MRCSP Phase I Geologic Characterization Report - Midwest ...

APPENDIX A: LOWER CRETACEOUS WASTE GATE FORMATION
141
Table A17-1.—Summary of depth, thickness, porosity, permeability and salinity
of the Waste Gate Formation (adapted from Hansen, 1982)
Well Name
Depth (ft.)
Thickness
(ft.)
Estimated Estimated Salinity
Sandstone Permeability (equivalent NaCl)
Porosity (%) (millidarcies) (parts per million)
DOE Crisfi eld Airport 3,900-4,225 325 24-27 1 75-120 3 33,700 5
63-122 4 72,000-80,000 6
J & J Taylor 4,975-5,915 940 21-24 1 29-63 4 24,700 5
91,300 6
Ohio Hammond 4,745-5,360 615 23-27 2 49-122 4 50,400 5
53,700 6
Socony-Mobil Bethards 5,020-6,565 1,545 19-24 2 16-63 4 70,200 5
97,400 6
Esso Ocean City 5,670-7,180 510 19-24 2 16-63 4 73,800 5
94,300 6
1
Compensated formation density log method
2
Short normal electric log method
3
Pumping test
4
Schlumberger formula
5
Self-Potential method
6
Resistivity method
clayey confining bed. As a consequence, the isolation of an individual
sand can never be assured. In practical terms the waste disposal
reservoir should be viewed as including not only the injection zone,
but one or two adjacent sands as well. Because the Waste Gate Formation
is hydrologically isolated from the shallow fresh-water fl ow
system, this contingency should not preclude waste injection unless
local conjunctive use of the Waste Gate is anticipated.
By restricting injecting pressures to 0.64 psi/ft, the minimum
pressure gradient at which hydraulic fracturing theoretically occurs,
Hansen (1982) has estimated that a 75-foot thick Waste Gate
sand could be expected to accept a waste stream of 30 to 115 gpm
for fl uids ranging in viscosity between 1 to 2.2 centipoises. Pretreatment
of the waste prior to injection may be required to prevent
deterioration of formation permeability due to precipitate reactions
between waste water and the formation water and matrix. For example,
certain types of acidic wastes may react with the feldspathic
aquifer material . . . producing clays that might reduce aquifer permeability
near the disposal well. At the very least entrained gasses
and suspended solids must be removed from the wastewater prior
to injection.
Hansen (1984, p. 20) concluded that the hydrogeologic setting
of the Waste Gate Formation is suitable for liquid waste disposal.
Transmissivity and storage properties should be sufficient to accept
wastewater in economic volumes within prescribed injection pressures.
Thirty to 115 gallons per minute of liquid waste could be injected
into typical Waste Gate sandstone without fracturing the rock
or its confining beds. By increasing the number of sandstone beds
within the injection target, larger volumes of liquid waste should be
able to be injected with no adverse affects.