PURPOSE: One of the important functions of the council is to prevent produced salt water from contaminating either surface or underground fresh water resources. When an oil or gas well is drilled, the bit usually penetrates fresh water strata at relatively shallow depths. This groundwater is commonly the only source of water for irrigation or for animal and human consumption. This rule provides procedures for protecting all fresh water and for acceptable safety standards for wells and surface installations so that the wild and uncontrolled flow of gusher wells or blowouts can be prevented. Plugging of wells when they are abandoned is consistent with a statewide effort to prevent contamination of water resources and would also be important should a given area prove to be productive as in secondary recovery activity.

1. (1) During the drilling of any well, surface casing will be set at the depth indicated on form OGC-3 or form OGC-3-I which has been approved by the state geologist and will be cemented from the setting depth to the surface. Before the bottom plug is drilled or before tests are initiated, the surface casing will stand cemented for the following periods of time: neat cement, for twenty-four (24) hours; neat cement with one percent (1%) CaCl2, for twelve (12) hours; neat cement with two percent (2%) CaCl2, for ten (10) hours; neat cement with three percent (3%) CaCl2, for eight (8) hours; and neat cement with four percent (4%) CaCl2, for six (6) hours. If other additives are to be used in the cement, the operator must contact the staff of the office of the state geologist for setting times appropriate for that particular cement.
2. (2) All wells drilled for oil, gas or injection shall be completed with a string(s) of casing which shall be properly cemented at sufficient depths to protect all water, oil or gas bearing strata and shall prevent their contents from passing into other strata. In the event wells are drilled with cable tools, temporary protective casing strings may be left uncemented. The specific casing and cementing requirements for injection wells shall be based on the depth to the base of the underground source of drinking water, the nature of the injected fluids and the hydraulic relationship between the injection zone and the base of the underground source of drinking water.
3. (3) In certain instances, 10 CSR 50-2.040(3) shall modify 10 CSR 50-2.040(1) as follows: In wells drilled to producing formations at a depth of no greater than eight hundred feet (800'), the state geologist may approve owner’s request to set a single casing string and to cement the string by placing sufficient cement to fill annular space no less than approximately forty feet (40') above the top of the producing horizon.
4. (4) During drilling and following completion of wells, surface well and producing installations shall conform to accepted safety standards.
5. (5) Whenever operations shall cease for a period of ninety (90) days on any well, the owner or operator of the well shall give notice to the council and, if the council shall deem it necessary to prevent the pollution of any fresh water strata or supply, shall cause the well to be temporarily plugged in accordance with the rules of the council and under its direction. If the operations on any well are not recommenced within a period of six (6) months after notice has been given, the well shall be deemed a permanently abandoned well and the owner or operator shall comply with the rules relating to the plugging and abandonment of wells. Provided, that upon application to the council prior to the expiration of the six (6)-month period and for good cause shown, the council may extend the period for an additional six (6) months and in like manner the council may grant additional six (6) month extensions, but the total time of such consecutive extensions shall not exceed two (2) years, unless a mechanical integrity test is performed as outlined in 10 CSR 50- 2.040(6) and the well capped at the surface, before the end of the two (2)-year extension period. The council may then permit the well to remain inactive status for a maximum of five (5) years and if not returned to active status within this time the well must be plugged.
6. (6) All new or newly converted injection wells shall be required to demonstrate mechanical integrity as defined by 10 CSR 50-1.030(1)(O) before operation may begin. All wells not permanently plugged and abandoned must demonstrate mechanical integrity at least every five (5) years for the absence of significant leaks from the outermost casing and the absence of significant fluid movement in vertical channels adjacent to the well bore. Demonstration of the absence of significant leaks shall utilize at least one (1) of the following procedures: A pressure test with liquid or gas, monitoring of annulus pressure in wells injecting at a positive pressure following an initial pressure test or any other test(s) that the state geologist considers effective. Demonstration of the absence of significant fluid movement in vertical channels adjacent to the well bore shall utilize at least two (2) of the following procedures: Cementing records (reviewed only once for the life of the well), tracer surveys, noise logs, temperature surveys or any other test(s) that the state geologist considers effective.
7. (7) A maximum injection pressure for injection wells shall be established by the state geologist so that the pressure in the injection zone during injection does not initiate new fractures or propagate existing fractures in the confining zone. The injection pressure also should not cause the injected fluid to migrate into an underground source of drinking water.
8. (8) All logs and other test data shall be sent to the state geologist before operation may begin. The state geologist shall inform the operator of a satisfactory or unsatisfactory demonstration of mechanical integrity by mail or telephone without delay.
9. (9) In order to insure that all existing injection wells are properly tested for mechanical integrity as required by federal regulation, at least one-fifth (1/5) of each operator’s injection wells drilled in Missouri prior to the State Underground Injection Control Program must demonstrate mechanical integrity as defined in 10 CSR 50-2.040(6) each year for the first five (5) years of the program. All injection wells, including new wells and newly converted wells must demonstrate mechanical integrity every five (5) years.
10. (10) If a well cannot demonstrate mechanical integrity the operator must cease operation of the well and immediately inform the state geologist. If corrective action cannot restore mechanical integrity within thirty (30) days after notification, the operator shall again notify the state geologist, who may grant an additional thirty (30) days before ordering the well to be plugged.
11. (11) The state geologist or an authorized representative shall have the authority to sample injected fluids at any time during injection operations.
12. (12) The operator is required to provide a one-fourth inch (1/4") female fitting, with cut-off valve, to the tubing to all wells drilled and completed as injection wells after the State Underground Injection Control Program is promulgated, so the injection pressure being used can be monitored by an authorized representative(s) of the state geologist. For wells that were injecting prior to promulgation of the State Underground Injection Control Program, the female fitting need not be added until the well is tested for mechanical integrity.

AUTHORITY: sections 259.060 and 259.070, RSMo 2000.* Original rule filed Oct. 11, 1966, effective Oct. 21, 1966. Amended: Filed Sept. 12, 1973, effective Sept. 22, 1973. Amended: Filed Oct. 14, 1981, effective Feb. 11, 1982. Amended: Filed Aug. 11, 1986, effective Oct. 27, 1986. *Original authority: 259.060, RSMo 1965, amended 1972 and 259.070, RSMo 1965, amended 1972, 1983.