Jack Moody
Mississippi Bureau of Geology
Jackson, Miss.
In 1901 the discovery of oil at Spindletop established the association of salt domes and oil and gas production. Spindletop, through time, also proved the enormous potential of salt dome production by yielding over 152 million barrels of oil.
Needless to say, Spindletop set off a search for salt domes throughout the entire Gulf Coast region. This search reached Mississippi in 1936 with the discovery of Midway Dome in Lamar County. During the 1930's and 40's many of Mississippi's 52 known salt domes were discovered. From the 1930's into the 1980's companies had success locating the domes, but the lack of significant associated oil production proved very disappointing. One exception was Glazier field in Perry County. Glazier, however, differs from the shallow piercement salt domes in that it is intermediate in its depth of penetration. At Glazier the cap rock is below the Eutaw and Tuscaloosa formations. Most of the shallow piercement salt domes penetrate these and younger formations. As late as the mid-1980's, many in the industry believed the Mississippi salt domes would not produce for various reasons, i.e., time of movement, rate of movement, etc. As 1990 dawns upon the survivors of the industry, the outlook for salt dome-related production in Mississippi is once again promising.
This bright outlook began with the discovery of Rodessa oil on the flanks of Oakley Dome in Hinds County, Miss. in 1985 Enserch drilled its 1 Prassel to a depth of 17,400 ft, plugged back, and perforated the Rodessa from 11,743-818 (gross). This initial well had led to 16 additional flank producers from four zones. Most of the wells were drilled to depths in the 12,000-13,000 ft range. As of January 1, 1989, the wells around the Oakley dome had produced over 1 million bbl of oil and continued producing at a rate of about 32,981 barrels of oil per month.
The next point of light came in 1986 when the Sun 1 W.W. Speed was completed on the flanks of Dont Dome in Covington County. The well was a dual completion from the Rodessa and Sligo. The Rodessa was perforated from 13,410-20 and flowed 3,300 mcfd and 158 bbl of condensate per day. The Sligo was shot from 14,029-46 and flowed 330 bbl of oil and 410 Mcfd. Oryx (Sun) has successfully offset the discovery with their 1 S.P. Speed. This well was perforated from 13,309-517 (Rodessa) and flowed 154 bbl of oil and 1,350 Mcfd through an 8/64-in. choke with a tubing pressure of 4,450 psi. There is also an interesting 100 ft Washita-Fredericksburg sand at 10,248 with shows of oil.
Following its success at Dont, Oryx drilled its next piercement discovery on the flanks of the Centerville Salt Dome in Jones County. The Oryx 1 Frankie Smith was completed from multiple zones in the lower Hosston. Through perforations at 15,906-938, 15,953-964, 15,995-16,030, 16,060-086, and 16,119-200 ft the well flowed 4,400 Mcfd and 1,224 bbl of condensate per day.
What information and similarities can be gathered from the three producing salt domes briefly discussed above? All are on the flanks of shallow piercement salt domes in Mississippi. Oakley has production on the west and southwest, southeast, and north flanks. Both Dont and Centerville produce on the south flanks, but neither are fully developed, so further drilling will if there is a preferential side for production. Radial faulting is associated with a number of these piercement salt domes. These faults can result in multiple fault blocks which produce independently of each other. Not only can the quality of production vary from block to block, but one block may not produce while another could be excellent. Therefore, one dry hole may not adequately test a salt dome. All three of the salt domes have multiple pay zones. Throughout the Mississippi Interior Salt Basin there is potential for thick reservoir pays. The steep dips associated with the flanks of these salt domes can cause some drilling problems, but can also result in large reserves being located under a relatively small amount of surface acreage.
The Mississippi salt dome piercement play has a lot to offer today's explorationist. There are a large number of unexplored or lightly tested domes. The presence of steeply dipping, thick, multiple pay zones equates to a large per well reserve potential. Several domes will be tested in 1990. If there is a reasonable amount of success the play will heat up.
Copyright 1990 Oil & Gas Journal. All Rights Reserved.