Convective and conductive heat transfer in sedimentary basins

摘要

AbstractIn the Earth's crust the temperature is largely controlled by heat conduction. However, under some circumstances, the thermal state is disturbed by advection of heat associated with groundwater flow. The corresponding thermal disturbance depends on the water flow velocity (modulus and direction) and therefore thermal data may be used to constrain the pattern of natural fluid flow. In this paper, some models of thermal disturbance induced by convective heat transfer are presented. They are based on the assumption that the water flow is concentrated in thin permeable structures such as aquifer or fault zones. The steady‐state and transient thermal effects associated with such scenarios are computed using a somewhat idealized model which depends on a small number of parameters: flow rate, time, aquifer geometry and thermal parameters of surrounding rocks. In order to extract the conductive and convective components of heat transfer from temperature data and to estimate the corresponding fluid flow rate, it is first necessary to estimate the thermal conductivity field. The problem of the estimation of thermal conductivity in clay‐rich rocks, based on laboratory andin‐situmeasurements, is emphasized. Then a method is proposed for the inversion of temperature data in terms of fluid flow. Vertical and lateral variations of thermal conductivity are taken into account and the fluid flow is assumed to be concentrated on a specified surface (2‐D quasi‐horizontal pattern). Thermal effects of the flow are simulated by a distribution of surface heat production which can be calculated and then inverted in terms of horizontal fluid flo