Oil and Gas at Your Door? (2005 Edition) - Earthworks

STAGES OF OIL & GAS DEVELOPMENT
Plugging Wells
Before a company permanently leaves a well site, the well should be plugged or capped. The
purpose of plugging is to prevent formation water from migrating into and contaminating
aquifers or surface water.
All oil and gas producing states have specific regulations governing the plugging and abandonment
of wells. 140 Generally, however, when a well is plugged there are a number of steps that
are taken. First, the downhole equipment is removed and the perforated sections of the well
bore are cleaned of scale and other wastes. Then, a minimum of three cement plugs, each
between 100-200 feet in length, are placed into the well. Plugs should be placed: 1) into the
perforated zones of the well, in order to prevent the inflow of fluid; 2) in the middle of the wellbore;
and 3) within a couple hundred feet of the surface. Also, fluid with an appropriate density
is placed between the cement plugs in order to maintain adequate pressure in the voids.
Finally, the casing is cut off below the surface and capped with a steel plate welded to the casing.
Surface reclamation should then be undertaken to restore natural soil consistency and
plant cover.
FIGURE I-22. LEFT-RIGHT: PLUGGED WELL, NOT RECLAIMED. PLUGGED WELL, RECLAIMED. Photo at right
used with permission of Vermejo Park Ranches.
Conversion to an Injection Well
If the well is located in an area where a company has many nearby wells still in production,
the company may decide to convert the well to an injection well. If this occurs, the well will be
regulated by the federal government as an Underground Injection Control (UIC) Class II
Injection well, and will be subject to the federal Safe Drinking Water Act and Underground
Injection Control Regulations. 141 Such a well can be used either for disposal of the produced
water from other wells, or as part of oil enhancement operations in the production field.
Reclamation
Federal, state, and sometimes local rules and regulations describe how reclamation is supposed
to occur when a site is abandoned. In some states, companies are required to provide
financial assurance (e.g., bonds) to ensure that some funds are available to plug the wells and
carry out the reclamation activities. Reclamation clauses in surface use agreements negotiated
during the early stages also come into play at this stage.
Full reclamation should leave the land, air and water in the same condition as before oil and
gas development was carried out. This is rarely the case. In many states, the unwillingness of
companies to completely restore the original environment is accepted by state governments.
Consequently, operators are required only to reclaim the land “as nearly as is possible” to it predevelopment
condition.
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