To: Big Dog who wrote (46523 ) 6/17/1999 12:18:00 AM From: Tomas Respond to of 95453
Offshore drilling: Efficiencies overshadowed by rig market realities Soft oil prices have dampened the thrill of some impressive advances in offshore drilling technology, writes Robert Steven Financial Times World Energy, June issue Continuous incremental improvement in drilling technology is enabling the oil industry to drill wells which would have been considered uneconomic or technically impossible just 10 years ago. Wells are being drilled horizontally with pinpoint accuracy to a distance of over 10 kilometres away. Multiple horizontal lateral branches can be successfully side-tracked from wells drilled from floating rigs to increase production from thin and previously unreachable reservoir horizons. In the region of $16bn is currently being spent by contractors to build a new generation of rigs to drill wells in three kilometres of water while also introducing time saving efficiencies of between 20 and 40 per cent into the well construction schedule. "One of the recent developments in drilling that has been most important," says Dave Herasimchuk, vice-president of market development at drilling contractor Global Marine, "is the ability to control precisely the direction and position of the wellbore." It is now routine to drill horizontally and control the position of the drill bit over 7,000 metres away. This capability has given a new lease of life to mature fields and basins around the world by developing reservoirs that were not previously accessible. "The changes that have taken place on the rig floor are much less revolutionary," says Mr Herasimchuk. "However, we are now building a new generation of rigs for deepwater operations, which in terms of size and capacity are a big step forward. To make this work we are tapping into state-of-the-art technologies for every component in the drilling process." Nevertheless, the fundamental principle of how a well is drilled has not changed in the past hundred years. There is an analogy with the internal combustion engine, which would still be recognisable to motoring pioneers although many of the modern components and efficiencies they have introduced would be unimaginable. In a similar manner, there has been a huge and accelerating development in all the technical components involved in drilling, both down the well and on the rig floor. However, in all but the most specialised situations, drilling and completing a well still demands a large derrick to support heavy lifting gear. A state-of-the-art rig floor incorporates widespread automation and computer control to maximise safety and efficiency but the basic process of drilling and casing a hole remains the same. Consequently as wells are drilled deeper and in greater water depths so the drilling equipment and the vessels needed to carry it grow bigger and more expensive. With a price tag of at least $300m the new breed of drilling rig needs to be contracted to operators on a long-term basis at rates of between $150,000 and $200,000 a day to be a viable investment. To justify higher costs operators are demanding new efficiencies to cut the time it takes to drill a well, particularly in deepwater. The Discoverer Enterprise, a $382m deepwater drillship being built by Transocean Offshore, is due to enter service with BP Amoco in the US in July. With a displacement of 100,000 tonnes it is one of the largest drillships yet built and will be able to support two entirely separate areas for simultaneous drilling activities, thereby reducing well construction time. Transocean expects the dual activity drilling system to bring efficiency improvements in well construction of up to 40 per cent, reducing the effective cost to the operator by 50 per cent due to savings in associated services. Other rig newbuilds are targeting efficiency savings of around 25 per cent by servicing a single drilling derrick with dual pipe-handling systems. This allows the process of making up drill pipe, casing and riser to be taken out of the critical path in well construction. The novel hydraulic RamRig drilling system developed by Maritime Hydraulics is just entering operational service on a mobile rig on the Bideford Dolphin with Saga Petroleum in Norway. It weighs 20 to 30 per cent less than conventional drilling packages on floating rigs, has a lower centre of gravity and a more compact design while also providing integrated active or passive heave compensation to counter the effect of vessel motion on the drill pipe. The next evolutionary step in offshore drilling technology could be the development of a truly lightweight package with the same performance as a standard heavy derrick. Coil tubing drilling offers potential by doing away with the need to make and break drill pipe. But there is still no viable alternative to a heavy-duty derrick and drawworks for installing well casing or deepwater riser pipe. Slim-hole drilling is also gaining ground, partly to reduce the weight demands placed on the surface equipment. Ironically, no matter how much drilling efficiency can be improved, it is still likely to have less impact on the net cost of drilling than the interplay of supply and demand in the rig market. The slump in oil prices during 1998 means there is currently a drilling rig surplus and a third generation semi-submersible can be hired in the North Sea for little more than $30,000 a day. As recently as the beginning of last year the same rig cost $160,000 a day. For the foreseeable future the greatest drilling cost efficiency that an oil company can achieve is to explore and develop when rig rates are low, counter to the conventional oil price-driven cycle.