DRILLING AND DEVELOPMENT

Deepwater drilling occurs from mobile offshore drilling units (MODU�s), such as semisubmersible units or drillships (figures 29 and 30), and from platform rigs.

Figure 29. The Deepwater Horizon, a dynamically positioned, semisubmersible drilling unit (photo courtesy of Transocean). (Click image to enlarge)

Figure 30. The Discoverer Deep Seas, a Class 1A1, double-hulled, dynamically positioned drillship (photo courtesy of Transocean). (Click image to enlarge)

Figure 31. Average number of rigs operating in the deepwater GOM. (White bars are estimates.)

There was a steady increase in the average number of rigs operating from 1992 to a peak in 2001.

However, in the past two years, the number of rigs operating has decreased 29 percent. Figure 32 shows the number of deepwater MODU�s by water-depth categories in the GOM and worldwide.

Approximately 28 percent of the world�s fleet of deepwater drilling rigs is committed to GOM service (Harding and Albaugh, 2003).

The pie chart within figure 32 shows the distribution of deepwater rigs by major operating area.

Figure 32. Approximate number of deepwater rigs (GOM and worldwide) subdivided according to their maximum water-depth capabilities. Inset shows the number of deepwater rigs in various locations.

Most, if not all, of the deepwater-capable drilling rigs are under long-term contractual arrangements. The reader is cautioned not to draw any conclusions from the rig count differences between figures 31 and 32.

As mentioned above, figure 31 includes platform rigs in addition to MODU�s; figure 32 addresses MODU�s only.

Further, not all MODU�s in figure 32 are operating at any given time and upgrades to MODU�s that increase their water-depth capability will alter the rig counts shown, so year-to-year comparisons may not be valid.

• Drilling Activity
• Development Systems
• Subsea Trends
• New Pipelines