MEMORANDUM 

TO: Docket # EPA-HQ-OAR-2011-0512 

FROM: Alexis McKittrick and Mark DeFigueiredo, EPA/CCD 

DATE: February 20, 2014 

SUBJECT: Proposed Minor Technical Corrections to Subpart W, Petroleum and Natural Gas 

Systems, in the Greenhouse Gas Reporting Program 

The EPA is proposing to make certain revisions to the petroleum and natural gas systems source 

category of the Greenhouse Gas Reporting Rule (40 CFR part 98, subpart W). The proposed 

changes revise calculation methods, amend monitoring and data reporting requirements, clarify 

certain terms and definitions, and correct technical and editorial errors identified during the 

course of implementation. 

The purpose of this memorandum is to provide a detailed list of minor or clarifying changes that 

are not discussed in the preamble to the proposed amendments to subpart W (“Revisions and 

Confidentiality Determinations for Petroleum and Natural Gas Systems; Proposed Rule”). 

Table 1 contains a list of the minor proposed changes, the current rule language for the 

requirement, and the proposed revised rule language. An explanation for the change is included. 

These changes are minor clarifications to better reflect EPA’s intent and include simple 

corrections to calculation terms or cross-references that do not revise the output of the 

calculations, harmonizing changes within a subpart (such as changes to terminology), simple 

editorial and minor error corrections, or removal of redundant text. Proposed revisions to the 

reporting section of subpart W are not included in this memorandum, but are discussed in a 

separate document included in this docket entitled, “Proposed Revisions to the Subpart W 

Reporting Requirements.” 
2 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

§98.232(c)(11), (d)(1), 

(e)(1), (f)(1),(g)(1), 

(h)(1) 

Reciprocating compressor 

rod packing venting 

Reciprocating compressor 

venting 

Harmonizing edit 

§98.232(i)(1) (1) Meters, regulators, and 

associated equipment at 

above grade transmissiondistribution transfer stations, 

including equipment leaks 

from connectors, block 

valves, control valves, 

pressure relief valves, orifice 

meters, regulators, and open 

ended lines. 

(1) Equipment leaks from 

connectors, block valves, 

control valves, pressure relief 

valves, orifice meters, 

regulators, and open-ended 

lines at above grade 

transmission-distribution 

transfer stations. 

Clarifying edit 

§98.232(i)(2) and 

(i)(4) 

(2) Equipment leaks from 

vaults at... 

(2) Equipment leaks at... Clarifying edit 

§98.232(i)(3) (3) Meters, regulators, and 

associated equipment at 

above grade meteringregulating station. 

(3) Equipment leaks at above 

grade metering-regulating 

stations that are not above 

grade transmission-distribution 

transfer stations. 

Clarifying edit 

§98.232(i)(5) (5) Pipeline main equipment 

leaks. 

(5) Distribution main 

equipment leaks. 

Clarifying edit 

§98.232(i)(6) (6) Service line equipment 

leaks. 

(6) Distribution services 

equipment leaks. 

Clarifying edit 

§98.233 throughout Methodologies Methods Clarifying edit 

CEMS Continuous emissions 

monitoring system (CEMS) 

Clarifying edit 

General Stationary Fuel 

Combustion 

General Stationary Fuel 

Combustion Sources 

Clarifying edit 

§98.233(a) and (c) Equation W-1 and W-2 

calculate mass emissions in 

CO2e. 

Removed term “Convi” so that 

Equations W-1 and W-2 

calculate volumetric emissions 

instead of mass emissions in 

CO2e. 

Global warming 

potential for methane 

removed from 

calculation. 

§98.233(a) and (c); 

Terms Masst,i” and 

“Massi” in Equations 

W-1 and W-2

Masst,i= Annual total mass 

GHG emissions in metric 

tons CO2e per year from 

natural gas pneumatic device 

venting (pump venting) for 

GHGi. 

Es,i = Annual total volumetric 

GHG emissions at standard 

conditions in standard cubic 

feet per year from natural gas 

pneumatic devices (pumps) for 

GHGi.

Revised intro paragraph 

(a) to reflect volumetric 

emissions of CH4 and 

CO2; Changed equation 

terms from “Masst,i” 

(Equation W-1) and 

“Massi” (Equation W2) to “Es,i” and revised 

units from mass to 

volumetric at standard 

condition (EPA is 

proposing to revise the 

reporting of annual 

emissions from each 

source from units of 

metric tons of CO2e to 
3 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

metric tons of each 

reported GHG). 

§98.233(a) and (c); 

Terms “Tt” and “T” in 

Equation W-1 and W-2 

Average estimated number of 

hours in the operating year 

the devices of each type were 

operational. Default is 8760 

hours 

Average estimated number of 

hours in the operating year the 

devices of each type were 

operational using engineering 

estimates based on best 

available data. Default is 8760 

hours 

Clarifying edit 

§98.233 (a) and (c); 

Term “EFt” in 

Equation W-1 and 

“EF” in Equation W-2 

EFt = Population emission 

factors for natural gas 

pneumatic device venting 

listed in Tables... 

EF = Population emission 

factors for natural gas 

pneumatic devices (natural 

gas driven pumps) listed in 

Tables... 

EFt = Population emission 

factors for natural gas 

pneumatic device vents (in 

standard cubic feet per hour 

per device) of each type “t” 

listed in Tables... 

EF = Population emissions 

factors for natural gas driven 

pneumatic devices (in standard 

cubic feet per hour per pump) 

listed in Table... 

Clarifying edit 

§98.233(c); Term 

“Count” in Equation 

W-2 

Count = Total number of 

natural gas pneumatic pumps 

Count = Total number of 

natural gas driven pneumatic 

pumps. 

Clarifying edit 

§98.233(a)(4) and 

(c)(2) 

None Calculate both CH4 and CO2

mass emissions from 

volumetric emissions using 

calculations in paragraph (v) 

of this section. 

Added (a)(4) and (c)(2) 

to convert volumetric to 

mass emissions. 

§98.233(d)(2) 

Term “VolCO2” in 

Equation W-3 

VolCO2 – Volumetric fraction 

of CO2 content in vent gas 

out of the AGR unit as 

determined in (d)(6) of this 

section. 

VolCO2 – Annual average 

volumetric fraction of CO2

content in vent gas flowing out 

of the AGR unit as determined 

in paragraph (d)(6) of this 

section. 

Clarified that the term 

should be an annual 

average 

§98.233(d)(3) 

Term “VolI” in 

Equations W-4A and 

W-4B 

VolI, - Volume fraction of 

CO2 content in natural gas 

into the AGR unit... 

VolI, - Annual average 

volumetric fraction of CO2

content in natural gas flowing 

into the AGR unit... 

Clarified that the term 

should be an annual 

average 

§98.233(d)(3); Term 

“Volo” in Equations 

W-4A and W-4B 

Volo– volume fraction of CO2

content in natural gas out of 

the AGR unit... 

Volo – Annual average 

volumetric fraction of CO2

content in natural gas flowing 

out of the AGR unit... 

Clarified that the term 

should be an annual 

average 

§98.233(d)(4) AspenTech HYSYS®, and 

API 4679 AMINECalc 

AspenTech HYSYS®, or API 

4679 AMINECalc 

Clarifying edit 

§98.233(d)(5) 

Similar changes for 

(d)(6,7,8) 

 Record the gas flow rate of 

the inlet and outlet natural 

gas stream of an AGR unit... 

For Calculation Method 3, 

record the gas flow rate of the 

inlet when using Equation W4A of this section or the gas 

flow rate of the outlet when 

using Equation W-4B of this 

Clarified instructions so 

that they refer to 

specific equations and 

calculation methods 
4 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

section for the natural gas 

stream of an AGR unit... 

§98.233(d)(6) If continuous gas analyzer is 

not available on the vent 

stack, either install a 

continuous gas analyzer or 

take quarterly gas samples 

from the vent gas stream to 

determine VolCO2 according 

to methods set forth in 

§98.234(b). 

For Calculation Method 2, if a 

continuous gas analyzer is not 

available on the vent stack, 

either install a continuous gas 

analyzer or take quarterly gas 

samples from the vent gas 

stream to determine VolCO2 in 

Equation W-3 of this section 

according to methods set forth 

in §98.234(b). 

§98.233(d)(7) If a continuous gas analyzer 

is installed on the inlet gas 

stream, then the continuous 

gas analyzer results must be 

used. If a continuous gas 

analyzer is not available, 

either install a continuous gas 

analyzer or take quarterly gas 

samples from the inlet gas 

stream to determine VolI

according to methods set 

forth in §98.234(b). 

For Calculation Method 3, if a 

continuous gas analyzer is 

installed on the inlet gas 

stream, then the continuous 

gas analyzer results must be 

used. If a continuous gas 

analyzer is not available, either 

install a continuous gas 

analyzer or take quarterly gas 

samples from the inlet gas 

stream to determine VolI in 

Equation W-4A or W-4B of 

this section according to 

methods set forth in 

§98.234(b). 

§98.233(d)(8) Determine volume fraction of 

CO2 content in natural gas 

out of the AGR unit using 

one of the methods specified 

in paragraph (d)(8) of this 

section. 

For Calculation Method 3, 

determine annual average 

volumetric fraction of CO2

content in natural gas flowing 

out of the AGR unit using one 

of the methods specified in 

paragraphs (d)(8)(i) through 

(d)(8)(iii) of this section. 

§98.233(d)(8)(ii) (ii) If a continuous gas 

analyzer is not available or 

installed, quarterly gas 

samples may be taken from 

the outlet gas stream to 

determine VolO according to 

methods set forth in 

§98.234(b). 

(ii) If a continuous gas 

analyzer is not available or 

installed, quarterly gas 

samples may be taken from the 

outlet gas stream to determine 

VolO in Equation W-4A or W4B of this section according to 

methods set forth in 

§98.234(b). 

Clarifying edits 

§98.233(d)(8)(iii) Use sales line quality 

specification for CO2 in 

natural gas. 

If a continuous gas analyzer is 

not available or installed, you 

may use sales line quality 

specification for CO2 in natural 

gas. 

Clarifying edit 

§98.233(d)(9) Calculate CO2 volumetric 

emissions at standard 

Calculate annual volumetric 

CO2 emissions at standard 

Clarified that the result 

is annual emissions. 
5 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

conditions using calculations 

in paragraph (t) of this 

section. 

conditions using calculations 

in paragraph (t) of this section. 

§98.233(d)(10) Mass CO2 emissions shall be 

calculated from volumetric 

CO2 emissions using 

calculations in paragraph (v) 

of this section. 

Calculate CO2 annual mass 

emissions at standard 

conditions using calculations 

in paragraph (v) of this 

section. 

Revised to specify 

emissions at standard 

conditions 

§98.233(d)(11) Determine if emissions from 

the AGR unit are recovered 

and transferred outside the 

facility. Adjust the emission 

estimated in paragraphs 

(d)(1) through (d)(10) of this 

section downward by the 

magnitude of CO2 emission 

recovered and transferred 

outside the facility. 

Determine if CO2 emissions 

from the AGR unit are 

recovered and transferred 

outside the facility. Adjust the 

CO2 emissions estimated in 

paragraphs (d)(1) through 

(d)(10) of this section 

downward by the magnitude of 

CO2 emissions recovered and 

transferred outside the facility. 

Clarifying edit 

§98.233(e)(1) (1) Calculation Methodology 

1. Calculate annual mass 

emissions from dehydrator 

vents with annual average 

daily throughput greater than 

or equal to 0.4 million 

standard cubic feet per day 

using a software program, 

such as AspenTech 

HYSYS® or GRI-GLYCalc, 

that uses the Peng-Robinson 

equation of state to calculate 

the equilibrium coefficient, 

speciates CH4 and CO2

emissions from dehydrators, 

and has provisions to include 

regenerator control devices, a 

separator flash tank, stripping 

gas and a gas injection pump 

or gas assist pump. A 

minimum of the following 

parameters determined by 

engineering estimate based 

on best available data must 

be used to characterize 

emissions from dehydrators: 

(1) Calculation Method 1. 

Calculate annual mass 

emissions from absorbent 

dehydrators that have an 

annual average of daily natural 

gas throughput that is greater 

than or equal to 0.4 million 

standard cubic feet per day by 

using a software program, such 

as AspenTech HYSYS® or 

GRI-GLYCalcTM, that uses 

the Peng-Robinson equation of 

state to calculate the 

equilibrium coefficient, 

speciates CH4 and CO2

emissions from dehydrators, 

and has provisions to include 

regenerator control devices, a 

separator flash tank, stripping 

gas and a gas injection pump 

or gas assist pump. The 

following parameters must be 

determined by engineering 

estimate based on best 

available data and must be 

used at a minimum to 

characterize emissions from 

dehydrators: 

Clarifying edits 

§98.233(e)(1)(iv) (iv) Absorbent circulation 

pump type (natural gas 

pneumatic/air 

pneumatic/electric). 

(iv) Absorbent circulation 

pump type (e.g., natural gas 

pneumatic/air 

pneumatic/electric). 

Clarifying edit 
6 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

§98.233(e)(1)(vi) (vi) Absorbent type: 

including triethylene glycol 

(TEG), diethylene glycol 

(DEG) or ethylene glycol 

(EG). 

(vi) Absorbent type (e.g., 

triethylene glycol (TEG), 

diethylene glycol (DEG) or 

ethylene glycol (EG)). 

Clarifying edit 

§98.233(e)(1)(xi) xi) Wet natural gas 

composition. Determine this 

parameter by selecting one of 

the methods described under 

paragraph (e)(1)(xi) of this 

section. 

(A) Use the wet natural gas 

composition as defined in 

paragraph (u)(2)(i) or 

(u)(2)(ii) of this section. 

(B) If wet natural gas 

composition cannot be 

determined using paragraph 

(u)(2)(i) or (u)(2)(ii) of this 

section, select a 

representative analysis. 

(xi) Wet natural gas 

composition. Determine this 

parameter using one of the 

methods described in 

paragraphs (e)(1)(xi)(A) 

through (e)(1)(xi)(D) of this 

section. 

(A) Use the GHG mole 

fraction as defined in 

paragraph (u)(2)(i) or (u)(2)(ii) 

of this section. 

(B) If the GHG mole fraction 

cannot be determined using 

paragraph (u)(2)(i) or (u)(2)(ii) 

of this section, select a 

representative analysis. 

Harmonizing edit 

§98.233(e)(2) (2) Calculation Methodology 

2. Calculate annual CH4 and 

CO2 emissions from glycol 

dehydrators with annual 

average daily throughput less 

than 0.4 million standard 

cubic feet per day using 

Equation W-5 of this section: 

(2) Calculation Method 2. 

Calculate annual volumetric 

emissions from glycol 

dehydrators that have an 

annual average of daily natural 

gas throughput that is less than 

0.4 million standard cubic feet 

per day using Equation W-5 of 

this section: 

Clarifies that result is 

annual volumetric 

emissions. 

Term “Count” in 

Equation W-5 

Count = Total number of 

glycol dehydrators with 

throughput less than 0.4 

million standard cubic feet 

per day. 

Count = Total number of 

glycol dehydrators that have 

an annual average of daily 

natural gas throughput that is 

less than 0.4 million standard 

cubic feet per day. 

Clarifying edits 

Term “P” in Equation 

W-6 

P p Corrects typo (to lower 

case). 

§98.233(f) (f) Well venting for liquids 

unloadings. Calculate CO2

and CH4 emissions from well 

venting for liquids unloading 

using one of the calculation 

methodologies described in 

paragraphs (f)(1), (f)(2) or 

(f)(3) of this section. 

(f) Well venting for liquids 

unloadings. Calculate annual 

volumetric natural gas 

emissions from well venting 

for liquids unloading using one 

of the calculation methods 

described in paragraphs (f)(1), 

(f)(2), or (f)(3) of this section. 

Calculate annual CH4 and CO2

volumetric and mass emissions 

using the method described in 

paragraph (f)(4) of this section. 

Clarifies that results of 

(f)(1), (f)(2), and (f)(3) 

are annual volumetric 

natural gas emissions 

and provides (f)(4) for 

calculation of annual 

CH4 and CO2

volumetric and mass 

emissions. 
7 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

§98.233(f)(1)(i) (i) Determine the well vent 

average flow rate as 

specified under paragraph 

(f)(1)(i) of this section for at 

least one well in a unique 

well tubing diameter group 

and pressure group 

combination in each subbasin category. 

(i) Determine the well vent 

average flow rate (“FR” in 

Equation W-7A of this 

section) as specified in 

paragraphs (f)(1)(i)(A) through 

(f)(1)(i)(C) of this section for 

at least one well in a unique 

well tubing diameter group 

and pressure group 

combination in each sub-basin 

category. Calculate emissions 

from wells with plunger lifts 

and wells without plunger lifts 

separately. 

Clarifies instructions so 

that they refer to 

specific equation terms 

and calculation 

methods 

§98.233(f)(1)(i)(A) (A) The average flow rate per 

hour of venting is calculated 

for each unique tubing 

diameter group and pressure 

group combination in each 

sub-basin category by 

dividing the recorded total 

flow by the recorded time (in 

hours) for all measured liquid 

unloading events with 

venting to the atmosphere. 

(A) Calculate the average flow 

rate per hour of venting for 

each unique tubing diameter 

group and pressure group 

combination in each sub-basin 

category by dividing the 

recorded total annual flow by 

the recorded time (in hours) 

for all measured liquid 

unloading events with venting 

to the atmosphere. 

Clarifies that recorded 

total flow is total 

annual flow. 

§98.233(f)(1)(i)(B) (B) This average flow rate 

per hour is applied to all 

wells in the same pressure 

group that have the same 

tubing diameter group, for 

the number of hours of 

venting these wells. 

(B) Apply the average hourly 

flow rate calculated under 

paragraph (f)(1)(i)(A) of this 

section to all wells in the same 

pressure group that have the 

same tubing diameter group, 

for the number of hours of 

venting these wells. 

Clarifying edits 

§98.233(f)(1)(i)(C) (C) A new average flow rate 

is calculated every other 

calendar year for each 

reporting sub-basin category 

starting the first calendar year 

of data collection. For a new 

producing sub-basin 

category, an average flow 

rate is calculated beginning 

in the first year of 

production. 

(C) Calculate a new average 

flow rate every other calendar 

year starting with the first 

calendar year of data 

collection. For a new 

producing sub-basin category, 

calculate an average flow rate 

beginning in the first year of 

production. 

Harmonizing edit with 

changes to term “FR” 

in Equation W-7. 

§98.233(f)(2) and 

(f)(3); Term “Es,n” of 

Equations W-8 and W9 

Es,n = Annual natural gas 

emissions at standard 

conditions, in cubic feet/year. 

Es = Annual natural gas 

emissions for each sub-basin at 

standard conditions, s, in cubic 

feet per year. 

Clarifying edits 
8 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

§98.233(f)(2) and 

(f)(3); Terms “p” and 

“q” of Equations W-8 

and W-9 

None p = Wells 1 through W with 

well venting for liquids 

unloading for each sub-basin. 

... 

q = Unloading event. 

Clarifies terms not 

previously defined 

§98.233(f)(2) and 

(f)(3); Term “Vp” of 

Equations W-8 and W9 

Vp = Number of unloading 

events per year per well, p. 

Vp = Total number of 

unloading events in the 

monitoring period per well, p. 

Corrects equation term 

to reflect the number of 

unloading events in 

each monitoring period. 

§98.233(f)(2) and 

(f)(3); Term “SFRp” of 

Equations W-8 and W9 

SFRp = Average flow-line 

rate of gas for well, p, at 

standard conditions in cubic 

feet per hour. Use Equation 

W-33 to calculate the average 

flow-line rate at standard 

conditions. 

SFRp = Average flow-line rate 

of gas for well, p, at standard 

conditions in cubic feet per 

hour. Use Equation W-33 of 

this section to calculate the 

average flow-line rate at 

standard conditions. 

Clarifying edit 

§98.233(f)(3)(i) and 

(ii) 

Reserved None Removes reserved 

paragraphs 

§98.233(f)(4) (4) Both CH4 and CO2

volumetric and mass 

emissions shall be calculated 

from volumetric natural gas 

emissions using calculations 

in paragraphs (u) and (v) of 

this section. 

(4) Calculate CH4 and CO2

volumetric and mass emissions 

from volumetric natural gas 

emissions using calculations in 

paragraphs (u) and (v) of this 

section. 

Applies active voice 

§98.233(g) 

introductory 

paragraph; 

§98.233(g)(3) 

(g) Gas well venting during 

completions and workovers 

from hydraulic fracturing. 

Calculate CH4, CO2 and N2O 

annual emissions from gas 

well venting during 

completions involving 

hydraulic fracturing in wells 

and well workovers using 

Equation W-10A or Equation 

W-10B of this section. 

Equation W-10A applies to 

well venting when the 

backflow rate is measured or 

calculated, Equation W-10B 

applies when the backflow 

vent or flare volume is 

measured. Use Equation W10A if the flow rate for 

backflow during well 

completions and workovers 

from hydraulic fracturing is 

known for the specified 

number of wells per 

paragraph (g)(1) in a subbasin and well type 

(g) Gas well venting during 

completions and workovers 

with hydraulic fracturing. 

Calculate annual volumetric 

natural gas emissions from gas 

well venting during 

completions and workovers 

involving hydraulic fracturing 

using Equation W-10A or 

Equation W-10B of this 

section. Equation W-10A 

applies to well venting when 

the flowback rate is measured 

from a specified number of 

example completions or 

workovers and Equation W10B applies when the 

flowback vent or flare volume 

is measured for each 

completion or workover. 

Completion and workover 

activities are separated into 

two periods, an initial period 

when flowback is routed to 

open pits or tanks and a 

subsequent period when gas 

Clarifies instructions; 

clarifies that results of 

(g)(1) and (g)(2) are 

annual volumetric 

natural gas emissions 

and clarifies (g)(3) for 

calculation of annual 

CH4 and CO2 

volumetric and mass 

emissions. 
9 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

(horizontal or vertical) 

combination. Use Equation 

W-10B if the flow volume 

for backflow during well 

completions and workovers 

from hydraulic fracturing is 

known for all wells in a subbasin and well type 

(horizontal or vertical) 

combination. Both CH4 and 

CO2 volumetric and mass 

emissions shall be calculated 

from volumetric total gas 

emissions using calculations 

in paragraphs (u) and (v) of 

this section. 

content is sufficient to route 

the flowback to a separator or 

when the gas content is 

sufficient to allow 

measurement by the devices 

specified in paragraph (g)(1) 

of this section, regardless of 

whether a separator is actually 

utilized. If you elect to use 

Equation W-10A of this 

section, you must follow the 

procedures specified in 

paragraph (g)(1) of this 

section. Emissions must be 

calculated separately for 

completions and workovers, 

for each sub-basin, and for 

each well type combination 

identified in paragraph (g)(2) 

of this section. You must 

calculate CH4 and CO2

volumetric and mass emissions 

as specified in paragraph 

(g)(3) of this section. If 

emissions from gas well 

venting during completions 

and workovers with hydraulic 

fracturing are routed to a flare, 

you must calculate CH4, CO2, 

and N2O annual emissions as 

specified in paragraph (g)(4) 

of this section. 

Term Es,n in Equations 

W-10A and W-10B 

Annual volumetric total gas 

emissions in cubic feet at 

standard conditions from gas 

well venting during 

completions or workovers 

following hydraulic 

fracturing for each sub-basin 

and well type (horizontal vs. 

vertical) combination. 

Annual volumetric natural gas 

emissions in standard cubic 

feet from gas well venting 

during completions or 

workovers following hydraulic 

fracturing for each sub-basin 

and well type combination. 

Clarifying edits 

Term W in equations 

W-10A and W-10B 

Total number of wells 

completed or worked over 

using hydraulic fracturing in 

a sub-basin and well type 

(horizontal vs. vertical) 

combination. 

Total number of wells 

completed or worked over 

using hydraulic fracturing in a 

sub-basin and well type 

combination. 

Clarifying edits 

Term FRMs of 

Equations W-10A and 

W-10B 

FRMs = Ratio of flowback 

during well completions and 

workovers from hydraulic 

fracturing to 30-day 

FRMs = Ratio of average 

flowback, during the period 

when sufficient quantities of 

gas are present to enable 

Harmonizing edits with 

changes to Equations 

W-10A and W-10B 
10 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

production rate from 

Equation W-12. 

separation, of well 

completions and workovers 

from hydraulic fracturing to 

30-day production rate 

Term EnFs,p in 

equations W-10A and 

W-10B 

Volume of CO2 or N2

injected gas in cubic feet at 

standard conditions that was 

injected into the reservoir 

during an energized fracture 

job for each well, p. If the 

fracture process did not inject 

gas into the reservoir, then 

EnFs,p is 0. If injected gas is 

CO2 then EnFs,p is 0. 

Volume of N2 injected gas in 

cubic feet at standard 

conditions that was injected 

into the reservoir during an 

energized fracture job for each 

well, p, as determined by using 

an appropriate meter according 

to methods described in 

§98.234(b), or by using 

receipts of gas purchases that 

are used for the energized 

fracture job. Convert to 

standard conditions using 

paragraph (t) of this section. If 

the fracture process did not 

inject gas into the reservoir or 

if the injected gas is CO2 then 

EnFs,p is 0. 

Clarifies acceptable 

measurement methods 

§98.233(g)(1)(i) Calculation Methodology 1. 

When using Equation W10A, for each measured well 

completion(s) in each gas 

producing sub-basin category 

and well type (horizontal or 

vertical) combination and for 

each measured well 

workover(s) in each gas 

producing sub-basin category 

and well type (horizontal or 

vertical) combination, a 

recording flow meter (digital 

or analog) shall be installed 

on the vent line, ahead of a 

flare or vent if used, to 

measure the backflow rate 

according to methods set 

forth in §98.234(b). 

Calculation Method 1. You 

must use Equation W-12A as 

specified in paragraph 

(g)(1)(iii) of this section to 

determine the value of FRMs. 

You must use Equation W12B as specified in paragraph 

(g)(1)(iv) of this section to 

determine the value of FRMi. 

The procedures specified in 

paragraphs (g)(1)(v) and 

(g)(1)(vi) also apply. When 

making flowback 

measurements for use in 

Equations W-12A and W-12B 

of this section, you must use a 

recording flow meter (digital 

or analog) installed on the vent 

line, ahead of a flare or vent, to 

measure the flowback rates in 

units of standard cubic feet per 

hour according to methods set 

forth in §98.234(b). 

Harmonizing changes 

with edits to Equation 

W-10A and W-10B 

§98.233(g)(1)(ii) (ii) Calculation Methodology 

2. When using Equation W10A, for each calculated 

horizontal well completion 

and each calculated vertical 

well completion in each gas 

(ii) Calculation Method 2. You 

must use Equation W-12A as 

specified in paragraph 

(g)(1)(iii) of this section to 

determine the value of FRMs. 

You must use Equation WHarmonizing changes 

with edits to Equation 

W-10A and W-10B 
11 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

producing sub-basin category 

and for each calculated well 

horizontal workover and for 

each calculated vertical well 

workover in each gas 

producing sub-basin 

category, record the well 

flowing pressure upstream 

(and downstream in subsonic 

flow) of a well choke 

according to methods set 

forth in §98.234(b) to 

calculate the well backflow 

during well completions and 

workovers from hydraulic 

fracturing. Calculate 

emissions using Equation W11A of this section for 

subsonic flow or Equation 

W-11B of this section for 

sonic flow. Use best 

engineering estimate based 

on best available data along 

with Equation W-11C of this 

section to determine whether 

the predominant flow is sonic 

or subsonic. If the value of R 

in Equation W-11C is greater 

than or equal to 2, then flow 

is sonic; otherwise, flow is 

subsonic. 

12B as specified in paragraph 

(g)(1)(iv) of this section to 

determine the value of FRMi. 

The procedures specified in 

paragraphs (g)(1)(v) and 

(g)(1)(vi) also apply. When 

calculating the flowback rates 

for use in Equations W-12A 

and W-12B of this section 

based on well parameters, you 

must record the well flowing 

pressure immediately upstream 

(and immediately downstream 

in subsonic flow) of a well 

choke according to methods 

set forth in §98.234(b) to 

calculate the well flowback. 

The upstream pressure must be 

surface pressure and reservoir 

pressure cannot be assumed. 

The downstream pressure must 

be measured after the choke 

and atmospheric pressure 

cannot be assumed. Calculate 

flowback rate using Equation 

W-11A of this section for 

subsonic flow or Equation W11B of this section for sonic 

flow. You must use best 

engineering estimates based on 

best available data along with 

Equation W-11C of this 

section to determine whether 

the predominant flow is sonic 

or subsonic. If the value of R 

in Equation W-11C is greater 

than or equal to 2, then flow is 

sonic; otherwise, flow is 

subsonic. Calculated FRa

values shall be converted from 

actual conditions upstream of 

the restriction orifice to 

standard conditions (FRs,p and 

FRi,p) for use in Equations W12A and W-12B of this section 

using Equation W-33 in 

paragraph (t) of this section. 

Term “FRa” of 

Equation W-11A and 

W-11B 

FRa = Average flow rate in 

cubic feet per hour, under 

actual subsonic flow 

conditions. 

FRa = Flowback rate in actual 

cubic feet per hour, under 

actual subsonic flow 

conditions. 

Harmonizing edits with 

changes to Equation W12a and W-12b 
12 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

Terms “P1”, “Tu”, and 

“P2” of Equation W11A 

P1 = Upstream pressure 

(psia). 

Tu = Upstream temperature 

(degrees Kelvin). 

P2 = Downstream pressure 

(psia). 

P1 = Pressure immediately 

upstream of the choke (psia). 

Tu = Temperature immediately 

upstream of the choke (degrees 

Kelvin). 

P2 = Pressure immediately 

downstream of the choke 

(psia). 

Clarifying edits 

Term “Tu” of Equation 

W-11B 

Tu = Upstream temperature 

(degrees Kelvin). 

Tu = Temperature immediately 

upstream of the choke (degrees 

Kelvin). 

Clarifying edits 

Terms “P1” and “P2” of 

Equation W-11C

P1 = Pressure upstream of the 

restriction orifice in pounds 

per square inch absolute. 

P2 = Pressure downstream of 

the restriction orifice in 

pounds per square inch 

absolute. 

P1 = Pressure immediately 

upstream of the choke (psia). 

P2 = Pressure immediately 

downstream of the choke 

(psia). 

Clarifying edits 

§98.233(g)(1)(iii) For Equation W-10A, the 

ratio of backflow rate during 

well completions and 

workovers from hydraulic 

fracturing to 30-day 

production rate is calculated 

using Equation W-12 of this 

section. 

For Equation W-10A of this 

section, calculate FRMs using 

Equation W-12A of this 

section. 

Harmonizing edits with 

changes to Equation W10A 

Terms “FRMs” and 

“FRs,p” of Equation W12A 

FRMs = Ratio of flowback 

rate during well completions 

and workovers from 

hydraulic fracturing to 30-

day production rate. 

FRs,p = Measured flowback 

rate from Calculation 

Methodology 1 described in 

paragraph (g)(1)(i) of this 

section or calculated flow 

rate from Calculation 

Methodology 2 described in 

paragraph (g)(1)(ii) of this 

section in standard cubic feet 

per hour for well(s) p for 

each sub-basin and well type 

(horizontal or vertical) 

combination. Measured and 

calculated FRa values shall be 

converted from actual 

conditions (FRa) to standard 

conditions (FRs,p) for each 

well p using Equation W-33 

FRMs = Ratio of average 

flowback rate during period of 

time when sufficient quantities 

of gas are present to enable 

separation of well completions 

and workovers from hydraulic 

fracturing to 30-day 

production rate for each subbasin and well type 

combination. 

FRs,p = Measured average 

flowback rate from Calculation 

Method 1 described in 

paragraph (g)(1)(i) of this 

section or calculated average 

flowback rate from Calculation 

Method 2 described in 

paragraph (g)(1)(ii) of this 

section, during the separation 

period in standard cubic feet 

per hour for well(s) p for each 

sub-basin and well type 

combination. Measured and 

Harmonizing edits with 

changes to Equation W10A 
13 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

in paragraph (t) of this 

section. You may not use 

flow volume as used in 

Equation W-10B converted 

to a flow rate for this 

parameter. 

calculated FRa values shall be 

converted from actual 

conditions upstream of the 

restriction orifice (FRa) to 

standard conditions (FRs,p) for 

each well p using Equation W33 in paragraph (t) of this 

section. You may not use flow 

volume as used in Equation 

W-10B converted to a flow 

rate for this parameter. 

Term “N” of Equation 

W-12A 

None N = Number of measured or 

calculated well completions or 

workovers using hydraulic 

fracturing in a sub-basin and 

well type combination. 

Harmonizing edits with 

changes to Equation W10A 

§98.233(g)(1)(iv) None For Equation W-10A of this 

section, calculate FRMi using 

Equation W-12B of this 

section. 

,

1

,

1

N

i p

p

i N

s p

p

FR

FRM

PR











 (Eq. W12B) 

Where: 

FRMi = Ratio of flowback gas 

rate while flowing to open 

tanks/pits during well 

completions and workovers 

from hydraulic fracturing to 

30-day production rate. 

FRi,p = Initial measured gas 

flowback rate from Calculation 

Method 1 described in 

paragraph (g)(1)(i) of this 

section or initial calculated 

flow rate from Calculation 

Method 2 described in 

paragraph (g)(1)(ii) of this 

section in standard cubic feet 

per hour for well(s), p, for 

each sub-basin and well type 

combination. Measured and 

calculated FRi,p values must be 

based on flow conditions at the 

beginning of the separation 

Harmonizing edits with 

changes to Equation W10A 
14 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

period and must be expressed 

at standard conditions. 

PRs,p = Average production 

flow rate during the first 30-

days of production after 

completions of newly drilled 

gas wells or gas well 

workovers using hydraulic 

fracturing, in standard cubic 

feet per hour of each well, p, 

that was measured in the subbasin and well type 

combination. 

N = Number of measured or 

calculated well completions or 

workovers using hydraulic 

fracturing in a sub-basin and 

well type combination. 

§98.233(g)(1)(v) and 

(vi) 

(iv) For Equation W-10A, the 

ratio of backflow rate during 

well completions and 

workovers from hydraulic 

fracturing to 30-day 

production rate for horizontal 

and vertical wells are applied 

to all horizontal and vertical 

well completions in the gas 

producing sub-basin and well 

type combination and to all 

horizontal and vertical well 

workovers, respectively, in 

the gas producing sub-basin 

and well type combination 

for the total number of hours 

of backflow for each of these 

wells. 

(v) For Equation W-10A, 

new flow rates for horizontal 

and vertical gas well 

completions and horizontal 

and vertical gas well 

workovers in each sub-basin 

category shall be calculated 

once every two years starting 

in the first calendar year of 

data collection. 

(v) For Equation W-10A of 

this section, the ratio of 

flowback rate during well 

completions and workovers 

from hydraulic fracturing to 

30-day production rate for 

horizontal and vertical wells 

are applied to all horizontal 

and vertical well completions 

in the gas producing sub-basin 

and well type combination and 

to all horizontal and vertical 

well workovers, respectively, 

in the gas producing sub-basin 

and well type combination for 

the total number of hours of 

flowback and for the first 30 

day average production rate 

for each of these wells. 

(vi) For Equation W-12A and 

W-12B of this section, 

calculate new flowback rates 

for horizontal and vertical gas 

well completions and 

horizontal and vertical gas 

well workovers in each subbasin category once every two 

years starting in the first 

calendar year of data 

collection. 

Renumbered and 

revised to harmonize 

with edits to Equation 

W-10A 
15 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

§98.233(g)(4) (5) Calculate annual 

emissions from gas well 

venting during well 

completions and workovers 

from hydraulic fracturing to 

flares as follows: 

(i) Use total gas well venting 

volume during well 

completions and workovers 

as determined in paragraph 

(g) of this section. 

(ii) Use the calculation 

methodology of flare stacks 

in paragraph (n) of this 

section to determine gas well 

venting during well 

completions and workovers 

using hydraulic fracturing 

emissions from the flare. This 

adjustment to emissions from 

completions using flaring 

versus completions without 

flaring accounts for the 

conversion of CH4 to CO2 in 

the flare. 

(4) Calculate annual emissions 

from gas well venting during 

well completions and 

workovers from hydraulic 

fracturing where all or a 

portion of the gas is flared as 

specified in paragraphs 

(g)(4)(i) and (g)(4)(ii) of this 

section. 

(i) Use the volumetric total 

natural gas emissions vented to 

the atmosphere during well 

completions and workovers as 

determined in paragraph (g) of 

this section to calculate 

volumetric and mass emissions 

using paragraphs (u) and (v) of 

this section. 

(ii) Use the calculation method 

of flare stacks in paragraph (n) 

of this section to adjust 

emissions for the portion of 

gas flared during well 

completions and workovers 

using hydraulic fracturing. 

This adjustment to emissions 

from completions using 

flaring, versus completions 

without flaring, accounts for 

the conversion of CH4 to CO2

in the flare and for the 

formation on N2O during 

flaring. 

Renumbered; clarifies 

calculation method 

where a portion of the 

gas is flared 

§98.233(h) 

introductory 

paragraph; 

§98.233(h)(1) 

Calculate CH4, CO2 and N2O 

annual emissions from gas 

well venting during 

completions and not 

involving hydraulic 

fracturing using Equation W13of this section. 

Calculate annual volumetric 

natural gas emissions from 

each gas well venting during 

workovers without hydraulic 

fracturing using Equation W13A of this section. Calculate 

annual volumetric natural gas 

emissions from each gas well 

venting during completions 

without hydraulic fracturing 

using Equation W-13B of this 

section. You must convert 

annual volumetric natural gas 

emissions to CH4 and CO2

volumetric and mass emissions 

as specified in paragraph 

(h)(1) of this section. If 

emissions from gas well 

Edits clarify 

instructions; clarifies 

that results of 

Equations W-13A and 

W-13B are annual 

volumetric natural gas 

emissions and clarifies 

(h)(1) for calculation of 

annual CH4 and CO2 

volumetric and mass 

emissions 
16 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

venting during completions 

and workovers without 

hydraulic fracturing are routed 

to a flare, you must calculate 

CH4, CO2, and N2O annual 

emissions as specified in 

paragraph (h)(2) of this 

section. 

Term “Tp” of Equation 

W-13 

Tp = Time each well 

completion without hydraulic 

fracturing, p, was venting in 

hours during the year. 

Tp = Time that gas is vented to 

either the atmosphere or a flare 

for each well, p, undergoing 

completion without hydraulic 

fracturing, in hours during the 

year. 

Clarifying edits 

§98.233(h)(2) (2) Calculate annual 

emissions from gas well 

venting during well 

completions and workovers 

not involving hydraulic 

fracturing to flares as 

follows: 

(i) Use the gas well venting 

volume during well 

completions and workovers 

as determined in paragraph 

(h) of this section. 

(ii) Use the calculation 

methodology of flare stacks 

in paragraph (n) of this 

section to determine gas well 

venting during well 

completions and workovers 

emissions without hydraulic 

fracturing from the flare. 

(2) Calculate annual emissions 

of CH4, CO2, and N2O from 

gas well venting to flares 

during well completions and 

workovers not involving 

hydraulic fracturing as 

specified in paragraphs 

(h)(2)(i) and (h)(2)(ii) of this 

section. 

(i) Use the gas well venting 

volume and gas composition 

during well completions and 

workovers that are flared as 

determined using the methods 

specified in paragraphs (h) and 

(h)(1) of this section. 

(ii) Use the calculation method 

of flare stacks in paragraph (n) 

of this section to determine 

emissions from the flare for 

gas well venting to a flare 

during completions and 

workovers without hydraulic 

fracturing. 

Clarifying edits 

§98.233(i) Blowdown vent stacks. 

Calculate CO2 and CH4

blowdown vent stack 

emissions from 

depressurizing equipment(s) 

to reduce system pressure for 

planned or emergency 

shutdowns resulting from 

human intervention or to take 

equipment out of service for 

maintenance (excluding 

depressurizing to a flare, 

over-pressure relief, 

Blowdown vent stacks. 

Calculate CO2 and CH4

blowdown vent stack 

emissions from the 

depressurization of equipment 

to reduce system pressure for 

planned or emergency 

shutdowns resulting from 

human intervention or to take 

equipment out of service for 

maintenance as specified in 

either paragraph (i)(2) or (i)(3) 

of this section. Equipment with 

Clarifies the 

applicability of 

requirements to 

equipment with a 

physical volume of less 

than 50 cubic feet 
17 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

operating pressure control 

venting and blowdown of 

non-GHG gases; desiccant 

dehydrator blowdown 

venting before reloading is 

covered in paragraph (e)(5) 

of this section) as follows: 

a unique physical volume of 

less than 50 cubic feet as 

determined in paragraph (i)(1) 

of this section are not subject 

to the requirements in 

paragraphs (i)(2) through (i)(4) 

this section. The requirements 

in this paragraph (i) do not 

apply to blowdown vent stack 

emissions from depressurizing 

to a flare, over-pressure relief, 

operating pressure control 

venting, blowdown of nonGHG gases, and desiccant 

dehydrator blowdown venting 

before reloading. 

§98.233(i)(1) (1) Calculate the unique 

physical volume (including 

pipelines, compressor case or 

cylinders, manifolds, suction 

bottles, discharge bottles, and 

vessels) between isolation 

valves determined by 

engineering estimates based 

on best available data. 

(1) Method for calculating 

unique physical volumes. You 

must calculate each unique 

physical volume (including 

pipelines, compressor case or 

cylinders, manifolds, suction 

bottles, discharge bottles, and 

vessels) between isolation 

valves, in cubic feet, by using 

engineering estimates based on 

best available data. 

Clarifies units 

§98.233(i)(2) (2) If the unique physical 

volume between isolation 

valves is greater than or equal 

to 50 cubic feet, retain logs of 

the number of blowdowns for 

each unique physical volume 

(including but not limited to 

compressors, vessels, 

pipelines, headers, 

fractionators, and tanks). 

Unique physical volumes 

smaller than 50 cubic feet are 

exempt from reporting under 

paragraph (i) of this section. 

None Harmonizing change 

with edits to Equations 

W-14A and W-14B 

§98.233(i)(3) (3) Calculate the total annual 

venting emissions for unique 

volumes using either 

Equation W-14A or W-14B 

of this section. 

(2) Method for determining 

emissions from blowdown 

vent stacks according to 

equipment type. If you elect to 

determine emissions according 

to each equipment type, using 

unique physical volumes as 

calculated in paragraph (i)(1) 

of this section, you must 

calculate emissions as 

Renumbered and 

revised; clarifies 

instructions for 

determining emissions 

by equipment type. 
18 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

specified in paragraphs 

(i)(2)(i) through (i)(2)(iii) of 

this section for each equipment 

type. Equipment types must be 

grouped into the following 

seven categories: station 

piping, pipeline venting, 

compressors, 

scrubbers/strainers, pig 

launchers and receivers, 

emergency shutdowns, and all 

other blowdowns greater than 

or equal to 50 cubic feet. 

(i) Calculate the total annual 

natural gas emissions from 

each unique physical volume 

that is blown down using 

either Equation W-14A or W14B of this section. 

.... 

(ii) Calculate the annual 

natural gas emissions, in cubic 

feet, from each equipment type 

by summing Es,n, as calculated 

in either Equation W-14A or 

Equation W-14B of this 

subpart, for all unique physical 

volumes associated with the 

equipment type. 

(iii) Calculate total annual CH4

and CO2 volumetric and mass 

emissions from each 

equipment type by using the 

annual natural gas emission 

value calculated in paragraph 

(i)(2)(ii) of this section for the 

equipment type and the 

calculation method specified in 

paragraph (i)(4) of this section. 

§98.233(i)(4) Calculate both CH4 and CO2

volumetric and mass 

emissions using calculations 

in paragraph (u) and (v) of 

this section. 

Method for converting from 

natural gas emissions to GHG 

volumetric and mass 

emissions. Calculate both CH4

and CO2 volumetric and mass 

emissions using the methods 

specified in paragraphs (u) and 

(v) of this section. 

Clarifying edits 

§98.233(j), (j)(1) 

introductory 

paragraph, (j)(2) 

introductory 

(j) ... not owned or operated 

by the reporter), calculate 

annual CH4 and CO2 

emissions using any of the 

(j) ... not owned or operated 

by the reporter), as specified in 

this paragraph (j). For wells 

flowing to gas-liquid 

Clarifies and 

consolidates 

instructions for use of 

calculation methods by 
19 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

paragraph, removal of 

(j)(3)introductory 

paragraph, removal of 

(j)(4), and revision and 

renumbering of 

paragraph (j)(5). 

calculation methodologies 

described in this paragraph 

(j). 

(1) Calculation Methodology 

1. For separators with annual 

average daily throughput of 

oil greater than or equal to 10 

barrels per day. Calculate... 

(2) Calculation Methodology 

2. Calculate annual CH4 and 

CO2 emissions from onshore 

production storage tanks for 

wellhead gas-liquid 

separators with annual 

average daily throughput of 

oil greater than or equal to 10 

barrels per day by.... 

(3) Calculation Methodology 

3. For wells with annual 

average daily oil production 

greater than or equal to 10 

barrels per day that flow 

directly to atmospheric 

storage tanks without passing 

through a wellhead separator, 

calculate annual CH4 and 

CO2 emissions by either of 

the methods in paragraph 

(j)(3) of this section: ... 

(4) Calculation Methodology 

4. For wells with annual 

average daily oil production 

greater than or equal to 10 

barrels per day that flow to a 

separator not at the well pad, 

calculate annual CH4 and 

CO2 emissions by either of 

the methods in paragraph 

(j)(4) of this section: ... 

(5) Calculation Methodology 

5. For well pad gas-liquid 

separators and for wells 

flowing off a well pad 

without passing through a 

gas-liquid separator with 

annual average daily 

throughput of oil less than 10 

barrels per day use.... 

separators with annual average 

daily throughput of oil greater 

than or equal to 10 barrels per 

day, calculate annual CH4 and 

CO2 using Calculation Method 

1 or 2 as specified in 

paragraphs (j)(1) and (j)(2) of 

this section. For wells flowing 

directly to atmospheric storage 

tanks without passing through 

a wellhead separator with 

throughput greater than 10 

barrels per day, calculate 

annual CH4 and CO2 emissions 

using Calculation Method 2 as 

specified in paragraph (j)(2) of 

this section. For wells flowing 

to gas-liquid separators or 

directly to atmospheric storage 

tanks with throughput less than 

10 barrels per day, use 

Calculation Method 3 as 

specified in paragraphs (j)(3) 

of this section. You must also 

calculate emissions that may 

have occurred due to dump 

valves not closing properly 

using the method specified in 

paragraphs (j)(6) of this 

section. If emissions from 

atmospheric pressure fixed 

roof storage tanks are routed to 

a vapor recovery system, you 

must adjust the emissions 

downward according to 

paragraph (j)(4) of this section. 

If emissions from atmospheric 

pressure fixed roof storage 

tanks are routed to a flare, you 

must calculate CH4, CO2, and 

N2O annual emissions as 

specified in paragraph (j)(5) of 

this section. 

removing and 

combining text from 

(j)(1) introductory, 

(j)(2) introductory, 

(j)(3) introductory, and 

(j)(4) paragraphs. 

Clarifies instructions in 

(j) intro to account for 

situations where part of 

the gas is recovered or 

flared 

§98.233(j)(1)(vii) (vii) Separator oil 

composition and Reid vapor 

pressure. If this data is not 

(vii) Separator oil composition 

and Reid vapor pressure. If 

this data is not available, 

Corrects reference 
20 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

available, determine these 

parameters by selecting one 

of the methods described 

under paragraph (j)(1) (vii) of 

this section. 

determine these parameters by 

using one of the methods 

described in paragraphs 

(j)(1)(vii)(A) through 

(j)(1)(vii)(C) of this section. 

§98.233(j)(9) and 

§98.233(l)(5) 

...emissions from volumetric 

natural gas emissions... 

...emissions from natural gas 

volumetric emissions... 

Grammatical 

correction; paragraph 

(j)(9) is renumbered to 

(j)(7) 

§98.233(k), (l), and 

(m) introductory 

paragraphs 

(k) .... calculate CH4, CO2

and N2O annual emissions 

from compressor scrubber 

dump valve leakage as 

follows. 

(l) .... Calculate CH4, CO2

and N2O (when flared) well 

testing venting and flaring 

emissions as follows: 

(m) ... Calculate CH4, CO2

and N2O (when flared) 

associated gas venting and 

flaring emissions not in 

conjunction with well testing 

(refer to paragraph (l): Well 

testing venting and flaring of 

this section) as follows: 

(k) ... calculate CH4 and CO2

annual emissions from 

compressor scrubber dump 

valve leakage as specified in 

paragraphs (k)(1) through 

(k)(3) of this section. If 

emissions from compressor 

scrubber dump valve leakage 

are routed to a flare, you must 

calculate CH4, CO2, and N2O 

annual emissions as specified 

in paragraph (k)(4) of this 

section. 

(l) ... Calculate CH4 and CO2

annual emissions from well 

testing venting as specified in 

paragraphs (l)(1) through (l)(5) 

of this section. If emissions 

from well testing venting are 

routed to a flare, you must 

calculate CH4, CO2, and N2O 

annual emissions as specified 

in paragraph (l)(6) of this 

section. 

(m) ... Calculate CH4 and CO2

annual emissions from 

associated gas venting not in 

conjunction with well testing 

(refer to paragraph (l): Well 

testing venting and flaring of 

this section) as specified in 

paragraphs (m)(1) through 

(m)(4) of this section. If 

emissions from associated gas 

venting are routed to a flare, 

you must calculate CH4, CO2, 

and N2O annual emissions as 

specified in paragraph (m)(5) 

of this section. 

Clarifies instructions; 

clarifies N2O to be 

calculated from 

emissions routed to a 

flare 
21 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

§98.233(k)(1) (k)(1) Monitor the tank vapor 

vent stack annually for 

emissions using an optical 

gas imaging instrument 

according to methods set 

forth in §98.234(a)(1) or by 

directly measuring the tank 

vent using a flow meter or 

high volume sampler 

according to methods in 

§98.234(b) through (d) for a 

duration of 5 minutes, or a 

calibrated bag according to 

methods in §98.234(b). Or 

you may annually monitor 

leakage through compressor 

scrubber dump valve(s) into 

the tank using an acoustic 

leak detection device 

according to methods set 

forth in §98.234(a)(5). 

(1) Except as specified in 

paragraph (k)(1)(iv) of this 

section, you must monitor the 

tank vapor vent stack annually 

for emissions using one of the 

methods specified in 

paragraphs (k)(1)(i) through 

(k)(1)(iii) of this section. 

(i) Use an optical gas imaging 

instrument according to 

methods set forth in 

§98.234(a)(1). 

(ii) Measure the tank vent 

directly using a flow meter or 

high volume sampler 

according to methods in 

§98.234(b) or (d) for a 

duration of 5 minutes. 

(iii) Measure the tank vent 

using a calibrated bag 

according to methods in 

§98.234(c) for a duration of 5 

minutes or until the bag is full, 

whichever is shorter. 

(iv) You may annually monitor 

leakage through compressor 

scrubber dump valve(s) into 

the tank using an acoustic leak 

detection device according to 

methods set forth in 

§98.234(a)(5). 

Clarifying edits 

§98.233(k)(2), 

(k)(2)(i), and (k)(4) 

(2) ... detects a leak, then use 

one of the following two 

methods in paragraph (k)(2) 

of this section to quantify 

annual emissions. 

(i) Use a meter, such as a 

turbine meter, calibrated bag, 

or high flow sampler to 

estimate tank vapor volumes 

from the vent stack according 

to methods set forth in 

§98.234(b) through (d)....If 

the vent is directly measured 

for five minutes under 

paragraph §98.233(k)(1) of 

this section to detect 

continuous leakage, this 

serves as the measurement. 

(2) ... detects a leak, then you 

must use one of the methods in 

either paragraph (k)(2)(i) or 

(k)(2)(ii) of this section and 

the requirements specified in 

paragraphs (k)(2)(iii) and 

(k)(2)(iv) of this section to 

quantify annual emissions. 

(i) Use a flow meter, such as a 

turbine meter, calibrated bag, 

or high volume sampler to 

estimate tank vapor volumes 

from the vent stack according 

to methods set forth in 

§98.234(b) through (d)....If 

the vent is directly measured 

for five minutes under 

paragraph (k)(1)(ii) or 

(k)(1)(iii) of this section to 

detect continuous leakage, this 

Clarifying edits; 

corrects references 
22 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

serves as the measurement. 

§98.233(k)(2)(iv) (iv) Calculate GHG 

volumetric and mass 

emissions at standard 

conditions.... 

(iv) Calculate CH4 and CO2

volumetric and mass emissions 

at standard conditions... 

Clarifying edits 

§98.233(k)(3) (3) If the leaking dump 

valve(s) is fixed following 

leak detection, the annual 

emissions shall be calculated 

from the beginning of the 

calendar year to the time the 

valve(s) is repaired 

(3) If a leaking dump valve is 

identified, the leak must be 

counted as having occurred 

since the beginning of the 

calendar year, or from the 

previous test that did not detect 

leaking in the same calendar 

year. If the leaking dump valve 

is fixed following leak 

detection, the leak duration 

will end upon being repaired. 

If a leaking dump valve is 

identified and not repaired, the 

leak must be counted as having 

occurred through the rest of 

the calendar year. 

Clarifying edits, 

including what to do if 

an earlier test showed 

no leak, and how to 

determine end of leak 

duration 

§98.233(k)(4) (4) Calculate annual 

emissions from storage tanks 

to flares as follows: 

(4) Calculate annual emissions 

from storage tanks to flares as 

specified in paragraphs 

(k)(4)(i) and (k)(4)(ii) of this 

section. 

Corrects reference 

§98.233(l)(2) and 

§98.233(m)(2) 

(l)(2) ... according to one of 

the two procedures in 

paragraph (l)(2) of this 

section to determine GOR: 

(m)(2) ...then use one of the 

two procedures in paragraph 

(m)(2) of this section to 

determine GOR: 

(l)(2) ... according to one of 

the procedures specified in 

paragraph (l)(2)(i) or (l)(2)(ii) 

of this section to determine 

GOR. 

(m)(2) ....then you must use 

one of the procedures specified 

in paragraphs (m)(2)(i) or 

(m)(2)(ii) of this section to 

determine GOR. 

Clarifying edits 

§98.233(l)(2)(ii) and 

§98.233(m)(2)(ii) 

(ii) Or you may use an 

industry standard practice as 

described in §98.234(b). 

(ii) You may use an industry 

standard practice as described 

in §98.234(b). 

Applies active voice 

§98.233(l)(3) (3) Estimate venting 

emissions using Equation W17A or Equation W-17B of 

this section. 

(3) Estimate venting emissions 

using Equation W-17A (for oil 

wells) or Equation W-17B (for 

gas wells) of this section. 

Clarifying edits 

Terms “FR” and “D” 

of Equations W-17A 

and W-17B 

FR = Flow rate in barrels of 

oil per day for the oil well(s) 

being tested. 

... 

D = Number of days during 

the year, the well(s) is tested. 

FR = Average annual flow rate 

in barrels of oil per day for the 

oil well(s) being tested. 

... 

D = Number of days during 

the calendar year that the 

Clarifying edits 
23 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

well(s) is tested. 

§98.233(l)(5) (5) Calculate both CH4 and 

CO2 volumetric and mass 

emissions from volumetric 

natural gas emissions using 

calculations in paragraphs (u) 

and (v) of this section. 

(5) Calculate both CH4 and 

CO2 volumetric and mass 

emissions from natural gas 

volumetric emissions using 

calculations in paragraphs (u) 

and (v) of this section. 

Clarifying edit 

§98.233(l)(6) and 

§98.233(m)(6) 

(l)(6) Calculate emissions 

from well testing to flares as 

follows: 

(i) Use the well testing 

emissions volume and gas 

composition as determined in 

paragraphs (l)(1) through (3) 

of this section. 

(m)(6) Calculate emissions 

from associated natural gas to 

flares as follows: 

(i) Use the associated natural 

gas volume and gas 

composition as determined in 

paragraph (m)(1) through (4) 

of this section. 

(l)(6) Calculate emissions from 

well testing if emissions are 

routed to a flare as specified in 

paragraphs (l)(6)(i) and 

(l)(6)(ii) of this section. 

(i) Use the well testing 

emissions volume and gas 

composition as determined in 

paragraphs (l)(1) through (4) 

of this section. 

(m)(5) Calculate emissions 

from associated natural gas if 

emissions are routed to a flare 

as specified in paragraphs 

(m)(5)(i) and (m)(5)(ii) of this 

section. 

(i) Use the associated natural 

gas volume and gas 

composition as determined in 

paragraph (m)(1) through 

(m)(4) of this section. 

Corrects references; 

§98.233(m)(6) is 

renumbered to (m)(5) 

§98.233(m)(1) (1) ... If GOR from each well 

is not available, the GOR 

from a cluster of wells in the 

same sub-basin category shall 

be used. 

(1) ... If GOR from each well 

is not available, use the GOR 

from a cluster of wells in the 

same sub-basin category. 

Applies active voice 

Term “Vp,q” of 

Equation W-18 

Vp,q = Volume of oil 

produced, for well p in subbasin q, in barrels in the 

calendar year during which 

associated gas was vented or 

flared. 

Vp,q = Volume of oil produced, 

for well p in sub-basin q, in 

barrels in the calendar year 

during time periods in which 

associated gas was vented or 

flared. 

Clarifying edits 

§98.233(n) (n) Flare stack emissions. 

Calculate CO2, CH4, and N2O 

emissions from a flare stack 

as follows: 

(n) Flare stack emissions. 

Calculate CO2, CH4, and N2O 

emissions from a flare stack as 

specified in paragraphs (n)(1) 

through (n)(9) of this section. 

Clarifying edits 

§98.233(n)(1) (1) ...If you do not have a 

continuous flow 

measurement device on the 

flare, you can install a flow 

measuring device on the flare 

or use engineering 

(1) ...If you do not have a 

continuous flow measurement 

device on the flare, you can 

use engineering calculations 

based on process knowledge, 

company records, and best 

Clarifying edit, 

corrects typo 
24 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

calculations based on process 

knowledge, company 

records, and best available 

data. 

available data. 

§98.233(n)(2) (2) ... you must use the 

appropriate gas compositions 

for each stream of 

hydrocarbons going to the 

flare as follows: 

(i) For onshore natural gas 

production, determine natural 

gas composition using 

(u)(2)(i) of this section. 

(ii) For onshore natural gas 

processing, when the stream 

going to flare is natural gas, 

use the GHG mole percent in 

feed natural gas for all 

streams upstream of the demethanizer or dew point 

control, and GHG mole 

percent in facility specific 

residue gas to transmission 

pipeline systems for all 

emissions sources 

downstream of the demethanizer overhead or dew 

point control for onshore 

natural gas processing 

facilities. For onshore natural 

gas processing plants that 

solely fractionate a liquid 

stream, use the GHG mole 

percent in feed natural gas 

liquid for all streams. 

(2) ... you must use the 

appropriate gas compositions 

for each stream of 

hydrocarbons going to the 

flare as specified in paragraphs 

(n)(2)(i) through (n)(2)(iii) of 

this section. 

(i) For onshore natural gas 

production, determine the 

GHG mole fraction using 

paragraph (u)(2)(i) of this 

section. 

(ii) For onshore natural gas 

processing, when the stream 

going to flare is natural gas, 

use the GHG mole fraction in 

feed natural gas for all streams 

upstream of the de-methanizer 

or dew point control, and GHG 

mole fraction in facility 

specific residue gas to 

transmission pipeline systems 

for all emissions sources 

downstream of the demethanizer overhead or dew 

point control for onshore 

natural gas processing 

facilities. For onshore natural 

gas processing plants that 

solely fractionate a liquid 

stream, use the GHG mole 

fraction in feed natural gas 

liquid for all streams. 

Clarifying edits 

Terms “Va”, “XCH4”, 

“XCO2”, and “Yj” of 

Equation W-19 and W20 

Va = Volume of gas sent to 

flare in cubic feet, during the 

year. 

... 

XCH4 = Mole fraction of CH4

in gas to the flare. 

XCO2 = Mole fraction of CO2

in gas to the flare.... 

Yj = Mole fraction of gas 

hydrocarbon constituents j 

(such as methane, ethane, 

propane, butane, and 

pentanes-plus). 

Vs = Volume of gas sent to 

flare in standard cubic feet, 

during the year as determined 

in paragraph (n)(1) of this 

section. 

... 

XCH4 = Mole fraction of CH4

in the feed gas to the flare as 

determined in paragraph (n)(2) 

of this section. 

XCO2 = Mole fraction of CO2

in the feed gas to the flare as 

determined in paragraph (n)(2) 

of this section. 

Specifies requirements 

for determining each 

parameter. 
25 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

...Yj = Mole fraction of 

hydrocarbon constituents j 

(such as methane, ethane, 

propane, butane, and pentanesplus) in the feed gas to the 

flare as determined in 

paragraph (n)(1) of this 

section. 

§98.233(n)(7) [Reserved] None Removes reserved 

requirements and 

renumbers following 

paragraphs 

§98.233(n)(9) (9) If you operate and 

maintain a CEMS that has 

both a CO2 concentration 

monitor and volumetric flow 

rate monitor, you must 

calculate only CO2 emissions 

for the flare. ... If a CEMS is 

used to calculate flare stack 

emissions, the requirements 

specified in paragraphs (n)(1) 

through (n)(7) are not 

required. If a CO2

concentration monitor and 

volumetric flow rate monitor 

are not available, you may 

elect to install a CO2

concentration monitor and a 

volumetric flow rate monitor 

that comply with all of the 

requirements specified for the 

Tier 4 Calculation 

Methodology in subpart C of 

this part (General Stationary 

Fuel Combustion). 

(8) If you operate and maintain 

a CEMS that has both a CO2

concentration monitor and 

volumetric flow rate monitor 

for the combustion gases from 

the flare, you must calculate 

only CO2 emissions for the 

flare. ...If a CEMS is used to 

calculate flare stack emissions, 

the requirements specified in 

paragraphs (n)(1) through 

(n)(7) are not required. 

Renumbers paragraph 

and removes redundant 

text 

§98.233(q) Leak detection and leaker 

emission factors. You must 

use the methods described in 

§98.234(a) to conduct leak 

detection(s) of equipment 

leaks from all component 

types listed in §98.232(d)(7), 

(e)(7), (f)(5), (g)(3), (h)(4), 

and (i)(1). This paragraph (q) 

applies to component types in 

streams with gas content 

greater than 10 percent CH4

plus CO2 by weight. 

Component types in streams 

with gas content less than 10 

Equipment leak surveys. You 

must use the methods 

described in §98.234(a) to 

conduct leak detection(s) of 

equipment leaks from all 

component types listed in 

§98.232(d)(7), (e)(7), (f)(5), 

(g)(3), (h)(4), and (i)(1). This 

paragraph (q) applies to 

component types in streams 

with gas content greater than 

10 percent CH4 plus CO2 by 

weight. Component types in 

streams with gas content less 

than or equal to 10 percent 

Makes terminology 

consistent with 

corresponding reporting 

section (§98.236(q)); 

clarifying edits 
26 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

percent CH4 plus CO2 by 

weight do not need to be 

reported. Tubing systems 

equal to or less than one half 

inch diameter are exempt 

from the requirements of this 

paragraph (q) and do not 

need to be reported. If 

equipment leaks are detected 

for sources listed in this 

paragraph (q), calculate 

equipment leak emissions per 

component type per reporting 

facility using Equations W30A or W-30B of this section 

for each component type. 

CH4 plus CO2 by weight are 

exempt from the requirements 

of this paragraph (q) and do 

not need to be reported. 

Tubing systems equal to or 

less than one half inch 

diameter are exempt from the 

requirements of this paragraph 

(q) and do not need to be 

reported. For industry 

segments listed in 

§98.230(a)(3) through (a)(8), if 

equipment leaks are detected 

for component types listed in 

this paragraph (q), then you 

must calculate equipment leak 

emissions per component type 

per reporting facility using 

Equations W-30 of this 

section. For the industry 

segment listed in 

§98.230(a)(8), the results from 

Equation W-30 of this section 

are used to calculate 

population emission factors on 

a meter/regulator run basis 

using Equation W-31 of this 

section. 

§98.233(q)(1) You must select to conduct 

either one leak detection 

survey in a calendar year or 

multiple complete leak 

detection surveys in a 

calendar year. The number of 

leak detection surveys 

selected must be conducted 

during the calendar year. 

You must conduct either one 

leak detection survey in a 

calendar year or multiple 

complete leak detection 

surveys in a calendar year. The 

leak detection surveys selected 

must be conducted during the 

calendar year. 

Grammatical 

corrections 

§98.233(q)(3) and 

(q)(4) 

... facilities shall use the 

appropriate default leaker 

emission factors listed in 

Table ... of this subpart for 

equipment leaks detected 

from valves, connectors, 

open ended lines, pressure 

relief valves, and meters. 

... facilities must use the 

appropriate default total 

hydrocarbon leaker emission 

factors for compressor 

components in gas service and 

non-compressor components 

in gas service listed in Table 

... of this subpart. 

Clarifying edits 

§98.233(q)(5) and 

(r)(3) 

(q)(5) Underground natural 

gas storage facilities for 

storage stations shall use the 

appropriate default leaker 

emission factors listed in 

Table W-4 of this subpart for 

(q)(5) Underground natural gas 

storage facilities must use the 

appropriate default total 

hydrocarbon leaker emission 

factors for storage stations in 

gas service listed in Table W-4 

Clarifying edits 
27 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

equipment leaks detected 

from valves, connectors, 

open ended lines, pressure 

relief valves, and meters. 

(r)(3) Underground natural 

gas storage facilities for 

storage wellheads shall use 

the appropriate default 

population emission factors 

listed in Table W-4 of this 

subpart for equipment leak 

from connectors, valves, 

pressure relief valves, and 

open ended lines. 

of this subpart. 

(r)(3) Underground natural gas 

storage facilities must use the 

appropriate default total 

hydrocarbon population 

emission factors for storage 

wellheads in gas service listed 

in Table W-4 of this subpart. 

§98.233(q)(6) and 

(r)(4) 

(q)(6) ... shall use the 

appropriate default leaker 

emission factors listed in 

Table W-5 of this subpart for 

equipment leaks detected 

from valves, pump seals, 

connectors, and other. 

(r)(4) ... shall use the 

appropriate default 

population emission factors 

listed in Table W-5 of this 

subpart for equipment leak 

from vapor recovery 

compressors. 

(q)(6) ... must use the 

appropriate default methane 

leaker emission factors for 

LNG storage components in 

gas service listed in Table W-5 

of this subpart. 

(r)(4) ... must use the 

appropriate default methane 

population emission factor for 

LNG storage compressors in 

gas service listed in Table W-5 

of this subpart. 

Clarifying edits 

§98.233(q)(7) and 

(r)(5) 

(q)(7) ... shall use the 

appropriate default leaker 

emission factors listed in 

Table W-6 of this subpart for 

equipment leaks detected 

from valves, pump seals, 

connectors, and other. 

(r)(5) ... shall use the 

appropriate default 

population emission factor 

listed in Table W-6 of this 

subpart for equipment leak 

from vapor recovery 

compressors. 

(q)(7) ... must use the 

appropriate default methane 

leaker emission factors for 

LNG terminals components in 

LNG service listed in Table 

W-6 of this subpart. 

(r)(5) ... must use the 

appropriate default methane 

population emission factor for 

LNG terminal compressors in 

gas service listed in Table W-6 

of this subpart. 

Clarifying edits 

§98.233(q)(8) Natural gas distribution 

facilities for above grade 

transmission-distribution 

transfer stations, shall use the 

appropriate default leaker 

emission factors listed in 

Natural gas distribution 

facilities must use Equation 

W-30 of this section and the 

default methane leaker 

emission factors for 

transmission-distribution 

Clarifying edits; 

grammatical correction 
28 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

Table W-7 of this subpart for 

equipment leaks detected 

from connectors, block 

valves, control valves, 

pressure relief valves, orifice 

meters, regulators, and open 

ended lines. Leak detection at 

natural gas distribution 

facilities is only required at 

above grade stations that 

qualify as transmissiondistribution transfer stations. 

Below grade transmissiondistribution transfer stations 

and all metering-regulating 

stations that do meet the 

definition of transmissiondistribution transfer stations 

are not required to perform 

component leak detection 

under this section. 

transfer station components in 

gas service listed in Table W-7 

of this subpart to calculate 

component emissions from 

annual equipment leak surveys 

conducted at above grade 

transmission-distribution 

transfer stations. Natural gas 

distribution facilities are 

required to perform equipment 

leak surveys only at above 

grade stations that qualify as 

transmission-distribution 

transfer stations. Below grade 

transmission-distribution 

transfer stations and all 

metering-regulating stations 

that do not meet the definition 

of transmission-distribution 

transfer stations are not 

required to perform equipment 

leak surveys under this section. 

§98.233(q)(8)(i) Natural gas distribution 

facilities may choose to 

conduct leak detection at the 

T-D transfer stations over 

multiple years, not exceeding 

a five year period to cover all 

T-D transfer stations. If the 

facility chooses to use the 

multiple year option then the 

number of T-D transfer 

stations that are monitored in 

each year should be 

approximately equal across 

all years in the cycle without 

monitoring the same station 

twice during the multiple 

year survey. 

Natural gas distribution 

facilities may choose to 

conduct equipment leak 

surveys at all above grade 

transmission-distribution 

transfer stations over multiple 

years, not exceeding a five 

year period to cover all above 

grade transmission-distribution 

transfer stations. If the facility 

chooses to use the multiple 

year option then the number of 

transmission-distribution 

transfer stations that are 

monitored in each year should 

be approximately equal across 

all years in the cycle. 

Clarifying edits 

§98.233(r) Population count and 

emission factors. This 

paragraph applies to 

emissions sources listed in 

§98.232 (c)(21), (f)(5), 

(g)(3), (h)(4), (i)(2), (i)(3), 

(i)(4), (i)(5), and (i)(6) on 

streams with gas content 

greater than 10 percent CH4

plus CO2 by weight. 

Emissions sources in streams 

with gas content less than 10 

Equipment leaks by population 

count. This paragraph applies 

to emissions sources listed in 

§98.232 (c)(21), (f)(5), (g)(3), 

(h)(4), (i)(2), (i)(3), (i)(4), 

(i)(5), and (i)(6) on streams 

with gas content greater than 

10 percent CH4 plus CO2 by 

weight. Emissions sources in 

streams with gas content less 

than or equal to 10 percent 

CH4 plus CO2 by weight are 

Makes terminology 

consistent with 

corresponding reporting 

section (§98.236(r)); 

clarifying edits 
29 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

percent CH4 plus CO2 by 

weight do not need to be 

reported. Tubing systems 

equal to or less than one half 

inch diameter are exempt 

from the requirements of 

paragraph (r) of this section 

and do not need to be 

reported. Calculate emissions 

from all sources listed in this 

paragraph using Equation W31 of this section. 

exempt from the requirements 

of this paragraph (q) and do 

not need to be reported. 

Tubing systems equal to or 

less than one half inch 

diameter are exempt from the 

requirements of paragraph (r) 

of this section and do not need 

to be reported. You must 

calculate emissions from all 

emission sources listed in this 

paragraph using Equation W32A of this section, except for 

natural gas distribution facility 

emission sources listed in 

§98.232 (i)(3). Natural gas 

distribution facility emission 

sources listed in §98.232 (i)(3) 

must calculate emissions using 

Equation W-32B and 

according to paragraph (r)(6) 

of this section. 

§98.233(r) Equations Eq. W-31 Eq. W-32A and Eq. W-32B Renumbered; 

harmonizing change 

with edits to §98.233(q) 

§98.233(r)(2) Onshore petroleum and 

natural gas production 

facilities shall use the 

appropriate default 

population emission factors 

listed in Table W-1A of this 

subpart for equipment leaks 

from valves, connectors, 

open ended lines, pressure 

relief valves, pump, flanges, 

and other. Major... 

Onshore petroleum and natural 

gas production facilities must 

use the appropriate default 

whole gas population emission 

factors listed in Table W-1A of 

this subpart. Major... 

Clarifying edit 

§98.233(r)(6) ... shall use the appropriate 

emission factors as described 

in paragraph (r)(6) of this 

section. 

... must use the appropriate 

methane emission factors as 

described in paragraph (r)(6) 

of this section. 

Clarifying edits 

§98.233(r)(6)(i) ... shall use the appropriate 

default population emission 

factors listed in Table W-7 of 

this subpart. Below grade TD transfer stations shall use 

the emission factor for below 

grade metering-regulating 

stations. 

... must use the appropriate 

default methane population 

emission factors listed in Table 

W-7 of this subpart. Below 

grade transmission-distribution 

transfer stations must use the 

emission factor for below 

grade metering-regulating 

stations. 

Clarifying edits 

§98.233(r)(6)(ii) Emissions from all above 

grade metering-regulating 

Above grade meteringregulating stations (that are not Harmonizing edits with 

changes to §98.233(q) 
30 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

stations (including above 

grade TD transfer stations) 

shall be calculated by 

applying the emission factor 

calculated in Equation W-32 

and the total count of 

meter/regulator runs at all 

above grade meteringregulating stations (inclusive 

of TD transfer stations) to 

Equation W-31. The facility 

wide emission factor in 

Equation W-32 will be 

calculated by using the total 

volumetric GHG emissions at 

standard conditions for all 

equipment leak sources 

calculated in Equation W30B in paragraph (q)(8) of 

this section and the count of 

meter/regulator runs located 

at above grade transmissiondistribution transfer stations 

that were monitored over the 

years that constitute one 

complete cycle as per 

paragraph (q)(8)(i) of this 

section. A meter on a 

regulator run is considered 

one meter/regulator run. 

Reporters that do not have 

above grade T-D transfer 

stations shall report a count 

of above grade meteringregulating stations only and 

do not have to comply with 

§98.236(c)(16)(xix). 

above grade transmissiondistribution transfer stations) 

must use the meter/regulator 

run population emission factor 

calculated in Equation W-31. 

Natural gas distribution 

facilities that do not have 

above grade transmissiondistribution transfer stations 

are not required to calculate 

emissions for above grade 

metering-regulating stations. 

§98.233(s)(2) Offshore production facilities 

that are not under BOEMRE 

jurisdiction shall use 

monitoring methods and 

calculation methodologies 

published by BOEMRE 

referenced in 30 CFR 

250.302 through 304 to 

calculate and report 

emissions (GOADS). 

Offshore production facilities 

that are not under BOEMRE 

jurisdiction shall use the most 

recent monitoring methods and 

calculation methods published 

by BOEMRE referenced in 30 

CFR 250.302 through 304 to 

calculate and report annual 

emissions (GOADS). 

Clarifying edits 

§98.233(s)(2)(i) For any calendar year that 

does not overlap with the 

most recent BOEMRE 

emissions study publication, 

For any calendar year that does 

not overlap with the most 

recent BOEMRE emissions 

study publication, you may 

Clarifying edits 
31 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

report the most recent 

reported emissions data with 

emissions adjusted... 

report the most recently 

reported emissions data 

submitted to demonstrate 

compliance with this subpart 

of part 98, with emissions 

adjusted ... 

§98.233(s)(3) ... shall once in every 4 years 

use the most recent 

BOEMRE data collection and 

emissions estimation 

methods to report emission 

from the facility sources. 

... shall once in every 4 years 

use the most recent BOEMRE 

data collection and emissions 

estimation methods to estimate 

emissions. These emission 

estimates would be used to 

report emissions from the 

facility sources as required in 

paragraph (1)(i) of this section. 

Clarifying edits 

§98.233(s)(4) ... shall use the most recent 

BOEMRE data collection and 

emissions estimation 

methods published by 

BOEMRE referenced in 30 

CFR 250.302 through 304 to 

calculate and report 

emissions (GOADS) to report 

emissions. 

... must use the most recent 

BOEMRE data collection and 

emissions estimation methods 

published by BOEMRE 

referenced in 30 CFR 250.302 

through 304 to calculate and 

report emissions. 

Applies active language 

and corrects 

typographical error 

§98.233(t) (t) Volumetric emissions. ... (t) GHG Volumetric emissions 

using actual conditions. ... 

Clarifying edits 

§98.233(u) (u) GHG volumetric 

emissions. Calculate GHG 

volumetric emissions at 

standard conditions as 

specified in paragraphs (u)(1) 

and (2) of this section, with 

mole fraction of GHGs in the 

natural gas determined by 

engineering estimate based 

on best available data unless 

otherwise specified. 

(u) GHG volumetric emissions 

at standard conditions. 

Calculate GHG volumetric 

emissions at standard 

conditions as specified in 

paragraphs (u)(1) and (2) of 

this section. 

Clarifying edits 

§98.233(u)(2)(iii), (v), 

and (vi) 

... You may use a default 95 

percent methane and 1 

percent carbon dioxide 

fraction for GHG mole 

fraction in natural gas. 

... You may use either a 

default 95 percent methane 

and 1 percent carbon dioxide 

fraction for GHG mole 

fraction in natural gas or site 

specific engineering estimates 

based on best available data. 

Clarifying edits 

§98.233(vii) ... You may use a default 95 

percent methane and 1 

percent carbon dioxide 

fraction for GHG mole 

fraction in natural gas. 

...You may use a default 95 

percent methane and 1 percent 

carbon dioxide fraction for 

GHG mole fraction in natural 

gas or site specific engineering 

estimates based on best 

available data. 

Clarifying edits 
32 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

§98.233(w) (w) ... Calculate CO2 pump 

blowdown emissions as 

follows: 

(1) Calculate the total volume 

in cubic feet ... 

(3) Calculate the total annual 

venting emissions using 

Equation W-37 of this 

section: 

(w) ... Calculate CO2 pump 

blowdown emissions from 

each EOR injection pump 

system as follows: 

(1) Calculate the total injection 

pump system volume in cubic 

feet ... 

 (3) Calculate the total annual 

CO2 emissions from each EOR 

injection pump system using 

Equation W-37 of this section: 

Clarifying edits 

Terms “MassCO2”, 

“N”, and “Vv” of 

Equation W-37 

MassCO2 = Annual EOR 

injection gas venting 

emissions in metric tons from 

blowdowns. 

N = Number of blowdowns 

for the equipment in the 

calendar year. 

Vv = Total volume in cubic 

feet of blowdown equipment 

chambers (including 

pipelines, manifolds and 

vessels) between isolation 

valves. 

MassCO2 = Annual EOR 

injection pump system 

emissions in metric tons from 

blowdowns. 

N = Number of blowdowns for 

the EOR injection pump 

system in the calendar year. 

Vv = Total volume in cubic 

feet of EOR injection pump 

system chambers (including 

pipelines, manifolds and 

vessels) between isolation 

valves. 

Clarifies terminology 

§98.233(x), (x)(1), and 

term “Shl” of Equation 

W-38 (§98.233(x)(2)) 

(x) ... Calculate dissolved 

CO2 in hydrocarbon liquids 

produced through EOR 

operations as follows: 

(1) ... Annual samples must 

be taken according to 

methods set forth in 

§98.234(b)... 

(2)... 

Shl = Amount of CO2 retained 

in hydrocarbon liquids in 

metric tons per barrel, under 

standard conditions. 

(x) ... Calculate CO2

emissions downstream of the 

storage tank from dissolved 

CO2 in hydrocarbon liquids 

produced through EOR 

operations as follows: 

(1) ... Annual samples of 

hydrocarbon liquids 

downstream of the storage 

tank must be taken according 

to methods set forth in 

§98.234(b) ... 

(2)... 

Shl = Amount of CO2 retained 

in hydrocarbon liquids 

downstream of the storage 

tank, in metric tons per barrel, 

under standard conditions. 

Clarifying edits 

§98.233(z)(1)(i) and 

(ii) 

All part 98 rule references in 

paragraphs (i) and (ii) 

Added § symbol (e.g., “for that 

tier listed in §98.33”) 

Corrects typographical 

error 

Term “Va” of 

Equations W-39A and 

W-39B 

Va = Volume of gas sent to 

combustion unit in cubic feet, 

during the year. 

Va = Volume of gas sent to 

combustion unit in actual 

cubic feet, during the year. 

Clarifying edit 

Terms “YCO2”, “Yj” 

and “YCH4” of 

Equations W-39A and 

Concentration of... Mole fraction of... Clarifying edit 
33 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

W-39B 

Term “HHV” of 

Equation W-40 

HHV = For the higher 

heating value for field gas or 

process vent gas, use 1.235 × 

10−3

 mmBtu/scf for HHV. 

HHV = Higher heating value 

of fuel, mmBtu/unit of fuel (in 

units consistent with the fuel 

quantity combusted). For the 

higher heating value for field 

gas or process vent gas, use 

1.235 × 10−3

 mmBtu/scf for 

HHV. 

Clarifying edit 

§98.234(a) You must use any of the 

methods described as follows 

in this paragraph to conduct 

leak detection(s) of 

equipment leaks and throughvalve leakage from all source 

types listed in §98.233(k), 

(o), (p) and (q) that occur 

during a calendar year, 

except as provided in 

paragraph (a)(4) of this 

section. 

You must use any of the 

methods described as follows 

in this paragraph to conduct 

leak detection(s) of equipment 

leaks and through-valve 

leakage from all source types 

listed in §98.233(k), (o), (p) 

and (q) that occur during a 

calendar year. 

Corrects reference error 

§98.234(d)(1) (1) A technician following 

manufacturer instructions 

shall conduct measurements, 

including equipment 

manufacturer operating 

procedures and measurement 

methodologies relevant to 

using a high volume 

sampler... 

(1) A technician following 

manufacturer instructions shall 

conduct measurements, 

including equipment 

manufacturer operating 

procedures and measurement 

methods relevant to using a 

high volume sampler... 

Harmonizing edit 

§98.234(h) None (h) For well venting for liquids 

unloading, if a monitoring 

period other than the full 

calendar year is used to 

determine the cumulative 

amount of time in hours of 

venting for each well (the term 

“Tp” in Equation W-7a and W7b of §98.233) or the number 

of unloading events per well 

(the term “Vp” in Equations 

W-8 and W-9 of §98.233), 

then the monitoring period 

must begin before February 1 

of the reporting year and must 

not end before December 1 of 

the reporting year. The end of 

one monitoring period must 

immediately precede the start 

of the next monitoring period 

for the next reporting year. All 

Harmonizing edit with 

changes to §98.233(f). 
34 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

production days must be 

monitored and all venting 

accounted for. 

§98.238 Component means each 

metal to metal joint or seal of 

non-welded connection 

separated by a compression 

gasket, screwed thread (with 

or without thread sealing 

compound), metal to metal 

compression, or fluid barrier 

through which natural gas or 

liquid can escape to the 

atmosphere. 

Equipment leak means those 

emissions which could not 

reasonably pass through a 

stack, chimney, vent, or other 

functionally-equivalent 

opening. 

Equipment leak detection

means the process of 

identifying emissions from 

equipment, components, and 

other point sources. 

None (these definitions 

removed in amendments) 

Harmonizing edits with 

changes to §98.233(q) 

and (r) 

§98.238 Compressor source means 

any type of vent or valve 

(e.g. wet seal, blowdown 

valve, isolation valve, or rod 

packing) on a reciprocating 

or centrifugal compressor. 

Manifolded group of 

compressor sources means a 

collection of any combination 

of manifolded group of 

compressor sources (as 

defined in this section) for 

centrifugal or reciprocating 

compressors that are 

manifolded to a common 

vent. 

Meter/regulator run means a 

series of components used in 

regulating pressure or 

metering natural gas flow or 

both. 

Compressor source means any 

type of vent or valve (i.e., wet 

seal, blowdown valve, 

isolation valve, or rod packing) 

on a centrifugal or 

reciprocating compressor. 

Manifolded group of 

compressor sources means a 

collection of any combination 

of manifolded compressor 

sources (as defined in this 

section) that are manifolded to 

a common vent. 

Meter/regulator run means a 

series of components used in 

regulating pressure or metering 

natural gas flow or both. At 

least one meter, at least on 

regulator, or any combination 

of both on a single run of 

piping is considered one 

meter/regulator run. 

Grammatical revisions; 

harmonizing edits 
35 

Table 1. Proposed Minor Technical Corrections 

Rule Citation Current Text Proposed Revised Text 

Reason for 

Proposed Change 

Sub-basin category, for 

onshore natural gas 

production, means ... Oil, 

high permeability gas, shale 

gas, coal seam, or other tight 

reservoir rock... Wells that 

produce from high 

permeability gas, shale gas, 

coal seam, or other tight 

reservoir rock are considered 

gas wells ... All wells that 

produce hydrocarbon liquids 

and do not meet the 

definition of a gas well in this 

sub-basin category definition 

are considered to be in the oil 

formation. All emission 

sources that handle 

condensate from gas wells in 

high permeability gas, shale 

gas, or tight reservoir rock 

formations are considered to 

be in the formation that the 

gas well belongs to and not in 

the oil formation. 

Sub-basin category, for 

onshore natural gas 

production, means ...Oil, high 

permeability gas, shale gas, 

coal seam, or other tight gas 

reservoir rock... Wells that 

produce only from high 

permeability gas, shale gas, 

coal seam, or other tight gas 

reservoir rock are considered 

gas wells ... All wells that 

produce hydrocarbon liquids 

(with or without gas) and do 

not meet the definition of a gas 

well in this sub-basin category 

definition are considered to be 

in the oil formation. All 

emission sources that handle 

condensate from gas wells in 

high permeability gas, shale 

gas, or tight gas reservoir rock 

formations are considered to 

be in the formation that the gas 

well belongs to and not in the 

oil formation.