11 AAC 87.120. Casing and cementing

(a) A proposed casing and cementing program must be included in the application for a drilling permit. A casing program must be designed to

(1) handle stress imposed by the maximum expected temperature and pressure and the physical effects of produced fluids and gases on casing and cement durability;

(2) provide suitable and safe operating conditions for the total depth proposed;

(3) confine fluids to the wellbore, unless slotted liners or perforated casings are used;

(4) prevent migration of fluids from one stratum to another;

(5) assure control of fluids at all well pressures and temperatures encountered;

(6) protect permafrost areas from thaw subsidence and freezeback effects;

(7) prevent contamination of strata bearing freshwater; and

(8) provide well control until the next string of casing is set.

(b) The conductor casing string may be set by drilling, driving, or jetting; if the hole is drilled, a sufficient quantity of cement must be used to fill the annular space to the surface or mud line.

(1) extend below the base of any freshwater sands or permafrost to a depth that will insure proper anchorage;

(2) be set into a competent stratum with sufficient cement in the annulus to circulate to the surface; if cement does not circulate to the surface when required, the annulus must be cemented before drilling ahead or initiating tests; and

(3) be cemented through a sufficient series of low permeability, competent lithologic units, such as claystone or siltstone, to insure a solid anchor for blowout prevention equipment and to protect useable groundwater and surface water from contamination.

(d) Intermediate casing must be set to maintain well control, and cemented over its full length.

(e) The production casing string may be set through or just above the production or injection interval and must be

(1) cemented with sufficient cement to fill the annular space from the shoe to the surface or lapped a minimum of 100 feet into intermediate casing string, if run; and

(2) tested in accordance with (i) of this section.

(f) Liners may be set as an intermediate or production string. A cemented liner must have a minimum of 100 feet of cemented lap with the next larger casing string. Before drilling ahead, cemented liner and lap must be tested by a fluid entry or pressure test, in accordance with (i) of this section, to determine that a seal between the liner and next larger string has been achieved.

(g) A cement plug or shoe in the casing strings required by (b) - (f) of this section must not be drilled until a minimum compressive strength of 300 psig at bottom-hole conditions has been attained according to the manufacturer's cement strength tables for the particular cement being used. Casings must be tested before drilling ahead in accordance with (i) of this section.

(h) Within permafrost intervals, fluids which have a freezing point above the minimum permafrost temperature may not be left in the annulus between any two strings of pipe, or inside the casing upon completion or suspension of a well without the commissioner's approval.

(i) With the exception of the conductor casing, before drilling out the casing or liner after cementing, all casing strings, liners, and liner laps must be tested to a surface pressure of 50 percent of the minimum internal yield strength of the casing or 1500 psig, whichever is lower. If the pressure declines more than 10 percent in 30 minutes or if there are indications of improper cementing such as lost returns, cement channelling, or mechanical failure of equipment, corrective measures must be taken until a satisfactory test is obtained. Test reports must be filed with the department within 30 days after testing.

(j) Variances or additional restrictions may be imposed as the commissioner considers necessary for special or unusual conditions.

History: Eff. 5/8/83, Register 86

Authority: AS 41.06.010

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