Introduction
This Geothermal Country Overview will feature Nicaragua. Nicaragua is home to the largest freshwater lake in Central America, Lake Nicaragua often referred to as ‘Mar Dulce’. This lake is home to some of the rarest freshwater sharks in the world. It is also home to a string of 40 (at least 19 active) volcanoes running northwest-southeast along the Pacific coast. Volcanoes play a special role in Nicaragua as they featured in the country’s coat of arms on its flag; utilized in a popular extreme sport, volcano boarding (riding on wooden boards down a volcano’s steep slope); and geothermal systems (associated with volcanoes) have been and are being explored and developed to produce electricity.
Geological Overview
Nicaragua is in Central America and is a part of the Central America Volcanic Arc (CAVA) which extends along the Pacific coastline from Guatemala through Belize, El Salvador, Honduras, Nicaragua, and Costa Rica to Panama. The arc was developed due to the active subduction of the Cocos oceanic plate under the Caribbean continental plate along the Mesoamerican trench. Nicaragua is divided into four physiographical provinces, from west to east these are:
- The Pacific Coastal Plain is divided into north and south sections separated by a hinge line aligned with the northwestern shore of Lake Nicaragua in the Nicaraguan Depression. This hinge line also coincides with a break and offset of the coastline and coincides approximately with an offset in the volcanic chain. The North is covered by younger (Tertiary – Quaternary) rocks while the south is dominated by older rocks (Cretaceous-Tertiary)
- The Nicaraguan Depression includes the Quaternary Volcanic Chain, a chain of volcanoes with an NW-SE orientation known as the Los Marabios range. The Nicaraguan depression is a major tectonic structure parallel to the Central American Trench, which extends the length of western Nicaragua. The depression has been defined as a half-graben (a zone of structural subsidence) limited by NW-SW striking normal faults, generally dipping NE. The Nicaraguan depression also hosts the Managua and Nicaragua lakes.
- The Interior Highlands are composed largely of volcanic rocks (Tertiary) with some metamorphic and sedimentary rocks of varying geological ages.
- The Atlantic Coastal Plain consists of quaternary sediments overlying tertiary volcanic rocks
Geothermal Fields
The geothermal resources of Nicaragua are in the SW section of the country in the Nicaraguan Depression associated with the Los Marabios Range. Twelve geothermal areas have been identified in Nicaragua (Figure 1). Only two of these fields are currently producing, while the others vary from reconnaissance to feasibility stages. This overview will cover 4 geothermal areas (the producing fields and fields further along in the pre/feasibility stages).
Figure 1: Geothermal areas of Nicaragua from (Aráuz Torres 2011)
Momotombo geothermal field:
The Momotombo geothermal field is in the South East section of the Los Marabios Range on the shores of Lake Managua and on the southern slope of the active Momotombo Volcano. Key faults in the field include the Momotombo (south-east), Bjornsson (north-east), Guatusa, and the Perez faults. Geothermal manifestations include fumaroles (associated with the Momotombo crater), hot springs (e.g. Tipitapa and San Luis), hydrothermally altered ground, and warm water wells (e.g. Hacienda Agua Caliente-Villa Salvadorita). Temperatures of the fumaroles are between 100 – 800 °C while the hot springs and warms wells range in temperature from 30 – 96 °C.
Geothermal studies began in the 1960s and the first wells were completed in the early 1970s. Since then 47 wells (Figure 2) have been drilled varying from 313 m to 2983 m in depth. Three different geothermal reservoirs have been identified: shallow (300 – 800 m), intermediate (800 -1700 m); and deep reservoir (1700 – 3000 m). The temperature of the shallow reservoir is between 200 – 230 °C and the deep reservoir is between 250-290°C. The geothermal waters are classified as sodium chloride.
Figure 2: Geothermal wells completed in Nicaragua (from various sources)
Several geophysical studies have been carried out in this geothermal field aimed at defining production target areas and specific drilling targets. This includes
- Schlumberger sounding
- Dipole mapping surveys
- Electromagnetic soundings
- Audio-magnetotelluric (AMT) surveys
- Gravity and magnetic
- Integrated geophysical studies: utilized several geophysical methods (self-potential, gravimetry, aeromagnetics, microearthquake monitoring, resistivity data) coupled with remote sensing (aerial photo, LandSat and RadarSat images) and temperature surveys.
San Jacinto – Tizate:
The San Jacinto-Tizate geothermal field is in northwestern Nicaragua and is part of the eastern Telica volcanic massif (this includes the San Jacinto and Santa Clara volcanos). Major faults in the area are NNE-trending, NW-trending, and volcano-tectonic ring faults. The area also includes the Telica-Rota Nature Reserve, a protected area. Thermal manifestations include steam-heated mud pools, fumaroles, and seasonal warm springs.
The first geoscientific studies of the area were conducted in 1953 where three shallow wells were drilled to a depth of 86 m. Exploration continued from the 1960s, including geological, geochemical, and geophysical surveys. The drilling of additional shallow temperature gradient wells indicated a high temperature (250 – 300 °C) resource. The geothermal area is divided into an eastern and a western section with development focused on the eastern region. A total of 16 wells (Figure 2) have been drilled with depths ranging from 721 – 2278 m.
Two geothermal reservoirs have been identified in the San Jacinto – Tizate area, a shallow and a deep. In the San Jacinto area, the shallow reservoir is between 350 – 680 m and the deep is from 880 – 1080 m. While in Tizate the shallow reservoir is between 550 – 1200 m and the deep is > 1600 m. The caprock is 300 – 400 m thick consisting of altered rock across both areas. Both geothermal reservoirs are liquid-dominated with sodium chloride waters. At shallow depths, temperatures range from 190 – 265 °C and in the deep reservoir, the highest temperatures are 265 – 304 °C.
Geophysical studies were carried out in this geothermal field including MT surveys identifying an extensive layer representing the clay cap above the high-temperature reservoir. Other structures identified to coincide with the El Tizate thermal area, geothermal manifestations, and production wells.
Casita Volcano – San Cristóbal Volcano:
The Casita – San Cristobal geothermal field is in northwestern Nicaragua. Key geological structures in the field include north-west and north-east (strike-slip) and north-south (normal) faults, pull-apart basins, and various volcanic features (Casita Volcano, Ollade crater, and La Pelona caldera).
Geothermal manifestations include fumaroles with steam at temperatures of 96°C (Ollade fumaroles). Steaming grounds are widespread east and southeast of the volcanic crater and on the northern rim of the La Pelona caldera. Geothermal springs (El Bonete and Monte Largo hot springs) reach temperatures of 85°C and groundwater wells (Las Grietas) temperatures of up to 50°C.
Geothermal exploration began in 1999 leading to detailed structural assessment and remote sensing and GIS studies (ASTER, SAR, and a detailed DEM). A slimhole well was completed on the slopes of the Casita volcano to a depth of 842 m (2011). Well testing confirmed the existence of a vapor-dominated reservoir at Casita, with temperatures of 230- 250°C (maximum 232°C at 696 m), and total gas content of about 0.7 wt %.
Geochemical studies on the Ollade fumarole indicate that the steam is derived from a vapor-dominated zone at temperatures of between 225 and 250°C. A hydro-geological model indicated a vapor dominated zone beneath Casita ridge overlying a neutral-chloride reservoir. Warm wells around Casita have neutral bicarbonate-sulphate chemistries while the El Bonete hot springs have neutral sulphate chemistries. Gas geothermometry indicates source temperatures more than 250°C with vapor-dominated conditions at shallow depths.
Geophysical surveys were carried to help delineate the extent and depth of the geothermal resource in the area. This includes MT and aeromagnetic surveys. An interesting thing to note is that geophysical surveys were carried with hopes of one day supplying power to the nearby El Limon gold mine.
El Hoyo – Monte Galán
The geothermal field lies on the axis of the Marabios range Nicaragua depression and is associated with the El Hoyo and Monte Galan Volcanoes. Key structures in the area include the Monte-Galán Caldera fracture systems (N-S trending?), the Hoyo and Picacho Volcanoes, and Cerro Colorado. Thermal manifestations include fumaroles, extensive hydrothermally altered ground, and hot springs (including the El Obraje Hot Springs)
Geothermal exploration began in 1996 and resulted in geological mapping and remote sensing; geochemical sampling; gas mapping; and geophysical surveys (MT, ground magnetic Gravimetry, controlled source audio magnetotellurics, Aeromagnetic soundings, Self-potential, and micro-seismic monitoring). Several anomalies were identified indicating a large geothermal resource characterized by shallow seismicity, fumarole activity, surface fractures, and high subsurface temperatures. Deep exploration began in 2009 and two commercial diameter wells (650 and 1623 m in depth) were drilled (Figure 2). Even though both wells were unsuccessful, the data obtained contributed to improving the understanding of the geothermal resource.
Status
CNE’s Geothermal Master Plan of 2001 projects that Nicaragua has nearly 5,500 MW of geothermal reserves. Of these, 303 MW are reservoirs established as proven reserves, 802 MW are probable reserves, and a further 4,375 MW are possible reserves (for more details about check Mostert Special Report 003/07 August 2007, Energy Sector Management Assistance Program).
Key geothermal updates in Nicaragua:
- The current installed capacity of Momotombo and San Jacinto-Tizate geothermal plants together is 150 MW.
- Geothermal energy provided 33.5% of all electricity generated in Nicaragua for the first 15 days of September 2020.
- In August 2020, Nicaragua’s Ministry of Energy Mines opened the process to receive expressions of interest from firms interested in carrying out geoscientific studies to determine the presence of a geothermal reservoir in the Cosigüina volcano geothermal area.
This concludes our Geothermal Country Overview on Nicaragua. We encourage you to scroll through our blog and read more Overviews and Geothermal Facts and Stats posts! Please follow, like, and share our work across social media.
Author: Jason Fisher
Other recent Geothermal Country Overviews’ include:
References/ Further Readings
Aráuz Torres, M.A., 2014. Modeling H2S Dispersion from San Jacinto-Tizate Geothermal Power Plant, Nicaragua (Doctoral dissertation). Faculty of Earth Sciences University of Iceland 2014.
Aráuz Torres, M.A., 2011. Environmental monitoring of geothermal projects in Nicaragua. Geothermal Training Programme Reports 2011, Number 6.
Bogie, I., Ussher, G.N. and Lawless, J.V., 2004. The Casita geothermal field, Nicaragua. In Proc. 26th New Zealand Geothermal Workshop, Taupo, New Zealand.
Ruiz Cordero, J.F., 2012. Geothermal Activity and Development in Nicaragua – Producing and Developing. Presented at “Short Course on Geothermal Development and Geothermal Wells”, organized by UNU-GTP and LaGeo, in Santa Tecla, El Salvador, March 11-17, 2012.
Kaspereit, D., Rickard, W., Osborn, W.L., Mann, M. and Perez, M., 2016. Field management and expansion potential of the Momotombo geothermal field using numerical simulation and conceptual modeling. In Proceedings, 41st Workshop on Geothermal Reservoir Engineering.
Klein, C.W., Henneberger, R.C., Robertson-Tait, A., Shultz, R.R., Sanyal, S.K., Velazquez M, L. and Guevara, G., 2001. A New Geothermal Resource Map of Nicaragua. Transactions-Geothermal Resources Council, pp.301-306.
Mackenzie, K.M., Steffen, M.W. and Phillips, R., 2012, November. Success of multiple-leg well completions at the San Jacinto-Tizate geothermal field, Nicaragua. In Proceedings of the New Zealand Geothermal Workshop (Vol. 2012, pp. 19-21).
Mayorga, A.Z., 2005, April. Nicaragua country update. In Proceedings of the World Geothermal Congress (pp. 24-29).
Ostapenko, S., Spektor, S., Davila, H., Porras, E. and Perez, M., 1996. A reservoir engineering assessment of the San Jacinto-Tizate geothermal field, Nicaragua (No. SGP-TR-151-4). Intergeoterm, SA, Managua, NI.
Porras, E.A., Tanaka, T., Fujii, H. and Itoi, R., 2007. Numerical modeling of the Momotombo geothermal system, Nicaragua. Geothermics, 36(4), pp.304-329.
Richter, A., 2020. Nicaragua – its geothermal potential, utilization and possible development. Think GeoEnergy.
Smith, A.T., 1997. Microseismicity Study of the El Hoyo-Monte Galan Geothermal Prospect, Nicaragua (No. UCRL-ID-127876). Lawrence Livermore National Lab, Livermore, CA (United States).
Solorzano, M.G. and Solorzano, M.G., 1990. Initial temperature distribution in the Mamotombo geothermal field, Nicaragua (No. 6). United Nations University.
Verma, M.P., Martinez, E., Sanchez, M., Miranda, K., Gerardo, J.Y. and Araguas, L., 1996. Hydrothermal model of the Momotombo geothermal system, Nicaragua (No. SGP-TR-151-5). Geotermia, Instituto de Investigaciones Electricas, Morelos, MX; Empresa
Nicaraguense de Energia de Electricidad, Managua, NI; Department of Research and Isotope, IAEA, Vienna, AT.
White, P., Lawless, J., Ussher, G. and Smith, A., 2008. Recent results from the San Jacinto-Tizate geothermal field, Nicaragua. In Proceedings of the New Zealand Geothermal Workshop.
White, P., Mackenzie, K., Brotheridge, J., Seastres, J., Lovelock, B. and Gomez, M., 2012. Drilling Confirmation of the Casita Indicated Geothermal Resource, Nicaragua. In Proceedings 34th New Zealand Geothermal Workshop.
Zuniga, A, and Medina, M., 2000. Nicaragua country update. Proceedings World Geothermal Congress 2000 (pp 509 – 514) Kyushu – Tohoku, Japan, May 28 – June 10, 2000.
Zúñiga, A., Su, M., Sánchez, M. and de Electricidad, E.N., 2003. Thermal manifestations in Nicaragua. GHC Bulletin, pp.23-25.
