Section 240.1110  Definitions


For the purpose of this Subpart, the term:


"Cased Well" means a well in which production casing has been set.


"Cement" means class A neat cement with a minimum weight of 14.5 pounds per gallon, unless the cement contains additives that improve the ability of the cement to provide necessary protection and that maintains a minimum compressive strength of 500 PSI after 72 hours. If fly ash is used as an additive, the maximum amount of fly ash allowable is 35% by weight of the total cement mixture.  Only Class C and Class F fly ash, as defined in ASTM standard C618 (Specification for Coal Fly Ash and Raw or Calcined Natural Possolan for Use in Concrete (2008)) (no later amendments or additions included), is allowable.  The generator of the fly ash must certify in writing to the cement blending company that the fly ash meets those specifications.  A copy of that certification is required to be provided to the Department upon request.  Also, 5% to 6% by weight of cement grade bentonite gel is required to be used in the cement and fly ash mixture. The gel is required to be cement grade and may be either wet or dry blended with the cement and fly ash mixture. The cement and fly ash dry mixture is required to be thoroughly and uniformly blended with either a mechanical or pneumatic cement blender prior to the addition of any water.  An authorized representative of the cement blending company is required to certify in writing that the dry mixture contains a maximum of 35% fly ash and has been properly blended.  The well cement contractor is required to provide the certification to the Department's representative prior to use of the mixture unless otherwise directed by the Department.  If the Department determines or has reason to believe, by testing or visual inspection, that the mixture has not been properly blended, the mixture shall not be used until properly blended and has been approved for use by a Department representative.


            "Circulation Method" means placement of cement used in plugging a well by circulating cement through a pipe set at a specified depth in the well.


            "Dump Bailer Method" means placement of cement used in plugging a well by using a dump bailer on a wire line.


            "Inactive Well" means a well that has ceased operation for a period of up to 24 consecutive months.


            "Mud" means a drilling mud with a minimum Marsh funnel viscosity of 45 seconds.  Mud may contain water (fresh or brine), bentonite, attapulgite or other additives if they do not reduce the viscosity below 45 seconds.


            "Plugging Fluid Waste" means plugging fluids, including cement, that are generated from the well during plugging activities.


            "Producing Lease" or "Producing Unit" means a lease or waterflood/enhanced oil recovery unit that has produced and sold oil within the preceding 12 month period.


            "Uncased Well" means a well in which production casing has not been set.


(Source:  Amended at 35 Ill. Reg. 13281, effective July 26, 2011)