NDAC 43-02-03-21
Casing, tubing, and cementing requirements
Cite as N.D. Admin. Code ยง 43-02-03-21
1.
All wells drilled must be constructed with strings of casing which must be properly cemented at
sufficient depths to adequately protect and isolate all formations containing water, oil, or gas or
any combination of these; protect the pipe through salt sections encountered; and isolate the
uppermost sand of the Dakota group. Cementing must be by the pump and plug method while
the drilling rig is on the well or other methods approved by the director.
2.
Drilling of the surface hole must be with freshwater-based drilling mud or other method
approved by the director which protects all freshwater-bearing strata. This includes water used
during the cementing of surface casing for displacement. The surface casing must consist of
new or reconditioned pipe that has been previously tested to one thousand pounds per square
inch [6900 kilopascals]. The surface casing must be set and cemented at a point not less than
fifty feet [15.24 meters] below the base of the Fox Hills formation. Sufficient cement must be
used on surface casing to fill the annular space behind the casing to the bottom of the cellar, if
any, or to the surface of the ground. If the annulus space is not adequately filled with cement,
the director must be notified immediately. The operator shall diligently perform remedial work
after obtaining approval from the director. All strings of surface casing must stand cemented
under pressure for at least twelve hours before drilling the plug. The term "under pressure" as
used herein must be complied with if one float valve is used or if pressure is otherwise held.
An appropriate accurate gauge must be maintained on the surface casing of any well, not
properly plugged and abandoned, to detect any buildup of pressure caused by the migration
of fluids. Surface casing pressure must be monitored and maintained to keep the hydrostatic
pressure at the surface casing shoe below the pressure the formation integrity test was
performed at.
3.
Surface casing strings must be allowed to stand under pressure until the tail cement has
reached a compressive strength of at least five hundred pounds per square inch
[3450 kilopascals]. All filler cements utilized must reach a compressive strength of at least two
hundred fifty pounds per square inch [1725 kilopascals] within twenty-four hours and at least
three hundred fifty pounds per square inch [2415 kilopascals] within seventy-two hours. All
compressive strengths on surface casing cement must be calculated at a temperature of
eighty degrees Fahrenheit [26.67 degrees Celsius].
4.
Production or intermediate casing strings must consist of new or reconditioned pipe that has
been previously tested to two thousand pounds per square inch [13800 kilopascals]. Such
strings must be allowed to stand under pressure until the tail cement has reached a
compressive strength of at least five hundred pounds per square inch [3450 kilopascals]. All
filler cements utilized must reach a compressive strength of at least two hundred fifty pounds
per square inch [1725 kilopascals] within twenty-four hours and at least five hundred pounds
per square inch [3450 kilopascals] within seventy-two hours, although in any horizontal well
performing a single stage cement job from a measured depth of greater than thirteen
thousand feet [3962.4 meters], the filler cement utilized must reach a compressive strength of
at least two hundred fifty pounds per square inch [1725 kilopascals] within forty-eight hours
and at least five hundred pounds per square inch [3450 kilopascals] within ninety-six hours. All
compressive strengths on production or intermediate casing cement must be calculated at a
temperature found in the Mowry formation using a gradient of 1.2 degrees Fahrenheit per one
hundred feet [30.48 meters] of depth plus eighty degrees Fahrenheit [26.67 degrees Celsius].
At a formation temperature at or in excess of two hundred thirty degrees Fahrenheit [110
degrees Celsius], cement blends must include additives to address compressive strength
regression.
5.
Each surface casing string must be tested by application of pump pressure of at least one
thousand pounds per square inch [6900 kilopascals] and each other casing string shall be
tested by application of pump pressure of at least one thousand five hundred pounds per
square inch [10350 kilopascals] immediately after cementing, while the cement is in a liquid
state, or the casing string must be pressure tested after all cement has reached five hundred
pounds per square inch [3450 kilopascals] compressive strength. If, at the end of thirty
minutes, this pressure has dropped more than ten percent, the casing must be repaired after
receiving approval from the director. Thereafter, the casing again must be tested in the same
manner. Further work may not proceed until a satisfactory test has been obtained. The casing
in a horizontal well may be tested by use of a mechanical tool set near the casing shoe after
the horizontal section has been drilled.
6.
All flowing wells must be equipped with tubing. A tubing packer must also be utilized unless a
waiver from the director is obtained after demonstrating the casing will not be subjected to
excessive pressure or corrosion. The packer must be set as near the producing interval as
practicable, but in all cases must be above the perforations.