Offshore, the pressure is always on – in real time. Deepwater wells, key to the energy industry's future, increasingly require new solutions and challenge the industry to perform at its best. Seismic and drilling technologies entered the water first and encountered the challenges of seismically identifying under-compacted formations and of drilling a stable hole. Completions followed, and the task of constructing maintenance-free installations, designing intelligent subsea sys-tems, and combating vessel motion was at hand.
Recent Schlumberger technology developments address these and other challenges. In some cases, the solution has been a new tool or completely new technique; in others, an innovative application of existing technology has provided the answer.
The subsea completion systems with a SenTREE 7 test tree set at a depth of 7,200 ft and a safety valve installation at 9,828 ft in the Gulf of Mexico upheld the company's 25-year track record in subsea completions. The modular design SenTREE 7 system is used in conjunction with horizontal tree systems and allows live wells to be controlled under a variety of well conditions and operational circumstances.
Technological developments in real-time data delivery and applications have moved at significant speed over the past few years, getting data to the client faster, in more secure, reliable, and convenient formats. The energy industry has benefited from these improvements perhaps more than other industries because of its global nature, with decision-makers at great distances from assets existing beneath the ocean floor.
In deepwater well construction, pore pressures can be high and fracture gradients low compared with land wells of the same depth. Accurate knowledge of pore pressures is a key requirement for safe and economic deepwater well construction. A tomography-based pore pressure prediction method devised by Schlumberger is extr- acting physically meaningful velocities from 3D seismic data. Real-time measurement of annular pressure while drilling helps monitor the equivalent circulating density of mud to allow drillers to keep within a sometimes narrow stability window.
Low fracture gradients and water-flow zones common to deepwater cause washouts and inadequate cementing, leading to adverse hole conditions for logging and completions. Logging- while-drilling measurements help obtain formation-evaluation information before hole conditions deteriorate.
Offshore West Africa, where operators are requiring more advanced stimulation alternatives, the Schlumberger Galaxie, a 220-ft stimulation vessel, is performing large-capacity treatments using up-to-the-minute technology. The recently commissioned vessel is equipped with advanced systems custom built for the high-permeability sandstone and carbonate formations native to West Africa.
Sand-face completion efficiency
Because polymer-type fluids have been found unsuitable for use in frac-and-pack workovers needed to stimulate sanded-out productive intervals in the Adriatic Sea and other offshore reservoirs, ClearFRAC (a polymer-free stimulation fluid) is being applied. Results are promising in these locations, with gas production more than doubled and the economic life of the platform extended in the Adriatic Sea.
In the cold deepwater, patented DeepCrete slurry is being used to combat long waiting-on-cement times that normally result from cool temperatures found in the seabed. The Deep-Crete slurry is formulated to hold up against water influx but remain light enough not to fracture weak formations.
Permanent monitoring systems measure and record well performance and reservoir behavior from sensors placed downhole during completion. These measurements made available via satellite give engineers information essential to dynamically manage hydrocarbon assets, allowing them to optimize production techniques, diagnose problems, refine field development, and take remedial action.
The PressureWatch quartz family of downhole gauges and WellWatcher systems have faithfully monitored reservoir and well behavior in North Sea wells in real time for more than eight years.
Trends continue toward subsea developments from which all production will come. As technology advances driven by real-time data continue to emerge, the deepwater tide continues to rise. Advances in subsea flowlines, production trees, electrical power distribution systems, fluid separation, and reinjection technology and multi-phase metering and pumping will move an increasing amount of activity to the seabed. For R&D alliances, the ultradeep will be the next technology proving ground.
Schlumberger takes leadership role in Eurogif
As a founding member of Eurogif, Schlumberger acknowledged the need in 1996 for the oil and gas service and supply industry to establish a trade association to communicate with EU institutions and member states. Dr. Claude Roulet, vice president of Technical Coordination, Schlumberger Europe and Eurogif vice-chairman and Technical Committee president, proactively participated in workshops to define the mission and organization of Eurogif as a trade association. He also coordinated workshops with oil and gas operators and national trade associations to identify industry challenges and essential thematic areas of required technology development.
In 1999, workshops were organized on these themes, with participation of research and development managers from large enterprises, mechanical engineering societies, public research laboratories, classification organizations, and public institutions that promote investment in research.
At the end of 2000, Dr. Gabriel Marquette, director of Schlumberger Technical Cooperation-Europe, assumed the role of Eurogif vice-chairman and president of the Technical Committee. Schlumberger remains an active member of several thematic networks (HSEQ, Information and Communication Technologies, Gas Chain Optimization) and coordinates the Thematic Network "Smart Reservoir Net," which involves over 50 members from 12 countries, including Russia.