Mississippi Lime Play
The Mississippi formation was historically considered tapped out by vertical drilling decades ago. It is only in recent years that horizontal drilling has established the opportunity for further exploitation of the reservoir. The horizontal wells drilled in the play have lateral lengths of between 2,500 feet and 5,000 feet and are fracture stimulated in 6-12 stages. The fracture stimulation treatments are not as large as those in the Bakken play or the other unconventional resource plays such as the Eagle Ford.
Geology
The Mississippian oil trend is an expansive carbonate stratigraphic trap producing at shallow depths ranging from 4,500 to 7,000 feet below the surface. The reservoirs lie at the regional Pennsylvanian/Mississippian unconformity, as a result of uplift, alteration and erosion of shallow marine Mississippian carbonates.
The uppermost Mississippian member is a widespread debris-flow deposit formed through a combination of uplift and erosion of the Mississippi Limestone, consisting of varying amounts of weathered chart, limestone and dolomite called the “Mississippi Chat”. The “Mississippi Lime” underlies the chat and also exhibits good reservoir characteristics. The formation was subject to weathering and digenesis and erosion at the regional unconformity. This results in greatly varying reservoir properties both horizontal and vertically. Where the digenesis and weathering have enhanced the reservoir properties, the porosity is generally 15-20 per cent. and can be more than 100 feet thick. Where it has not been enhanced, the porosity is only 4-6 per cent. and has low permeability. This results in lateral discontinuous reservoirs that are ideally developed with horizontal drilling technology.