor affecting the thermal conductivity of rock powder. This is based on a combination of laboratory tests, theoretical model prediction, geophysical logging of the formation porosity, and studying thermal conductivity tests and prediction models for drilling cuttings
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