Document ID: EPA-HQ-OAR-2010-0505-7563
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2016-06-03T04:00Z

MEMORANDUM

FROM:	ICF International

TO:	Ravi Srivastava, EPA OAQPS 

THRU:	Graham Fitzsimons, EC/R

DATE:	 	April 14, 2016

SUBJECT:	Characterization of Wells Across the U.S. Relative to a Gas to Oil Ratio of 300
--------------------------------------------------------------------------------

This memorandum documents the technical analysis performed to characterize oil and gas wells with respect to gas to oil ratio (GOR) for the first 30 days of production.  This document analyzes roughly 37,800 oil and gas well completions across the United States in year 2014.      
Characterization of Oil and Gas Well Completions
A frequency analysis was performed for all oil and gas well completions in 2014 with a gas to oil ratio of 300 scf/bbl or less based on their gas production values, as shown in Figure 1 below.         

Figure 1: Oil and Gas Well Completion Counts According to Gas Production Rates for GORs <= 300 scf/bbl

For each of the gas production ranges in Figure 1, summary statistics were calculated for oil production values and summarized in Table 1 below.  It can be observed that for the majority of gas production values, with the exception of a few outliers, median and average values are consistently less than 100 bbls/day.  There are several wells with "0" oil production. This is because these wells do not report any oil sales and therefore the GOR is assumed to be zero, as the GOR cannot be calculated (denominator term in the GOR calculation being zero). In reality, however, these zero GOR cases can represent one of two scenarios, (a) extremely low volumes of hydrocarbon liquids production in which case it is not reported as a sale volume, and (b) truly zero liquids production as in the case of coalbed methane wells.
Table 1: Oil Production (bbls/day) Statistics for Gas Production Ranges (MMscfd) for GOR <=300
                                       
Oil and gas well splits were also calculated according to a GOR cut-off for all well completions in the dataset.  Tables 2 and 3 below provide these splits for GOR's above and below 300 and whether or not a well is oil or gas according to a gas well cutoff of 10,000 scf/bbl or 100,000 scf/bbl.  
Table 2: Oil and Gas Well Splits with Gas Well Cutoff of 10,000 scf/bbl for GORs above and below 300
                                       
Table 3: Oil and Gas Well Splits with Gas Well Cutoff of 100,000 scf/bbl for GORs above and below 300