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Permalink Reply by Skip Peel - Mineral Consultant on August 19, 2011 at 5:42

Excerpt from Arkansas Geological Survey web page (emphasis added is my own):

 

Sligo Formation

The Sligo Formation is in the upper Coahuila Series of the Lower Cretaceous period and underlies the Pine Island black shale section of the Trinity group and above the Hosston sands and shales. The Sligo Formation is in conformable contact with the overlying Pine Island, but is time-transgressive on the Hosston Formation as indicated by the dark shallow water marine sediments overlying the nonmarine Hosston sediments. The Sligo in the "Ark-La-Tex" region is composed primarily of gray to brown shales, limy shales and limestones, locally containing lentils of dark gray oolitic argillaceous fossiliferous and sandy limestones and light to dark gray and brown fossiliferous shales. The thickness of the Sligo is less than 100 ft in south Arkansas and greater than 500 ft in central Louisiana.

The type locality of the Sligo Formation is the Sligo field in Bossier Parish, Louisiana. Production from the Sligo is generally referred to as the Pettet Limestone, a term that refers to a productive, porous, pelletal-ooid limestone. The Pettet porosity zones of the Sligo formation have accounted for a major portion of the gas production and a considerable portion of the oil production in the North Louisiana, Arkansas and East Texas areas. Production is obtained from anticlines, fault traps and stratigraphic porosity traps. Of these the stratigraphic trap is by far the most important from the standpoint of accumulated production.

Permalink Reply by Skip Peel - Mineral Consultant on August 19, 2011 at 14:12

Here is a link to a recent Pettet Lime (Sligo) unit application in Webster Parish.

 

http://ucmwww.dnr.state.la.us/ucmsearch_070611/UCMRedir.aspx?url=ht...

Permalink Reply by Phillip Pruitt II on August 19, 2011 at 9:51

According to this powerpoint, the Sligo Formation is quite prolific as far as oil and gas.

http://berg-hughes.tamu.edu/papers/conventional_petroleum/undis_undev_deep_gas_resrce.pdf

Permalink Reply by Skip Peel - Mineral Consultant on August 19, 2011 at 10:04

Last Sligo completion in Bear Creek Field.  It's a horizontal El Paso well.

 

COMPLETED 8-16-08; GAS; SLIGO; 1536 MCFD; 5 BCD; 14/64 CHOKE; 51 GVTY; 1200FP; 1300 CP; PERFS 6974-10,750' MD; 6501-6589' TVD

Permalink Reply by Phillip Pruitt II on August 19, 2011 at 10:34

Is El Paso retrying this kind of well with deeper drilling? The well you listed had a TVD of only 6589'.

Permalink Reply by Skip Peel - Mineral Consultant on August 19, 2011 at 10:39

That's the True Vertical Depth of the Sligo formation in that area.  A number of companies are experimenting with horizontal wells in shallow oil producing formations.  Devon drilled a horizontal Mooringsport well in Winn Parish not long ago.  The Sligo and Mooringsport are old historic conventional reservoirs.  The are sporadically productive across NW. LA.

Permalink Reply by Phillip Pruitt II on August 19, 2011 at 10:55

When the well is permitted, where is the information located on the permit that differentiates if the well is either horizontal or vertical?

Permalink Reply by Skip Peel - Mineral Consultant on August 19, 2011 at 10:57

Most operators place an "H" at the end of the well name to indicate a horizontal well.  Also horizontal well permits will list a TVD and a MD.  Vertical wells only list a MD (Measured Depth).