| (a) Wells shall be sited in such a fashion that they
inject into a formation which is beneath the lowermost formation containing,
within one quarter mile of the well bore, an underground source of
drinking water (USDW).
(b) Plans and specifications. Except as specifically
required in the terms of the disposal well permit, the drilling and
completion of the well shall be done in accordance with all permit
application plans and specifications.
(c) Any proposed changes to the plans and specifications
must be in accordance with §331.62(a)(3) of this title (relating
to Construction Standards).
(d) Casing and cementing.
(1) Wells shall be cased and cemented to prevent the
movement of fluids into or between USDW. The casing and cement used
in the construction of each newly drilled well shall be designed for
the life expectancy of the well. In determining and specifying casing
and cementing requirements, the following factors shall be considered:
(A) depth of lowermost USDW or freshwater aquifer;
(B) depth to the injection zone;
(C) injection pressure, external pressure, internal
pressure, and axial loading;
(D) hole size;
(E) size and grade of all casing strings (wall thickness,
diameter, nominal weight, length, joint specification, and construction
material);
(F) the maximum burst and collapse pressures, and tensile
stresses which may be experienced at any point along the length of
the casings at any time during the construction, operation, and closure
of the well;
(G) corrosive effects of injected materials, formation
fluids, and temperatures;
(H) lithology of injection and confining zones;
(I) types and grades of cement;
(J) quantity and chemical composition of the injected
fluid; and
(K) cement and cement additives which must, at a minimum,
be of sufficient quality and quantity to maintain integrity over the
design life of the well.
(2) Surface casing shall be set to a minimum subsurface
depth which extends into a confining bed below the lowest formation
containing a USDW or freshwater aquifer.
(3) A second or long string casing, using a sufficient
number of centralizers, shall be set into the salt formation.
(4) The cement for that part of the casing opposite
a salt formation shall be prepared with salt-saturated cementing material.
(e) Injection tubings. Except for circulation of drilling
fluids during well construction, all injection activities for bedded
salt cavern construction and waste disposal in a bedded salt cavern
shall be performed using removable injection tubing(s) suspended from
the wellhead.
(1) All injection activities during bedded salt cavern
construction shall be performed with the annulus between the tubing
and long string casing filled with a noncorrosive fluid sufficient
to protect the long string casing seat.
(2) All injection of waste into a bedded salt cavern
shall be performed through tubing with a packer to seal the annulus
between the tubing and casing near the bottom of the casing, or tubing
with an approved fluid seal as an alternative. The tubing, packer,
and fluid seal shall be designed for the expected service.
(f) Well annulus system factors for consideration.
In determining and specifying requirements for a tubing and packer
system or tubing with a fluid seal, the following factors shall be
considered and addressed:
(1) depth of setting;
(2) characteristics of injection fluid and waste;
(3) injection pressure;
(4) annular pressure;
(5) rate, temperature, and volume of injected waste;
(6) size of casing; and
(7) tensile, burst, and collapse strengths of the tubing.
(g) Logs and tests.
(1) Geophysical logging. Appropriate logs and other
tests shall be conducted during the drilling and construction phases
of the well including drilling into the salt. All logs and tests shall
be interpreted by the service company which processed the logs or
conducted the test, or by other qualified persons. At a minimum the
following logs and tests shall be conducted:
(A) deviation checks on all holes, conducted at sufficiently
frequent intervals to assure that avenues for fluid migration in the
form of diverging holes are not created during drilling;
(B) a spontaneous potential and resistivity log;
(C) from the ground surface or from the base of conductor
casing to the total investigated depth including all core hole or
pilot hole:
(i) natural gamma ray log;
(ii) compensated density and neutron porosity logs;
(iii) acoustic or sonic log;
(iv) inclination (directional) survey; and
(v) caliper log (open hole);
(D) from the ground surface or from the base of conductor
casing to the lowermost casing seat:
(i) cement bond with variable density log;
(ii) temperature log (cased hole); and
(iii) casing inspection log; and
(E) fracture detector log from the base of the surface
casing to the total investigated depth including all core hole or
pilot hole.
(2) Pressure tests.
(A) After installation and cementing of casings, and
before drilling out the cemented casing shoe, surface casing shall
be pressure tested at mill test pressure or 80% of the calculated
internal pressure at minimum yield strength, and the intermediate
and long string casing shall be tested to 1,500 pounds per square
inch (psi) for 30 minutes, unless otherwise specified by the executive
director.
(B) After drilling out the cemented long string casing
shoe, and before drilling more than 100 feet of core hole or pilot
hole below the long string casing shoe, the bond between the salt,
cement, and casing shall be tested at a pressure of 0.8 psi per foot
of depth.
(C) The pilot hole and/or core hole shall be tested
between the long string casing shoe and the total investigated depth,
at a casing seat pressure of 0.8 psi per foot of depth.
(3) Coring.
(A) Core samples. Full-hole cores shall be taken from
selected intervals of the injection zone and lowermost overlying confining
zone; or, if full-hole coring is not feasible or adequate core recovery
is not achieved, sidewall cores shall be taken at sufficient intervals
to yield representative data for selected parts of the injection zone
and lowermost overlying confining zone. Core analysis shall include
a determination of permeability, porosity, and bulk density.
(B) In situ permeability, lithostatic gradients, and
fracture pressure gradients shall be determined in the core hole for
the salt, within the cavern injection interval.
(4) Before commencement of injection for cavern construction,
any portion of the pilot hole or core hole that extends beyond the
intended wall of the cavern shall be filled with salt-saturated cement
from total investigated depth back to the designed cavern boundary.
(5) Well integrity testing. The mechanical integrity
of a well must be demonstrated before initiation of injection activities.
A mechanical integrity test shall consist of:
(A) a pressure test with liquid or gas;
(B) a temperature, noise log, or oxygen activation
log;
(C) a casing inspection log, if required by the executive
director; and
(D) any other test required by the executive director.
(h) Compatibility. All well materials must be compatible
with formations and fluids with which the materials may be expected
to come into contact. A well shall be deemed to have compatibility
as long as the materials used in the construction of the well meet
or exceed standards developed for such materials by the American Petroleum
Institute, the American Society for Testing Materials, or comparable
standards acceptable to the executive director.
(i) Pre-injection units.
(1) The injection pump system shall be designed to
assure that the surface injection pressure limitations authorized
by the well permit shall not be exceeded.
(2) Instrumentation shall be installed to continuously
monitor changes in annulus pressure and annulus fluid volume for the
purpose of detecting well malfunctions.
(3) Pre-injection units, while allowing for pressure
release, shall be designed to prevent the release of unauthorized
cavern contents to the atmosphere.
Cont'd... |
