Natural Gas Productive Capacity for the Lower-48 States - Methodology -
The monthly capacity projections are the sum of capacity forecasts for older wells and new wells.
- New well capacity is a function of the number of new well completions, which depends on the monthly drilling rig forecast based on the monthly price and production forecasts in EIA's January 2001 Short Term Energy Outlook (STEO).
- The Drilling Rig Model uses oil and gas revenue to project total active rigs and the percent of rigs drilling for gas. A well/rig ratio for each of ten U.S. supply areas is used to convert the number of gas rigs to well completions. This ratio includes an efficiency factor that models the efficiency losses normally seen when the number of drilling rigs increases.
- The wellhead capacity to produce gas from these new well completions is determined by a hyperbolic function relating monthly production rate to cumulative production and calibrated to the most recent 3 years of data.
- To determine old well capacity, the wells are grouped by vintage year. Productive capacity is modeled for each vintage using the same hyperbolic function relating monthly production rate to cumulative production. A monthly projection is made for each vintage and then all vintages are summed.