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## MEMORANDUM **TO:** Mark de Figueiredo, EPA **FROM:** Casey MacQueen, ERG

Jessica Gray, P.E. , E RG **DATE:** August 18, 2015 **SUBJECT: DrillingInfo Processing Methodology**  ERG’s analysis started with the May 2014 data set that was delivered to EPA/OECA/Office of Compliance (OC)
— a processed version of data originally obtained from Drilling I nfo in February 2014
. ERG’s deliverable accompanying this documentation memorandum is limited to records that meet the following criteria:

 Wells with gas or hydrocarbon liquid production during 2010 to 2012; and  Wells with completion year of 2010 to current ( note, the more recent wells may not yet have reported production). The processing methodology used to compile the OC data set upon whic h this analysis is based incorporates various assumptions as documented in

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Table 1 below (e.g., how the methodology combines records with duplicate API numbers) . Additionally, ERG notes that some well production data are reported to states on a lease

- level (i.e., covering multiple wells) rather than on an individual well

- level. ERG’s general approach to processing such records is to distribute lease

- level production ac ross all wells on the lease (i.e., the total production for the lease is divided evenly among all the wells on the lease) . Specifically, note that for records with lease

- level reporting :

 All wells on a lease are assigned the FIRST_PROD_DATE of the first well on the lease, and lease

level production from the FIRST_PROD_DATE forward is distributed across all wells currently on the lease.

 The initial production values (e.g., FIRST6_LIQ) associated with the earliest well on the lease are distributed across all wells currently on the lease.

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Table 2 provides a summary of the lease

- level reporting by state for wells with production during 2010
– 2012
.

### 4 **Table 1** **. Field Names and Descriptions**  **Column Name Description**  ENTITY_ID DrillingInfo assigned unique property ID. Note: for instances where duplicate API numbers were combined, the minimum value was selected. SPOT_ID DrillingInfo assigned unique ID for multiple API numbers on one lease or directional side tracks for the same location. API_NO API assigned number of a well on the property. PROPERTY_TYPE Property type (WELL – Well; UNIT
– Unit; LEASE
– Lease; SWD
– Salt water disposal; DRIP POINT
– Drip Point; COM
- Completion). Note: for instances where duplicate API numbers were combined, the minimum value was selected. PRODUCTION_TYPE Production type (e.g., oil, gas, coalbed methane, injection). Note: for instances where duplicate API numbers were combined, the production type fields are comma separated. PROD_TYPE_CLASS Classification of reported PRODUCTION_TYPE into standardized categories: D&A (drilled and abandoned), gas, injection, O&G (oil and gas), oil, and other
. PROD_FLAG Production flag to indicate whether the well should be producing liquids. This is “Yes” for “Gas,” “Oil,” and “O&G” production type classification. LIQUID_PROD_TYPE Liquid production type (i.e., unknown, condensate, or oil) based on the producti on type classification (gas = condensate, oil = oil, all others = unknown) and well test data (revise unknown assignments based on the test liquid gravity; oil if liquid gravity <40 and condensate if liquid gravity ≥40). WELL_NAME Operator assigned well/l ease name of the property. Note: for instances where duplicate API numbers were combined, the minimum value was selected. LEASE_NO State number assigned to the property or lease or unit the property is part of. Note: for instances where duplicate API numbers were combined, the minimum value was selected. WELL_NO Operator assigned well number of the property. Note: for instances where duplicate API numbers were combined, the minimum value was selected. CURR_OPER_NAME Current operator name. Note: for instances where duplicate API numbers were combined, the minimum value was selected. COMMON_OPER_NAME Corporate entity that is determined by DI Desktop to own the current operator. Note: for instances where duplicate API numbers were combined, the minimum value was selected. LATITUDE_NAD83 Surface latitude the property is located in; for multi

-well properties DI Desktop picked a well to designate the location of the property, NAD83. Note: for instances where duplicate API numbers were combined, the maximu m value was selected. LONGITUDE_NAD83 Surface longitude the property is located in; for multi

-well properties DI Desktop picked a well to designate the location of the property, NAD83. Note: for instances where duplicate API numbers were combined, the min imum value was selected. COUNTY County the property is located in. Note: for instances where duplicate API numbers were combined, the minimum value was selected. FIPS_CODE Federal Information Processing Standard county code based on county or GIS analysis using latitude and longitude. STATE State the property is located in. Note: for instances where duplicate API numbers were combined, the minimum value was selected. EPA_REGION EPA region the property is located in. OFFSHORE Indicates if the pro perty is located offshore. Note: for instances were duplicate API numbers were combined, the maximum value was selected.

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**Column Name Description**  BASIN Basin the property is located in. Note: for instances where duplicate API numbers were combined, the minimum value was selected. RESERVOIR Reservoir the property is located in. Note: for instances where duplicate API numbers were combined, the minimum value was selected. FORMATION Formation the property is reporting from. Note: for instances where duplicate API numbers were combined, the minimum value was selected. FIELD Field name the property is reporting from. Note: for instances where duplicate API numbers were combined, the minimum value was selected. RESERVOIR_TYPE Determined based on RESERVOIR, FIELD, and STATE CV
– Conventional; CB
– Coal Bed Methane; LP – Low Permeability; SH
– Shale; Blank
– Unknown UNCONV_RESERVOIR Determined based on reservoir type; Yes = CB, LP, and SH; No = CV or Blank. STATUS Current status of the well (e.g., active, inactive, shut in). Note: for instances where duplicate API numbers were combined, the minimum value was selected. TOTAL_DEPTH Total depth the property was drilled to. Note: for instances where duplicate API numbers were combined, the maximum value was selected. DRILL_TYPE Drill type (U
– Unknown ; H – Horizontal; V
– Vertical; D
– Directional). Note: for instances where duplicate API numbers were combined, the minimum value was selected. SPUD_DATE Latest date drilling commenced on property. Note: for instances where duplicate API numbers were combined, the minimum value was selected. COMPLETION_DATE Latest completion date of the property. Note: for instances where duplicate API numbers were combined, the minimum value was selected. PLUG_DATE Date the well was plugged. Note: for instances where duplicate API numbers were combined, the maximum value was selected. COMPLETION_YEAR Determined based on completion date year, if populated, or minimum production year. HF Yes if drill type is horizontal (H) or unconventional reservoir is yes (i.e., coalbed methane (CB), low permeability (LP), or shale (SH)). FIRST_PROD_DATE First date DI Desktop has reported production for the property. Note: for instances where duplicate API numbers were combined, the minimum value was selected. LAST_PROD_DATE Last date DI Desktop has reported production for the property. Note: Even though the date may be represented as mm/dd/yyyy, it is for the month listed, not just the individual day. For example, production through December 2009 is listed as 12/1/2009. Note: for instances where duplicate API numbers were combined, the maximum value is selected. FIRST_LIQ Liquid production reported in Bbl during the first month of production. FIRST_GAS Gas production reported in MCF during the first month of production. FIRST6_LIQ The sum of 1 st 6 calendar months of liquid production reported in Bbl . The first month is the first month of the production of any type of product. FIRST6_GAS The sum of 1 st 6 calendar months of gas production reported in MCF. The first month is the first month of the production of any type of product. FIRST12_LIQ The sum of the 1 st 12 calendar months of liquid production reported in Bbl . The first month is the first month of production of any type of production. FIRST12_GAS The sum of the 1 st 12 calendar months of gas production reported in MCF. The first month is the first month of production of any type of production. SUMOFLIQ_DAILY Average daily liquid production in last 12 months, summed over duplicate API numbers.

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**Column Name Description**  SUMOFGAS_DAILY Average daily gas production in last 12 months, summed over duplicate API numbers. SUMOFLIQ_CUM Cumulative liquid production of property, reported in bbl, summed over duplicate API numbers. SUMOFGAS_CUM Cumulative gas production of property, reported in MCF, summed over duplicate API numbers. SUMOFWTR_CUM Cumulative water production of property, summed over duplicate API numbers. LIQ_GRAV Gravity of the liquid produced from the property. Note: for instances where duplicate API numbers were combined, the maximum value was selected. GAS_GRAV Gravity of the gas produced from the property. Note: for instances where duplicate API numbers were combined, the maximum value was selected. GOR Gas to oil ratio of the property. Note: for instances where duplicate API numbers were combined, the maximum value was selected. GOR_LATEST_MO Gas to oil ratio of the property for the latest month of production. Note: for instances where duplicate API numbers were combined, the maximum value was se lected. GOR_CUM Gas to oil ratio of the property for all months of production. Note: for instances where duplicate API numbers were combined, the maximum value was selected. YIELD Oil to gas ratio of the property. Note: for instances where duplicate API numbers were combined, the minimum value was selected. MONTHS_PRODUCED Number of months a property has reported liquid, gas, or water production. Note: for instances where duplicate API numbers were combined, the maximum value was selected. SUMOFLIQ_YEAR Liquid production, reported in bbl, for the 12 months ending with LAST_PROD_DATE, summed over duplicate API numbers. SUMOFGAS_YEAR Gas production, reported in MCF, for the 12 months ending with LAST_PROD_DATE, summed over duplicate API numbers. SUMOFWTR_YEAR Water production, reported in bbl, for the 12 months ending with LAST_PROD_DATE, summed over duplicate API numbers. SUMOFLIQ10 Liquid production, reported in bbl, summed over duplicate API numbers. SUMOFGAS10 Gas production, reported in MCF, summed over duplicate API numbers. SUMOFWTR10 Water production, reported in bbl, summed over duplicate API numbers. SUMOFLIQ11 Liquid production, reported in bbl, summed over duplicate API numbers. SUMOFGAS11 Gas production, reported in MCF, summed over dupli cate API numbers. SUMOFWTR11 Water production, reported in bbl, summed over duplicate API numbers. SUMOFLIQ12 Liquid production, reported in bbl, summed over duplicate API numbers. SUMOFGAS12 Gas production, reported in MCF, summed over duplicate API numbers. SUMOFWTR12 Water production, reported in bbl, summed over duplicate API numbers. SUMOFLIQ13 Liquid production, reported in bbl, for 2013, summed over duplicate API numbers. SUMOFGAS13 Gas production, reported in MCF, for 2013, summed over dupli cate API numbers. SUMOFWTR13 Water production, reported in bbl, for 2013, summed over duplicate API numbers. PROD10_FLAG Yes/No flag indicating if liquid and/or gas production >0. PROD11_FLAG Yes/No flag indicating if liquid and/or gas production >0. PROD12_FLAG Yes/No flag indicating if liquid and/or gas production >0. PROD13_FLAG Yes/No flag indicating if liquid and/or gas production >0.

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**Column Name Description**  NNA_FLAG Flag for whether the well is located in an 8

-hour ozone nonattainment area (2008 standard), as defined with the GIS layer available here: http://www.epa.gov/airquality/greenbook/gis_download.html. The flag identifies the specific type of 8

-hour ozone classification the well is located within (i.e., extreme, severe 15, serious, moderate, or marginal). SSA_F LAG Flag for if the well is located over a sole source aquifer, as defined with the GIS layer available here: http://water.epa.gov/infrastructure/drinkingwater/sourcewater/protection/solesourc eaquifer.cfm. “Yes” means the well is over a sole source aquifer
. FEDERAL_FLAG Flag for if the well is located on federal lands, as defined with the GIS layer available here: http://nationalatlas.gov/atlasftp.html?openChapters=chpbound#chpbound. "Yes" means the well is on federal land. ACTIVE_FLAG Yes/No flag indicating active status based on latest production date. ACTIVE_PROD_FLAG Yes/No flag indicating whether entity produced liquid and/or gas in 2009

-2012, using the production flags. SHALE_FLAG Yes/No flag for Pennsylvania only indicating if the type of producti on is shale gas.

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**Table 2** **. Summary of Lease -** **level Reporting for Wells with Production during 2010 –**  **2012**

**State Total # Wells**  **Total # Lease****** **level Reports # Wells with** 

**Lease -** **level Reporting**  **% of Total**

**Wells with**  **Lease -** **level Reporting**  TX 607,985 31,449 289,122 48 KS 138,891 35,351 133,515 96 OK 96,327 2,213 4,426 5 PA 81,980 21 42 0.1 WV 59,874
- - - CA 59,633
- - - NM 52,768 1 2 0.004 OH 48,902
- - - CO 46,663
- - - WY 44,294
- - - LA 41,780 511 1,022 2 KY 18,444 1,402 2,804 15 MI 16,352 1,192 13,285 81 UT 12,377
- - - NY 11,952
- - - MT 11,773
- - - AR 10,899 4 8 0.1 ND 8,801
- - - AL 7,147 62 124 2 VA 6,426
- - - MS 4,899
- - - AK 2,558
- - - NE 2,444 20 40 2 TN 1,766
- - - SD 276
- - - FL 94 6 12 13 NV 78 4 8 10 MO 67
- - - AZ 30
- - - OR 30
- - - MD 8
- - - IL 6
- - - Note : This table does not include all wells in the deliverable, only those with reported production during 2010
–2012.