PURPOSE: This rule provides the definitions for terms used in 10 CSR 50 that are not defined in section 259.050, RSMo.

1. (1) The terms used in 10 CSR 50 have the meanings set forth in section 259.050, RSMo, or this rule, unless the context of the term clearly indicates otherwise.

   1. (A) Terms beginning with the letter A.

      1. 1. Abandoned site, any property or lease

that is no longer operated as an active site for oil and gas production and injection projects.

1. 2. Abandoned well, a well that is no

longer operated for its intended use and has not been shut in, converted to another type of well, or plugged. 10 CSR 50-1

1. 3. Area of review, an area surrounding

an injection well(s) that extends a minimum of one-half (1/2) mile from the well(s) or from the unit boundary of an enhanced recovery project.

1. 4. Area of review well, any well includ-

ing, but not limited to, water wells, abandoned wells, plugged wells, and dry holes, located within the area of review, which penetrates the injection interval.

1. (B) Terms beginning with the letter B.

   1. 1. (Reserved)

2. (C) Terms beginning with the letter C.

   1. 1. Casing, the impervious, durable,

tubular materials used to line a wellbore.

1. 2. Casinghead gas, gas produced that

was in solution with oil in its original state in the reservoir.

1. 3. Cement, portland cement or a blend

of portland cement.

1. 4. Coalbed natural gas, natural gas pro-

duced from either coal seams or associated shale.

1. 5. Commercial well, a well from which

oil or gas is recovered and sold, traded, or otherwise used for profit.

1. 6. Common source of supply, synony-

mous with “pool” as defined in Chapter 259, RSMo.

1. 7. Confining strata, geologic stratum or

strata that serve as a barrier between water-, oil-, or gas-bearing strata.

1. 8. Core, a continuous section of geolog-

ic materials recovered during drilling.

1. 9. Corrective action, remedial action on

any well to prevent the migration of fluids from the surface or from one (1) stratum to another.

1. 10. Correlative rights, the right of each

owner or operator in a pool to obtain that owner’s or operator’s just and equitable share of the oil or gas resource, or an economic equivalent of that share of the resource, produced in a manner or amount that will not have any of the following effects:

1. A. Damage the reservoir;
2. B. Take an undue proportion of the

obtainable oil or gas; or

1. C. Cause undue drainage between

developed leases.

1. 11. Council, the State Oil and Gas

Council established by section 259.010, RSMo.

1. (D) Terms beginning with the letter D.

   1. 1. (Reserved)

2. (E) Terms beginning with the letter E.

   1. 1. Enhanced recovery, any process used

to increase the recovery of oil or gas from a pool through secondary or tertiary recovery. Enhanced recovery includes, but is not limited to, water floods, pressure maintenance projects, cycling or recycling projects, steam floods, fire floods, carbon dioxide injection projects, high-density well drilling projects, and approved technologies that are either unconventional or in any way redirect the natural movement of oil or gas or formation water in the pool. Enhanced recovery typically involves the use of injection wells of some kind as part of a production unit.

1. 2. Enhanced recovery injection well, an

injection well used to move underground fluids to production wells through the use of water, steam, gas, or any other substance in order to redirect or facilitate the natural movement of oil, gas, or water in a pool.

1. 3. Exempted aquifer, an aquifer or its

portion that meets the criteria in the definition of Underground Source of Drinking Water set forth in paragraph (1)(U)1. of this rule but which has been exempted for operation of an injection well.

1. (F) Terms beginning with the letter F.

   1. 1. Fluid, any material or substance

which flows or moves whether in a semisolid, liquid, sludge, or gaseous state.

1. 2. Formation water, water that occurs

naturally within the pores of a geologic formation or stratum.

1. (G) Terms beginning with the letter G.

   1. 1. (Reserved)

2. (H) Terms beginning with the letter H.

   1. 1. Horizontal well, a well drilled at an

angle to the vertical, typically parallel to the geologic strata containing oil or gas.

1. (I) Terms beginning with the letter I.

   1. 1. Increased well density, the drilling of

an additional primary production well in a spacing unit.

1. 2. Injection, emplacement of fluids into

the subsurface through a well.

1. 3. Injection well, a well into which flu-

ids are injected during all or part of the life of the well for disposal or enhanced recovery projects or for underground storage of gas that is liquid at standard temperature and pressure, but not including oilor gas-producing wells undergoing approved well stimulation treatment.

1. 4. Injection zone, a geological stratum,

group of strata, or part of a stratum that receives fluids through a well.

1. (J) Terms beginning with the letter J.

   1. 1. (Reserved)

2. (K) Terms beginning with the letter K.

   1. 1. (Reserved)

3. (L) Terms beginning with the letter L.

   1. 1. Location exception, authorization

given by the state geologist to drill a well at a location other than that which is prescribed by these regulations.

1. (M) Terms beginning with the letter M.

   1. 1. Mechanical integrity, a well has

mechanical integrity if there is no significant leakage in the casing, tubing, or packer; and there is no significant fluid movement into an underground source of drinking water through vertical channels adjacent to the wellbore.

1. 2. Missouri nomenclature, Missouri-

specific geologic terminology as provided by the state geologist including, but not limited to, names of geologic strata, pools, and geologic features.

1. 3. Multiple completion, the completion

of any well that permits production from two (2) or more pools that are completely segregated by confining strata.

1. (N) Terms beginning with the letter N.

   1. 1. (Reserved)

2. (O) Terms beginning with the letter O.

   1. 1. Observation well, a well that is used

to monitor the operational integrity and conditions of oil, gas, and storage operations, including physical or chemical parameters of a reservoir or geologic formation or strata, and is not used currently as a production, injection, disposal, or water well.

1. 2. Oil and Gas Remedial Fund, the fund

established by section 259.190.5, RSMo into which forfeited bond monies and proceeds from the sale of illegal oil, illegal gas, and illegal product are deposited, which is to be used for plugging abandoned wells as provided for in 10 CSR 50-2.060(3)(F).

1. 3. Oil and Gas Resources Fund, the

fund established by section 259.052, RSMo, into which all gifts, donations, transfers, moneys appropriated by the General Assembly, permit application fees, operating fees, closure fees, late fees, severance fees, and bequests are deposited, which is to be used to administer the provisions of Chapter 259, RSMo, and implementing regulations, and to collect, process, manage, interpret, and distribute geologic and hydrologic resource information pertaining to oil and gas potential.

1. 4. Open well, a well that has not been

plugged including, but not limited to, abandoned, operating, or shut-in wells.

1. 5. Operator, a person who drills, main-

tains, operates, or controls wells associated with oil or gas production, storage, or injection projects.

1. (P) Terms beginning with the letter P.

   1. 1. Person, any individual, partnership,

co-partnership, firm, company, public or private corporation, association, joint stock company, trust, estate, governmental or political subdivision, or any other legal entity.

1. 2. Plugged well, a well that has been

filled or partially filled with cement or other materials to prevent the migration of fluids within the well.

1. 3. Pooling, the contractual agreement of

those holding the rights to mineral interests within a single spacing unit for primary production, whether that agreement is voluntary or by order of the council, to produce oil or gas or both from that unit.

1. 4. Primary production, the process of

recovery of oil or gas from a pool in which one (1) well is capable of efficiently draining the pool or portion thereof that resides within the confines of the spacing unit and the drainage of oil, gas, or formation water into the well occurs naturally.

1. 5. Private domestic consumption, gas

used from an on-site well(s) for the sole purpose of providing gas for a private dwelling or business and not for resale or trade.

1. 6. Produced water, formation water that

is associated with the production of oil or gas and either requires disposal or is used as part of an enhanced recovery project.

1. 7. Production unit, an uninterrupted

block of acreage of any size and any shape that has a definite outer boundary and in which wells may be drilled for enhanced recovery. The acreage that composes a production unit may include default spacing units, acreage for which spacing units have or have not been explicitly ordered by the state geologist or council, pooled or non-pooled mineral acreage, and all or parts of past and present production units.

1. 8. Production well, any well used for

recovery of oil or gas or both.

1. (Q) Terms beginning with the letter Q.

   1. 1. (Reserved)

2. (R) Terms beginning with the letter R.

   1. 1. Recompletion, the process of rework-

ing or repairing a well after its initial well completion.

1. 2. Reference well, a well used to collect

data to establish a maximum injection pressure as approved by the state geologist.

1. (S) Terms beginning with the letter S.

   1. 1. Seismic shot hole, a hole drilled for

the purpose of generating a seismic signal to be used in the exploration or development of oil or gas or both.

1. 2. Shut-in well, any well that has not

been operated for ninety (90) calendar days or more.

1. 3. Spacing Unit, an arbitrary block of

acreage of specified size and shape for a single pool that is based on the U.S. Public Land Survey System in which only one (1) production well may be drilled for primary production that is no closer than a specified minimum distance from the unit boundary.

1. 4. Special project, research and devel-

opment of a new process or technology that increases the amount of oil or gas recoverable from a pool or improves oil or gas operations.

1. 5. Spill or release, any threatened or real

emission, discharge, spillage, leakage, pumping, pouring, emptying, or dumping of a substance into or onto the land, air, or waters of the state, unless done in compliance with the conditions of a federal or state permit, unless the substance is confined and is expected to stay confined to property owned, leased, or otherwise controlled by the person having control over the substance.

1. 6. Spud date, the date of first penetra-

tion of the earth with a drilling bit.

1. 7. Storage well, a well used to inject or

extract natural gas or other gaseous hydrocarbons for storage purposes.

1. 8. Stratum or strata, a layer or layers of

rock composed of substantially the same lithology that is distinctive visually from other layers above and below; often a lithologic unit.

1. 9. Stratigraphic test well, a well drilled

to obtain information on the thickness, lithology, sequence, porosity, permeability, or any other properties of rock, or to locate the position of a geologic horizon in the evaluation of potentially productive oil or gas strata and is not utilized for generating a seismic signal.

1. (T) Terms beginning with the letter T.

   1. 1. (Reserved)

2. (U) Terms beginning with the letter U.

   1. 1. Underground source of drinking

water, an aquifer or any portion thereof that—

1. A. Supplies any private well or public

water supply system; or

1. B. Contains a sufficient quantity of

groundwater to supply a private well or public water system; and

1. (I) Currently supplies drinking

water for human consumption; or

1. (II) Contains less than ten thousand

(10,000) mg/L total dissolved solids; and

1. C. Is not an exempted aquifer.
2. 2. Unitization, the contractual agree-

ment of mineral interests owners to form a production unit through a voluntary process or order of the council, to produce oil or gas from that production unit and to designate the operator of the unit.

1. (V) Terms beginning with the letter V.

   1. 1. (Reserved)

2. (W) Terms beginning with the letter W.

   1. 1. Waters of the state, has the same

meaning as defined in the Missouri Clean Water Law, section 644.016, RSMo.

1. 2. Well, has the meaning as defined in

section 259.050(16). Wells drilled for the production of water are regulated by the Water Well Drillers’ Act, Chapter 256, RSMo, and the implementing Missouri Well Construction rules, 10 CSR 23. A well includes, but is not limited to, the following:

1. A. Disposal well;
2. B. Enhanced recovery injection well;
3. C. Horizontal well;
4. D. Injection well;
5. E. Observation well;
6. F. Production well;
7. G. Seismic shot hole;
8. H. Storage well; or
9. I. Stratigraphic test well.
10. 3. Well stimulation treatment, a treat-

ment of a well designed to enhance oil and gas production or recovery by increasing the secondary permeability of the geologic strata. Well stimulation is a short-term and non-continual process for the purposes of opening and stimulating channels for the flow of oil or gas or both. Examples of well stimulation treatments include hydraulic fracturing, acid fracturing, and acid matrix stimulation. Well stimulation treatment does not include routine well cleanout work; routine well maintenance; routine treatment for the purpose of removal of geologic strata damage due to drilling; bottom hole pressure surveys; routine activities that do not affect the integrity of the well or the geologic strata; the removal of scale or precipitate from the perforations, casing, or tubing; or a treatment that does not penetrate into the geologic strata more than thirty-six (36) inches from the wellbore.

1. 4. Whipstock, a long wedge-shaped

steel device or casing that uses an inclined plane to cause the bit to deflect from the original borehole at a slight angle, sometimes used in an oil or gas well to control directional drilling, to straighten crooked boreholes, or to sidetrack to avoid unretrieved items left in a well.

1. (X) Terms beginning with the letter X.

   1. 1. (Reserved)

2. (Y) Terms beginning with the letter Y.

   1. 1. (Reserved)

3. (Z) Terms beginning with the letter Z.

   1. 1. (Reserved)

1. (2) All other words used in this rule have their usual customary and accepted meaning, and all words of a technical nature, or specific to the oil and gas industry, will be given that meaning which is generally accepted in the oil and gas industry.

AUTHORITY: sections 259.050, 259.070, 259.140, and 259.190, RSMo 2016.* Original rule filed Oct. 11, 1966, effective Oct. 22, 1966. Amended: Filed Sept. 12, 1973, effective Sept. 22, 1973. Amended: Filed Oct. 14, 1981, effective Feb. 11, 1982. Amended: Filed Sept. 13, 1983, effective Dec. 11, 1983. Amended: Filed May 18, 1987, effective July 24, 1987. Amended: Filed Sept. 15, 2015, effective March 30, 2016. Amended: Filed June 27, 2018, effective Feb. 28, 2019. 10 CSR 50-1

*Original authority: 259.050, RSMo 1965, amended 1972, 1987, 2015; 259.070, RSMo 1965, amended 1972, 1983, 1987, 1993, 1995, 2012, 2015; 259.140, RSMo 1965; and 259.190, RSMo 1965, amended 1983, 2015.