--------------------------------------------------------------------------------
MEMORANDUM
TO:	Mark de Figueiredo, EPA
FROM: 	Casey MacQueen, ERG
	Jessica Gray, P.E., ERG	
DATE: 	August 18, 2015
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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 DrillingInfo 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 which this analysis is based incorporates various assumptions as documented in 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 across 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.

Table 2 provides a summary of the lease-level reporting by state for wells with production during 2010 - 2012.

      

                     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 production 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/lease 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 maximum 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 minimum 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 property is located offshore. Note: for instances were duplicate API numbers were combined, the maximum value was selected.
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.
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 selected.
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 duplicate 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 duplicate 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.
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_FLAG
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/solesourceaquifer.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 production is shale gas.


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. 
