Geopressuring Mechanism of Smackover Gas Reservoirs, Jackson Dome Area, Mississippi (includes associated papers 6558 and 6559 )
- C.A. Stuart (Shell Oil Co.) | H.G. Kozik (Shell Oil Co.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- May 1977
- Document Type
- Journal Paper
- 579 - 585
- 1977. Society of Petroleum Engineers
- 1.6 Drilling Operations, 5.1.1 Exploration, Development, Structural Geology, 4.1.5 Processing Equipment, 5.2 Reservoir Fluid Dynamics, 4.1.2 Separation and Treating, 5.3.4 Integration of geomechanics in models, 5.9.2 Geothermal Resources
- 0 in the last 30 days
- 144 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 10.00|
|SPE Non-Member Price:||USD 30.00|
To help understand the problems associated with geopressures in the Mississippi salt basin, Smackover sour gas reservoirs were studied and a geopressuring mechanism was concerned. The concept presented is that gas was sealed in a confined container, and then geopressured by the temperature and pressure of the earth's crust with subsequent burial.
Geopressures of the Smackover sour gas reservoirs in the Jackson Dome area of the Mississippi salt basin appear to be created by the temperatures and overlying weight of the earth's crust. Calculations indicate that the geopressure cell was sealed and geopressuring started at a depth of about 12,500 ft. With burial that occurred thereafter, the pore-gas pressure increased in accordance with the equation for real gases that combines Boyle's and Charles' laws. The Smackover exists at 12,000 ft on the north flank and plunges to about 27,000 ft at the synclinal axis of the basin. The geopressure gradients of the reservoirs increase with depth from hydropressures in the 12,500-ft Loring reservoir to 19.0 lb/gal, or 0.99 psi/ft, in the 22,100-ft Southwest Piney Woods reservoir. The measured reservoir pressure is 21,835 psi. This is the highest pressure and pressure gradient of a potential reservoir ever recorded in the Gulf of Mexico basin. Calculations indicate that this pressuring mechanism could create a geopressure gradient up to 24.4 lb/gal (1.28 psi/ft) at the synclinal axis of this subregional province;however, it is not known whether a rock can hold such a pressure gradient. Porosity reduction by compaction appears to decelerate with geopressuring and essentially stops when the pore-gas pressure approaches the geostatic pressure.
Geopressures are found in increasing numbers in the Mississippi salt basin as more deep wells are drilled. To help understand the problems associated with these pressures, a geopressuring mechanism for the Smackover sour gas reservoirs was conceived and is presented here. The concept is simply that gas was sealed in a confined container, and then was geopressured by the temperature and pressure of the earth's crust with subsequent burial. The concept conforms to the "seal and pressurize" method of geopressuring. The pressuring source of heat and weight of the earth's crust is essentially the same as that proposed for the generation of geopressures for the entire Gulf of Mexico salt basin and other basins. The seal of the geopressures in the review area is different from that for the Texas-Louisiana Cenozoic salt basin. The seal, however, is not the subject of this discussion. Several pressuring sources for creating geopressures have been proposed by other investigators; some have proposed that the Mississippi salt basin has a different pressuring source than the Cenozoic salt basin. Other pressuring sources have been proposed by Parkers for the origin of geopressures in Mississippi. The area discussed is a corridor traversing the Loring, Pelahatchie, Thomasville, Piney Woods, and Southwest Piney Woods fields, adjacent to the Jackson Dome in the Mississippi salt basin, as illustrated in Fig. 1. Smackover sour gas has been found in the five fields, ranging in depth from 12,450 to 22,100 ft. The Smackover area of the Jurassic age in this basin is 1,200 ft thick, exists at 12,000 ft on the north rim, and plunges to 27,000 ft in the geosynclinal axis of the basin.
|File Size||1010 KB||Number of Pages||7|