06/01804 Geothermal reservoir monitoring by continuous self-potential measurements, Mori geothermal field, Japan

Recoverable geothermal resources are very important for geothermal development and utilization. Generally, the recovery factor is a measure of available geothermal resources in a geothermal field. However, it has been a pre-determined ratio in practice and sustainable utilization of geothermal resources was not considered in the previous calculation of recoverable resources. In this work, we have attempted to develop a method to calculate recoverable geothermal resources based on a numerical thermo-hydraulic coupled modeling of a geothermal reservoir under exploitation, with an assumption of sustainability. Taking a geothermal reservoir as an example, we demonstrate the effectiveness of the method. The recoverable geothermal resources are 6.85 × 1018 J assuming a lifetime of 100 years in a well doublet pattern for geothermal heating. We further discuss the influence of well spacing on the recoverable resources. It is found that 600 m is the optimal well spacing with maximum extracted energy that conforms to the limit of the pressure drop and no temperature drop in the production well. Under the uniform well distribution pattern for sustainable exploitation, the recovery factor is 26.2%, which is higher than the previous value of 15% when depending only on lithology. The proposed method for calculating the recoverable geothermal resources is instructive for making decisions for sustainable exploitation.

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An Approach for Estimating Geothermal Reservoir Productivity under Access Limitations Associated with Snowy and Mountainous Prospects

10.5772/intechopen.96314 ◽

2021 ◽

Author(s):

Mitsuo Matsumoto

Keyword(s):

Early Time ◽

Geothermal Field ◽

Geothermal Reservoir ◽

Well Testing ◽

Reservoir Pressure ◽

New Approach ◽

Frequency Distributions ◽

Arbitrary Time ◽

Active Exploration ◽

Time Limitations

This chapter describes an approach to estimate reservoir productivity during the active exploration and development of a geothermal prospect. This approach allows a reservoir model to be updated by overcoming the severe time limitations associated with accessing sites for drilling and well testing under snowy and mountainous conditions. Performed in parallel with the conventional standard approach, the new approach enables us to obtain a first estimate of the reservoir productivity at an early time and to make successful project management decisions. Assuming a practical geothermal field, the procedures of the new approach are demonstrated here in detail. Finally, frequency distributions for the expected production rates and changes in the reservoir pressure at an arbitrary time are obtained during an assumed operational period.

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RESISTIVITY, SELF‐POTENTIAL, AND INDUCED‐POLARIZATION SURVEYS OF A VAPOR‐DOMINATED GEOTHERMAL SYSTEM

Geophysics ◽

10.1190/1.1440400 ◽

1973 ◽

Vol 38 (6) ◽

pp. 1130-1144 ◽

Cited By ~ 83

Author(s):

A. A. R. Zohdy ◽

L. A. Anderson ◽

L. J. P. Muffler

Keyword(s):

Geothermal Field ◽

Induced Polarization ◽

Hot Water ◽

Thermal Waters ◽

Geothermal System ◽

Electrical Soundings ◽

Lateral Extent ◽

High Concentrations ◽

Lake Deposits ◽

Self Potential

The Mud Volcano area in Yellowstone National Park provides an example of a vapor‐dominated geothermal system. A test well drilled to a depth of about 347 ft penetrated the vapor‐dominated reservoir at a depth of less than 300 ft. Subsequently, 16 vertical electrical soundings (VES) of the Schlumberger type were made along a 3.7‐mile traverse to evaluate the electrical resistivity distribution within this geothermal field. Interpretation of the VES curves by computer modeling indicates that the vapor‐dominated layer has a resistivity of about 75–130 ohm‐m and that its lateral extent is about 1 mile. It is characteristically overlain by a low‐resistivity layer of about 2–6.5 ohm‐m, and it is laterally confined by a layer of about 30 ohm‐m. This 30‐ohm‐m layer, which probably represents hot water circulating in low‐porosity rocks, also underlies most of the survey at an average depth of about 1000 ft. Horizontal resistivity profiles, measured with two electrode spacings of an AMN array, qualitatively corroborate the sounding interpretation. The profiling data delineate the southeast boundary of the geothermal field as a distinct transition from low to high apparent resistivities. The northwest boundary is less distinctly defined because of the presence of thick lake deposits of low resistivities. A broad positive self‐potential anomaly is observed over the geothermal field, and it is interpretable in terms of the circulation of the thermal waters. Induced‐polarization anomalies were obtained at the northwest boundary and near the southeast boundary of the vapor‐dominated field. These anomalies probably are caused by relatively high concentrations of pyrite.

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Feasibility, Design and authorization of a zero-emission Geothermal Power Plant in Italy; Case Study: “Montenero” Project

10.5194/egusphere-egu2020-20541 ◽

2020 ◽

Author(s):

Paolo Basile ◽

Roberto Brogi ◽

Favaro Lorenzo ◽

Tiziana Mazzoni

Keyword(s):

Power Plant ◽

Power Plants ◽

Geothermal Field ◽

Geothermal Reservoir ◽

Gas Content ◽

Geothermal Resources ◽

Geothermal Fluid ◽

Geothermal Power Plant ◽

Green Power ◽

Geothermal Power

Social consensus is a condition precedent for any intervention having an impact on the territory, such as geothermal power plants. Therefore, private investors studied and proposed innovative solution for the exploitation of the medium enthalpy geothermal resource, with &#8220;zero emissions&#8221; in atmosphere, with the target of minimizing its environmental impact. &#8220;Montenero&#8221; project, developed by GESTO Italia, complies with this precondition.The area covered by the exploration and exploitation permit is located on the northern edge of the great geothermal anomaly of Mt. Amiata (Tuscany), about 10 km north of the geothermal field of Bagnore, included in the homonymous Concession of Enel Green Power.The geological - structural setting of the area around the inactive volcano of Mt. Amiata has been characterized by researches for the geothermal field of Bagnore, carried out by Enel Green Power over the years. The geothermal reservoir is present in the limestone and evaporitic rocks of the &#8220;Falda Toscana&#8221;, below which stands the Metamorphic Basement, as testified by the wells of geothermal field of Bagnore. The foreseen reservoir temperature at the target depth of 1.800 m is 140 &#176;C, with an incondensable gas content of 1,8% by weight.The project was presented to the authorities in 2013 and it is now undergoing exploitation authorization and features the construction of a 5 MW ORC (Organic Ranking Circle) binary power plant. The plant is fed by three production wells for a total mass flow rate of 700 t/h. The geothermal fluid is pumped by three ESPs (Electrical Submersible Pump) keeping the geothermal fluid in liquid state from the extraction through the heat exchangers to its final reinjection three wells.The reinjection temperature is 70 &#176;C and the circuit pressure is maintained above the incondensable gas bubble pressure, i.e. 40 bar, condition which prevents also the formation of calcium carbonate scaling. The confinement of the geothermal fluid in a &#8220;closed loop system&#8221; is an important advantage from the environmental point of view: possible pollutants presented inside the geothermal fluid are not released into the environment and are directly reinjected in geothermal reservoir.The environmental authorization procedure (obtained) has taken into account all the environmental aspects concerning the natural matrices (air, water, ground, ...) potentially affected by the activities needed for the development, construction and operation of &#8220;Montenero&#8221; ORC geothermal power plant. A numerical modeling was designed and applied in order to estimate the effect of the cultivation activity and to assess the reinjection overpressure (seismic effect evaluation). The project also follows the &#8220;best practices&#8221; implemented in Italy by the &#8220;Guidelines for the usage of medium and high enthalpy geothermal resources&#8221; prepared in cooperation between the Ministry of Economic Development and the Ministry of the Environment.

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