A preliminary assessment of a medium-enthalpy geothermal resource in Nagu (Tibet) people's republic of China
The Nagqu geothermal field is a single-phase, liquid-dominated system at reservoir conditions, having a high gas content. This field is located at an elevation of about 4,500 m (asl), in the vicinity of the City of Nagqu, which is one of the most important cities of Tibet.The reservoir rock is made of a highly fractured, low-permeability sedimentary sequence. During the implementation of the study described in this paper, fluid production was mainly obtained from two out of four possible productive wells. The main fault systems are located in a NE-SW and E-W directions, which seem to control fluid movement at depth. The geothermal field is restricted to a small area where hydrothermal manifestations are located. Reservoir temperature is 114 C, gas content is in the range of 0.5 to 0.6% by mass, being mainly CO{sub 2}. Reservoir transmissivity in the area of the wells is very high. Reservoir response to changes in flow rate in any of the producing wells could be detected almost immediately in the observation wells, which were distant between 300 to 900 m, depending on the production-observation well arrangement. Calcium carbonate scaling was present in all producing wells. This deposition was controlled by the CO{sub 2} partial pressure. Description of well testing results is provided, as well as the thermodynamics and geochemistry of reservoir fluids.
- Research Organization:
- Aquater S.p.A., San Lorenzo, Campo, IT; Istituto Internazional per le Ricerche Geotexmiche, Pisa, IT; Geothermal Development Corporation of Tibet Autonomous Region, Beijing, CN
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 887492
- Report Number(s):
- SGP-TR-134-17; TRN: US200619%%235
- Resource Relation:
- Conference: Proceedings, sixteenth workshop on geothermal reservoir engineering, Stanford University, Stanford, CA, January 23-25, 1991
- Country of Publication:
- United States
- Language:
- English
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