Detailed Description :

Initial Facilities

The PY-3 offshore production facilities comprise subsea wells producing through flexibles to a leased semi-sub production platform, Tahara. After 3-stages of stabilization, crude oil from the platform is pumped via subsea pipelines and a CALM buoy to a FSO unit, Endeavor, from that is periodically offloaded to shuttle tankers. Produced gas is continuously flared and cleaned produced water discharged overboard. In addition, there is a water injection unit that pumps treated seawater to subsea injection wells.

Scope of Work

Hardy Oil was intending to increase oil production by connecting additional subsea wells, increasing water injection and, eventually, gas lifting wells. As the FPU and FSO leases were coming to an end, Hardy contracted ode to study the existing facilities and to investigate whether it would be preferable to retain and upgrade the existing production facilities, or to allow the leases to run out and to provide replacement vessels.

The initial work consisted of:

• Verification of existing design to identify pinch points
• Identification of a number of options for eliminating pinch points on the existing vessels
• Identification of options for replacement of the existing FPU and FSO, including like-for-like, FPSO and fixed platform
• Consideration of other options such as multiphase pumps
• Presentation of screening study to field partners to agree a short list to be taken forward to the second phase of the study

The short listed options were then studied further, including:

• Market survey to identify available FPSOs
• Pipeline studies for exporting gas and oil
• HAZID
• Phasing of facility upgrades
• Advantages and disadvantages of each option
• Schedules and costs
• Presentation of study finding to partners
• Preparation of a final report

To meet Clients' desire to minimize deferred production, development of cost and schedule for upgrade of the existing facilities was based on carrying out all modifications offshore. To achieve this, a more detailed construction study was performed to identify the type of construction vessels required and their durations.

In addition to the above, the FSO CALM buoy was encountering hose tangling that required the use of an expensive support vessel to hold the FSO off the buoy. ode investigated options for replacing the buoy, but concluded that none would eliminate the problem. However, after examining the operating records, ode proposed a low cost, easily implemented solution that would retain the existing buoy, but avoid the need for a tug.

Engineering disciplines included -