Regulations last checked for updates: Jan 30, 2025

Title 40 - Protection of Environment last revised: Nov 08, 2025
§ 99.50 - What facilities qualify for the exemption of emissions from permanently shut-in and plugged wells?

(a) The total facility applicable emissions for the WEC applicable facility containing permanently shut-in and plugged wells must exceed 0 mt as calculated in accordance with § 99.21(a).

(b) This exemption is applicable to WEC applicable facilities in the onshore petroleum and natural gas production, offshore petroleum and natural gas production, or underground natural gas storage industry segments, as those industry segment terms are defined in § 98.230 of this chapter, that permanently shut-in and plug one or more wells during the reporting year.

(c) For the purposes of applying this exemption, a permanently shut-in and plugged well is one that has been permanently sealed, following all applicable local, State, or Federal regulations in the jurisdiction where the well is located, to prevent any potential future leakage of oil, gas, or formation water into shallow sources of potable water, onto the surface, or into the atmosphere. Site reclamation following placement of a metal plate or cap is not required to be completed for the well to be considered permanently shut-in and plugged for the purposes of this part.

§ 99.51 - What are the reporting requirements for the exemption for wells that were permanently shut-in and plugged?

(a) For a WEC applicable facility meeting the applicability provisions of § 99.50, you may elect to report information regarding an exemption for wells that were permanently shut-in and plugged. The exemption information to be reported is described in paragraph (b) of this section. The exemption information shall be submitted as described § 99.7.

(b) Report the following information for each well meeting the applicability provisions of § 99.50 that was permanently shut-in and plugged in the reporting year.

(1) Well ID number as reported in part 98, subpart W of this chapter. If no well ID number is reported for the well to part 98, subpart W, report the well ID number as defined in this part.

(2) Date the well was permanently shut-in and plugged, which for the purposes of this exemption, is the date when welding or cementing of a metal plate or cap onto the casing end was completed.

(3) The statutory citation for each applicable State, local, and Federal regulation stipulating requirements that were applicable to the closure of the permanently shut-in and plugged well.

(4) A certification that the requirements in each of the applicable State, local, and Federal regulations identified in paragraph (b)(3) of this section were followed.

(5) If the WEC applicable facility is in the onshore petroleum and natural gas production or underground natural gas storage industry segment and the WEC obligated party calculated methane emissions attributable to the well from wellhead equipment leaks using the methods in § 99.52(b)(5) of this section, you must indicate the method used to calculate equipment leak emissions attributable to the well (i.e., § 99.52(b)(5)(i), (ii), or (iii)). For a WEC applicable facility in the underground natural gas storage industry segment, you must also report the information specified in paragraphs (b)(5)(i) through (iv) of this section, as applicable. For a WEC applicable facility in the onshore petroleum and natural gas production industry segment, you must also report the information specified in paragraphs (b)(5)(i) through (iii) of this section, as applicable. All WEC applicable facilities must report the information specified in paragraph (b)(5)(v).

(i) If the method in § 99.52(b)(5)(i) is used to calculate equipment leak emissions attributable to the well, you must report the following information for each leak: the leak detection survey method used, the component type as reported in § 98.236(q) of this chapter, the volumetric flow rate of the natural gas leak in standard cubic feet per hour and the duration of the measured leak as determined in accordance § 99.52(b)(5)(i), in hours.

(ii) If the method in § 99.52(b)(5)(ii) is used to calculate equipment leak emissions attributable to the well, you must report the following information for each component identified as leaking: the leak detection survey method used, the component type as specified in § 98.233(q)(2)(iii) or (vii) of this chapter, as applicable, and the time the surveyed component is assumed to be leaking and operational as determined in accordance § 99.52(b)(5)(ii), in hours.

(iii) If the method in § 99.52(b)(5)(iii) is used to calculate equipment leak emissions attributable to the well, you must report the counts of each component type listed in § 98.233(r)(3) of this chapter that are associated with the well, as applicable.

(iv) Indicate whether you used the default concentration of CH4 (0.975) or a facility-specific CH4 concentration in the total hydrocarbon of the feed natural gas. If you used the facility-specific CH4 concentration in the total hydrocarbon of the feed natural gas, report the value.

(v) The quantity of methane emissions attributable to the well from wellhead equipment leaks as calculated in accordance with § 99.52(b)(5)(i), (b)(5)(ii), or (b)(5)(iii), as applicable, for the reporting year, in metric tons CH4.

(6) If the WEC applicable facility is in the onshore petroleum and natural gas production and calculated methane emissions attributable to the well from associated gas flaring and completions and workovers without hydraulic fracturing and with flaring using equation E-6 of this section, you must report the information specified in paragraphs (b)(6)(i) and (ii) of this section.

(i) The volume of gas sent to the flare from the plugged well, in thousand scf.

(ii) The quantity of methane emissions attributable to the well from associated gas flaring and from completions and workovers without hydraulic fracturing and with flaring as calculated in accordance with § 99.52(b)(6), as applicable, in metric tons CH4.

(7) The emissions attributable to the well calculated using equation E-1, E-2, E-3, or E-4 in § 99.52(b), as applicable, in metric tons CH4.

(c) The total quantity of methane emissions attributable to all wells that were permanently shut-in and plugged at a WEC applicable facility meeting the applicability provisions of § 99.50 during the reporting year, calculated using equation E-7 in § 99.52(c), in metric tons CH4.

§ 99.52 - How are the net emissions attributable to all wells at a WEC applicable facility that were permanently shut-in and plugged in the reporting year quantified?

(a) For the purposes of this section, the following source types (as specified in part 98, subpart W of this chapter) constitute emissions directly attributable to an onshore petroleum and natural gas production, offshore petroleum and natural gas production, or underground natural gas storage well, as applicable:

(1) Wellhead equipment leaks.

(2) Liquids unloading.

(3) Completions and workovers with hydraulic fracturing.

(4) Completions and workovers without hydraulic fracturing.

(5) Associated natural gas venting and flaring.

(6) Well testing.

(7) Drilling mud degassing.

(b) Calculate the annual emissions attributable to each well that was permanently shut-in and plugged during the reporting year and included in the submittal pursuant to § 99.51 using equations E-1, E-2, E-3, or E-4 of this section, as applicable.

(1) For onshore petroleum and natural gas production wells that are part of a WEC applicable facility that are permanently shut-in and plugged in reporting years 2025 and later, equation E-1 of this section must be used to quantify the methane emissions directly attributable to each permanently shut-in and plugged well.

Where: EPW,CH4 = The quantity of methane emissions directly attributable to an individual well that was permanently shut-in and plugged during the reporting year at a WEC applicable facility meeting the applicability provisions of § 99.50, mt CH4. ELeaks,CH4 = The quantity of methane emissions attributable to the well from wellhead equipment leaks as calculated in accordance with paragraphs (b)(5)(i), (b)(5)(ii), or (b)(5)(iii) of this section, as applicable, for the reporting year, mt CH4. ELU,CH4 = The quantity of methane emissions attributable to the well from liquids unloading as reported pursuant to § 98.236(f)(1)(x) or (f)(2)(viii) of this chapter, as applicable, for the reporting year, mt CH4. ECWwHF,CH4 = The total quantity of methane emissions attributable to the well from completions and workovers with hydraulic fracturing as reported pursuant to § 98.236(g)(9) of this chapter for the reporting year, mt CH4. ECWwoHF,CH4 = The total quantity of methane emissions attributable to the well from completions and workovers without hydraulic fracturing and without flaring as reported pursuant to § 98.236(h)(1)(vi) and (h)(3)(iv) of this chapter for the reporting year, mt CH4. EAGV,CH4 = The quantity of methane emissions attributable to the well from associated gas venting as reported pursuant to § 98.236(m)(7)(viii) of this chapter for the reporting year, mt CH4. EF,CH4 = The quantity of methane emissions attributable to the well from associated gas flaring and from completions and workovers without hydraulic fracturing and with flaring as calculated in accordance with paragraph (b)(6) of this section, as applicable, mt CH4. EWT,CH4 = The total quantity of methane emissions attributable to the well from well testing as reported pursuant to § 98.236(l)(1)(vii), (l)(2)(vii), (l)(3)(vi), and (l)(4)(vi) of this chapter, as applicable, for the reporting year, mt CH4. EDMD,CH4 = The quantity of methane emissions attributable to the well from drilling mud degassing as reported pursuant to § 98.236(dd)(1)(viii), (dd)(2)(iv), or (dd)(3)(iv) of this chapter, as applicable, for the reporting year, mt CH4.

(2) For onshore petroleum and natural gas production wells that are part of a WEC applicable facility that are permanently shut-in and plugged in reporting year 2024, equation E-2 of this section must be used to quantify the methane emissions attributable to the well:

Where: EPW,CH4 = The quantity of methane emissions attributable to an individual well that was permanently shut-in and plugged during the reporting at a WEC applicable facility meeting the applicability provisions of § 99.50, mt CH4. ELkQ,CH4 = The WEC applicable facility total quantity of methane emissions from equipment leaks reported pursuant to § 98.236(q)(2)(ix) of this chapter for the reporting year, mt CH4. ELkR,CH4 = The WEC applicable facility total quantity of methane emissions from equipment leaks reported pursuant to § 98.236(r)(1)(v) of this chapter for the reporting year, mt CH4. ELU,CH4 = The WEC applicable facility total quantity of methane emissions from liquids unloading as reported pursuant to § 98.236(f)(1)(x) and (f)(2)(viii) of this chapter for the reporting year, mt CH4. ECWwHF,CH4 = The WEC applicable facility total quantity of methane emissions from completions and workovers with hydraulic fracturing as reported pursuant to § 98.236(g)(9) of this chapter for the reporting year, mt CH4. ECWwoHF,CH4 = The WEC applicable facility total quantity of methane emissions from completions and workovers without hydraulic fracturing as reported pursuant to § 98.236(h)(1)(vi), (h)(2)(vi), (h)(3)(iv) and (h)(4)(iv) of this chapter for the reporting year, mt CH4. EAGV,CH4 = The WEC applicable facility quantity of methane emissions from associated gas venting as reported pursuant to § 98.236(m)(7)(iv) of this chapter for the reporting year, mt CH4. EAGF,CH4 = The WEC applicable facility quantity of methane emissions from associated gas flaring as reported pursuant to § 98.236(m)(8)(iii) of this chapter for the reporting year, mt CH4. EWT,CH4 = The WEC applicable facility total quantity of methane emissions from well testing as reported pursuant to § 98.236(l)(1)(vii), (l)(2)(vii), (l)(3)(vi), and (l)(4)(vi) of this chapter, as applicable, for the reporting year, mt CH4. Qng,PW = The total annual quantity of natural gas that is produced and sent to sale from the well in the reporting year, as reported pursuant to § 98.236(aa)(1)(iii)(C) of this chapter, in thousand standard cubic feet. 6 = Conversion factor from thousand standard cubic feet of natural gas to barrel of oil equivalent. Qoil,PW = The total quantity of crude oil and condensate that is produced and sent to sale from the well in the reporting year, as reported pursuant to § 98.236(aa)(1)(iii)(D)of this chapter, in barrels. Qng,WAF = The total quantity of natural gas that is produced and sent to sale from the WEC applicable facility in the reporting year, as reported pursuant to § 98.236(aa)(1)(i)(B) of this chapter, in thousand standard cubic feet. Qoil,WAF = The total quantity of crude oil and condensate that is produced and sent to sale from the WEC applicable facility in the reporting year, as reported pursuant to § 98.236(aa)(1)(i)(C) of this chapter, in barrels.

(3) For offshore petroleum and natural gas production wells that are part of a WEC applicable facility that are permanently shut-in and plugged in any reporting year, equation E-3 of this section must be used to quantify the methane emissions attributable to the well.

Where: EPW,CH4 = The quantity of methane emissions attributable to an individual well that was permanently shut-in and plugged during the reporting year at a WEC applicable facility meeting the applicability provisions of § 99.50, mt CH4. ELeaks,CH4 = The WEC applicable facility total quantity of methane emissions from non-compressor component level fugitives (i.e., equipment leaks), mt CH4. For reporting year 2024, use the value reported pursuant to § 98.236(s)(2) of this chapter for the reporting year. For reporting year 2025 and later, use the value reported to § 98.236(s)(3)(ii) of this chapter for the reporting year. EDMD,CH4 = The WEC applicable facility total annual quantity of methane emissions from drilling mud degassing, mt CH4. For reporting year 2024, use the value reported pursuant to § 98.236(s)(2) of this chapter for the reporting year. For reporting year 2025 and later, use the value reported to § 98.236(s)(3)(ii) of this chapter for the reporting year. Qng,PW = The total quantity of natural gas that is produced and sent to sale from the well in the reporting year as reported pursuant to § 98.236(aa)(2)(iii) of this chapter, in thousand scf. 6 = Conversion factor from thousand standard cubic feet of natural gas to barrel of oil equivalent. Qoil,PW = The total quantity of crude oil and condensate that is produced and sent to sale from the well in the reporting year, as reported pursuant to § 98.236(aa)(2)(iv) of this chapter, in barrels. Qng,WAF = The total quantity of natural gas that is produced and sent to sale from the WEC applicable facility in the reporting year, as reported pursuant to § 98.236(aa)(2)(i) of this chapter, in thousand scf. Qoil,WAF = The total quantity of crude oil and condensate that is produced and sent to sale from the WEC applicable facility in the reporting year, as reported pursuant to § 98.236(aa)(2)(ii) of this chapter, in barrels.

(4) For underground natural gas storage wells that are part of a WEC applicable facility that are permanently shut-in and plugged in any reporting year, equation E-4 of this section must be used to quantify the methane emissions attributable to the well.

Where: EPW,CH4 = The quantity of methane emissions directly attributable to an individual well that was permanently shut-in and plugged during the reporting year at a WEC applicable facility meeting the applicability provisions of § 99.50, mt CH4. ELeaks,CH4 = The quantity of methane emissions attributable to the well from storage wellhead equipment leaks in accordance with paragraphs (b)(5)(i), (b)(5)(ii) or (b)(5)(iii) of this section, as applicable, for the reporting year, mt CH4.

(5) You must quantify equipment leak methane emissions from the permanently shut-in and plugged well at the WEC applicable facility in accordance with the methods in (b)(5)(i) through (iii) of this section. You must use the same calculation method for equipment leaks reported pursuant to § 98.236(q) or (r) of this chapter in the part 98 report for the well-pad site or facility, as applicable, which is associated with the permanently shut-in and plugged well.

(i) If equipment leak surveys and measurement were used to quantify methane emissions from the permanently shut-in and plugged well and reported pursuant to § 98.236(q) of this chapter in the part 98 report for a WEC applicable facility, you must calculate the methane emissions (i.e., EMeasured Leak, CH4) for each measured wellhead leak in accordance with equation E-5A. The sum of the quantified methane emissions from each measured wellhead leak at the permanently shut-in and plugged well calculated in accordance with equation E-5A shall be considered “ELeaks, CH4” in Equations E-1 and E-4 of this section, as applicable.

Where: EMeasured Leak,CH4 = The quantity of methane emissions attributable to a measured leak from a wellhead leak component at the permanently shut-in and plugged well, mt CH4. p = Component type as reported in accordance with § 98.236(q) of this chapter, as applicable. z = An individual component of type “p” detected as leaking and measured at the permanently shut-in and plugged well in any leak survey during the year. Qp,z = Volumetric flow rate of the natural gas leak for component “z” of component type “p” converted to standard conditions according to § 98.233(q)(3)(iii) of this chapter, scf whole gas/hour/component, as applicable. MCH4 = The mole fraction of CH4 in produced gas for the well. For onshore petroleum and natural gas production wells, use the mole fraction of CH4 in produced gas for the sub-basin associated with the well, as reported pursuant to § 98.236(aa)(1)(ii)(I) of this chapter, unitless. For underground natural gas wellheads, use 0.975 or the concentration of CH4 in the total hydrocarbon of the feed natural gas, unitless. Tp,z = The total time the surveyed and measured component “z” of component type “p” was assumed to be leaking and operational, in hours. If one leak detection survey is conducted in the calendar year, assume the component was leaking for the entire calendar year, hours. If multiple leak detection surveys are conducted in the calendar year, assume a component found leaking in the first survey was leaking since the beginning of the year until the date of the survey, hours; assume a component found leaking in the last survey of the year was leaking from the preceding survey through the end of the year, hours; assume a component found leaking in a survey between the first and last surveys of the year was leaking since the preceding survey until the date of the survey, hours; and sum times for all leaking periods. For each leaking component, account for time the component was not operational (i.e., not operating under pressure) using the same estimates and available data used for calculating the total time the surveyed and measured components were leaking and operational in accordance with § 98.233(q)(3)(ii) of this chapter. k = The factor to adjust for undetected leaks by respective leak detection method. For reporting year 2024, k equals 1. For reporting year 2025 and later, k equals 1.25 for the methods in § 98.234 (a)(1), (3) and (5) of this chapter; k equals 1.55 for the method in § 98.234(a)(2)(i) of this chapter; and k equals 1.27 for the method in § 98.234(a)(2)(ii) of this chapter. Select the factor for the leak detection method used for the permanently shut-in and plugged well, unitless. ρCH4 = Density of methane, 0.0192 mt/Mscf. 10−3 = Conversion factor from scf to Mscf.

(ii) If equipment leak surveys and leaker emission factors were used to quantify methane emissions from the permanently shut-in and plugged well and reported pursuant to § 98.236(q) of this chapter in the part 98 report for a WEC applicable facility, equation E-5B of this section must be used to calculate ELeaks,CH4.

Where: ELeaks,CH4 = The quantity of methane emissions attributable to the well from wellhead equipment leaks as reported pursuant to § 98.236(q) of this chapter for the reporting year, mt CH4. p = Component type as specified in § 98.233(q)(2)(iii) and (vii) of this chapter, as applicable. Np = The number of component types reported pursuant to § 98.233(q)(2)(ii) of this chapter for which there were detected leaks at the well reported pursuant to § 98.233(q)(2)(iii) or (vii) of this chapter, as applicable. EFp = The leaker emission factor for component “p” as specified in § 98.233(q)(2)(iii) or (vii) of this chapter, scf whole gas/hour/component, as applicable. MCH4 = For onshore petroleum and natural gas production wells, the mole fraction of CH4 in produced gas for the sub-basin associated with the well, as reported pursuant to § 98.236(aa)(1)(ii)(I) of this chapter, unitless. For underground natural gas wellheads, the mole fraction of CH4 equals 0.975 for CH4 or concentration of CH4, in the total hydrocarbon of the feed natural gas. xp = The total number of specific components of type “p” detected as leaking at the permanently shut-in and plugged well in any leak survey during the year. A component found leaking in two or more surveys during the year is counted as one leaking component. Tp,z = The total time the surveyed component “z” of component type “p” was assumed to be leaking and operational, in hours. If one leak detection survey is conducted in the calendar year, assume the component was leaking for the entire calendar year, hours. If multiple leak detection surveys are conducted in the calendar year, assume a component found leaking in the first survey was leaking since the beginning of the year until the date of the survey, hours; assume a component found leaking in the last survey of the year was leaking from the preceding survey through the end of the year, hours; assume a component found leaking in a survey between the first and last surveys of the year was leaking since the preceding survey until the date of the survey, hours; and sum times for all leaking periods. For each leaking component, account for time the component was not operational (i.e., not operating under pressure) using the same estimates and available data used for calculating the total time the surveyed components were leaking and operational in accordance with § 98.233(q)(2) of this chapter. k = The factor to adjust for undetected leaks by respective leak detection method. For reporting year 2024, k equals 1. For reporting year 2025 and later, k equals 1.25 for the methods in § 98.234 (a)(1), (3) and (5) of this chapter; k equals 1.55 for the method in § 98.234(a)(2)(i) of this chapter; and k equals 1.27 for the method in § 98.234(a)(2)(ii) of this chapter. Select the factor for the leak detection method used for the permanently shut-in and plugged well, unitless. ρCH4 = Density of methane, 0.0192 mt/Mscf. 10−3 = Conversion factor from scf to Mscf.

(iii) If equipment leaks by population count were used to quantify methane emission from the permanently shut-in and plugged well and reported pursuant to § 98.236(r) of this chapter in the part 98 report for a WEC applicable facility, equation E-5C of this section must be used to calculate ELeaks,CH4.

Where: ELeaks,CH4 = The annual quantity of methane emissions attributable to the well from wellhead equipment leaks as reported pursuant to § 98.236(r) of this chapter for the reporting year, mt CH4. Countwh = Underground natural gas storage facilities must count each component at the storage wellhead listed in § 98.233(r)(3) of this chapter. Onshore petroleum and natural gas production must use a value of 1 wellhead. EFwh = The population emission factor for wellheads, as listed in § 98.233(r)(2) and (3) of this chapter, as applicable. MCH4 = For onshore petroleum and natural gas production wells, the mole fraction of CH4 in produced gas for the sub-basin associated with the well as reported pursuant to § 98.236(aa)(1)(ii)(I) of this chapter, unitless. For underground natural gas wellheads, the mole fraction of CH4 equals 0.975 for CH4 or concentration of CH4, in the total hydrocarbon of the feed natural gas. T = The total time that has elapsed from the beginning of the reporting year until the date the well was plugged in accordance with § 99.51(b)(2), hours. ΡCH4 = Density of methane, 0.0192 mt/Mscf. 10−3 = Conversion factor from scf to Mscf.

(6) For onshore petroleum and natural gas production wells that are part of a WEC applicable facility that are permanently shut-in and plugged in reporting years 2025 and later, equation E-6 of this section must be used to quantify the methane emissions attributable to the well from associated gas flaring and completions and workovers without hydraulic fracturing and with flaring:

Where: EF,CH4 = The quantity of methane emissions from associated gas flaring and from completions and workovers without hydraulic fracturing and with flaring attributable to the plugged well for the reporting year, mt CH4. VPW = The volume of gas sent to the flare from the plugged well, scf. If flow for each stream to the flare is measured or determined in accordance with § 98.233(n)(3)(ii) of this chapter and that stream contains only the flow from the plugged well, use the flow for that individual stream as reported to § 98.236(n)(11) of this chapter. If flow is measured at the inlet to the flare in accordance with § 98.233(n)(3)(i) of this chapter or the stream flow measured or determined in accordance with § 98.233(n)(3)(ii) of this chapter includes flow from other sources, use an engineering estimate based upon best available information of the portion of flow from the plugged well. XCH4 = Annual average mole fraction of CH4 in the gas sent to the flare from the plugged well. If you determine composition of each stream routed to the flare as specified in § 98.233(n)(4)(iii) of this chapter and that stream contains only the flow from the plugged well, use the mole fraction for the individual stream as reported to § 98.236(n)(14) of this chapter. Otherwise, use the average mole fraction of CH4 in produced gas for the sub-basin in which the plugged well is located as reported to § 98.236(aa)(1)(ii)(I) of this chapter. ηD = Flare destruction efficiency, as reported to § 98.236(n)(13) of this chapter. ZL = Fraction of the feed gas sent to the burning flare, equal to 1− ZU. ZU = Fraction of the feed gas sent to the flare when it is un-lit, as reported to § 98.236(n)(12) of this chapter. ρCH4 = Density of methane at 60 °F and 14.7 psia. Use 0.0192 kg/ft 3. 10−3 = Conversion from kilograms to metric tons.

(c) Calculate the total emissions attributable to all wells included in the submittal received pursuant to § 99.51 using equation E-7 of this section:

Where: EPlug,CH4 = The total quantity of methane emissions, as determined in subpart E of this part, at the WEC applicable facility attributable to all wells that were permanently shut-in and plugged during the reporting year meeting the applicability provisions of § 99.50, mt CH4. EPW,j,CH4 = The annual quantity of methane emissions attributable to a well “j” that was permanently shut-in and plugged during the reporting year at a WEC applicable facility meeting the applicability provisions of § 99.50 calculated using equation E-1, E-2, E-3, or E-4 of this section, as applicable. N = Total number of wells that were permanently shut-in and plugged during the reporting year in accordance with all applicable closure requirements at a WEC applicable facility.
source: 89 FR 91165, Nov. 18, 2024, unless otherwise noted.
cite as: 40 CFR 99.50