(a) General. (1) A copy of the H2S Drilling Operations Plan shall be available during operations at the well site, beginning when the operation is subject to the terms of this subpart (i.e., 3 days or 500 feet of known or probable H2S zone).

(2) Initial H2S training shall be completed and all H2S related safety equipment shall be installed, tested, and operational when drilling reaches a depth of 500 feet above, or 3 days prior to penetrating (whichever comes first) the first zone containing or reasonably expected to contain H2S. A specific H2S operations plan for completion and workover operations will not be required for approval. For completion and workover operations, all required equipment and warning systems shall be operational and training completed prior to commencing operations.

(3) If H2S was not anticipated at the time the APD was approved, but is encountered in excess of 100 ppm in the gas stream, the following measures shall be taken:

(i) The operator shall immediately ensure control of the well, suspend drilling ahead operations (unless detrimental to well control), and obtain materials and safety equipment to bring the operations into compliance with the applicable provisions of this subpart.

(ii) The operator shall notify the authorized officer of the event and the mitigating steps that have or are being taken as soon as possible, but no later than the next business day. If said notification is subsequent to actual resumption of drilling operations, the operator shall notify the authorized officer of the date that drilling was resumed no later than the next business day.

(iii) It is the operator's responsibility to ensure that the applicable requirements of this subpart have been met prior to the resumption of drilling ahead operations. Drilling ahead operations will not be suspended pending receipt of a written H2S Drilling Operations Plan(s) and, if necessary, Public Protection Plan(s) provided that complete copies of the applicable Plan(s) are filed with the authorized officer for approval within 5 business days following resumption of drilling ahead operations.

(b) Locations. (1) Where practical, 2 roads shall be established, 1 at each end of the location, or as dictated by prevailing winds and terrain. If an alternate road is not practical, a clearly marked footpath shall be provided to a safe area. The purpose of such an alternate escape route is only to provide a means of egress to a safe area.

(2) The alternate escape route shall be kept passable at all times.

(3) For workovers, a secondary means of egress shall be designated.

(c) Personnel protection—(1) Training program. The operator shall ensure that all personnel who will be working at the wellsite will be properly trained in H2S drilling and contingency procedures in accordance with the general training requirements outlined in API RP-49, Section 2 (incorporated by reference, see § 3176.11). (The use of later editions of API RP-49 is deemed to comply with the requirements of this paragraph (c)(1).) The operator also shall ensure that the training will be accomplished prior to a well coming under the terms of this subpart (i.e., 3 days or 500 feet of known or probable H2S zone). In addition to the requirements of API RP-49, a minimum of an initial training session and weekly H2S and well control drills for all personnel in each working crew shall be conducted. The initial training session for each well shall include a review of the site-specific Drilling Operations Plan and, if applicable, the Public Protection Plan.

(i) All training sessions and drills shall be recorded on the driller's log or its equivalent.

(ii) For drilling/completion/workover wells, at least 2 briefing areas shall be designated for assembly of personnel during emergency conditions, located a minimum of 150 feet from the well bore, and 1 of the briefing areas shall be upwind of the well at all times. The briefing area located most normally upwind shall be designated as the “primary briefing area.”

(iii) One person (by job title) shall be designated and identified to all on-site personnel as the person primarily responsible for the overall operation of the on-site safety and training programs.

(2) Protective equipment. (i) The operator shall ensure that proper respiratory protection equipment program is implemented, in accordance with ANSI Z88.2-1992 (incorporated by reference, see § 3176.11). (The use of ANSI Z88.2-1980 is deemed to comply with the requirements of this paragraph (d)(2)(i).) Proper protective breathing apparatus shall be readily accessible to all essential personnel on a drilling/completion/workover site. Escape and pressure-demand type working equipment shall be provided for essential personnel in the H2S environment to maintain or regain control of the well. For pressure-demand type working equipment those essential personnel shall be able to obtain a continuous seal to the face with the equipment. The operator shall ensure that service companies have the proper respiratory protection equipment when called to the location. Lightweight, escape-type, self-contained breathing apparatus with a minimum of 5-minute rated supply shall be readily accessible at a location for the derrickman and at any other location(s) where escape from an H2S contaminated atmosphere would be difficult.

(ii) Storage and maintenance of protective breathing apparatus shall be planned to ensure that at least 1 working apparatus per person is readily available for all essential personnel.

(iii) The following additional safety equipment shall be available for use:

(A) Effective means of communication when using protective breathing apparatus;

(B) Flare gun and flares to ignite the well; and

(C) Telephone, radio, mobile phone, or any other device that provides communication from a safe area at the rig location, where practical.

(3) H2S detection and monitoring equipment. (i) Each drilling/completion site shall have an H2S detection and monitoring system that automatically activates visible and audible alarms when the ambient air concentration of H2S reaches the threshold limits of 10 and 15 ppm in air, respectively. The sensors shall have a rapid response time and be capable of sensing a minimum of 10 ppm of H2S in ambient air, with at least 3 sensing points located at the shale shaker, rig floor, and bell nipple for a drilling site and the cellar, rig floor, and circulating tanks or shale shaker for a completion site. The detection system shall be installed, calibrated, tested, and maintained in accordance with the manufacturer's recommendations.

(ii) All tests of the H2S monitoring system shall be recorded on the driller's log or its equivalent.

(iii) For workover operations, 1 operational sensing point shall be located as close to the wellbore as practical. Additional sensing points may be necessary for large and/or long-term operations.

(4) Visible warning system. (i) Equipment to indicate wind direction at all times shall be installed at prominent locations and shall be visible at all times during drilling operations. At least 2 such wind direction indicators (i.e., windsocks, windvanes, pennants with tailstreamers, etc.) shall be located at separate elevations (i.e., near ground level, rig floor, and/or treetop height). At least 1 wind direction indicator shall be clearly visible from all principal working areas at all times so that wind direction can be easily determined. For completion/workover operations, 1 wind direction indicator shall suffice, provided it is visible from all principal working areas on the location. In addition, a wind direction indicator at each of the 2 briefing areas shall be provided if the wind direction indicator(s) previously required in this paragraph (c)(4)(i) are not visible from the briefing areas.

(ii) At any time when the terms of this subpart are in effect, operational danger or caution sign(s) shall be displayed along all controlled accesses to the site.

(iii) Each sign shall be painted a high visibility red, black and white, or yellow with black lettering.

(iv) The sign(s) shall be legible and large enough to be read by all persons entering the well site and be placed a minimum of 200 feet but no more than 500 feet from the well site and at a location which allows vehicles to turn around at a safe distance prior to reaching the site.

(v) The sign(s) shall read: “DANGER—POISON GAS—HYDROGEN SULFIDE,” and in smaller lettering: “Do Not Approach If Red Flag is Flying” or equivalent language if approved by the authorized officer. Where appropriate, bilingual or multilingual danger sign(s) shall be used.

(vi) All sign(s) and, when appropriate, flag(s) shall be visible to all personnel approaching the location under normal lighting and weather conditions.

(vii) When H2S is detected in excess of 10 ppm at any detection point, red flag(s) shall be displayed.

(5) Warning system response. When H2S is detected in excess of 10 ppm at any detection point, all non-essential personnel shall be moved to a safe area and essential personnel (i.e., those necessary to maintain control of the well) shall wear pressure-demand type protective breathing apparatus. Once accomplished, operations may proceed.

(d) Operating procedures and equipment—(1) General/operations. Drilling/completion/workover operations in H2S areas shall be subject to the following requirements:

(i) If zones containing in excess of 100 ppm of H2S gas are encountered while drilling with air, gas, mist, other nonmud circulating mediums or aerated mud, the well shall be killed with a water- or oil-based mud and mud shall be used thereafter as the circulating medium for continued drilling.

(ii) A flare system shall be designed and installed to safely gather and burn H2S-bearing gas.

(iii) Flare lines shall be located as far from the operating site as feasible and in a manner to compensate for wind changes. The flare line(s) mouth(s) shall be located not less than 150 feet from the wellbore unless otherwise approved by the authorized officer. Flare lines shall be straight unless targeted with running tees.

(iv) The flare system shall be equipped with a suitable and safe means of ignition.

(v) Where noncombustible gas is to be flared, the system shall be provided supplemental fuel to maintain ignition.

(vi) At any wellsite where SO2, may be released as a result of flaring of H2S during drilling, completion, or workover operations, the operator shall make SO2, portable detection equipment available for checking the SO2 level in the flare impact area.

(vii) If the flare impact area reaches a sustained ambient threshold level of 2 ppm or greater of SO2 in air and includes any occupied residence, school, church, park, or place of business, or other area where the public could reasonably be expected to frequent, the Public Protection Plan shall be implemented.

(viii) A remote controlled choke shall be installed for all H2S drilling and, where feasible, for completion operations. A remote-controlled valve may be used in lieu of this requirement for completion operations.

(ix) Mud-gas separators and rotating heads shall be installed and operable for all exploratory wells.

(2) Mud program. (i) A pH of 10 or above in a fresh water-base mud system shall be maintained to control corrosion, H2S gas returns to surface, and minimize sulfide stress cracking and embrittlement unless other formation conditions or mud types justify to the authorized officer a lesser pH level is necessary.

(ii) Drilling mud containing H2S gas shall be degassed in accordance with API RP-49, sec. 5.14 (incorporated by reference, see § 3176.11), at an optimum location for the rig configuration. These gases shall be piped into the flare system. (The use of later editions of API RP-49 is deemed to comply with the requirements of this paragraph (d)(2)(ii).)

(iii) Sufficient quantities of mud additives shall be maintained on location to scavenge and/or neutralize H2S where formation pressures are unknown.

(3) Metallurgical equipment. (i) All equipment that has the potential to be exposed to H2S shall be suitable for H2S service. Equipment which shall meet these metallurgical standards include the drill string, casing, wellhead, blowout preventer assembly, casing head and spool, rotating head, kill lines, choke, choke manifold and lines, valves, mud-gas separators, drill-stem test tools, test units, tubing, flanges, and other related equipment.

(ii) To minimize stress corrosion cracking and/or H2S embrittlement, the equipment shall be constructed of material whose metallurgical properties are chosen with consideration for both an H2S working environment and the anticipated stress. The metallurgical properties of the materials used shall conform to NACE MR 0175-2021 (incorporated by reference, see § 3176.11). (The use of NACE MR 0175-90 through NACE MR 0175-2021 is deemed to comply with the requirements of this paragraph (d)(3)(ii).) These metallurgical properties include the grade of steel, the processing method (rolled, normalized, tempered, and/or quenched), and the resulting strength properties. The working environment considerations include the H2S concentration, the well fluid pH, and the wellbore pressures and temperatures. Elastomers, packing, and similar inner parts exposed to H2S shall be resistant at the maximum anticipated temperature of exposure. The manufacturer's verification of design for use in an H2S environment shall be sufficient verification of suitable service in accordance with this subpart.

(4) Well testing in an H2S environment. Testing shall be performed with a minimum number of personnel in the immediate vicinity which are necessary to safely and adequately operate the test equipment. Except with prior approval by the authorized officer, the drill-stem testing of H2S zones shall be conducted only during daylight hours and formation fluids shall not be flowed to the surface (closed chamber only).