3D numerical modeling of hydrothermal processes during the lifetime of a deep geothermal reservoir

Understanding hydrothermal processes during production is critical to optimal geothermal reservoir management and sustainable utilization. This study addresses the hydrothermal (HT) processes in a geothermal research doublet consisting of the injection well E GrSk3/90 and production well Gt GrSk4/05 at the deep geothermal reservoir of Groß Schönebeck (north of Berlin, Germany) during geothermal power production. The reservoir is located between ?4050 to ?4250 m depth in the Lower Permian of the Northeast German Basin. Operational activities such as hydraulic stimulation, production (T = 150°C; Q = ?75 m³ h^?1; C = 265 g l^?1) and injection (T = 70°C; Q = 75 m³ h^?1; C = 265 g l^?1) change the HT conditions of the geothermal reservoir. The most significant changes affect temperature, mass concentration and pore pressure. These changes influence fluid density and viscosity as well as rock properties such as porosity, permeability, thermal conductivity and heat capacity. In addition, the geometry and hydraulic properties of hydraulically induced fractures vary during the lifetime of the reservoir. A three‐dimensional reservoir model was developed based on a structural geological model to simulate and understand the complex interaction of such processes. This model includes a full HT coupling of various petrophysical parameters. Specifically, temperature‐dependent thermal conductivity and heat capacity as well as the pressure‐, temperature‐ and mass concentration‐dependent fluid density and viscosity are considered. These parameters were determined by laboratory and field experiments. The effective pressure dependence of matrix permeability is less than 2.3% at our reservoir conditions and therefore can be neglected. The results of a three‐dimensional thermohaline finite‐element simulation of the life cycle performance of this geothermal well doublet indicate the beginning of thermal breakthrough after 3.6 years of utilization. This result is crucial for optimizing reservoir management. Geofluids (2010) 10 , 406–421     

Was the Fishing Village of Lepenski Vir Built by Europe’s First Farmers?

Journal of World Prehistory - It is now widely accepted that agriculture and settled village life arrived in Europe as a cultural package, carried by people migrating from Anatolia and the Aegean...     

Transition from hunting to animal husbandry in Southern,Western and Eastern Finland: new dated osteological evidence

The beginning of animal husbandry in Finland is one of the most debated topics in Finnish archaeology. For this study a total of 69 bone materials from archaeological sites in Southern, Western and Eastern Finland, dating from the Middle Neolithic to the Early Metal Period, were analysed: 52 represented identifiable animal bones. These data were complemented with those from previously analysed bone materials. A total of 19 domestic animal bones were radiocarbon-dated to determine their connection with a particular cultural period. However, 13 of them proved to belong to the historical and not the prehistoric period, emphasizing the importance of radiocarbon-dating and context awareness when interpreting prehistoric bone materials. Among the radiocarbon-dated material were the oldest dated sheep, cattle and horse bones in Finland. The oldest radiocarbon-dated domestic animal bone in Finland, from sheep or goat, derives from the Late Stone Age Kiukainen Culture site, while cattle and horse bones date to the Bronze Age. This is later than expected. However, the available material does not exclude the possibility that some animal husbandry was practised in Finland earlier. Nevertheless, domestic animal bones are rare in samples dated to the cultural periods studied, while hunting and fishing represented important subsistence activities.