It is intended in our study that we can understand the characteristics of thermal properties of common sedimentary formations, and also that we obtain some useful mathematical formulation for their practical applications. Starting from the geometric mean model for the bulk thermal conductivity of composite materials, we have derived a set of general formulas for converting the observed values of porosity into three thermal properties (heat capacity, specific heat, and thermal diffusivity) of unconsolidated sediment samples. As a field example, for the clayey and sandy sediments of the eastern flank of the Juan de Fuca Ridge area, western offshore of North America, we show the particular functional relationships of how the four thermal properties, including thermal conductivity, are described mathematically when porosity is taken as the primary independent parameter. For the two major types of sediments, we have determined the standard values of solid grain thermal properties (thermal conductivity, thermal diffusivity, specific heat, and heat capacity) based on all the measured data. We can show that those standard values are compatible with another set of solid grain thermal properties which are estimated using the mineral composition data for the samples of the “clay” and “sand” types, respectively, in the studied area. We also make a brief mention about the future tasks of our studies on thermal properties prediction, in order to improve the method into the one with higher practical applicability.

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 Temperature change at the ground surface slowly propagates into subsurface formations by thermal diffusion, which enables us to estimate the ground surface temperature (GST) history of the past several hundred years from temperature profiles measured in boreholes. This method has been applied to GST reconstruction studies mainly in North America and Europe. We show how the past GST change disturbs the subsurface temperature distribution for simple cases. Inversion analysis of the subsurface temperature profile calculated from a hypothetical nearly linear change in GST demonstrates that GST history can be well reconstructed from borehole temperature data. We applied this method to Bangkok and the surrounding area, where many groundwater monitoring wells are available for temperature profile logging. Temperature measurements were conducted at 44 stations in 2004, 2006 and 2008. Selected profiles at six stations were analyzed to reconstruct GST histories of the last 300 years using a model taking account of multi-layered formations. All of the estimated GST histories show surface warming in the last century. The amount of temperature increase varies by site and ranges from 0.4 to 2.4 K, larger in the city than in suburban and rural areas. This tendency may reflect urbanization process in the Bangkok metropolitan area such as heat island effect and land use change. We estimated the amount of heat stored in the subsurface since 1900 based on the reconstructed GST histories. The subsurface heat storage in the city of Bangkok is much larger than the average in the Northern hemisphere. These types of analyses of GST history and subsurface heat storage will provide useful information on global warming and thermal influence of urbanization.

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 A brief review is presented on insitu measurements of formation temperature that has been conducted in seafloor boreholes drilled under the ocean drilling program (ODP) and its successor, integrated ocean drilling program (IODP). The best way to measure accurate formation temperatures in boreholes is to insert temperature sensors beyond the drillbit into the sediment layer that is not thermally disturbed by the drilling. One is to use hydraulic piston coring system, where a temperature sensor and data logging system is mounted in the cutting shoe part. The other is to use a temperature probe or tapered lance. Depending on the stiffness of formation, the former allows to obtain in-situ temperature down to ∼100 m below sea floor, whereas the latter can penetrate to ∼400 m below sea floor. The overall accuracy of the temperature is on the order of 0.1 K to 1 K, which is mainly restricted by the crack created in the formation and the frictional heat caused at the time of penetration into the sediment. So far measurements were made in various environments such as in the hydrothermal areas or around subduction zones, and some evidence for subseafloor fluid migration has been obtained.

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 The temperature in the oil field has been used as a parameter to characterize a relatively wide variety of time-response events such as fracture, fluid and gas flow, cementing, and drilling conditions. Also, it has been utilized for monitoring the production conditions as well as for the prevention or estimation of hazardous conditions. On the other hand, thermal properties play a very important and useful role in helping to understanding the process to reach steady-state conditions and in predicting such behaviors in later timescales. Through consideration of temperature logging and monitoring, oil and gas temperature during production and transportation, thermal production, and thermal properties' measurement, this paper describes an overview of how temperature and thermal properties are applied in the oil field and explain the future of such implications.

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