| Abstract |
The Azufres geothermal system is located in the State of Michoacán, 80 km east of the city of Morelia and 16 km northwest of Ciudad Hidalgo. It was explored in the mid 1970s and since then it has been under development for more than 30 years. At the present Los Azufres is generating 191.6 MWe and it is under construction a new 50 MWe unit in the northern part of the field that will be commissioned December 2014. In order to supply enough steam for the installed capacity in the field, several actions have been taken. Those actions consist of wells intervention (directional wells, mechanical cleaning or acidification), perforation of new wells, etc. In the past Los Azufres had employed the conventional overbalanced drilling technology and more than 70 wells were drilled with this technique, which used a drilling mud prepared with bentonite clay in order to provide stability to the hole, reduce friction of the drill bit and drag cutting to the surface. However, due to formation damage suffered in the vicinity of the wells because of the invasion of drilling mud and cuttings, reducing the production output of wells, it was decided to change to underbalanced drilling. In this work, production results of 6 new wells drilled using underbalanced drilling technique are presented. The analysis indicates that the wells have been completed without formation damage and the production results indicated values among 30 to 86 t/h of steam, equivalent to 4 – 11 MWe. |