The trend of significant deepwater discoveries has continued over the last decade, with over 250 billion barrels of oil equivalent (bboe) found to date in waters deeper than 200 metres. Deepwater resources account for around 30 per cent of the global conventional reserves yet to be discovered, indicating that we can expect to have another 20 years of deepwater discoveries at current rates. Of course many assumptions have to be realised for that future to materialise.
Over the past decade deepwater areas have dominated with Brazil and Angola leading, along with many other significant areas. And within that deepwater category, there have been three distinct exploration themes: deltas, pre-salt rifts, and stratigraphic traps. These discoveries will turn into production through this decade and underpin production growth. They also indicate a significant future of more discoveries. So, deepwater has real momentum for the future. Fundamental to that future is the continued development of technology, both to explore for new basins, plays and prospects, and to develop and produce discoveries.
Deepwater engineering technology
Our journey into deep waters began with the extreme MetOcean conditions in the North Sea in the early 1970s. We then took a major step forward in the early 1990s with the development of the Foinaven and Schiehallion fields, West of Shetland, using moored FPSOs. Later, in Angola, we followed this trend with the giant FPSO Greater Plutonio, and today we are commissioning our second FPSO in Angola, PSVM.
The Gulf of Mexico required a different solution because of the threat of hurricanes. There we built moored structures, either as tension leg platforms (TLPs) like Holstein, or spars, as on Mad Dog because they remain fixed in place during hurricanes. As we moved into deeper water with larger, more complex developments, we needed bigger platforms to accommodate all our equipment. So we built Thunderhorse, still the largest semi-submersible production unit in the world, and Atlantis, the deepest water one at the time of commission.
Looking forward, the key issue is how we accommodate the weight of equipment required for large, complex developments in very deep waters. We can place equipment on the sea floor but we cannot generate the power required to drive these huge developments underwater. Over the next years, offshore installations will see a decrease in surface footprint matched by an increasing sub-sea one. With this comes a huge rise in demand for power generation, which will be needed to operate rotating equipment, process oil, gas and water, and for export, communications and people.
This is clearly displayed in our Mad Dog Spar, which has three levels of facilities stacked on top of each other and a drill rig on top of that, all in a space the size of a football field. The spar is an 80 million barrels per day (mmbpd) and 60 million standard cubic feet per day (mmscfd) facility, limited not by resources (we are currently engineering Phase 2) but by scale, and by the extent to which the spar’s buoyancy can support an increasing weight load and diminishing space. So the technology of the future must target lighter-weight facilities and efficient topside components that can deliver the same or more capability with a smaller footprint. This will allow us greater flexibility in field development.
Having maxed out on these constructions, we are ready for a radical solution: reconfigure topsides’ equipment so that they can be placed on the seafloor. There is huge advantage in this. It is also an inherently safer solution as we separate man from equipment and, eventually, from the processing of petroleum. Such a simple idea – but such a huge step it seems. As we move to this subsea world a further step change will be required in power generation. With sufficient power we can operate subsea pumps to provide high pressure water injection capability from the seafloor. This debottlenecks the host facility and eliminates risks associated with high-pressure risers and flowlines, to deliver water to the seabed. It also secures additional recovery of hydrocarbons from the reservoir.
We believe we can accelerate production and increase ultimate recovery by 10 per cent through subsea boosting of three-phase reservoir fluids to the surface. This benefit can be gained from many of our deepwater assets and is being realized today. However, the duty of service of these systems needs to be significantly increased. We are developing high-boost, multiphase pumps to deliver high differential pressure for resources that cannot be produced easily with a single phase pump, or that would require a more complex system with subsea separation compatible with the single phase pump.
A glimpse into the future
Finally, I would like to talk about a system that is not yet developed, but we’re working on it now – a 20Kpsi Deepwater System. In the Gulf of Mexico, Egypt and the Caspian, BP has material resources with well-head pressures in excess of 15kpsi. While we can drill these today, the technology to produce them does not exist. We are implementing a major technology programme to develop the next generation of technology to drill, complete and produce reservoirs at pressures in excess of our current limitation of 15,000 psi and approximately 121°C. This will require the development of four key systems:
– Wells and their completions
– Rigs, blow-out preventers (BOPs) and risers
– Subsea production
– Well intervention and containment.
There are two implications in this:
1. Rigs with 50 per cent increase in hook load to manage the approximately 3mmlbs casing strings and completions required.
2. High Integrity Pressure Protection System (HIPPs), which maintains full shut-in pressure capability upstream of the unit but allows a lower working pressure for all components downstream of the device.
These systems will be located on the seabed. In addition to its high pressure capability, the HIPPs sensing and control system must be highly reliable; both of these functions are extremely challenging. Such high pressure and high temperature requirements will necessitate significant developments in metallurgy technology and the capabilities of non-metallic components and sealing elements. The prize is significant, in terms of both the resources we know about today and those that are yet to be found.
