Permittees shall construct and case all geothermal wells in
a manner to protect or minimize damage to life, health, property, ground water
and surface waters, geothermal resources, other natural resources, the
environment and the public welfare. No permittee shall construct, operate,
maintain, convert, plug, abandon or conduct any other injection activity in a
manner that allows the movement of fluid containing any contaminant into
underground sources of drinking water, if the contaminant may cause a violation
of drinking water regulations or rules or may otherwise adversely affect the
health of persons. The permittee has the burden of showing that it meets these
requirements. The permittee shall attach the permanent well head completion
equipment to the production casing or to the intermediate casing if production
casing does not reach the surface. The permittee shall install an annular
blowout preventer on wells when the division deems it necessary. All surface,
intermediate and production casing strings reaching the surface shall provide
adequate anchorage for BOPE, pressure control and protection for all natural
resources. The casing design criteria listed below represent minimum
requirements.
A.
Conductor
casing. The permittee shall install a minimum of 40 feet of conductor
casing. The permittee shall cement the annular space solid to the surface. The
permittee shall allow a 24-hour cure period for the grout prior to drilling out
the shoe unless the permittee uses additives, approved by the division, to
obtain early strength.
B.
Surface casing. A surface casing shall provide for control of
formation fluids, for protection of shallow usable ground water and for
adequate anchorage for BOPE. The permittee shall cement all surface casing
solid to the surface. The permittee shall allow a 24-hour cure period prior to
drilling out the shoe of the surface casing unless the permittee uses
additives, approved by the division, to obtain early strength. The permittee
shall set sufficient casing to reach a depth below all known or reasonably
estimated levels of fresh water and water of present or future value for
domestic, commercial or agricultural use and to protect those aquifers and to
prevent blowout or uncontrolled flows.
C.
Intermediate casing.
Intermediate casing is required for protection against unusual pressure zones,
cave-ins, wash-outs, abnormal temperature zones, uncontrollable lost
circulation zones or other drilling hazards. The permittee shall cement
intermediate casing strings solid to the surface or to the top of the liner
hanger whenever the permittee runs intermediate casing string as a liner. The
permittee shall pressure test the liner lap, of any unslotted liner, prior to
resumption of drilling.
D.
Production casing. The permittee shall set production casing above
or through the producing or injection zone and cement it above the injection
zones. The permittee shall use sufficient cement to exclude overlying formation
fluids from the geothermal zone, to segregate zones and to prevent movement of
fluids behind the casing into zones that contain fresh ground water. The
permittee shall either cement production casing solid to the surface or lap it
into intermediate casing, if run. If the permittee laps production casing into
an intermediate casing, the casing overlap shall be at least 100 feet, cemented
solid and pressure tested to ensure its integrity.
E. All casing materials shall be suitable for
the proposed operating design stresses and temperatures.
