250.490—Hydrogen sulfide.
(1)
Take all necessary and feasible precautions and measures to protect personnel from the toxic effects of H2 S and to mitigate damage to property and the environment caused by H2 S. You must follow the requirements of this section when conducting drilling, well-completion/well-workover, and production operations in zones with H2 S present and when conducting operations in zones where the presence of H2 S is unknown. You do not need to follow these requirements when operating in zones where the absence of H2 S has been confirmed; and
Facility means a vessel, a structure, or an artificial island used for drilling, well-completion, well-workover, and/or production operations.
H
2
S absent means:
(1)
Drilling, logging, coring, testing, or producing operations have confirmed the absence of H2 S in concentrations that could potentially result in atmospheric concentrations of 20 ppm or more of H2 S; or
(2)
Drilling in the surrounding areas and correlation of geological and seismic data with equivalent stratigraphic units have confirmed an absence of H2 S throughout the area to be drilled.
H
2
S present means that drilling, logging, coring, testing, or producing operations have confirmed the presence of H2 S in concentrations and volumes that could potentially result in atmospheric concentrations of 20 ppm or more of H2 S.
H
2
S unknown means the designation of a zone or geologic formation where neither the presence nor absence of H2 S has been confirmed.
Well-control fluid means drilling mud and completion or workover fluid as appropriate to the particular operation being conducted.
(1)
Request and obtain an approved classification for the area from the Regional Supervisor before you begin operations. Classifications are “H2 S absent,” H2 S present,” or “H2 S unknown”;
(3)
Support your request with available information such as geologic and geophysical data and correlations, well logs, formation tests, cores and analysis of formation fluids; and
(4)
Submit a request for reclassification of a zone when additional data indicate a different classification is needed.
(d) What do I do if conditions change?
If you encounter H2 S that could potentially result in atmospheric concentrations of 20 ppm or more in areas not previously classified as having H2 S present, you must immediately notify MMS and begin to follow requirements for areas with H2 S present.
(e) What are the requirements for conducting simultaneous operations?
When conducting any combination of drilling, well-completion, well-workover, and production operations simultaneously, you must follow the requirements in the section applicable to each individual operation.
(f)
Requirements for submitting an H
2
S Contingency Plan. Before you begin operations, you must submit an H2 S Contingency Plan to the District Manager for approval. Do not begin operations before the District Manager approves your plan. You must keep a copy of the approved plan in the field, and you must follow the plan at all times. Your plan must include:
(4)
Other key positions, how these positions fit into your organization, and what the functions, duties, and responsibilities of those job positions are;
(5)
Actions that you will take when the concentration of H2 S in the atmosphere reaches 20 ppm, who will be responsible for those actions, and a description of the audible and visual alarms to be activated;
(6)
Briefing areas where personnel will assemble during an H2 S alert. You must have at least two briefing areas on each facility and use the briefing area that is upwind of the H2 S source at any given time;
(7)
Criteria you will use to decide when to evacuate the facility and procedures you will use to safely evacuate all personnel from the facility by vessel, capsule, or lifeboat. If you use helicopters during H2 S alerts, describe the types of H2 S emergencies during which you consider the risk of helicopter activity to be acceptable and the precautions you will take during the flights;
(8)
Procedures you will use to safely position all vessels attendant to the facility. Indicate where you will locate the vessels with respect to wind direction. Include the distance from the facility and what procedures you will use to safely relocate the vessels in an emergency;
(9)
How you will provide protective-breathing equipment for all personnel, including contractors and visitors;
(10)
The agencies and facilities you will notify in case of a release of H2 S (that constitutes an emergency), how you will notify them, and their telephone numbers. Include all facilities that might be exposed to atmospheric concentrations of 20 ppm or more of H2 S;
(11)
The medical personnel and facilities you will use if needed, their addresses, and telephone numbers;
(12)
H2 S detector locations in production facilities producing gas containing 20 ppm or more of H2 S. Include an “H2 S Detector Location Drawing” showing:
(13)
Operational conditions when you expect to flare gas containing H2 S including the estimated maximum gas flow rate, H2 S concentration, and duration of flaring;
(14)
Your assessment of the risks to personnel during flaring and what precautionary measures you will take;
(15)
Primary and alternate methods to ignite the flare and procedures for sustaining ignition and monitoring the status of the flare (i.e., ignited or extinguished);
(17)
Portable or fixed sulphur dioxide (SO2 )-detection system(s) you will use to determine SO2 concentration and exposure hazard when H2 S is burned;
(18)
Increased monitoring and warning procedures you will take when the SO2 concentration in the atmosphere reaches 2 ppm;
(19)
Personnel protection measures or evacuation procedures you will initiate when the SO2 concentration in the atmosphere reaches 5 ppm;
(21)
Any special equipment, procedures, or precautions you will use if you conduct any combination of drilling, well-completion, well-workover, and production operations simultaneously.
(g) Training program—
(1) When and how often do employees need to be trained?
All operators and contract personnel must complete an H2 S training program to meet the requirements of this section:
(i)
You must have documentation of this training at the facility where the individual is employed; or
(3) What training do I need to give to visitors and employees previously trained on another facility?—
(i)
Trained employees or contractors transferred from another facility must attend a supplemental briefing on your H2 S equipment and procedures before beginning duty at your facility;
(ii)
Visitors who will remain on your facility more than 24 hours must receive the training required for employees by paragraph (g)(4) of this section; and
(iii)
Visitors who will depart before spending 24 hours on the facility are exempt from the training required for employees, but they must, upon arrival, complete a briefing that includes:
(A)
Information on the location and use of an assigned respirator; practice in donning and adjusting the assigned respirator; information on the safe briefing areas, alarm system, and hazards of H2 S and SO2; and
(4) What training must I provide to all other employees?
You must train all individuals on your facility on the:
(i)
Hazards of H2 S and of SO2 and the provisions for personnel safety contained in the H2 S Contingency Plan;
(iii)
Location of protective breathing equipment, H2 S detectors and alarms, ventilation equipment, briefing areas, warning systems, evacuation procedures, and the direction of prevailing winds;
(iv)
Restrictions and corrective measures concerning beards, spectacles, and contact lenses in conformance with ANSI Z88.2, American National Standard for Respiratory Protection (incorporated by reference as specified in § 250.198 );
(v)
Basic first-aid procedures applicable to victims of H2 S exposure. During all drills and training sessions, you must address procedures for rescue and first aid for H2 S victims;
(5) Do I need to post safety information?
You must prominently post safety information on the facility and on vessels serving the facility (i.e., basic first-aid, escape routes, instructions for use of life boats, etc.).
(h)
Drills. (1) When and how often do I need to conduct drills on H
2
S safety discussions on the facility? You must:
(i)
Conduct a drill for each person at the facility during normal duty hours at least once every 7-day period. The drills must consist of a dry-run performance of personnel activities related to assigned jobs.
(ii)
At a safety meeting or other meetings of all personnel, discuss drill performance, new H2 S considerations at the facility, and other updated H2 S information at least monthly.
(i)
Drilling, well-completion, and well-workover operations at the facility until operations are completed; and
(i) Visual and audible warning systems—
(1) How must I install wind direction equipment?
You must install wind-direction equipment in a location visible at all times to individuals on or in the immediate vicinity of the facility.
(2) When do I need to display operational danger signs, display flags, or activate visual or audible alarms?—
(i)
You must display warning signs at all times on facilities with wells capable of producing H2 S and on facilities that process gas containing H2 S in concentrations of 20 ppm or more.
(ii)
In addition to the signs, you must activate audible alarms and display flags or activate flashing red lights when atmospheric concentration of H2 S reaches 20 ppm.
(3) What are the requirements for signs?
Each sign must be a high-visibility yellow color with black lettering as follows:
| Letter height | Wording |
|---|---|
| 12 inches | Danger. |
| Poisonous Gas. | |
| Hydrogen Sulfide. | |
| 7 inches | Do not approach if red flag is flying. |
| (Use appropriate wording at right) | Do not approach if red lights are flashing. |
(4) May I use existing signs?
You may use existing signs containing the words “Danger-Hydrogen Sulfide-H2 S,” provided the words “Poisonous Gas. Do Not Approach if Red Flag is Flying” or “Red Lights are Flashing” in lettering of a minimum of 7 inches in height are displayed on a sign immediately adjacent to the existing sign.
(5) What are the requirements for flashing lights or flags?
You must activate a sufficient number of lights or hoist a sufficient number of flags to be visible to vessels and aircraft. Each light must be of sufficient intensity to be seen by approaching vessels or aircraft any time it is activated (day or night). Each flag must be red, rectangular, a minimum width of 3 feet, and a minimum height of 2 feet.
(6) What is an audible warning system?
An audible warning system is a public address system or siren, horn, or other similar warning device with a unique sound used only for H2 S.
(8) What actions must I take when the alarms are activated?
When the warning devices are activated, the designated responsible persons must inform personnel of the level of danger and issue instructions on the initiation of appropriate protective measures.
(j)
H
2
S-detection and H
2
S monitoring equipment —(1) What are the requirements for an H
2
S detection system? An H2 S detection system must:
(ii)
Activate audible and visual alarms when the concentration of H2 S in the atmosphere reaches 20 ppm.
(2) Where must I have sensors for drilling, well-completion, and well-workover operations?
You must locate sensors at the:
(3) Do I need mud sensors?
The District Manager may require mud sensors in the possum belly in cases where the ambient air sensors in the mud-return system do not consistently detect the presence of H2 S.
(4) How often must I observe the sensors?
During drilling, well-completion and well-workover operations, you must continuously observe the H2 S levels indicated by the monitors in the work areas during the following operations:
(5) Where must I have sensors for production operations?
On a platform where gas containing H2 S of 20 ppm or greater is produced, processed, or otherwise handled:
(i)
You must have a sensor in rooms, buildings, deck areas, or low-laying deck areas not otherwise covered by paragraph (j)(2) of this section, where atmospheric concentrations of H2 S could reach 20 ppm or more. You must have at least one sensor per 400 square feet of deck area or fractional part of 400 square feet;
(iii)
You must have a sensor within 10 feet of each vessel, compressor, wellhead, manifold, or pump, which could release enough H2 S to result in atmospheric concentrations of 20 ppm at a distance of 10 feet from the component;
(iv)
You may use one sensor to detect H2 S around multiple pieces of equipment, provided the sensor is located no more than 10 feet from each piece, except that you need to use at least two sensors to monitor compressors exceeding 50 horsepower;
(v)
You do not need to have sensors near wells that are shut in at the master valve and sealed closed;
(A)
The location of system fittings, flanges, valves, and other devices subject to leaks to the atmosphere; and
(vii)
The District Manager may require additional sensors or other monitoring capabilities, if warranted by site specific conditions.
(6)
How must I functionally test the H
2
S Detectors? —(i) Personnel trained to calibrate the particular H2 S detector equipment being used must test detectors by exposing them to a known concentration in the range of 10 to 30 ppm of H2 S.
(ii)
If the results of any functional test are not within 2 ppm or 10 percent, whichever is greater, of the applied concentration, recalibrate the instrument.
(7) How often must I test my detectors?—
(i)
When conducting drilling, drill stem testing, well-completion, or well-workover operations in areas classified as H2 S present or H2 S unknown, test all detectors at least once every 24 hours. When drilling, begin functional testing before the bit is 1,500 feet (vertically) above the potential H2 S zone.
(ii)
When conducting production operations, test all detectors at least every 14 days between tests.
(iii)
If equipment requires calibration as a result of two consecutive functional tests, the District Manager may require that H2 S-detection and H2 S-monitoring equipment be functionally tested and calibrated more frequently.
(8) What documentation must I keep?—
(i)
You must maintain records of testing and calibrations (in the drilling or production operations report, as applicable) at the facility to show the present status and history of each device, including dates and details concerning:
(9) What are the requirements for nearby vessels?
If vessels are stationed overnight alongside facilities in areas of H2 S present or H2 S unknown, you must equip vessels with an H2 S-detection system that activates audible and visual alarms when the concentration of H2 S in the atmosphere reaches 20 ppm. This requirement does not apply to vessels positioned upwind and at a safe distance from the facility in accordance with the positioning procedure described in the approved H2 S Contingency Plan.
(10) What are the requirements for nearby facilities?
The District Manager may require you to equip nearby facilities with portable or fixed H2 S detector(s) and to test and calibrate those detectors. To invoke this requirement, the District Manager will consider dispersion modeling results from a possible release to determine if 20 ppm H2 S concentration levels could be exceeded at nearby facilities.
(i)
Monitor the SO2 concentration in the air with portable or strategically placed fixed devices capable of detecting a minimum of 2 ppm of SO2 ;
(iii)
Implement the personnel protective measures specified in the H2 S Contingency Plan if the SO2 concentration in the work area reaches 2 ppm; and
(iv)
Calibrate devices every 3 months if you use fixed or portable electronic sensing devices to detect SO2.
(12) May I use alternative measures?
You may follow alternative measures instead of those in paragraph (j)(11) of this section if you propose and the Regional Supervisor approves the alternative measures.
(13) What are the requirements for protective-breathing equipment?
In an area classified as H2 S present or H2 S unknown, you must:
(i)
Provide all personnel, including contractors and visitors on a facility, with immediate access to self-contained pressure-demand-type respirators with hoseline capability and breathing time of at least 15 minutes.
(ii)
Design, select, use, and maintain respirators in conformance with ANSI Z88.2 (incorporated by reference as specified in § 250.198 ).
(iii)
Make available at least two voice-transmission devices, which can be used while wearing a respirator, for use by designated personnel.
(v)
Store protective-breathing equipment in a location that is quickly and easily accessible to all personnel.
(vii)
Ensure that vessels attendant to facilities carry appropriate protective-breathing equipment for each crew member. The District Manager may require additional protective-breathing equipment on certain vessels attendant to the facility.
(viii)
During H2 S alerts, limit helicopter flights to and from facilities to the conditions specified in the H2 S Contingency Plan. During authorized flights, the flight crew and passengers must use pressure-demand-type respirators. You must train all members of flight crews in the use of the particular type(s) of respirator equipment made available.
(ix)
As appropriate to the particular operation(s), (production, drilling, well-completion or well-workover operations, or any combination of them), provide a system of breathing-air manifolds, hoses, and masks at the facility and the briefing areas. You must provide a cascade air-bottle system for the breathing-air manifolds to refill individual protective-breathing apparatus bottles. The cascade air-bottle system may be recharged by a high-pressure compressor suitable for providing breathing-quality air, provided the compressor suction is located in an uncontaminated atmosphere.
(k) Personnel safety equipment—
(1) What additional personnel-safety equipment do I need?
You must ensure that your facility has:
(i)
Portable H2 S detectors capable of detecting a 10 ppm concentration of H2 S in the air available for use by all personnel;
(ii)
Retrieval ropes with safety harnesses to retrieve incapacitated personnel from contaminated areas;
(iii)
Chalkboards and/or note pads for communication purposes located on the rig floor, shale-shaker area, the cement-pump rooms, well-bay areas, production processing equipment area, gas compressor area, and pipeline-pump area;
(v)
At least three resuscitators on manned facilities, and a number equal to the personnel on board, not to exceed three, on normally unmanned facilities, complete with face masks, oxygen bottles, and spare oxygen bottles.
(iii)
Provide movable ventilation devices in work areas. The movable ventilation devices must be multidirectional and capable of dispersing H2 S or SO2 vapors away from working personnel.
(3) What other personnel safety equipment do I need?
You must have the following equipment readily available on each facility:
(i)
A first-aid kit of appropriate size and content for the number of personnel on the facility; and
(l)
Do I need to notify MMS in the event of an H
2
S release? You must notify MMS without delay in the event of a gas release which results in a 15-minute time-weighted average atmospheric concentration of H2 S of 20 ppm or more anywhere on the OCS facility. You must report these gas releases to the District Manager immediately by oral communication, with a written follow-up report within 15 days, pursuant to §§ 250.188 through 250.190.
(m) Do I need to use special drilling, completion and workover fluids or procedures?
When working in an area classified as H2 S present or H2 S unknown:
(2)
If you use water-base well-control fluids, and if ambient air sensors detect H2 S, you must immediately conduct either the Garrett-Gas-Train test or a comparable test for soluble sulfides to confirm the presence of H2 S.
(3)
If the concentration detected by air sensors in over 20 ppm, personnel conducting the tests must don protective-breathing equipment conforming to paragraph (j)(13) of this section.
(4)
You must maintain on the facility sufficient quantities of additives for the control of H2 S, well-control fluid pH, and corrosion equipment.
(i) Scavengers.
You must have scavengers for control of H2 S available on the facility. When H2 S is detected, you must add scavengers as needed. You must suspend drilling until the scavenger is circulated throughout the system.
(ii) Control pH.
You must add additives for the control of pH to water-base well-control fluids in sufficient quantities to maintain pH of at least 10.0.
(iii) Corrosion inhibitors.
You must add additives to the well-control fluid system as needed for the control of corrosion.
(5)
You must degas well-control fluids containing H2 S at the optimum location for the particular facility. You must collect the gases removed and burn them in a closed flare system conforming to paragraph (q)(6) of this section.
(n) What must I do in the event of a kick?
In the event of a kick, you must use one of the following alternatives to dispose of the well-influx fluids giving consideration to personnel safety, possible environmental damage, and possible facility well-equipment damage:
(1)
Contain the well-fluid influx by shutting in the well and pumping the fluids back into the formation.
(2)
Control the kick by using appropriate well-control techniques to prevent formation fracturing in an open hole within the pressure limits of the well equipment (drill pipe, work string, casing, wellhead, BOP system, and related equipment). The disposal of H2 S and other gases must be through pressurized or atmospheric mud-separator equipment depending on volume, pressure and concentration of H2 S. The equipment must be designed to recover well-control fluids and burn the gases separated from the well-control fluid. The well-control fluid must be treated to neutralize H2 S and restore and maintain the proper quality.
(o)
Well testing in a zone known to contain H
2
S. When testing a well in a zone with H2 S present, you must do all of the following:
(1)
Before starting a well test, conduct safety meetings for all personnel who will be on the facility during the test. At the meetings, emphasize the use of protective-breathing equipment, first-aid procedures, and the Contingency Plan. Only competent personnel who are trained and are knowledgeable of the hazardous effects of H2 S must be engaged in these tests.
(2)
Perform well testing with the minimum number of personnel in the immediate vicinity of the rig floor and with the appropriate test equipment to safely and adequately perform the test. During the test, you must continuously monitor H2 S levels.
(3)
Not burn produced gases except through a flare which meets the requirements of paragraph (q)(6) of this section. Before flaring gas containing H2 S, you must activate SO2 monitoring equipment in accordance with paragraph (j)(11) of this section. If you detect SO2 in excess of 2 ppm, you must implement the personnel protective measures in your H2 S Contingency Plan, required by paragraph (f) of this section. You must also follow the requirements of § 250.1164. You must pipe gases from stored test fluids into the flare outlet and burn them.
(5)
Use tubulars suitable for H2 S service. You must not use drill pipe for well testing without the prior approval of the District Manager. Water cushions must be thoroughly inhibited in order to prevent H2 S attack on metals. You must flush the test string fluid treated for this purpose after completion of the test.
(p) Metallurgical properties of equipment.
When operating in a zone with H2 S present, you must use equipment that is constructed of materials with metallurgical properties that resist or prevent sulfide stress cracking (also known as hydrogen embrittlement, stress corrosion cracking, or H2 S embrittlement), chloride-stress cracking, hydrogen-induced cracking, and other failure modes. You must do all of the following:
(1)
Use tubulars and other equipment, casing, tubing, drill pipe, couplings, flanges, and related equipment that is designed for H2 S service.
(2)
Use BOP system components, wellhead, pressure-control equipment, and related equipment exposed to H 2 S-bearing fluids in conformance with NACE Standard MR0175-03 (incorporated by reference as specified in § 250.198 ).
(3)
Use temporary downhole well-security devices such as retrievable packers and bridge plugs that are designed for H2 S service.
(4)
When producing in zones bearing H2 S, use equipment constructed of materials capable of resisting or preventing sulfide stress cracking.
(5)
Keep the use of welding to a minimum during the installation or modification of a production facility. Welding must be done in a manner that ensures resistance to sulfide stress cracking.
(q)
General requirements when operating in an H
2
S zone —(1) Coring operations. When you conduct coring operations in H2 S-bearing zones, all personnel in the working area must wear protective-breathing equipment at least 10 stands in advance of retrieving the core barrel. Cores to be transported must be sealed and marked for the presence of H2 S.
(2) Logging operations.
You must treat and condition well-control fluid in use for logging operations to minimize the effects of H2 S on the logging equipment.
(3) Stripping operations.
Personnel must monitor displaced well-control fluid returns and wear protective-breathing equipment in the working area when the atmospheric concentration of H2 S reaches 20 ppm or if the well is under pressure.
(4)
Gas-cut well-control fluid or well kick from H
2
S-bearing zone. If you decide to circulate out a kick, personnel in the working area during bottoms-up and extended-kill operations must wear protective-breathing equipment.
(5) Drill- and workover-string design and precautions.
Drill- and workover-strings must be designed consistent with the anticipated depth, conditions of the hole, and reservoir environment to be encountered. You must minimize exposure of the drill- or workover-string to high stresses as much as practical and consistent with well conditions. Proper handling techniques must be taken to minimize notching and stress concentrations. Precautions must be taken to minimize stresses caused by doglegs, improper stiffness ratios, improper torque, whip, abrasive wear on tool joints, and joint imbalance.
(6) Flare system.
The flare outlet must be of a diameter that allows easy nonrestricted flow of gas. You must locate flare line outlets on the downside of the facility and as far from the facility as is feasible, taking into account the prevailing wind directions, the wake effects caused by the facility and adjacent structure(s), and the height of all such facilities and structures. You must equip the flare outlet with an automatic ignition system including a pilot-light gas source or an equivalent system. You must have alternate methods for igniting the flare. You must pipe to the flare system used for H2 S all vents from production process equipment, tanks, relief valves, burst plates, and similar devices.
(7) Corrosion mitigation.
You must use effective means of monitoring and controlling corrosion caused by acid gases (H2 S and CO2) in both the downhole and surface portions of a production system. You must take specific corrosion monitoring and mitigating measures in areas of unusually severe corrosion where accumulation of water and/or higher concentration of H2 S exists.