An approach for heat flow determination in the absence of geothermal gradient measurements: west Anatolia example

Abstract

In western and southwestern Anatolia, the geothermal gradient cannot be accurately measured in many wells due to the complex horizontal water cycle. The aim of this study is to calculate the geothermal gradients by using a new approach for such wells. In this case, the first step is to calculate the geothermal gradients in order to estimate the heat flow values around the wells. Naturally, a direct heat flow estimate cannot be made for wells without a geothermal gradient. However, the heat flow values can be indirectly obtained by different methods. Curie point depth, silica geothermometer, and magnetotelluric conductive layer depth are some of these indirect methods. In this study, we used the heat flow data based on the Curie depth. In this approach, Curie temperature gradients are calculated using the Curie heat flow values and thermal conductivities for problematic wells. An empirical relationship between the Curie temperature gradient and the correctly measured temperature gradients in the region was established. With this relationship, it is possible to make an approach from the current Curie temperature gradient to the normal temperature gradient. In this way, heat flow can also be calculated for areas where no geothermal gradient can be obtained, and heat flow distribution over the whole area can be given. This proposed approximation, to obtain thermal gradient and heat flow, can also be extended to any other region.