The drilling of geothermal wells in El Salvador started in the late 60´s when 3
deep exploratory wells were drilled (AH-1, CH-1 and TR-1) at present 96
commercial casing wells have been drilled in the whole country. The standard
casing programme is 9 5/8” for production casing and 7” or 7 5/8” for slotted
linner, in some cases 13 3/8 and 9 5/8 also have been used. In the late 90, in
order to reduce the formation damage air, aerated mud or foam was used at
the Berlin field, where almost 300ºC is measured.
The use of directional wells was also implemented mainly to reduce the
environmental impacts of the civil works. The rock formation is andesite lavas,
tuff and clays, however hydrothermal alteration is normally found in the shallow
or deeper zones. The main constraints or problems during the drilling
operation are the loss circulation in the preliminary stages, several permeable
zones at different depths in the same hole, blow out in shallow thermal
aquifers and formation collapses or large severity that normally could cause
stuck of the pipe string, the use of lubricating fluids, back reaming or back off
operation must be necessary to recover the pipe or also the complete hole.
In spite of the normal problems during the drilling operations, the wells are
the unique way to get out the fluid and energy from the reservoir and an
alternative to convert in reality the use of the geothermal energy in El Salvador.