GEOTHERMAL ASSESSMENT OF A DEPLETED NATURALLY FRACTURED RESERVOIR IN ZHARKENT BASIN: A REVIEW

Abstract

Although contemporary study is sparse, several researches have been undertaken to analyze the expected energy production potential of Kazakhstan's sedimentary geothermal resources. The available evidence demonstrates the potential is scattered, fragmentary, and not always consistent. However, detailed data on geothermal resources exist in Kazakhstan's national archives and should be gathered and evaluated. Kazakhstan is considered to possess significant low-temperature geothermal resources, mostly in sedimentary basins in nature. Kazakhstan's population has a substantial demand for acceptable heating services, and low-temperature geothermal resources are particularly well suited for district heating and other direct consumption applications. The basins of Ustyurt-Buzashin and Manguyshiak in SW Kazakhstan and the W-Ily (Almaty) and E-Ily (Zharkent) basins in SE Kazakhstan are thought to have the highest concentrated potential. Due to their relatively large surface area, the first two are also among the basins with the most extractable energy per basin. Basins having a high extractable energy density (per km2) are considered the most promising for geothermal potential, since they should need less widespread drilling of production wells. The geothermal resources in the Zharkent sub-basin in southern and southern-eastern Kazakhstan look to be the most promising, based on their high geothermal gradients, low concentration of dissolved solids, and significant natural recharge via precipitation. Other research in the South and South-East area may uncover additional viable geothermal resources. Due to the closed nature of the majority of sedimentary geothermal reservoirs, reinjection can be applied. After energy has been recovered from the water, geothermal reinjection involves returning part, or possibly all water produced from a geothermal reservoir back into the geothermal system. Water from a different source is sometimes injected into geothermal reservoirs. This will not be essential immediately in all sites inside the Zharkent sub-basin due to natural recharge, but will become necessary over time as geothermal development increases. Most other sedimentary geothermal resources in Kazakhstan will undoubtedly require the reinfection process from the start of large-scale usage.