Mr. Erik Milito - The House Committee on Natural Resources ...

HYDRAULIC FRACTURING OPERATIONS—WELL CONSTRUCTION AND INTEGRITY GUIDELINES 13
7.6 Horizontal Wells
Drilling and completing horizontal wells is an evolving technology. Horizontal wells offer benefits that improve the
production performance for certain types of producing formations. Horizontal wells also allow operators to develop
resources with significantly fewer wells than may be required with vertical wells. Operators can drill multiple horizontal
wells from a single surface location, thereby, reducing the cumulative surface impact of the development operation.
However, horizontal wells are significantly more expensive to drill and maintain. In some areas, the typical cost of a
horizontal well may be two to three times the cost of a vertical well.
As discussed earlier, horizontal wells are typically drilled vertically to a “kick-off” point where the drill bit is gradually
turned from vertical to horizontal. Figure 3 illustrates a vertical and horizontal well for comparison. So the
considerations and recommendations for setting conductor, surface, intermediate production casing strings are the
same as those for vertical wells.
In horizontal wells, an “open-hole” completion is an alternative to setting the casing through the producing formation
to the total depth of the well. In this case, the bottom of the production casing is installed at the top of the productive
formation or open-hole section of the well. In this alternative, the producing portion of the well is the horizontal portion
of the hole and it is entirely in the producing formation. In some instances, a short section of steel casing that runs up
into the production casing, but not back to the surface, may be installed. Alternatively, a slotted or preperforated steel
casing may be installed in the open-hole portion. <strong>The</strong>se alternatives are generally called a “production liner,” and are
typically not cemented into place.
In the case of an open-hole completion, tail cement should extend above the top of the confining formation (the
formation that limits the vertical growth of the fracture).
Figure 3—Example of a Horizontal and Vertical Well