Anadarko Petroleum has taken on a challenging project with the Prosperidade development in Mozambique. But the company plans to draw on lessons from its involvement in Ghanas Jubilee field development to unlock Mozambiques huge gas resources, as Russell McCulley reports.
Although a final investment decision isn't expected until late 2013, development plans are coming into focus for Prosperidade, in Mozambiques 2.6 million acre offshore area 1 block. According to Anadarkos senior construction project advisor Richard Cain, the region has great gas potential but is beset by remoteness and a lack of infrastructure.
As with Jubilee, where Anadarko is a 23.49% partner with operator Tullow Oil (OE March 2009), recent offshore finds by Anadarko and area 4 operator Enimark the start of activity in a frontier region. The similarity in Mozambique is that we're going into a country that is nowhere near the oil & gas industry, Cain says. In fact, it's probably about as remote from the oil & gas industry as you can get. The north of the country, where Prosperidade is located, is still pretty wild, he adds. There are some roads up there, but they look like the road to my deer lease.
Anadarko has drilled 11 successful exploration and appraisal wells in area 1 since 2010; with recent discoveries at the Golfhino and Atum prospects, which appear to be connected, estimates now put the Rovuma Basin block at up to 100tcf of natural gas in place, not including the recent Tubaro discovery and a number of other prospects.
Development plans
Initial development plans call for two 5mmtpa liquefaction trains connected to shore by four 22in, 240km-long pipelines capable of delivering up to 4bcf/d of gas, with first shipments anticipated in 2018. The current subsea layout includes 60 wells, with expansion likely: Cain says the LNG plant could be designed to accommodate up to 10 trains.
Some of our discovery wells have over 700ft of pay in them. So we're probably going to go to 7in trees, he notes. We're in a lot of flux; we're trying to figure out which direction to go in a lot of different areas, but our conceptual subsea layout right now is for 60 wells.
It's going to be quite a development, he declares.
Anadarko has deemed the massive gas finds offshore Mozambique a transformational opportunity for the developing nation. But infrastructure challenges remain. In Ghana, Tullow invested some $42 million on civil engineering work alone, including offices, updates of pre-Second World War ports, housing and aviation facilities. This is the very thing that we're doing in Mozambique right now as we get ready to pursue our goals, Cain explains.
Transocean's Deepwater Millennium drillship conducts a flow test in Anadarko's area 1 licence offshore Mozambique.In addition to the infrastructure challenges, the Prosperidade partners will be faced with meeting still-evolving local content requirements in Mozambique. On the deepwater exploration front recent area 1 wells have been drilled in water depths ranging from Atum's 3285ft to 5400ft, at Barquentine they realize they don't have a whole lot to offer, Cain points out. Construction of the LNG plant, however, could employ thousands, he says, along with the jobs that will come with road and dock improvements. Anadarko plans to set up training centers well in advance of first production. The government is being very understanding.
Other challenges involve technology and logistics. Typical for Africa, the subsea terrain features deep canyons that the heavy wall pipelines must traverse. Installation and construction will take place in a very remote location; deepwater installation of a heavy wall pipeline is a challenge in itself. According to Cain, Anadarko anticipates high currents in places and steep Talus slope negotiation, with a 300m drop within a kilometer of shore.
Compression study
The partners will launch a compression study in the near future to determine a strategy for a possible tie-in of floating infrastructure. Our base plan allows for tie-in of some FPSUs, he says. We're hoping that maybe some of the subsea compression technology will be mature enough in 10-12 years, when the need may arise, he adds. We may go that route as well.
Jubilee, which reached first oil in December 2010, less than 31/2 years after discovery, provides an example in that it follows the same lines about developing an oil & gas industry in a country thats never had it before, Cain notes. There were some advantages in Ghana: for one, the generous reservoirs contain light oil, and the option of using an FPSO was never in question. On the other hand, the accelerated development scheme urged by the government meant that there was little room for error in the construction schedule and supply chain. Sembcorp Marine's Jurong Shipyard converted and delivered the 120,000b/d capacity Kwame Nkrumah FPSO less than two years after receiving the letter of intent; while ostensibly playing a supporting role to operator Tullow, Anadarko brought more expertise to the integrated FPSO team.
Intecsea was contracted to provide engineering services at a time when many firms were facing long backlogs. They had the number of people we needed with the right discipline, Cain recalls. The design phase was compressed in order to line up equipment delivery to meet the tight deadline. We chose suppliers with proven track records and utilized our suppliers standard subsea distribution equipment, he says. It wasn't exactly what we wanted, but it did the job and it did it well, and that's all we needed to do. And we applied that principle to other equipment.
According to Cain, careful planning allowed the Jubilee teams to save three to five days of fabrication on each structure, for a total of more than a month. FMC Technologies provided nine enhanced horizontal subsea production trees, two horizontal subsea gas injection trees and six horizontal water injection trees, along with five, four-slot production manifolds, two water injection manifolds and one gas injection manifold. Technip fabricated risers and flowlines. The FPSO was installed in 3610ft water depths at Jubilee, which straddles the Deepwater Tano and West Cape Three points licence areas.
On the subsea side, all the components and equipment were delivered within the projects scheduled constraints, Cain notes. So we went from a blank piece of paper to things on the boat over to Ghana in 21 months. Crews discovered that wires on the flying leads had been improperly twisted, he says. To FMCs credit, they got us some new flying leads and we got all that taken care of before first oil.
Drillship rig floor action during Mozambique natural gas flow testing.Jubilee came in 6% over budget, primarily because of the chances we took in the design phase, notably a reliance on models that underestimated the intermediate currents in the water column, Cain explains. As a result, risers and umbilicals had to be tethered to the seafloor. A second water injection riser was also added.
On the upside, operator Tullow and partners required suppliers to send a representative to biweekly meetings throughout the development phase to avoid surprises and foster accountability.
The fast pace was possible for Jubilee because of the nature of the field, and the size of it, Cain says. And being in Africa, the design concept was pretty obvious. But it might not be appropriate for all future developments, and we're finding that out in Mozambique.
Anadarko operates Mozambique's area 1 licence with 36.5% interest. Partners are Mitsui (20%), BPRL Ventures (10%), Videocon (10%), and Cove Energy (8.5%). Mozambique's Empresa Nacional de Hidrocarbonetos carries 15% interest through the exploration phase. OE
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