Section 5. Crude oil and natural gas resource development

Monthly Energy Review, May, 2005

The April 2005 rotary rig count was 1,334, 2 percent higher than the count in March 2005 and 16 percent higher than the count in April 2004. Of the total number of rigs in operation, 1,241 were onshore and 93 were offshore. For April 2005, the number of onshore rigs was up 17 percent but the number of offshore rigs was the same as the April 2004 count. Rotary rigs drilling for natural gas as a share of total rigs stood at 87 percent in April 2005.

Total footage drilled in April 2005 was 18.8 million feet, 1 percent higher than the footage drilled in March 2005 and up 13 percent from that drilled in April 2004.

The number of exploratory and development crude oil and natural gas wells drilled during April 2005 was 2,892, 1 percent higher than the number drilled in March 2005 and up 13 percent from the number drilled in April 2004. The number of crude oil wells drilled was 634, and the number of natural gas wells was 2,258, slightly lower but 17 percent higher, respectively, than their April 2004 levels.

The number of dry holes drilled in April 2005 was 402, up 1 percent from the number drilled in March 2005 and up 42 percent from the number drilled in April 2004.

There were 2.2 thousand well service rigs active in April 2005, 3 percent higher than the previous month and 8 percent higher than the count a year ago.

The number of seismic crews active in the 48 States onshore in April 2005 was 38, 2 more than a year earlier. The number of crews active in the 48 States offshore was 12, 3 more than a year earlier. No crews were active in Alaska in April 2005, the same as a year earlier.

Crude Oil and Natural Gas Resource Development

Table 5.2 Notes

Three well types are considered in the Monthly Energy Review (MER) drilling statistics: "completed for crude oil," "completed for natural gas," and "dry hole." Wells that productively encounter both crude oil and natural gas are categorized as "completed for crude oil." Both development wells and exploratory wells (new field wildcats, new pool tests, and extension tests) are included in the statistics. All other classes of wells drilled in connection with the search for producible hydrocarbons are excluded.

Prior to the March 1985 MER, drilling statistics consisted of completion data for the above types and classes of wells as reported to the American Petroleum Institute (API) during a given month. Due to time lags between the date of well completion and the date of completion reporting to the API, as-reported well completions proved to be an inaccurate indicator of drilling activity. During 1982, for example, as-reported well completions rose, while the number of actual completions fell. Consequently, the drilling statistics published since the March 1985 MER are Energy Information Administration (EIA) estimates produced by statistically imputing well counts and footage based on the partial data available from the API. These estimates are subject to continuous revision as new data, some of which pertain to earlier months and years, become available. Additional information about the EIA estimation methodology may be found in "Estimating Well Completions," the feature article published in the March 1985 MER.

Users of the well completion and footage figures published by the Energy Information Administration (EIA) prior to August 1998 should be aware that these data have been revised. The published well completion and footage figures are produced by the Well Completion Estimation Procedure (WELCOM) based on drilling records provided under contract to the EIA. Problems in the files received by EIA necessitated revision of the historical series for well completions and footage drilled. Queries regarding this matter may be directed to William Trapmann (202-586-6408 or william.trapmann@eia.doe.gov).