Revitalization of abandoned oil and gas wells for a geothermal heat exploitation by means of closed circulation: Case study of the deep dry well Pčelić-1

Abstract

The aim of our research is to use abandoned deep-hydrocarbon reservoirs and dry wells in the Croatian part of the Pannonian Basin as a geothermal energy source. Croatia has been exploring and exploiting hydrocarbon reserves in the Pannonian Basin from the mid-20th century. Therefore, many oil and gas wells are reaching the end of their production phase and many are already abandoned. These wells could be considered for geothermal energy production through the coaxial heat exchanger principle, which is usually used in shallow geothermal energy extraction. Using the abandoned deep well Pčelić located in the Drava subbasin as a case study, we have derived the available energy and fluid temperature changes during 20 years of operation for two cases: one with a constant base heat load throughout the year and the second as a variable heat load depending on outside air temperatures. We determined that the maximum potential heat extraction in a variable system is 1750 MWh per year, with 1.5 MW of peak heating power in winter, depending on the sink temperature, climate, and consumer input data. The maximum theoretical constant heat extraction for possible industrial direct heating could be 400 kW during the entire period of 20 years, with fluid temperature reaching steady state at a favorable 50°C. To define steady-state ratio between extracted heat and consumed energy at the circulating pump, we evaluated seasonal performance factor (SPF) analysis similar to heat pump systems. Lower values of SPF linked to a higher flow rate implies higher energy extraction. Our results show that when using a lower flow, steady-state SPF ratio is as high as 280, and for a higher flow, steady-state SPF ratio drops to only 25.

Geoenergy potential of the Croatian part of Pannonian Basin: insights from the reconstruction of the pre-Neogene basement unconformity

“…Stratigraphic and lithological outline was obtained from Lučić et al, 2001;Saftić et al, 2003 andPavelić &Kovačić, 2018, in which the main stratigraphic contacts are defined with their corresponding ages and lithological composition of stratigraphic units. For estimation of the heat flow, the input data were obtained from works that are of regional coverage (Békési et al, 2017;Lenkey, Dövényi, Horváth, & Cloething, 2002) with local corrections from Cvetković, Emanović, Stopar, and Slavinić (2018) and calibration data from wells acquired from published sources (Energy Institute Hrvoje Požar & Orkustofnun, 2017; Kolenković, 2012;Kurevija & Vulin, 2011;Kurevija, Kljaić, & Vulin, 2010;Kurevija, Vulin, & Macenić, 2014;Macenić & Kurevija, 2018;Novak Zelenika, 2005). Input data regarding paleo-water depth (PWD) values were taken from regional studies (Ćorić et al, 2009;Krijgsman, Stoica, Vasiliev, & Popov, 2010;Lučić et al, 2001;Magyar, Geary, & Müller, 1999;Pavelić, 2001;Pavelić & Kovačić, 2018;Rögl, 1996Rögl, , 1998.…”

Producing geothermal energy with a deep borehole heat exchanger: Exergy optimization of different applications and preliminary design criteria

“…Furthermore, many works have proposed the use of the DBHE to repurpose depleted oil&gas wells Davis and Michaelides 2009;Templeton et al 2014;Feng et al 2015;Noorollahi et al 2015;Wight and Bennet, 2015), where a great amount of hot water is often present and the expensive phases of exploration, drilling and construction have already been concluded. Regarding the final use of the extracted heat, some authors have evaluated the potential electricity production via ORC plants (see Nalla et al 2005;Wang et al 2009;David and Michaelides 2009;Akhmadullin and Tyagi 2014;Noorollahi et al 2015;Wight and Bennet 2015; whereas others of them (see Morita et al 1992;Kohl et al 2002;Mottaghy and Dijkshoorn 2012;Templeton et al 2014;Le Lous et al 2015;Caulk and Tomac 2017;Macenić and Kurevija 2018) recommend the direct use of the heat. The paper of Wang et al (2017) illustrates a field test and the numerical investigation conducted in Xi'an, China, where the 3 DBHEs have been connected to heat pumps to provide heating and cooling for a residential area and a commercial area.…”

Selecting the Optimal Use of the Geothermal Energy Produced with a Deep Borehole Heat Exchanger: Exergy Performance

“…[3,5,8,15,19,20] have evaluated the potential electricity production via organic Rankine cycle (ORC) plants with maximum values of 350 kW. In other studies, the heating and cooling applications are recommended for the final use, see [9,10,17,21,22].…”