Transocean’s Discoverer Clear Leader drilled the Jack / St Malo production wells under a five-year contract that was signed in 2009.
The Jack / St Malo deep water project comprises the joint development of the Jack and St Malo oilfields, which are situated in the Gulf of Mexico. The fields are located 40km away from each other.
The Jack field lies in Walker Ridge blocks 758 and 759 at a water depth of 7,000ft. Chevron owns a 50% interest in the field while Maersk and Statoil hold 25% each.
The St Malo field lies in Walker Ridge Block 678 at a water depth of 2,100ft. Chevron is the operator with a 51% interest. Other partners include Petrobras (25%), Statoil (21.50%), ExxonMobil (1.25%) and ENI (1.25%).
The deepwater project was approved by the partners in October 2010. An investment of $7.5bn will be made in the initial development phase of the project. The first production was announced in December 2014. The production is expected to be ramped up to 94,000 barrels of crude oil and 21 million cubic feet of natural gas a day in the coming years.
Jack field discovery
The St Malo field was discovered in October 2003 by a well drilled by Transocean’s Discoverer Spirit drillship. The well struck a net oil pay of 1,400ft.
The Jack field was discovered in July 2004 by the exploration well Jack-1. The well was drilled by Transocean’s Discoverer Deep Seas drillship to a depth of 29,000ft. It struck 350ft of net oil pay.
Geology and reserves
The Jack and St Malo field reservoirs are located in a geological formation known as the ‘lower tertiary’ trend. The formation was deposited more than 65m years ago about 20,000ft below the seabed.
“The Jack field lies in Walker Ridge blocks 758 and 759 at a water depth of 7,000ft.”
It covers an area larger than 300 miles off the Gulf Coast of the US between Texas and Louisiana. The formation is estimated to contain vast resources for long-life projects of up to 30 to 40 years.
The total recoverable resources of the two fields are estimated at over 500m oil-equivalent barrels.
Development of the Jack fields
The development of Jack / St Malo fields is being carried out in phases. The initial phase of development involved drilling ten production wells: four at Jack and six at St Malo.
The development also involved drilling 43 subsea wells, which are tied back to a semisubmersible floating production unit.
The second well, Jack-2, was drilled at the Jack field by Transocean’s Discoverer Deep Seas drillship in 2005. The Cajun Express semisubmersible was used in 2006 to conduct a production test on the well.
Appraisal drilling commenced at the St Malo field in May 2004. An appraisal well was drilled to a depth of 7,036ft of water in July 2004. The well struck 400ft of net oil pay.
Transocean’s Discoverer Clear Leader was used to drill the wells in the initial phase of development, under a five-year contract that was signed in 2009.
Jack semi-submersible floating production facility
The fields were developed by a massive floating semi-submersible production facility, which is installed at a depth of 7,000ft. Its topsides weigh 33,000t and the facility has a capacity of 170,000bopd and 42mmscf per day of natural gas making it the biggest of its kind in the Gulf of Mexico.
It acts as a hub for the 43 subsea wells, which are divided into three clusters comprising subsea wells, pumps and other equipment on the seafloor, and are tied back to the facility.
The hull of the production facility was moored, and the topsides and other equipment including piles and tendons were delivered at the offshore location in March 2014. The equipment was carried over Crowley Maritime Corp’s Ocean class tugs.
Pipeline
A crude oil export pipeline is installed from the fields to a processing facility owned and operated by Shell in Green Canyon block 19 (GC19).
From GC19, the project partners have the option of transporting the crude oil to various refineries on the Gulf Coast region.
The pipeline is 220km long with a diameter of 24in and reaches a maximum depth of 2,140m. The Chevron Pipeline Company has built and will operate the pipeline for the Amberjack Pipeline Company (APC).
APC is a joint venture between Chevron Pipeline Company and Shell Pipeline Company.
