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•F=: • MIfJ[fJG AND RECL AMATION PLAPJ October, 1979 h17. GUNNISON NO . 1 f•1IfJ[ Revised 9/24;631 manner. A ceme nt plug vrill be placed in the bottom of the hole through the F seam and a safe distance into the overlying material . This is possible since most of the r•rater loss oc curs in the Darren Member. A cement surface plug will then be placed in the top six to ten feet of the hole. Return Flow - Uncased drill holes that are drilled with water or mud and for which it is possible to get return flows at the surface vrill be sealed in the following manner. The viscosity of the drilliny fluid or mud will be increased by 20 seconds per quart above the normal drilling fluid in the hole at the time of abandonment. The hole will be cemented from the bottom through the F coal wain a safe distance into the overlying material. This will create a cement seal at the bottom of the hole through the F coal seam and any lower coal seams and a mud seal on top of the cement. A six to ten foot surface plug of cement will then be placed at the surface. Cased Holes - Due to large water losses that occur in the Darren 14ember, very often casing has to be set front the surface to tfre tap of the F seam in order to core through the F seam or any lower seams. Often it is im- possible to recover this casing when drilling activities are finished. When this situation occurs, the casing is left in the hole and the hole is sealed in the following manner. A cement plug is placed from the bottom of the hole up into the bottom of the casiny. Then a cement surface plug is placed in the top six to ten feet of the cased hole. Well Sealing Procedures Abandoned wells will be sealed in the following manner. A cement plug will be placed from the bottom of the hole up into the bottom of the casing. A cement surface plug will be placed in the top six to ten feet of the hole. 3-49a