Gulf of Mexico Blocks EB 945, 946, 988 & 989

Landmark: World Water Depth Record of 1,420 m (4,650 ft) at Time of Completion

Project Overview

• Contract Award: 1999
• Sales: Houston, Texas
• Fabrication: Houston, Texas
• Service Base: Houston, Texas
• Host Type: DDCV*
• Contract Type: EPC

* Deep Draft Caisson Vessel

Project Characteristics

• No. Trees: 6
• Water Depth: 1,420 m (4,650 ft)
• Tree Type: Horizontal
• Tree Pressure: 10,000 psi
• Tree Bore Size: 4"x2"
• Hydrocarbon: Oil/Gas

Project Ownership

• ExxonMobil 67%
• BP 33%

 

Scope of Work

• Six (6) horizontal 4"x2" 10,000 psi subsea trees
• Trees designed to be "wet parked" for a period of up to six (6) months or more by virtue of special pressure barriers and mechanisms containing long-term protective fluids
• Two (2) production manifold systems
• Electro-hydraulic installation workover control system using HXT/manifold subsea control module during installation
• API material class FF
• 5-1/2" tubing hanger with downhole hydraulic lines: SCSSV, DHCI and downhole electrical
• Mono-pressure 4,000 psi electro-hydraulic controls
• 26 km (16 miles) tieback to the Hoover DDCV located in 1,460 m (4,800 ft) of water
• System integration testing, offshore installation support and technical assistance

 

Comments

The Diana floating production unit is located in the Gulf of Mexico at East Breaks 945. From July 1999 to 2001, ExxonMobil installed six (6) horizontal trees that were "wet parked" in a cluster arrangement at a new world water depth record of 1,420 m (4,650 ft) by Cal-Dive International’s Uncle John Multi-Service Vessel (MSV). The Uncle John also installed two (2) manifolds controlled by FMC Kongsberg Subsea electro-hydraulic control systems.

Trees were guidelineless funnel down (GLL FD) for both the tree-to-wellhead and BOP-to-tree interfaces. The tubing hanger was designed for 5-1/2" tubing, and with five (5) downhole hydraulic lines. Mono-pressure 4,000 psi electro-hydraulic control system minimized lines in production umbilical. The project also features remotely operated vehicle (ROV) retrievable control modules and real-time sand probe to enable erosion detection.

The unique design of the tree allows wet parking for long periods by virtue of special pressure barriers and mechanisms containing long-term protective fluids. The novel method of wet parking and using the blowout preventer (BOP) to move the tree saved ExxonMobil considerable days of rig time.