November 2018 Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990-2017: Other Updates Under Consideration In supporting documentation associated with the development of EPA's 2018 Inventory of U.S. Greenhouse Gas Emissions and Sinks (GHGI), EPA stated plans to consider improvements to the 2019 GHGI including incorporating newly reported data from EPA's Greenhouse Gas Reporting Program (GHGRP) and assessing options to update activity data sources and/or methodologies related to onshore oil and gas wells. In June 2018, EPA released two memos detailing preliminary considerations for such improvements: • Inventory of U.S. GHG Emissions and Sinks 1990-2017: Updates Under Consideration for Incorporating GHGRP Data (June 2018 GHGRP-based Updates memo)1 • Inventory of U.S. GHG Emissions and Sinks 1990-2017: Updates Under Consideration for Well-Related Activity Data (June 2018 Well-related Activity Updates memo)2 EPA reviewed stakeholder feedback on the June 2018 memos and held two public meetings (June 6, 2018 webinar and October 17, 2018 workshop). EPA released two memos in October 2018 that focused on specific GHGRP- based updates: • Inventory of U.S. GHG Emissions and Sinks 1990-2017: Updates Under Consideration for Natural Gas Gathering and Boosting Emissions (October 2018 G&B Updates memo)3 • Inventory of U.S. GHG Emissions and Sinks 1990-2017: Updates Under Consideration for Liquefied Natural Gas Segment Emissions (October 2018 LNG Updates memo)4 This memo summarizes previous analyses from the June 2018 memos and includes additional analyses and considerations toward updating the emissions and/or activity data for the sources listed in in Table 1 below. This memo also introduces a new topic under consideration for potential GHGI improvements—accounting for anomalous leak events that are not likely reflected in current GHGI emission factors (EFs). EPA continues to seek stakeholder feedback on how to use available data and improve methodologies for the sources discussed in this memo; refer to Section 4 for specific questions. Table 1. Topics Covered in this Memo Topic Discussed in Memo Section... New Information since June 2018 Preliminary Updates Memos Incorporating Available GHGRP Data 1 Incorporating GHGRP data for hydraulically fractured (HF) oil well completions and workovers 1.1 • Summary of stakeholder feedback (Section 1.1.4) Incorporating GHGRP data for flaring N2O emissions 1.2 • None Incorporating GHGRP data for transmission pipeline blowdowns 1.3 • Analysis of available data (Section 1.3.2) • Time series considerations (Section 1.3.3) • Preliminary national emissions estimates (Section 1.3.4, Table 7) • Summary of stakeholder feedback Updating Well-related Activity Data 2 Updating well drilling activity estimates 2.1 • Summary of stakeholder feedback 1 https://www.epa.gov/sites/production/files/2018-06/documents/2019-ghgi-updates-incorporating-ghgrp-data_2018-06-08.pdf 2 https://www.epa.gov/sites/production/files/2018-06/documents/2019-ghgi-updates-well-activity_2018-06-08.pdf 3 https://www.epa.gov/sites/production/files/2018-10/documents/ghgi_2018stakeholders_boosting.pdf 4 https://www.epa.gov/sites/production/files/2018-10/documents/ghgi_2018stakeholders_segment.pdf Page 1 of 19 ------- November 2018 Updating well completions and workovers activity estimates 2.2 • Analysis of reported gas well event GHGRP data compared to GHGI (Table 8) • Summary of stakeholder feedback Defining oil versus gas well types 2.3 • Analysis of alternative definition (Figure 1) • Summary of stakeholder feedback Updating heavy versus light crude equipment service assumptions 2.4 • Analysis of available EIA data • Summary of stakeholder feedback Identifying HF wells 2.5 None Anomalous Leak Event Emissions 3 New topic 1 Incorporating Available GHGRP Data Subpart W of the EPA's GHGRP collects annual activity and emissions data on numerous sources from onshore natural gas and petroleum systems that meet a reporting threshold of 25,000 metric tons of C02 equivalent (mt C02e) emissions. Facilities that meet the subpart W reporting threshold have been reporting since reporting year (RY) 2011; however, HF oil well completions and workover data elements and transmission pipeline blowdowns were first required to be reported in RY2016. Subpart W activity and emissions data are currently used in the GHGI to calculate CH4 and C02 emissions for many production, processing, and transmission and storage sources. GHGRP subparts W and Y (petroleum refining) include reporting of N20 from flaring. The GHGRP calculation methodologies specify that subpart W reporters must calculate N20 emissions from flares using an EF of 0.0001 kg N20 per million BTU, and subpart Y reporters using an EF of 0.0003 kg N20 per million BTU. N20 emissions are also reported to GHGRP for engine exhaust and other combustion sources, combustion emissions from which are generally included within GHGI estimates from fuel combustion, separate from natural gas and petroleum systems. The GHGRP data used in the analyses discussed in this memo are those reported to the EPA as of August 5, 2017. Appendix A documents the subpart W calculation methodologies for certain sources discussed in this memo. EPA will assess data for RY2017 as they become available. Stakeholders have suggested additional or alternate uses of GHGRP data, such as for certain sources using measurement data only. Stakeholders have also suggested modifications to the reported GHGRP data for use in the GHGI, such as through removal of stakeholder-identified outliers. In the current GHGI, EPA uses the publicly available GHGRP data set without modification for the GHGI, to ensure transparency and reproducibility of GHGI estimates. Prior to public release of the GHGRP data, the EPA has a multi-step data verification process for the data, including automatic checks during data-entry, statistical analyses on completed reports, and staff review of the reported data. Based on the results of the verification process, the EPA follows up with facilities to resolve identified potential issues before public release. 1.1 Incorporating GHGRP Data for HF Oil Well Completions and Workovers As discussed above, HF oil well completions and workovers were newly required to be reported in RY2016. EPA analyzed the RY2016 subpart W data for this source as an initial step for considering potential updates to the existing GHGI methodology. 1.1.1 Current GHGI Methodology In the current GHGI methodology for HF oil well completions, controlled and uncontrolled CH4 EFs were developed using data analyzed for the 2015 NSPS OOOOa proposal. The current GHGI estimates C02 emissions using C02 EFs developed by applying a default production segment ratio of C02-to-CH4 gas content. As such, this approach for does not fully account for C02 emissions from flaring. The 2018 GHGI activity data time series (counts of HF oil well completions, which is also referenced in calculating non-HF oil well completions), was developed from analyzing Drillinglnfo data on well-level dates of completion or first reported production. The existing GHGI methodology also includes assumptions to develop activity factors Page 2 of 19 ------- November 2018 (AFs) for apportioning total counts into control categories. In 2008, Colorado and Wyoming adopted regulations that require reduced emission completions (RECs); the current GHGI assumes that 7% of completions are RECs with 95% control efficiency, from 2008 forward. For workovers, the current GHGI methodology estimates emissions from all oil well workovers without distinguishing HF from non-HF, using an EF developed for conventional wells and an assumption that 7.5% of all oil wells are worked over in each year. 1.1.2 Analysis of Available Data EPA analyzed the RY2016 subpart W data for HF oil well completions and workovers to consider updating the existing GHGI methodology, which estimates emissions from HF oil well completions based on historical rulemaking data and does not include a specific emissions estimate for HF oil well workovers (as discussed in Section 4.1). The new subpart W data allow development of separate GHGI emissions estimates for HF completions and workovers, in parallel control categories that exist for HF gas well events (reflecting combinations of REC use, venting, and flaring).5 Additionally, as summarized in Section 4.1, the current GHGI HF oil well completion C02 EF is calculated by applying an associated gas C02-to-CH4 content ratio, which does not account for C02 conversion during hydrocarbon combustion. This current methodological limitation would be obviated by using subpart W data to directly calculate CH4 and C02 EFs, parallel to the current methodology for HF gas well events. This section documents development of EFs and activity data for HF oil well completions and workovers according to the general methodology used in the current GHGI for HF gas well completions and workovers. The 2018 Well- related Activity Data companion memo details considerations for potentially improving the approach to estimating national total activity data for all completions and workovers (e.g., Drillinglnfo query methodology, workover rate assumptions). Table 2 below shows EFs calculated using RY2016 subpart W data for HF oil well completions and workovers for each event type/control category, compared to current GHGI EFs. Table 3 shows AFs for each event type/control category. Table 2. Emission Factors Calculated from Subpart W Compared to Current GHGI, for Year 2016 Event Type Control Category CH4 EF (mt/event) CO; EF (mt/event) 2018 GHGI Subpart W 2018 GHGI Subpart W Non-REC Vent 6.76 36.0 0.38 0.8 Flare 1.1 248.8 REC Vent 0.34 1.3 0.02 0.1 Flare 2.6 287.1 5 The GHGI methodology for HF gas well completions and workovers incorporates GHGRP data. For HF gas well completions and workovers, EFs are developed from reporting year-specific GHGRP subpart W data (2011 through 2016), with year 2011 EFs applied for earlier time series years. The EFs are developed for four control categories: non-REC/vented; non-REC/flared; REC/vented; and REC/flared. The total counts of HF completions are developed from Drillinglnfo data for years prior to 2011, and GHGRP data are used for year 2011 forward (as the directly reported counts are higher than Drillinglnfo-based estimates). The counts are apportioned into control categories based on year-specific GHGRP data for 2011-2016; for years 1990-2000, it is assumed all events are non-REC, and 10% of events flare; interpolation is used to develop AFs in intermediate years. For HF gas well workovers, it is assumed that 1% of the count of existing HF gas wells in a given year (estimated from analyzing Drillinglnfo data) are worked over. Page 3 of 19 ------- November 2018 Table 3. Activity Factors Calculated from Subpart W Compared to Current GHGI, for Year 2016 Event Type Control Category HF Completions HF Workovers Subpart W 2018 GHGIJ Subpart W # of Events % of total # of Events % of total # of Events % of total Non-REC Vent 111 3% 11,567 93% 35 11% Flare 542 13% 16 5% REC Vent 1,345 33% 871 7% 186 56% Flare 2,061 51% 93 28% Total 4,059 100% 12,438 100% 330 100% a - For years 2008 forward, the current GHGI assumes 7% of HF oil well completions are controlled via REC due to state- specific regulations. The current GHGI does not include specific estimates for HF oil well workovers. To develop national total activity data for HF oil well completions, EPA analyzed counts derived from the Drillinglnfo data set compared to reported counts. For HF gas well completions, counts reported under GHGRP exceed Drillinglnfo-based estimates, so are assumed to represent national coverage and used directly as national total activity in the GHGI. For HF oil well completions, this is not the case; Drillinglnfo-based counts exceed reported counts. Therefore, to develop the preliminary national emissions estimates presented in Section 1.1.4, Drillinglnfo-based activity data are used in conjunction with the EFs and AFs in Table 2 and Table 3, respectively. Workover data are not contained within EPA's Drillinglnfo analysis data set, so an assumption of 1% annual workover rate is applied for HF gas wells in the current GHGI. In each year of the time series, 1% of existing HF wells (estimated from the Drillinglnfo data set) are assumed to undergo workovers. For HF gas wells, this approach results in national total activity data that exceed HF workover counts reported under subpart W. For the preliminary national emissions estimates presented in Section 4.4, EPA applies the same assumption to HF oil wells to calculate national total workover activity. Similar to HF gas wells, this approach results in national total activity data that exceed HF oil well workover counts reported under subpart W. As stated above, the 2018 Well-related Activity Data companion memo details considerations for potentially improving the approach to estimating national total activity data for all completions and workovers in the GHGI, which might include refining the Drillinglnfo query methodology and/or further incorporating subpart W data. For example, the 2018 Well-related Activity Data memo estimates that within the RY2015-2016 subpart W data for gas wells, an overall workover rate is 5-6% in recent years (compared to the current GHGI assumption of 4.35% for non-HF gas wells and 1% for HF gas wells). 1.1.3 Regional Variability and Time Series Considerations For HF oil well completions and workovers, this memo presents preliminary emissions estimates (see Section 4.4) according to the existing GHGI methodology to develop estimates for HF gas well events; EFs and AFs are calculated at the national level. EPA seeks stakeholder feedback on whether a region-specific approach should be considered for these sources. To develop the time series AFs for HF oil well completions and workovers based generally on the existing methodology for gas well events, and incorporating current control assumptions for HF oil well events, the following assumptions could be applied: • For years 1990-2007, all completions and workovers are non-REC, and 10% of events flare. • For the first year in which subpart W data are available, 2016, control fractions across the four categories are developed directly from reported subpart W data. Page 4 of 19 ------- November 2018 • For intermediate years, 2008-2015, control fractions are developed through linear interpolation. This produces AFs across the time series that are generally consistent with the existing GHGI assumption that oil well RECs are introduced beginning in year 2008, during which 7% of completions and workovers are REC, and 10% of both REC and non-REC events flare. EPA seeks feedback on the assumptions above used to develop these control category AFs. To apply EFs across the time series, EPA would apply year-specific EFs for GHGRP years, and EFs from the earliest GHGRP year to all prior years, consistent with the approach for HF gas well events. For the 2019 GHGI, this approach means that EFs calculated from RY2016 data would be applied for years 1990-2016, and RY2017 data would be used to develop EFs for year 2017. 1.1.4 Preliminary National Emissions Estimates Table 4 below shows national total activity data and CH4 emissions for select time series years based on the updates under consideration described above. Table 4. Preliminary National Activity and Emissions Estimates for HF Oil Well Completions and Workovers, Select Years Data Element 1990 2000 2005 2010 2015 2016 HF oil well completions (#) 3,075 2,246 4,594 8,188 12,438 12,438 Non-REC/Vent (%) 90% 90% 90% 61% 12% 3% Non-REC/Flare (%) 10% 10% 10% 11% 13% 13% REC/Vent(%) 0% 0% 0% 11% 29% 33% REC/Flare (%) 0% 0% 0% 17% 45% 51% HF oil well workovers (#) 846 848 947 1,235 1,916 1,884 Non-REC/Vent (%) 90% 90% 90% 64% 19% 11% Non-REC/Flare (%) 10% 10% 10% 8% 5% 5% REC/Vent(%) 0% 0% 0% 19% 50% 56% REC/Flare (%) 0% 0% 0% 9% 25% 28% Total CH4 emissions (kt) 128 101 180 222 95 46 2018 GHGI CH4 emissions (kt)a 21 15 31 52 79 79 Total CO2 emissions (kt) 100 79 142 688 2,179 2,402 2018 GHGI CO2 emissions (kt)a 1 1 2 3 4 4 a - Does not include estimate for workovers. The 2018 GHGI does not specifically estimate emissions from HF oil well workovers; the estimate for all (non-HF and HF) oil well workovers is negligible compared to the magnitude of other estimates shown in this table (<0.1 kt across the time series). Stakeholder feedback generally supported incorporating GHGRP data for this source, using an approach consistent with that currently used for HF gas well events. Stakeholders expressed interest in developing separate EFs for completions versus workovers (in the current approach for both gas and oil well events, both types of events are combined). EPA reviewed available data and notes that due to the approach wherein year-specific EFs are calculated for each of four control categories, the number of data points in some categories is relatively small. Therefore, EPA intends to implement the existing approach in the 2019 GHGI, wherein HF oil well completions and workovers data are combined to calculate EFs (while activity for each event type is separately estimated). 1.2 Flaring N2O Emissions Updates Under Consideration The current GHGI does not estimate N20 emissions for natural gas and petroleum systems. However, with recent updates that use GHGRP data to estimate CH4 and C02 flaring emissions, the EPA is considering updates to incorporate N20 emissions for the same flaring sources. The EPA would apply the existing source-specific methodology for using GHGRP CH4 data to develop N20 EFs. Page 5 of 19 ------- November 2018 For purposes of presenting preliminary national total flaring N20 emission estimates, EPA calculated a ratio of the GHGRP reported N20 emissions to C02 emissions and then multiplied the N20-to-C02 ratio by the 2018 GHGI C02 emissions, for each emission source. Table 5 presents reported GHGRP N20 and C02 flaring emissions, the calculated N20-to-C02 ratio, 2018 GHGI C02 emissions, and the resulting scaled N20 emissions, for RY2016. This table focuses on sources that currently use a GHGRP-based methodology in the GHGI, but also includes reference GHGRP data for sources in this memo where updates are being considered. Table 5. Preliminary National N20 Emissions Estimates for Flaring Sources in Natural Gas and Petroleum Systems, Year 2016 GHGRP Flaring Estimated Emission Source GHGRP N20 C02 Ratio of 2018 GHGI National (as reported)3 (as reported) N20:C02 CO2 Total N2O (mt) (mt) (xl00,000) (mt) (mt) Natural Gas & Petroleum Production Tank Flaring 9.3 4,966,089 - 8,510,234 16.7 NG: Large Condensate Tanks w/Flares 1.0 1,063,935 0.1 1,172,292 1.0 NG: Small Condensate Tanks w/Flares + 31,800 0.1 35,039 + Petro: Large Oil Tanks w/Flares 8.2 3,859,139 0.2 7,281,742 15.6 Petro: Small Oil Tanks w/Flares + 11,215 0.1 21,161 + Associated Gas 21.6 7,312,187 - 9,102,967 26.9 Petro: Associated Gas Flaring 21.6 7,312,187 0.3 9,102,967 26.9 NG: Flared Gas Well Completions and Workovers 2.1 135,343 - 186,054 2.3 HF Completions - Non-REC with Flaring + 8,872 0.2 8,710 + HF Completions - REC with Flaring 2.1 110,800 1.9 110,998 2.1 Non-HF Completions - flared + 1,876 0.2 16,407 + HF Workovers - Non-REC with Flaring + 279 0.4 10,669 + HF Workovers - REC with Flaring + 1,582 0.2 33,436 0.1 Non-HF Workovers - flared 0 11,933 0 5,836 0 Petro: Flared Oil Well HF Completions and Workovers 18.2 757,150 - 4,382 + HF Completions - Non-REC with Flaring 0.3 136,782 0.2 4,365a + HF Completions - REC with Flaring 17.9 618,126 2.9 16a + HF Workovers - Non-REC with Flaring + 2,024 0.1 NEa + HF Workovers - REC with Flaring 0 218 0 NEa 0 Miscellaneous Production Flaring 7.7 2,633,587 - 3,583,254 10.4 NG 3.3 991,718 0.3 1,128,617 3.8 Petro 4.4 1,641,869 0.3 2,454,637 6.6 Well Testing + 13,800 - 34,803 0.1 NG 0 220 0 323 0 Petro + 13,580 0.2 34,481 0.1 Gathering and Boosting 25.9 5,930,105 - 225,373 1.0 Gathering and Boosting Stations 25.9 5,930,105b 0.4 225,373ab 1.0 Offshore Production 10.9 457,617 - - - Offshore Flaring 10.9 457,617 2.4 368,840° 10.9° Natural Gas Processing Flare Stacks 10.4 3,621,791 0.3 5,404,328 15.5 Transmission and Storage Transmission Station Flare Stacks + 25,116 0.05 88,409 + Storage Station Flare Stacks + 2,343 0.2 15,307 + Page 6 of 19 ------- November 2018 GHGRP Flaring Estimated Emission Source GHGRP N20 C02 Ratio of 2018 GHGI National (as reported)3 (as reported) N20:C02 CO2 Total N2O (mt) (mt) (xl00,000) (mt) (mt) LNG Storage Station Flare Stacks + 2,506 _d NE +d LNG Import/Export Station Flare Stacks 0.2 97,940 _d NE 0.2d Petroleum Refining Flare Stacks 36.0 3,604,229 1.0 3,604,229 36.0 NE - Not estimated + Does not exceed 0.05 mt a - Current GHGI does not rely on subpart W data for this source, and 2018 GHGI estimated C02 emissions shown in this table do not fully account for combustion. Using C02 emissions estimates developed under the draft subpart W-based approaches discussed in the June 2018 GHGRP-based Updates memo, national N20 emissions would be approximately 53 mt for flared oil well HF completions and workovers and 28 mt for G&B station flaring. b - C02 includes vented and fugitive sources, in addition to flared sources. c - Current GHGI does not rely on subpart W data for this source. As the GHGRP reported C02 emissions exceed the current GHGI estimate, the as-reported GHGRP N20 emissions are shown. d - Current GHGI does not estimate flaring C02 from these sources. Therefore, as-reported GHGRP N20 emissions are shown as surrogate for national estimates. 1.3 Transmission Pipeline Blowdowns Updates Under Consideration As discussed above, transmission pipeline blowdowns were newly required to be reported in RY2016. EPA analyzed the RY2016 subpart W data for this source as an initial step for considering potential updates to the existing GHGI methodology. 1.3.1 Current GHGI Methodology The current GHGI shows emissions from transmission pipeline blowdowns as "pipeline venting for routine maintenance and upsets." Emissions are calculated using a CH4 EF from GRI/EPA 1996 and annual transmission pipeline miles from the U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration (PHMSA). C02 emissions are calculated from the CH4 EF and a default downstream gas profile of 93.4% CH4 and 1.0% C02. 1.3.2 Analysis of Available Data A subpart W transmission pipeline facility must report blowdown emissions from natural gas transmission pipelines (as defined at 40 CFR 98.238) that it owns and operates. EPA calculated a transmission pipeline blowdown EF from the subpart W data by summing the reported emissions and dividing by the reported transmission pipeline miles. Table 6 shows the calculated subpart W EF compared to the current GHGI EF. Note, the subpart W RY2016 data reflect approximately 50% of the total transmission pipeline mileage estimated in the current GHGI for year 2016 (147,000 of 300,000 miles). Table 6. Emission Factors (mt/pipeline mile) Calculated from Subpart W Compared to Current GHGI, for Year 2016 Data Source CH4 CO2 2018 GHGI 0.6 0.01 Subpart W 1.2 0.02 EPA compared subpart W reporters of this source to a PHMSA data set that includes transmission pipeline mileage by company, state and type (i.e., interstate or intrastate). Based on a preliminary analysis, approximately 71% of the national total interstate transmission pipeline miles and 11% of intrastate transmission pipeline miles were reported to subpart W in RY2016. EPA may further consider this distinction and calculate unique EFs for interstate and intrastate pipelines, which would be paired with activity data specific to each type. Page 7 of 19 ------- November 2018 1.3.3 Time Series Considerations Preliminary stakeholder feedback suggested that the reported subpart W data for this source might not be representative of national emissions in recent years (e.g., facilities meeting the reporting threshold might generally have larger-diameter pipelines leading to higher emissions per mile). As discussed above, EPA is considering whether sufficient data are available to develop separate EFs and accompanying activity data for interstate versus intrastate pipelines as a potential means to recognize differences in the reporting versus nonreporting population. Establishing subcategories might offer improved representativeness, but is dependent on identifying an accurate method for categorizing subpart W data (interstate versus instrastate designation is not directly reported but might be inferred through analysis of external data sets such as published by PHMSA) and the statistical characterization of reported data points in each category (e.g., whether the data set size and variance support establishing separate EFs). EPA continues to seek stakeholder feedback on how subpart W data for this source might be used to inform time series trends, including specific new questions in Section 4 regarding the establishment of subcategories. 1.3.4 Preliminary National Emissions Estimates Table 7 below shows national total emissions for select time series years based on one approach EPA is considering for the 2019 GHGI public review draft: using existing GHGI activity (pipeline miles) for all years; existing EFs for years 1990 through 1992; newly calculated EFs from subpart W data starting in year 2016; and linear interpolation to calculate EFs in intermediate years. EPA notes that multiple approaches are under consideration and seeks stakeholder feedback on the most appropriate approach. Note, the current GHGI methodology involves first calculating potential emissions for this source (i.e., EF multiplied by activity), then subtracting voluntary reductions (i.e., quantity of emissions reduced as reported to EPA's GasSTAR program) to calculate net emissions. EPA seeks stakeholder feedback on whether and how to reflect voluntary reductions in the update under consideration (e.g. does the updated approach reflect net emissions, and therefore an adjustment to include Gas STAR would double count reductions?). Table 7. Preliminary National Emissions Estimates for Transmission Pipeline Blowdowns, Select Years Data Element 1990 2000 2005 2010 2015 2016 2018 GHGI # Pipeline miles 291,925 298,957 300,468 304,803 300,376 300,645 Cm EF (mt/mile) 0.61 0.61 0.61 0.61 0.61 0.61 CO2 EF (mt/mile) 0.018 0.018 0.018 0.018 0.018 0.018 Potential total CH4 emissions (kt) 178 182 183 186 184 183 Net total CH4 emissions (kt) 178 149 58 58 124 124 Total CO2 emissions (kt) 5 5 5 5 5 5 Update under consideration CH4 EF (mt/mile) 0.61 0.81 0.93 1.05 1.17 1.20 CO2 EF (mt/mile) 0.018 0.020 0.021 0.022 0.024 0.024 Total CH4 emissions (kt) 178 241 279 320 353 360 Total CO2 emissions (kt) 5 6 6 7 7 7 EPA continues to seek stakeholder feedback on how subpart W data for this source might be used to update the time series estimates in the GHGI, including specific new questions in Section 4 regarding EFs calculated from subpart W data. Page 8 of 19 ------- November 2018 2 Updating Well-related Activity Data Appendix B provides a table that shows all well-related activity data over the time series as used in the 2018 GHGI, as well as data elements from updates under consideration, as discussed below. Note that several existing GHGI methodologies documented e.g., developing counts of active wells) rely on EPA's analysis of Drillinglnfo's subscription-based digital Dl Desktop raw data feed6; this data set is referred to throughout this memo as "Drillinglnfo data." 2,1 Well Drilling The U.S. Department of Energy's Energy Information Administration (DOE/EIA) no longer maintains the Monthly Energy Review well drilling activity data set that was used to develop well drilling activity inputs in past GHGIs (most recent estimates cover through 2010), so the GHGI requires a new data source for the entire time series, or at least from 2011 forward. As described in the June 2018 Well-related Activity Updates memo, EPA did not identify another data set published by EIA that provides complete well drilling activity over the GHGI time series. EPA developed a methodology for querying the Drillinglnfo data set to develop estimates of wells drilled and presented preliminary results in the June 2018 Well-related Activity Updates memo. The Drillinglnfo-based approach is: • Count all wells drilled in time series year N with: o Onshore location -and- o Spud date within year N -or- spud date not reported, but date of first production within year N+l • Apportion counts between oil, gas, and dry production types o Dry or temporarily inactive (TIA) wells drilled: spud date within year N, but no production is reported in year N+l o Gas wells drilled: GOR in year N+l >100 mcf/bbl o Oil wells drilled: GOR in year N+l < 100 mcf/bbl • Apportion dry/TIA counts to natural gas and petroleum systems according to the year-specific split between gas wells drilled and oil wells drilled. Stakeholder feedback on the Drillinglnfo-based approach noted that preliminary estimates appeared reasonable for incorporation into the GHGI. For a Drillinglnfo-based methodology, EPA sought feedback on a few additional considerations. First, whether this approach adequately accounts for dry wells (which are spud but do not achieve reportable production levels). Based on preliminary analysis of results, this approach does appear to sufficiently represent dry wells at comparable levels to the EIA data set; on average, dry wells (not including TIA wells which report production after year N+l) contribute 10% of total wells drilled. Second, whether this approach is overly inclusive of wells that may not be drilled for oil and gas production purposes but are present in the Drillinglnfo data set. Second, how to account for time series coverage issues. For states without recently released data, EPA plans to develop a surrogate methodology wherein an early year's data are assigned to recent years to fill state-level data gaps, similar to the existing approach for counts of active wells. Additionally, total wells drilled in most recent time series year cannot be fully estimated by the current approach (i.e., GOR in year N+l is not available); EPA plans to implement a surrogate approach of using the previous year's estimate. Appendix B shows well drilling counts across the time series in the 2018 GHGI and preliminary estimates by the Drillinglnfo data analysis approach described above. 6 https://info.drillinginfo.com/products/di-plus/ Page 9 of 19 ------- November 2018 2.2 Well Completions and Workovers As described above, the current methodology for well completion and workover event counts involves a mix of Drillinglnfo data analyses, GHGRP data analyses, and historical assumptions. EPA has conducted a preliminary analysis to assess how completion counts and workover rates reflected in the subpart W data compare to current GHGI assumptions. Regarding workover rates, the subpart W data reporting structure and requirements limit the level of detail for such an analysis, due to: (1) there is not a specific reporting element indicating whether reported wells are HF or non-HF; and (2) non-HF oil well workovers are not reported. EPA therefore analyzed the number of completion and workover events and the overall gas well workover rate, as summarized in Table 8. In response to stakeholder feedback, EPA developed the following considerations based on this analysis and the estimation that approximately 70% of gas wells in the U.S. are covered by subpart W reporting: • Non-HF gas well completion counts might be over-estimated in recent years of the GHGI. • Non-HF gas well workover counts might be under-estimated in recent years of the GHGI. • HF gas well workover counts might be over-estimated in recent years of the GHGI. Table 8. Comparison of Gas Well Event Activity Data and Calculated Workover Rate Activity Data Element Current GHGI GHGRP As-reported Basis 2015 2016 2015 2016 # Non-HF gas well completions Scaled from 400 events/year in 1992 786 770 108 88 # Non-HF gas well workovers 4.35% of active non-HF gas wells 7,549 7,315 18,031 14,957 # HF gas well workovers 1% of active HF gas wells 2,521 2,487 263 103 Overall gas well workover rate 4.35% of active non-HF gas wells; 1% of active HF gas wells 6%a 5%a a - Calculated using number of reported gas well workover events (with and without HF) divided by the number of producing wells at the end of the calendar year (reported under 40 CFR 98.236(aa), found in the "sub-basin characterization" table). Appendix B shows all categories of completion and workover counts across the entire time series in the 2018 GHGI. EPA seeks stakeholder feedback on improving the current methodology in the 2019 GHGI; see Section 4 for specific stakeholder feedback requests. 2.3 Definition of Oil versus Gas Well The current methodology estimates the count of active gas wells in a given year as all wells in the Drillinglnfo data set with a GOR > 100 mcf/bbl in that year, and active oil wells as those with GOR < 100 mcf/bbl. By this definition, oil wells include associated gas wells. Other data sets (e.g., those published by EIA) use different GOR thresholds for defining oil versus gas wells and might have different underlying assumptions regarding whether associated gas wells are a subset of oil wells. A value of 6 mcf/bbl is another common definition threshold, based on the oil and gas energy equivalence factor (6 mcf gas provides roughly the same amount of energy as 1 bbl oil equivalent (BOE); BOE is commonly used in financial statements to combine oil and gas production into a single measure). EPA reviewed available data reported under GHGRP subpart W to evaluate how reported GOR values compare to the current GHGI methodology and consider whether the current production type delineation threshold of 100 mcf/bbl is appropriate. Per subpart W, oil wells are defined as producing from an oil formation, not defined by a specific GOR threshold. Table 9 below summarizes reported GOR data based on EPA's review of subpart W RY2015-2016 summary data (Envirofacts table EF_W_FACILITY_OVERVIEW, containing data for over 400,000 wells reported to the EPA as of Page 10 of 19 ------- November 2018 August 5, 2017). For most oil wells reported under subpart W (73%), the sub-basin level average GOR falls within the current GHGI definition (<100 mcf/bbl); while a significant fraction (27%) have higher average GORs. At a lower delineation threshold (e.g., 6 mcf/bbl), an even higher fraction of subpart W oil wells (roughly 50%) would be considered gas wells. Therefore, based on this analysis, EPA finds support for the current approach to delineating oil versus gas wells, but seeks stakeholder feedback (see Section 4 for specific requests on this topic). Table 9. 2018 GHGI Well-Related Activity Data Summary # Oil Wells with Specified GOR (mcf/bbl) Reporting Year GOR <10 10< GOR <100 100< GOR <1,000 GOR >1,000 2015 123,446 28,104 11,674 48,091 [58%] [13%] [6%] [23%] 2016 117,538 33,346 21,068 32,781 [57%] [16%] [10%] [16%] Combined 240,984 61,450 32,742 80,872 [58%] [15%] [8%] [19%] In response to recent stakeholder feedback, EPA calculated oil and gas well counts across the time series by two different GOR delineation thresholds (100 mcf/bbl and 6 mcf/bbl). The results of this sensitivity analysis are shown in Figure 1. 100 mcf/bbl: Active - Gas 100 mcf/bbl: Active - Oil — — — 6 mcf/bbl: Active - Gas — — — 6 mcf/bbl: Active - Oil 700,000 200,000 100,000 600,000 577,515 534,302 -j 500,000 400,000 300,000 462,218 Figure 1. Active Oil and Gas Well Counts by Two Different GOR Delineation Thresholds 2.4 Heavy versus Light Crude Equipment Service Heavy crude is defined as oil with lower than 20° API gravity. The GHGI uses separate EFs and activity data for wellheads, separators, and headers in heavy versus light crude service. Currently, the total counts of wellheads and headers are split into heavy versus light crude categories using an assumed split between heavy crude wells Page 11 of 19 ------- November 2018 (7.05% of all oil wells) and light crude wells (92.95%). As documented in the 1999 EPA/ICF report7, this assumption, and its extension to wellhead and header activity, was developed for a 1995 base year; this split is currently applied to calculate equipment counts in all time series years. The split between heavy and light crude separators in base year 1995 is also documented in the 1999 EPA/ICF report: EPA assumed 90.1% of separators are in light crude service, and 9.9% in heavy crude service, and applied this split to all time series years. EPA has identified multiple data sources that might facilitate improvement to the current methodology by allowing calculation of the heavy versus light crude equipment splits in recent years. GHGRP subpart W collects average API gravity data associated with production in all oil sub-basins. Based on an analysis of RY2015 and RY2016 data, 19% and 18%, respectively, of oil wells reporting to GHGRP produce heavy crude. This value is higher than the current assumption of 7.05% of wells producing heavy crude (and subsequent assumption that 7.05% of wellheads and headers are in heavy crude service). To follow the existing methodology which assumes that per well equipment counts are the same for heavy crude and light crude wells (with the exception of separators, where on average over the time series each heavy crude well has 0.47 separators while each light crude well has 0.32 separators), EPA might analyze subpart W data specifically for facilities that produce heavy crude versus light crude. For this approach, however, only a subset of onshore production facility data can be analyzed—those with either all heavy crude sub-basin formation types or all light crude sub-basin formation types—since equipment counts (e.g., separators) are reported at a basin level. Table 10 summarizes the data availability and preliminary estimates of separator activity factors based on this approach. EPA might use subpart W data to update the equipment count splits in recent years and reflect updated industry trends. Table 10. Subpart W Equipment Counts3 Count of Separators/ Number of Data Separators Count of Wellheads Wellhead Points (Facilities) Data Set 2015 2016 2015 2016 2015 2016 2015 2016 Notes/Methodology All onshore oil prod Counts from records classified 76,690 86,890 213,380 221,326 0.36 0.39 319 315 in Table R.4 as "Crude oil production equipment"15 Counts from records in Table Heavy R.4 - from facilities that crude-only 1,818 345 40,894 40,063 0.04 0.01 14 14 produce only heavy crude (all facilities sub-basins are oil with API gravity <20 in Table AA.l.ii) Counts from records in Table Light crude- R.4 - from facilities that only 22,153 23,048 54,098 51,428 0.41 0.45 102 103 produce only light crude (all facilities sub-basins are oil with API gravity >20 in Table AA.l.ii) a - Data reported as of August 5, 2017. b - For this approach, data from all facilities reporting presence of crude oil production equipment for equipment leak calculations can be used (ignoring the reported sub-basin formation type(s)). EPA also reviewed the methodology documented in the 1999 Radian report which was the basis for the 1999 EPA/ICF report estimates. The 1999 Radian report methodology analyzed state-level reported heavy oil production as a fraction of total oil production, then applied that fraction to state-level oil well counts to estimate heavy oil well counts in each state, and finally summed heavy oil well counts to estimate the national population fraction. This approach does not facilitate development of a heavy versus light split for equipment other than wellheads (e.g., a specific split for separators as in the current methodology); additionally, inherent in this 7 Estimates of Methane Emissions from the U.S. Oil Industry (Draft Report). Prepared by ICF International. Office of Air and Radiation, U.S. Environmental Protection Agency. October 1999. Page 12 of 19 ------- November 2018 approach is an assumption that heavy and light crude wellheads have the same average production rates. EPA recently reviewed EIA state-level production and API gravity data and estimated that 4-5% of crude produced in the lower 48 states in recent years is heavy crude. Due to the assumptions and limitations of this analysis (i.e., using production split between heavy and light as surrogate for wellhead split), EPA is focusing further efforts toward how subpart W data, such as that summarized in Table 10, might be used to update the GHGI for recent time series years. EPA seeks stakeholder feedback on the data sources and approaches described above, or other methodologies to consider for improving this aspect of the oil production segment major equipment activity estimates; see Section 4 for specific stakeholder feedback requests on this topic. 2,5 Identification of HF Wells Appendix B shows current GHGI estimates of HF gas and oil well counts. There are limited public data estimating national total counts comparable to the GHGI; Appendix B shows year 2016 estimates from ElA's Today in Energy website. EPA seeks stakeholder feedback on data sources and methodologies that might be used to update the current approach for identifying HF gas and oil wells within the Drillinglnfo data set. EPA might retain the current assumption that all horizontally drilled wells are hydraulically fractured but update the methodology for identifying wells that do not report horizontal drill type but would be expected to be hydraulically fractured based on location in an unconventional formation. EPA is considering reviewing subpart W sub-basin-level (county-level) data to assess whether a crosswalk of location and HF indication might be constructed from or verified using reporting data, in order to estimate total national HF well counts (at least for recent time series years). si Anomalous Leak Events In recent GHGIs, EPA incorporated an emissions estimate for the Aliso Canyon gas leak during years 2015 and 2016 in the storage well category. EPA used the California Air Resources Board (CARB) published estimate of the methane release from the leak.8 EPA seeks stakeholder feedback on existing data sources or suggested methodologies for identifying similar events across natural gas and petroleum systems, with emissions beyond what is likely accounted for in GHGI EFs. 4 Requests fc keholder Feedback HF Oil Well Completions and Workovers (Section 1.1) 1. EPA seeks feedback on the national representativeness of subpart W-based HF oil well completion and workover emissions factors (emissions per event) and activity factors (i.e., allocation of total event counts across four control categories). 2. EPA seeks feedback on how to consider regional and temporal variability for HF oil well completions and workovers. 3. EPA seeks stakeholder feedback on the methodology and assumptions for allocating events into the four control categories across the time series (i.e., control category AFs, as detailed in Section 4.2). Specifically, for years 1990-2007, it is assumed all events are non-REC, and 10% of events flare; in contrast, the GHGI methodology for HF gas well event AFs assumes that RECs are introduced earlier, in year 2000. 4. Historical analyses for HF gas well events data (RY2011-2015) included all HF well event data reported, and therefore might have included reported data from HF oil well events if any reporters reported data from these activities in those years. Should EPA revisit these historical EFs (e.g., discard from the EF data 8 https://www.epa.gov/sites/production/files/2017-04/documents/2017_aliso_canyon_estimate.pdf Page 13 of 19 ------- November 2018 set any events seemingly conducted at oil wells? develop factors specific to oil well events prior to RY2016?)? N2Q Emissions (Section 1.2) 5. EPA seeks feedback on updating the GHGI to include N20 from flaring, based on GHGRP data. a. Specifically, EPA seeks feedback on time series calculations—such as whether calculated ratios of N20:C02 from GHGRP from 2016 (or several years') data could be applied to each year of the time series from 1990-2017. 6. EPA seeks feedback on other available data sources for N20 emissions. Transmission Pipeline Blowdowns (Section 1.3) 7. EPA seeks feedback on the general use of subpart W data to update the current GHGI methodology for this source. 8. Are the EFs calculated from RY2016 subpart W data (shown in Table 6) nationally representative,specifically: a. Should EFs calculated from subpart W data be applied to the non-reporting population (approximately 50% of national total pipeline mileage) or is there a more appropriate approach for estimating emissions from this population? b. Do available subpart W data support development of subcategories that might improve EF representativeness—for example interstate versus intrastate EFs? 9. EPA seeks feedback on time series calculations, specifically a. Whether GHGI EFs be retained for early time series years or if subpart W EFs should be applied for all years. b. Whether year-specific EF(s) should be developed from subpart W data for RY2016 forward. Based on preliminary analyses, EPA notes significant variation in calculated EFs in the available years of subpart W data. Specifically, the average RY2016 CH4 EF was calculated to be 1.2 mt/mile, compared to 0.6 mt/mile using recently published RY2017 data. EPA seeks stakeholder feedback on whether these differences reflect industry trends, or if an approach such as combining early reporting years' data is appropriate. 10. EPA seeks feedback on whether and how to include GasSTAR reductions in an updated methodology for this source. Well Drilling (Section 2.1) 11. EPA seeks stakeholder feedback on data available to improve annual national activity estimates for well drilling across the time series. EPA seeks feedback on the most appropriate data source for updating the GHGI, whether it is highlighted in Section 2.1 (i.e., EIA or Drillinglnfo) or another source that should be considered. 12. EPA seeks feedback on how to ensure time series consistency, given the current EIA data source provides annual activity through 2010. Should a new data source cover only recent years, or be used to entirely replace current estimates? 13. As EPA further considers developing annual well drilling activity estimates from Drillinglnfo data, feedback is sought on the specific methodology and other considerations outlined in Section 2.1. Specifically: a. Whether this approach adequately accounts for dry wells (which are spud but do not achieve reportable production levels). Based on preliminary analysis of results, this approach does appear to sufficiently represent dry wells at comparable levels to the EIA data set; on average, dry wells (not including TIA wells which report production after year N+l) contribute 10% of total wells drilled. b. Whether this approach is overly inclusive of wells that may not be drilled for oil and gas production purposes but are present in the Drillinglnfo data set (e.g., wells drilled specifically for Page 14 of 19 ------- November 2018 injection). EPA expects a minor contribution from such wells, since estimates developed from the Drillinglnfo approach under consideration are comparable with EIA estimates for the overlapping time frame (1990-2010), as shown in Appendix B. EPA estimates that that injection wells might contribute approximately 2-4% to total counts; it is difficult to identify such wells in the Drillinglnfo data set due to the presence of hundreds of reported production types. EPA seeks feedback on how the Drillinglnfo-based methodology might take this issue into account. c. How to account for time series coverage issues (due to states with lagging reporting and therefore not fully represented in the Drillinglnfo data set in recent years). Well Completions and Workovers (Section 2.2) 14. EPA seeks stakeholder feedback on how to use available data to improve national activity estimates for well completion and workover events—specifically, how Drillinglnfo and subpart W data sets might be used in conjunction, or if one data set should be used to develop estimates and the other to verify estimates. Definition of Oil vs. Gas Well (Section 2.3) 15. EPA seeks stakeholder feedback on whether the current methodology for counting and allocating active well counts between oil and gas should be updated, and if so, how. Heavy vs. Light Crude Equipment Service (Section 2.4) 16. Based on RY2015 and RY2016 subpart W data, 19% and 18%, respectively, of oil wells in that data set produce heavy crude (API gravity less than 20), compared to the current GHGI basis of 7.05%. This updated heavy crude fraction is based on reported data for approximately 210,000 active oil wells (out of approximately 580,000 active oil wells nationwide). EPA seeks stakeholder feedback on incorporating this updated fraction into the GHGI time series. a. Should EPA consider developing geographic-specific (e.g., NEMS region-level) estimates of heavy crude well fractions? b. Should EPA retain the estimate of 7.05% of oil wells producing heavy crude (developed for base year 1995) for early years of the time series, and interpolate to the updated fraction based on subpart W data? Or is a different approach more appropriate—for example, where the heavy crude fraction is more tailored to the specific time period, rather than a set or linearly increasing value? EPA seeks information on data sources that might offer information to implement a more tailored approach. 17. How should EPA use API gravity data in conjunction with equipment count data reported under subpart W to improve oil production segment major equipment activity estimates? For example, Table 10 above presents activity factors for separators per oil well developed specifically for heavy and light crude populations. a. Should EPA retain the current approach of extending the heavy/light crude well count split to wellhead and header activity data (for example, 19% of oil wells produce heavy crude, therefore 19% of headers are in heavy crude service)? b. Should EPA retain the current approach of developing specific activity factors for separators in heavy versus light crude service, as shown in Table 10? Identification of HF Wells (Section 2.5) 18. EPA seeks stakeholder feedback on whether it is reasonable to retain the current assumption that all wells with horizontal drill type according to the Drillinglnfo data set are hydraulically fractured, or if there are recommendations for improving this assumption. 19. EPA seeks input on publicly available data sources and methodologies that might be used to identify wells that do not report horizontal drill type in the Drillinglnfo data set but would be expected to be Page 15 of 19 ------- November 2018 hydraulically fractured based on location in an unconventional formation (i.e., used to create a new formation type crosswalk). a. EPA specifically seeks feedback on how GHGRP subpart W data might be used in this step to construct or verify such a crosswalk. Anomalous Leak Events (Section 3) 20. EPA seeks stakeholder feedback on existing data sources or suggested methodologies for identifying similar events across natural gas and petroleum systems, with emissions beyond what is likely accounted for in GHGI EFs. 21. EPA seeks information from stakeholders on any anomalous leak events that have occurred over the 1990-2017 time series that should be included in the 2019 GHGI, in addition to the Aliso Canyon leak in years 2015 and 2016. Page 16 of 19 ------- November 2018 Appendix A, GHGRP Measurement Methodologies from Data Sources Considered for Updates Emission Source Measurement and/or Calculation Type # Sources Location & Representativeness EF Calculation Method Oil Well HF Completions and Workovers Emissions calculated for each event, based on (1) measured actual flowback gas volumes from the well or (2) calculated flowback gas volume based on well parameters (e.g., pressure differentials, temps). If flared, then flare control efficiency is applied. Emissions data (for 2016) are available for 4,059 completions and 330 workover events at HF oil wells Facilities in the U.S. that exceed 25,000 mt C02e reporting threshold. For this memo, the EPA used reported data to calculate, event/control category specific (e.g., REC, flare), average EFs Flare Stacks CH4 and C02 emissions calculated using: (1) gas volume sent to the flare, (2) combustion efficiency (from manufacturer or assume 98%), fraction of feed gas sent to an un-lit flare, and (3) gas composition for C02, CH4, and hydrocarbon constituents. N20 emissions calculated using amount of fuel combusted, fuel heating value, and prescribed EF of 1.0 x 10-4 kg N20/mmBtu Varies by industry segment Facilities in the U.S. that exceed 25,000 mt C02e reporting threshold. For this memo, to estimate emissions for each source, EPA calculated a ratio of the GHGRP reported N20 emissions to C02 emissions and then multiplied the N20-to-C02 ratio by the 2018 GHGI C02 emissions Transmission Blowdown Vent Stack Emissions calculated using: • Blowdown volumes, number of blowdowns, and the ideal gas low modified for compressibility; or • Flow meter to measure emissions for all equipment associated with a blowdown event. Blowdown volumes <50 scf are exempt. Emissions data (for 2016) are available from 9,093 blowdowns (which occurred over 147,187 miles). Facilities in the U.S. that exceed 25,000 mt C02e reporting threshold. For this memo, EPA calculated EFs as a straight average of all available data. Page 17 of 19 ------- November 2018 Appendix B. Well-Related Activity Data 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Well counts 2018 GHGI Non-HF gas wells 135,552 141,052 139,823 140,834 142,127 142,245 144,501 144,082 148,078 148,112 144,545 156,621 157,696 162,506 167,595 168,855 175,567 178,970 187,366 186,667 187,098 187,153 182,776 179,300 179,305 173,544 168,151 HF gas wells 62,074 78,538 76,875 82,527 88,242 90,423 99,399 103,820 108,880 113,260 122,364 135,526 142,815 154,003 162,832 179,615 195,683 207,348 227,138 234,576 242,301 248,162 250,614 248,528 252,141 252,107 248,730 Total active gas wells 197,626 219,590 216,698 223,361 230,369 232,668 243,900 247,902 256,958 261,372 266,909 292,147 300,511 316,509 330,427 348,470 371,250 386,318 414,504 421,243 429,399 435,315 433,390 427,828 431,446 425,651 416,881 Non-HF oil wells * 469,317 467,760 454,605 446,499 432,774 423,199 418,579 419,582 401,394 381,938 382,314 379,071 375,274 372,953 372,994 374,960 379,859 380,541 391,513 387,949 389,226 393,598 401,244 404,373 405,284 398,424 373,608 HF oil wells* 84,582 88,843 86,070 87,745 87,088 84,442 86,754 87,650 84,935 82,132 84,785 86,243 86,547 88,223 91,457 94,672 98,627 97,217 112,992 113,657 123,494 135,121 151,260 165,297 184,166 191,593 188,356 Total active oil wells 553,899 556,603 540,675 534,244 519,862 507,641 505,333 507,232 486,329 464,070 467,099 465,314 461,821 461,176 464,451 469,632 478,486 477,758 504,505 501,606 512,720 528,719 552,504 569,670 589,450 590,017 561,964 Total HF wells * 146,656 167,381 162,945 170,272 175,330 174,865 186,153 191,470 193,815 195,392 207,149 221,769 229,362 242,226 254,289 274,287 294,310 304,565 340,130 348,233 365,795 383,283 401,874 413,825 436,307 443,700 437,086 Total active wells 751,525 776,193 757,373 757,605 750,231 740,309 749,233 755,134 743,287 725,442 734,008 757,461 762,332 777,685 794,878 818,102 849,736 864,076 919,009 922,849 942,119 964,034 985,894 997,498 1,020,896 1,015,668 978,845 EIA Today in Energy Total HF wells NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA 670,000 Total active wells NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA NPA 977,000 Drilling event counts 2018 GHGI Gas wells drilled (incl. fraction of dry) 15,096 13,066 10,887 13,047 12,232 10,465 11,498 14,473 14,507 14,564 19,863 25,350 20,041 23,582 27,180 31,969 36,536 36,255 35,824 20,266 18,837 18,837 18,837 18,837 18,837 18,837 18,837 Oil wells drilled (incl. fraction of dry) 17,234 16,796 12,540 11,744 9,587 10,679 11,255 14,105 9,575 5,818 9,424 10,208 7,830 9,251 9,877 12,053 14,893 14,816 18,478 12,537 17,774 17,774 17,774 17,774 17,774 17,774 17,774 Total wells drilled 32,330 29,862 23,427 24,791 21,819 21,144 22,753 28,578 24,082 20,382 29,287 35,558 27,871 32,833 37,057 44,022 51,429 51,071 54,302 32,803 36,611 36,611 36,611 36,611 36,611 36,611 36,611 Preliminary Drillinglnfo Data Analysis (described in Section 2.1)a Gas 13,417 6,719 7,464 6,794 7,208 7,648 16,608 9,557 9,089 10,507 14,449 17,131 14,390 17,237 20,018 23,060 24,733 24,964 23,600 11,636 12,172 9,206 5,512 4,725 4,385 2,580 1,550 Oil 15,013 11,030 11,854 10,720 9,145 10,210 18,925 12,636 7,746 8,447 10,981 11,232 9,558 11,570 13,498 15,553 16,951 18,820 18,633 12,566 20,697 25,874 29,953 30,422 30,209 14,049 8,246 Dry/TIA 7,971 5,650 5,220 4,641 4,249 3,909 4,228 4,601 3,898 3,601 5,095 6,782 4,875 5,549 6,477 6,872 9,190 7,631 9,232 4,773 5,614 6,271 5,781 5,304 7,037 3,861 1,964 Gas wells drilled (incl. fraction of dry/TIA) 17,179 8,858 9,481 8,594 9,081 9,322 18,584 11,538 11,193 12,503 17,344 21,227 17,319 20,557 23,886 27,164 30,186 29,315 28,759 13,931 14,251 10,852 6,410 5,438 5,277 3,179 1,861 Oil wells drilled (incl. fraction of dry/TIA) 19,222 14,541 15,057 13,561 11,521 12,445 21,177 15,256 9,540 10,052 13,181 13,918 11,504 13,799 16,107 18,321 20,688 22,100 22,706 15,044 24,232 30,499 34,836 35,013 36,354 17,311 9,899 Total wells drilled 36,401 23,399 24,538 22,155 20,602 21,767 39,761 26,794 20,733 22,555 30,525 35,145 28,823 34,356 39,993 45,485 50,874 51,415 51,465 28,975 38,483 41,351 41,246 40,451 41,631 20,490 11,760 Completion event counts 2018 GHGI Gas well non-HF completions 365 405 400 412 425 429 450 458 474 482 493 539 555 584 610 643 685 713 765 778 793 804 800 790 796 786 770 Gas well HF completions 3,769 3,630 2,630 3,425 3,322 3,034 4,057 5,352 4,785 4,583 6,881 8,675 7,536 8,911 10,459 12,866 14,176 14,206 15,223 8,811 8,691 9,749 7,665 7,382 7,141 5,272 3,105 Oil well non-HF completions 9,764 9,644 6,395 5,916 4,742 5,855 6,203 7,671 5,359 3,476 5,844 5,791 4,285 4,618 5,046 6,185 7,369 7,142 8,305 6,117 7,565 3,252 0 0 0 3,315 3,315 Oil well HF completions 3,075 2,944 3,007 2,940 2,606 2,393 2,633 3,535 2,323 1,329 2,246 3,097 2,490 3,511 3,743 4,594 6,016 6,229 8,328 5,073 8,188 12,501 16,335 17,332 19,154 12,438 12,438 Workover event counts Page 18 of 19 ------- November 2018 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2018 GHGI Gas well non-HF workovers 5,897 6,136 6,082 6,126 6,183 6,188 6,286 6,268 6,441 6,443 6,288 6,813 6,860 7,069 7,290 7,345 7,637 7,785 8,150 8,120 8,139 8,141 7,951 7,800 7,800 7,549 7,315 Gas well HF workovers 621 785 769 825 882 904 994 1,038 1,089 1,133 1,224 1,355 1,428 1,540 1,628 1,796 1,957 2,073 2,271 2,346 2,423 2,482 2,506 2,485 2,521 2,521 2,487 Oil well workovers 41,542 41,745 40,551 40,068 38,990 38,073 37,900 38,042 36,475 34,805 35,032 34,899 34,637 34,588 34,834 35,222 35,886 35,832 37,838 37,620 38,454 39,654 41,438 42,725 44,209 44,251 42,147 * Values not published in the 2018 GHGI, but underlie the current estimates of HF oil well completion event counts N/A - Not applicable NPA - Not publicly available NE - Not estimated a - Results of preliminary approach discussed in Section 2.1. This does not include state-level adjustments to account for lagging reporting that EPA implements for other well-related data elements that are based on Drillinglnfo data. After adjustments that would be implemented in a final methodology, estimates in recent years (e.g., 2015 forward) will likely increase. Page 19 of 19 ------- |