Many people ask us how many wells have been hydraulically fractured in the United States. It is an excellent question, but not one that is easily answered; most states don’t release data on well stimulation activities. Also, since the data are released by state regulatory agencies, it is necessary to obtain data from each state that has oil and gas data to even begin the conversation. We’ve finally had a chance to complete that task, and have been able to aggregate the following totals:
While data on hydraulically fractured wells is rarely made available, the slant of the wells are often made accessible. The well types are as follows:
- Directional: Directional wells are those where the top and the bottom of the holes do not line up vertically. In some cases, the deviation is fairly slight. These are also known as deviated or slant wells.
- Horizontal: Horizontal wells are directional wells, where the well bore makes something of an “L” shape. States may have their own definition for horizontal wells. In Alaska, these wells are defined as those deviating at least 80° from vertical. Currently, operators are able to drill horizontally for several miles.
- Directional or Horizontal: These wells are known to be directional, but whether they are classified as horizontal or not could not be determined from the available data. In many cases, the directionality was determined by the presence of directional sidetrack codes in the well’s API number.
- Vertical: Wells in which the top hole and bottom hole locations are in alignment. States may have differing tolerances for what constitutes a vertical well, as opposed to directional.
- Hydraulically Fractured: As each state releases data differently, it wasn’t always possible to get consistent data. These wells are known to be hydraulically fractured, but the slant of the well is unknown.
- Not Fractured: These wells have not been hydraulically fractured, and the slant of the well is unknown.
- Unknown: Nothing is known about the slant, stimulation, or target formation of the well in question.
- Unknown (Shale Formation): Nothing is known about the slant or stimulation of the wells in question; however, it is known that the target formation is a major shale play. Therefore, it is probable that the well has been hydraulically fractured, with a strong possibility of being drilled horizontally.
Wells that have been hydraulically fractured might appear in any of the eight categories, with the obvious exception of “Not Fractured.” Categories that are very likely to be fractured include, “Horizontal”, “Hydraulically Fractured”, and “Unknown (Shale Formation),” the total of which is about 32,000 wells. However, that number doesn’t include any wells from Texas or Colorado, where we know thousands wells have been drilled into major shale formations, but the data had to be placed into categories that were more vague.
Oil and gas wells in the United States, as of February 2014. Location data were not available for Maryland (n=104), North Carolina (n=2), and Texas (n=303,909). To access the legend and other map tools, click the expanding arrows icon in the top-right corner.
The standard that we attempted to reach for all of the well totals was for wells that have been drilled but have not yet been plugged, which is a broad spectrum of the well’s life-cycle. In some cases, decisions had to be made in terms of which wells to include, due to imperfect metadata.
No location data were available for Maryland, North Carolina, or Texas. The first two have very few wells, and officials in Maryland said that they expect to have the data available within about a month. Texas location data is available for purchase, however such data cannot be redistributed, so it was not included on the map.
It should not be assumed that all of the wells that are shown in the map above the shale plays and shale basin layers are actually drilled into shale. In many cases, however, shale is considered a source rock, where hydrocarbons are developed, before the oil and gas products migrate upward into shallower, more conventional formations.
The raw data oil and gas data is available for download on our site in shapefile format.