Depth poses sandstone questions
Looking Deep in the Shelf Reveals More Prospects
James R. “Jim Bob” Moffett, co-chairman of the board at McMoRan Exploration, likes to say he cut his teeth on the onshore Miocene.
The veteran geologist and explorer eventually moved outward onto the Gulf of Mexico shelf to make the most of the deep Miocene techniques he had honed in the onshore environment.
It proved to be a smart move.
Following successes in the shallow water deep gas, such as the high-profile Flatrock Field at South Marsh Island, it was only natural for McMoRan to move on to explore the ultra deep horizons below 25,000 feet.
As a result, Moffett et al currently are reveling in being in the midst of some major rockin’ action at their latest gig dubbed Davy Jones.
The company’s recent ultra deep discovery at the Davy Jones prospect was drilled to 28,603 feet and encountered total possibly productive net sands as much as 200 feet in six zones in the Wilcox section of the Eocene-Paleocene.
It could be one of the largest discoveries on the Gulf shelf in decades – and this may be only a hint of what’s to come.
In its exploration program looking for ultra-deep prospects on the shelf, McMoRan has identified several deep large structural features below a regional salt weld, with drilling targets that range from Middle Miocene to Lower Paleocene.
The deep structures identified were interpreted on regional 2-D seismic data, on pre-stack time migrated 3-D seismic data and proprietary reprocessed pre-stack depth migrated 3-D seismic data, according to the company authors of a paper scheduled for presentation at the annual AAPG meeting in New Orleans.
They noted that available deep well data were utilized to calibrate the geologic model for the section above the salt weld.
They commented also that the ultra-deep prospects are similar to deep, large sub-salt structural traps in the deepwater Gulf with reservoirs of Middle Miocene to Lower Paleocene age at depths below 20,000 feet subsea.
These reservoirs in both the deep water and the shelf were deposited in deepwater depositional environments.
Sand risk, including preservation of porosity and permeability with depth of burial, is a major risk factor for deep sandstone reservoirs in the shallow water areas of the Gulf of Mexico shelf.
Prior to Davy Jones, McMoRan re-entered the Blackbeard well in South Timbalier Block 168 and deepened it from 30,067 feet measured depth (MD) to 32,997 feet MD. The well discovered four hydrocarbon-bearing intervals within the Miocene section.
The company intends to drill additional ultra-deep wells in 2010.