1. (a) A descriptive list of the critical drilling and production well work that is likely to be conducted on the lease, such as:

   1. (1) Drilling in close proximity to another well.
   2. (2) Drilling into a known lost circulation zone or into a zone capable of flowing oil and/or gas.
   3. (3) Continuation of drilling into zones that are suspected to be capable of flowing oil and/or gas or into zones suspected to be abnormally pressured.

   4. (4) If zones capable of flowing oil and/or gas are exposed or suspected to be exposed in the well then the following are considered to be critical operations:

      1. (A) Pulling out of the hole.
      2. (B) Fishing operations.
      3. (C) Drill-Stem testing.
      4. (D) Wireline logging in open hole.
      5. (E) Running casing.
      6. (F) Cutting and recovering casing.
      7. (G) Perforating casing.
      8. (H) Well completion work.
      9. (I) Remedial well work.
      10. (J) Well stimulation.

2. (b) A descriptive list of circumstances or conditions under which the critical drilling and production well work shall be ceased, limited, or not commenced. This list shall be developed from all the factors and conditions relating to the lease and shall take into account but may not to be limited to the following:

   1. (1) Whether or not well operations are being conducted from a mobile rig or a fixed structure.
   2. (2) Adverse meteorological or oceanographical conditions exist or are anticipated soon.
   3. (3) Limited availability and capability of oil containment and cleanup equipment.
   4. (4) Significant increase in oil spill control system response time for any reason.
   5. (5) Personnel or equipment for conducting a particular critical operation are not available.
   6. (6) Insufficient supply of drilling mud materials on the drill site for emergency well control purposes.
   7. (7) Transportation equipment for personnel, supplies and oil spill containment and cleanup equipment is not readily available.
   8. (8) Construction and maintenance work involving welding, moving heavy equipment, etc. is being performed.
   9. (9) Other factors peculiar to the particular lease under consideration.
3. (c) When any circumstance or condition listed or described in the plan occurs or other operational limits are encountered, the lessee shall cease, limit, or not commence the affected critical operation(s) as set forth in Section 2141(a).
4. (d) Any deviation from the approved plan shall require prior written approval by the Staff. If emergency action requires deviation from the plan, and there is inadequate time to seek the Staff's approval, the Staff shall be notified immediately after said deviation occurs.
5. (e) The plan shall be reviewed at least annually and any changes thereto shall be submitted to the Staff for approval.

The primary purpose of a Critical Operations and Curtailment Plan is to provide additional precautionary measures to minimize the likelihood of an oil spill incident occurring from offshore drilling and production well work during (1) adverse weather and sea conditions when oil spill containment and recovery equipment, material and techniques are not effective and marine transportation is severely hampered; and (2) the time that oil spill containment and recovery equipment, material, manpower, and transportation thereof are not readily available to the site of operation.

Certain operations performed in drilling and production well work are more critical than others with respect to well control and accidental discharge of oil and gas. This is particularly so when subsurface forations are exposed in the well that are capable of flowing oil and gas to the surface or when the well has been pressured by outside means. It is these critical operations that should be ceased, limited or not commenced in order to minimize the likelihood of an oil spill occurring during adverse weather and sea conditions which could seriously impede both well control and oil cleanup efforts.

The lessee shall file with the Staff, for its approval, a Critical Operations and Curtailment Plan to be followed while conducting drilling and/or production well work on the lease. A plan shall be filed for each exploratory well as required in Section 2128(d)(2) in order to accommodate different drilling rigs, circumstances and conditions. A separate plan shall be filed for development drilling and production well work on the lease. These plans shall contain the following: