The underwater arena of subsea

Jim Tait of FMC Technologies delves into the underwater arena of subsea technology.

When did FMC enter the Subsea Arena?
Jim Tait. FMC Technologies history began in 1967, when they sold and delivered their first subsea tree, which operated at a depth of 20 metres in the waters of the Gulf of Mexico. Since that first well, FMC has constructed and installed around 1300 trees on some 260 projects worldwide through six major manufacturing facilities in Houston, Brazil, Scotland, Norway, Singapore and Malaysia. FMC Technologies now offers a wide range of vertical and horizontal Subsea tree solutions able to operate in pressures up to 15,000 psi and water depths of 10,000 ft.

How is the Subsea Market Changing?
JT. The subsea production business is constantly evolving. We continue to move technology forward in order to unlock hydrocarbons resources that were previously inaccessible or non-commercial. Most notably, the drive in recent years has been to complete projects in deeper water, permit production from higher pressure and temperatures reservoirs, increase our distance from subsea development to host facilities and provide additional data from subsea equipment to optimise reservoir output and implement planned maintenance programmes. In addition, we aim to consistently improve the reliability and availability of subsea equipment while reducing installed costs.

Significant investment has been made in the development of subsea boosting and separation systems with FMC providing six complete systems in the four major deepwater basins. Technologies vary from relatively simple seafloor boosting to gas, oil, water and sand separation. Boosting and separation technologies have now been retrofitted to brown field as well as been incorporated in green field developments.  

The technology permits production from reservoirs with low flowing pressures and or heavy oil. Separation of the oil or the water from the process stream reduces hydrate risk and optimises flow assurance with the overall net effect of improving reservoir recovery efficiency.

Using this technology, fluids can be processed on the seafloor and transported to the host facility before final separation takes place - a two step process. The next evolution is to achieve both first stage and second stage separation on the seabed. This would allow export quality fluid to be produced from a subsea field and facilitate delivery of hydrocarbons from subsea direct to the market.

There will be an increasing need for subsea processing in deepwater offshore Africa due to a predominance of shallow, low pressure reservoirs with long water column and high gas to oil ratios that creates lift, flow assurance and hydrate problems.

Are there other areas that FMC is working to provide Increase Oil Recovery?
JT. Investment costs for a subsea well are actually lower than for a platform well. However, intervention costs for subsea wells are extremely high compared to the platform equivalent. This is due to the high cost associated with mobilising a rig to perform the subsea intervention. Platform wells in contrast can be readily re-entered at a comparatively low cost.

If the reservoir requires a lot of maintenance and the well needs to be re-entered many times after it has started to produce, then the platform well becomes cost effective. In addition, the low cost of entry to the platform well enables the operator to perform operations that increases the reservoir recovery factor. The fact that well interventions are more costly on a subsea well than on the platform well leads to fewer interventions that historically lead to a lower overall recovery rate from a subsea development.

FMC has developed technology that significantly reduces the intervention cost for subsea wells. Riser-less well intervention from a low cost monohull vessel is the solution developed. FMC has been operational with this type of system together with Island Offshore since 2004. By 2009, FMC were operational simultaneously with three such vessels in the North Sea where there is a high critical mass of subsea wells and an aging well population. The application for Africa is evident with a high installed well count already in Angola followed by Nigeria and Equatorial Guinea.

The barriers to having all offshore developments comprised of only subsea wells are being removed by use of low cost and efficient well intervention systems and subsea processing. The day we can develop offshore fields without the use of manned platforms, we can significantly lower the operational cost of a field. This is the next major step. Improved technology is not simply for use on new 'green' fields but may also be put to use to maximise potential of existing brown field developments - there is no easier hydrocarbon to find than in an existing reservoir. Cost effective extraction of that resource is key to 'Enhanced Oil Recovery'.

The industry continues to face many technology challenges but the future is bright, the future is subsea.

Jim Tait is Sales and Marketing Manager for FMC Technologies, Africa and Caspian.