Assessing Geothermal Energy Production Potential of Cambrian Geothermal Complexes in Lithuania

Abstract

Lithuania has a geothermal anomaly situated in the southwestern region of the country. This anomaly is comprised of two primary geothermal complexes located in western Lithuania. The first complex is characterized by the Pärnu–Kemeri Devonian sandstone aquifers, which exhibit exceptionally good flow properties. However, the reservoir temperatures in this complex only reach up to 45 °C. The second complex encompasses Cambrian sandstone reservoirs. Although these Cambrian sandstone reservoirs exhibit high temperatures, with the highest reservoir temperatures reaching up to 96 °C, these Cambrian sandstone reservoirs have less favorable petrophysical properties. This study focuses on the high temperature Cambrian Geothermal sandstone reservoirs. The study aims to conduct a geological screening of the existing and depleted hydrocarbon reservoirs with high water production rates. After initial data gathering, numerical modeling is employed with the help of mechanistic box models to evaluate the geothermal potential of the selected sites for commercial development. Ultimately, the study identifies the top five screened sites, which could be developed further for techno-economical modelling.

Unlocking Geothermal Energy: A Thorough Literature Review of Lithuanian Geothermal Complexes and Their Production Potential

“…In the context of the Lithuanian geothermal system, an analytical and geological screening assessment, complemented by a techno-economic model, has been executed, and the outcomes are detailed in [27]. These findings underscore the substantial potential within depleted oil and gas reservoirs for geothermal development in Lithuania.…”

“…Utilization of Lithuanian hydrocarbon reservoirs for geothermal energy production has been investigated in the screening study presented in [27], where series of numerical simulation models are used for evaluating the geothermal energy production potential of a number of Cambrian reservoir sites. The modeling work presented in [27] only evaluated sites using an injector-producer pair; additional work can also be carried out where existing oil production wells, which are now producing 100% water, could be horizontally extended to increase their production. Such ideas need to be investigated using reservoir models, a work which we will consider in future publications.…”

“…Such ideas need to be investigated using reservoir models, a work which we will consider in future publications. In a similar manner to the screening study presented in [27], a screening study targeting Devonian geothermal complexes is also required.…”

“…It will help to clarify the poro-perm relationships before and after the injection of produced water, influence of precipitation/dissolution kinetics, reservoir mineralogy, and working conditions [4,6,9,12,15,18,22]. A similar modeling approach has been used in the geothermal screening of Lithuanian geothermal complexes in [27], where details of a modeling approach involving THMC-type model construction and use for screening is presented.…”

“…The main idea to be extracted in such early stages of development is that it comes down to heat production cost-EUR/MWh. Subsurface models, which are starting to be developed in the reference paper [27] for geothermal screening, give us the energy output, whereas the city gives the demand depending on its size.…”