EXPLORATION New Albany shale gas flow starts in western Indiana

A group led by Seminole Land & Cattle Co., Seminole, Okla., started gas sales in late January from Devonian New Albany shale in Greene County, Ind.

The formation has physical similarities to Devonian Antrim shale in the Michigan basin (OGJ, Jan. 22, p. 53). No tax credits are associated with the New Albany development.

Seminole is not releasing gas flow rates. The wells are still being dewatered.

The state has included the new producing formation in Simpson Chapel field.

Project planning

The group received strong bottomhole support from industry partners who wanted to acquire current factual information on hydraulic fracturing techniques, pressure information, and production data.

Initial planning for the project required drilling, on 80 acre spacing, three producers and a saltwater disposal well (Fig. 1 [34994 bytes]). The three producers, in 20-6n-4w, Greene County, Ind., are the Minihan Oil & Gas, Seminole, Okla., 2, 4, and 1 Cochrane. The 5 Cochrane, TD 1,754 ft, an existing dry hole, was reentered and converted to a saltwater disposal well. The operator expected from the beginning to handle a large volume of formation water from New Albany, so the saltwater disposal system was integral to the project.

As TD was reached on each well, production casing was cemented to surface and the drilling rig moved to the next location.

Prior to completion attempts all pipeline ditches were dug, lines laid, the compressor set, sales meter set, separators set, and well equipment installed. All wells were then perforated (Fig. 2 [62671 bytes]), acidized, and fraced in a "back to back" operation with the same group of service trucks until all the wells were completed. This helped reduce project cost.

Area geology

The Minihan wells are located along the updip edge of the Terre Haute reef bank, 2 miles southeast of the Simpson Chapel Gas Storage Unit, owned and operated by Citizens Gas & Coke Utility, Indianapolis (OGJ, Feb. 27, 1995, p. 58).

That unit provides gas storage in the Devonian Geneva dolomite. The Geneva dolomite is draped over an underlying Silurian reef. This drape over an older reef provides the structure for the storage facility.

Wells in the area show little structural elevation difference when contoured on the top of the New Albany shale. Not much is known about deeper formations.

The geological reason for selecting the location for the producing wells was to take advantage of a good fracture svstem that Minihan/Buzzard, a Fort Worth geological consulting firm for Seminole Land & Cattle Co., felt was available. Structure was not the deciding factor, nor was isopach thickness, in the selection of locations.

The lithology of the Mississippian carbonate bank, where it overlies the Terre Haute reef bank, requires close geological attention to the samples because there are many complicated and rapid facies changes in very short distances, particularly from limestone to dolomite. Porosity quickly comes and goes.

Close monitoring of the cuttings by the wellsite geologist in a fractured shale reservoir is a must to avoid missing gas shows. Close attention to the drilling mud is necessary to prevent drilling problems.

Deep snow and mud restricted access to the area during much of early 1996. The operator is not releasing frac or flow test information on the wells at this time but has given permission to use tops for the structure map (Fig. 1 [34994 bytes]).

One of Seminole Land & Cattle's partners, Citizens Gas & Coke, purchases the gas from the Cochrane wells.