Liquid rich zones

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.
Operations

The Mississippi Lime formation

The Mississippian oil and gas bearing system is a proven commercial trend that has been producing from several thousand vertical wells for more than 50 years. The play area includes multiple counties of the Northwest Shelf of the Anadarko Basin and the Nemaha Uplift in North Central Oklahoma and Southern Kansas.

The core of the play involves drilling horizontal laterals in existing vertical wells or new horizontal wells in the vicinity of historical Mississippi Lime producers or dry holes. These liquid-rich zones were once thought to have been drained by vertical, conventional drilling many years ago. Now, with the technological advancements made with horizontal drilling and fracture stimulation, operators are able to recover significant amounts of hydrocarbons.

A sample of operators targeting Mississippian Lime and/or Chat

Mississippian Lime

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 Mississippian Limestone, consisting of varying amounts of weathered chert, limestone and dolomite called the “Mississippi Chat”. The “Mississippian 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 to 20% and can be more than 100 feet thick. Where it has not been enhanced, the porosity is only 4-6% and has low permeability. This results in laterally discontinuous reservoirs that are ideally developed with horizontal drilling technology. The formation’s geology is well understood as a result of the thousands of vertical wells drilled and produced there since the 1940s.

The horizontal wells drilled in the play have lateral lengths of between 2,500 ft and 5,000 ft and are fracture stimulated in 6-12 stages. The fracture stimulation treatments are not as large as those in the Bakken play or the Eagle Ford. As a result of the shallow depths and smaller fracture stimulation treatments required, the typical completed well costs range between $2.4-$2.9 million. Current drilling times are approximately 17-28 days from spud to rig release.

Cross section of Mississippi Lime Formation

Mississippian Formation