Offshore oil and gas fields exist along the continental shelf of every continent—even Antarctica. Commercial fields are in operation offshore Africa, Asia, Australia, North America, and South America. Documented offshore production activities began in 1896 from a pier in Santa Barbara County, California. Today, offshore production facilities may be located hundreds of kilometers from land, in water depths approaching 10 000 m. Offshore wells may be platform based or subsea. Expected well productive life may be as short as 10 years or greater than 50 years. A common factor among all the varied aspects of offshore production is the role of technical advancements that enable continued safe, environmentally responsible, economic developments.
Permanently installed downhole instrumentation and control valves (intelligent wells) allow for continuous monitoring and control of multiple zones within a well. The resulting improved reservoir-management capability can lead to higher recoveries. As we move to deeper, hotter reservoirs, operators are pressing suppliers to continue to improve the reliability of gauges and valves. Fiber-optic cables support improved data collection. Completion practices and equipment designs for sand control have moved from simple screens to engineered gravel packs. Scale-inhibitor squeezes and treated proppants are used to minimize downhole scale deposition. These technologies are enabling subsea wells in deeper waters and at greater distances from a host production facility.
Highly reliable subsea separation, compression, and pumping systems are the next stage in offshore-production-technology development. Minimizing backpressure on the wellhead to maximize production is a philosophy applied at nearly every field. If the separator is moved to the same plane as the wellhead, the minimum wellhead pressure can be reduced significantly. Reliable subsea power transmission is enabling more subsea pressure-boosting options. Multiphase pressure-boosting designs have matured and are being installed at existing and new fields. Multiphase metering is accepted for both subsea and topside installations.
Modular subsea separation/pressure-boosting system designs that allow component replacement address some of the reliability risks. Subsea produced-water handling (and sand management) is not a clear picture. If produced water can be separated effectively at the wellhead and reliably reinjected, then flowlines and topside-equipment sizes could be reduced. Hydrate and scale management in the flowlines will be simpler. However, all parties need to agree on an acceptable water-quality description and operating protocols if the quality is not achieved. Multidisciplinary discussions continue toward this common goal.
This Month's Technical Papers
Rigless Intervention Case Studies in the North Sea and Equatorial Guinea
Offshore Water-Disposal Wells: Formation Damage and Treatment
Reducing Intervention in Subsea Wells With Fiber-Optic Technology
Recommended Additional Reading
IPTC 16702 Deepwater Production Improvement Through Proactive Reservoir Management and Conformance Control by Rahim Masoudi, Petronas, et al.
IPTC 16914 Downhole Oil and Water Separation: A New Start by Ed Sheridan, Baker Hughes, et al.
OTC 24090 Downhole Scale Management on the Alba Field: A Case History by R. Farrell, Baker Hughes, et al.
| Sally A. Thomas, SPE, is a principal engineer in production technology at ConocoPhillips. She holds BS and MChE degrees from Oklahoma State University in chemical engineering. Thomas’ entire career has been with Conoco and ConocoPhillips. Early responsibilities focused on produced water; within the research and development organization, she conducted process development and field demonstration studies for produced-water recycling and enhanced-oil-recovery projects. After Thomas transferred to process engineering, she developed expertise in process and hydraulic simulation for both ongoing-operations optimization and for new projects. Although mostly stationed in the US, Thomas has had international assignments in the UAE, UK, and Venezuela. She has served in SPE local-section offices, regional-meetings organizing committees, as a technical-paper reviewer, as chair of the SPE Books Committee, and as a member of the SPE Projects, Facilities, and Construction Advisory Committee and the JPT Editorial Committee. |