Reservoir Processes Related to Exploitation in Los Azufres (M&amp;#233;xico) Geothermal Field Indicated by Geochemical and Production Monitoring Data

Víctor Manuel Arellano,Alfonso Aragón,Lisette Reyes,Emigdio Casimiro,Miguel Ramírez,Adriana Paredes,Rosa María Barragán,Siomara López

doi:10.4236/ijg.2015.69083

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.

Highlights

The Los Azufres geothermal field is an intensely-fractured, two-phase, volcanic hydrothermal system located in the northern portion of the Mexican Volcanic Belt, in the state of Michoacán, at an average elevation of 2800 m.a.s.l. (Figure 1)
Reservoir engineering and geochemical conceptual models of the Los Azufres system were established [2] [3] which constitute the reference conditions that allow characteristic changes in parameters over time to be related to exploitation
The Los Azufres geothermal field is operated by the Comisión Federal de Electricidad (CFE)

Summary

Introduction

The Los Azufres geothermal field is an intensely-fractured, two-phase, volcanic hydrothermal system located in the northern portion of the Mexican Volcanic Belt, in the state of Michoacán, at an average elevation of 2800 m.a.s.l. (Figure 1). The Los Azufres geothermal field is an intensely-fractured, two-phase, volcanic hydrothermal system located in the northern portion of the Mexican Volcanic Belt, in the state of Michoacán, at an average elevation of 2800 m.a.s.l. The installed capacity of the field is 227.4 MWe [1]. The installed capacity of the field was 88 MWe during that time. In order to support decisions on field polices regarding sustainable exploitation, the objective of this work was to investigate the exploitation-related processes through the analysis of geochemical and production data of 39 wells. The Los Azufres geothermal field is operated by the Comisión Federal de Electricidad (CFE). All of the injection wells are located on the west side of the field. Injectors Az-3, 15, 52, and 61 are located in the northern production area, whereas Az-7A and 8 are in the south

Objectives

Methods

Results