Reinjection in geothermal fields: An updated worldwide review 2020

Fluid circulation and reservoir conditions of the Los Humeros Geothermal Field (LHGF), Mexico, as revealed by a noble gas survey

A noble gas and 87Sr/86Sr study in fluids of the Los Azufres geothermal field, Mexico – Assessing impact of exploitation and constraining heat sources

Fluid geochemistry of the Los Humeros geothermal field (LHGF - Puebla, Mexico): New constraints for the conceptual model

An analytical methodology for reservoir characterization was applied in the central and southwestern zones of Los Humeros geothermal field (LHGF). This study involves analysis of temperature, pressure, enthalpy and permeability in wells and their distribution along the area. The wells located in the central western side of the geothermal field are productive, whereas those located at the central-eastern side are non-productive. Through temperature profiles, determined at steady state in the analyzed wells, it was observed that at bottom conditions (approximately 2300 m depth), temperatures vary between 280 and 360 °C. The temperatures are higher at the eastern side of central zone of LHGF. A review of transient pressure tests, laboratory measurements of core samples, and correlation of circulation losses during drilling suggest that permeability of the formation is low. The enthalpy behavior in productive wells shows a tendency of increase in the steam fraction. It was found that productivity behavior has inverse relation with permeability of rock formation. Further, it is observed that an imbalance exists between exploitation and recharge. It is concluded from the results that the wells located at central-eastern area have low permeability and high temperature, which indicates possibility of heat storage.

Analysis of heterogeneous characteristics in a geothermal area with low permeability and high temperature

In this work, the response to exploitation of the Los Humeros geothermal reservoir was inferred through the study of the changes in production of wells, the thermodynamic conditions of reservoir fluids, and the chemical compositions of fluids over time. Up to 2012, almost 123 million tons of fluids had been extracted from the reservoir. Well bottom conditions (pressure and enthalpy) were calculated using heat and flow simulation. The changes in the composition of fluids seem to be related to boiling. In high-enthalpy wells, condensation in the well or in the reservoir was inferred to occur. Results also showed a decreasing trend in fluid salinity due to increasing boiling and condensation. The average reservoir liquid saturation for the field has a decreasing trend over time. Analysis of gas data suggested that the number of wells produce either a steam phase or condensed reinjection returns. According to the results, five main processes were identified: (a) pressure decrease and enthalpy increase that produces a moderate boiling process with steam gain; (b) iSignificant boiling and steam condensation; (c) production of returns from reinjection; (d) interaction with deep fluids, and (e) decrease in reservoir liquid saturation due to insufficient recharge.

The Response to Exploitation of the Los Humeros (México) Geothermal Reservoir

A combined analysis of
geochemical and production data of 39 wells of the Los Azufres (Mexico)
geothermal field (227.4 MWe) over time was developed to investigate the
exploitation-related processes for 2003-2011. In the south zone, important
effects of reinjection were observed through Cl increases in some wells (up to
8000 mg/kg) while in wells with significant boiling, Cl has decreased. In most
of the north zone wells, the variations in gas data indicated boiling and
condensation of a highly gas-depleted brine, which seems to consist of
reinjection fluids. It is suggested that this process maintains the production
in the zone relatively stable. The main reservoir exploitation-related
processes found were: 1) production of reinjection returns; for this, it was possible
to distinguish a) wells that produce liquid and steam from injection, and b)
wells that produce steam from injection and sometimes condensed steam from
injection; 2) boiling: two types of boiling were identified: a) boiling with
steam gain, and b) boiling with steam loss. The results indicated that an
effective reservoir recharge occurs since very moderate production declining
rates were found.

/pdf/reservoir-processes-related-to-exploitation-in-los-azufres-4qtd5ssm45.pdf

Siomara López

Papers

The Response to Exploitation of the Los Humeros (México) Geothermal Reservoir

Reservoir Processes Related to Exploitation in Los Azufres (México) Geothermal Field Indicated by Geochemical and Production Monitoring Data