Miguel Ramírez

Bio: Miguel Ramírez is an academic researcher from Comisión Federal de Electricidad. The author has contributed to research in topics: Geothermal gradient & Volcanic belt. The author has an hindex of 4, co-authored 8 publications receiving 80 citations.

The structural architecture of the Los Humeros volcanic complex and geothermal field

Abstract: The Los Humeros Volcanic Complex (LHVC) is a large silicic caldera complex in the Trans-Mexican Volcanic Belt (TMVB), hosting a geothermal field currently in exploitation by the Comision Federal de Electricidad (CFE) of Mexico, with an installed capacity of ca. 95 MW of electric power. Understanding the structural architecture of LHVC is important to get insights into the interplay between the volcano-tectonic setting and the characteristics of the geothermal resources in the area. The analysis of volcanotectonic interplay in LHVC benefits from the availability of subsurface data obtained during the exploration of the geothermal reservoir that allows the achievement of a 3D structural view of the volcano system. The LHVC thus represents an important natural laboratory for the development of general models of volcano-tectonic interaction in calderas.

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

Abstract: 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.

Chemical Modeling of Fluids from the Las Tres Vírgenes B. C. S. (México) Geothermal Field

Abstract: The Las Tres Virgenes geothermal field is a liquid-dominated resource located in the Baja California Peninsula (Mexico) that currently has an installed power capacity of 10 MWe. The exploitation of this field has been limited because of a large, mostly calcite scaling potential of produced fluids which makes necessary the use of commercial inhibitors that suppress calcite and anhydrite deposition, in most of the wells. In this work the chemical composition of fluids from wells of the Las Tres Virgenes field was used to perform equilibrium modeling for a wide range of temperatures to investigate the saturation indices of hydrothermal minerals and to identify desirable production conditions for the wells at which calcite scaling could be avoided. The wells studied were LV-1, LV-3, LV-4, LV-5, LV-11 and LV-13 while input data corresponded to an early production stage of the wells. Chemical speciation was calculated by using the WATCH program, the temperature ranged from 150 to 300°C with calculations every 2°C. The behavior of the saturation indices of minerals vs temperature for the wells LV-1, LV-3 and LV-5 suggested more than one fluid-mineral equilibrium temperature, (at about 180, 220 and 240°C for well LV-1; 220, 250 and 270°C for well LV-3 and 180, 200 and 240°C for well LV-5) indicating the occurrence of multiple fluid entries. This is consistent with the temperature differences obtained when using different (Na/K, Na-K-Ca and quartz) geothermometers. We conclude that observed scaling phenomena in these wells is probably due to mixing of different fluids in the well. In well LV-4 the mineral equilibrium temperatures were found within the relatively narrow interval 257-268°C, indicating no significant multiple fluid entries and reservoir fluid temperature in the feeding area of this well in its early production stage. Based on fluid-mineral equilibria, the reservoir temperature for wells LV-11 and LV-13 could be at least 290°C, quartz equilibrium occurs at 290 and 300°C respectively, and as was stated for well LV-4, no multiple entries were identified at early production conditions in both wells. Calcite was found to be oversaturated in the wells LV-1 and LV-3 for almost all the studied temperatures; for the wells LV-4 and LV-11 calcite showed equilibrium at 190°C; for the well LV-5 at 180°C while for the well LV-13 such equilibrium occurs at 225°C. Anhydrite showed equilibrium at 200°C in well LV-5; 220°C in LV-1; 230°C in LV-13; 250°C in LV-3 and LV-4 and 290°C in LV-11. Our results show oversaturation of calcite and anhydrite at higher temperatures, consistently with the reverse solubility of these minerals. Based on these results, separation pressures for the fluids were recommended although it is well known that the separation process itself could promote calcite precipitation, because of fluid degassing.

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

Abstract: 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.

Reinjection in Geothermal Fields: A Worldwide Review Update

Abstract: Reinjection is very important for all types geothermal reservoirs under production and it can become the key factor in the success or failure of the geothermal power development This work gives an up-to-date description and analysis of worldwide experience of reinjection in geothermal reservoirs to provide guidelines for the optimum implementation of reinjection In 2011, Kaya et al [1] conducted a review of worldwide experiences of injection in geothermal fields, based on published information from 91 electric-power producing geothermal developments In the present review, we have extended the database to 126 geothermal developments and added an additional five years of reported field experience This updated review, investigates past and current reinjection strategies implemented in the geothermal fields and the response of different types of geothermal reservoirs to these strategies The location of reinjection wells and the amount of reinjected fluid, in addition to problems, adverse effects and benefits associated with production, have been taken into consideration This study shows that the design of reinjection is most often empirical and site-specific, because the effect of injection on production depends on the setting of the given geothermal system However, there are some generic similarities depending on whether the system is vapour-dominated, liquid dominated, or hot-water Experience has shown that reinjection should be planned as early as possible in the field development process and it should be flexible, as it is likely to change with time An optimum reinjection strategy should balance the requirements of sustaining the reservoir pressure and preventing early thermal breakthrough of reinjected water The effects of reinjection on the natural hot recharge and, therefore, on energy recovery from the system may also be important

Review of failure modes in supercritical geothermal drilling projects

Abstract: Supercritical geothermal resources located close to the transition between the brittle–ductile zone have been proven to exist at drillable depths. This was demonstrated by several deep geothermal drilling campaigns throughout the years, starting in the late 1970s. The interest in exploring supercritical resources is particularly strong, as it was revealed that one such well might significantly increase the production output and simultaneously decrease the need for drilling operations within a particular geothermal field. Deep drilling projects exploring supercritical resources such as these carried out in Iceland, Italy or Japan, where temperatures went significantly above the critical point and hostile geothermal fluids were produced, faced a variety of challenges during drilling operations and fluid production. The most critical of these exerted major thermally driven loads upon the cemented casing strings, leading to serious damages and eventually to well abandonment. This research presents an extensive literature search on failure modes of 20 wells from different high-enthalpy geothermal fields around the world, experiencing temperatures greater than the critical point of pure water and gives an overview of areas of improvements and potential solutions in regards to the drilling and well completion technology.