The Potential of Depleted Oil Reservoirs for High-Temperature Storage Systems

Abstract

HT-ATES (high-temperature aquifer thermal energy storage) systems are a future option to shift large amounts of high-temperature excess heat from summer to winter using the deep underground. Among others, water-bearing reservoirs in former hydrocarbon formations show favorable storage conditions for HT-ATES locations. This study characterizes these reservoirs in the Upper Rhine Graben (URG) and quantifies their heat storage potential numerically. Assuming a doublet system with seasonal injection and production cycles, injection at 140 °C in a typical 70 °C reservoir leads to an annual storage capacity of up to 12 GWh and significant recovery efficiencies increasing up to 82% after ten years of operation. Our numerical modeling-based sensitivity analysis of operational conditions identifies the specific underground conditions as well as drilling configuration (horizontal/vertical) as the most influencing parameters. With about 90% of the investigated reservoirs in the URG transferable into HT-ATES, our analyses reveal a large storage potential of these well-explored oil fields. In summary, it points to a total storage capacity in depleted oil reservoirs of approximately 10 TWh a−1, which is a considerable portion of the thermal energy needs in this area.

Geochemical Changes Associated with High-Temperature Heat Storage at Intermediate Depth: Thermodynamic Equilibrium Models for the DeepStor Site in the Upper Rhine Graben, Germany

“…High-temperature heat storage in the subsurface is feasible in abandoned hydrocarbon reservoirs [2]. These reservoirs have an added economic advantage in that their geology, geo-and petrophysical properties, depths, and geometries have already been extensively characterized.…”

Appraising Mahallat Geothermal Region using thermal surveying data accompanied by the geological, geochemical and gravity analyses

“…After exploration, a wide variety of methods can be exerted to model and simulate the hot underground reservoir. Temperature, pressure, flow regime, fracture network are known as the most important factors [14][15][16][17][18] .In the most simplified cases, a geothermal reservoir can be explored merely because of observable surface evidence such as hot springs. But, sophisticated exploration procedures are required to make a reliable prediction on the geothermal potential of a prospect.…”

“…Installation of the first Iranian geothermal power plant at the Sabalan Field (northwest of Iran) is the result of some country-wide exploration projects. In addition, further detailed geothermal exploration studies have been carried out in different parts of Iran [17][18][19][20][21][22][23][24][25]26 .Mahallat is also another possible geothermal site located in the Markazi Province of Iran. Three negative gravity anomaly zones and faults (acting as preferential pathways for hydrothermal fluids circulation) are confirmed in this area [21][22][23][24][25][26][27][28][29] .…”

“…After exploration, a wide variety of methods can be exerted to model and simulate the hot underground reservoir. Temperature, pressure, flow regime, fracture network are known as the most important factors [14][15][16][17][18] .…”

“…Installation of the first Iranian geothermal power plant at the Sabalan Field (northwest of Iran) is the result of some country-wide exploration projects. In addition, further detailed geothermal exploration studies have been carried out in different parts of Iran [17][18][19][20][21][22][23][24][25]26 .…”