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Deepwater Gulf of Mexico - America's Expanding Frontier
SOURCE: U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region






DRILLING ACTIVITY

The number of deepwater wells drilled generally increased from 1992 through 2001; however, the activity has declined in the last two years.

Only original boreholes and sidetracks are included in the well counts used in this report. Wells defined as “by-passes” are specifically excluded.

A “by-pass” is a section of well that does not seek a new objective; it is intended to drill around a section of the wellbore made unusable by stuck pipe or equipment left in the wellbore.

Figure 33 shows that most of the drilling has occurred in the 1,500- to 4,999-ft (457- to 1,524-m) water-depth range.

Figure 33. All deepwater wells drilled in the Gulf of Mexico, subdivided by water depth. (Click the image to enlarge)
Figure 33. All deepwater wells drilled in the Gulf of Mexico, subdivided by water depth. (Click the image to enlarge)

Despite an overall decline in recent years, considerable drilling activity occurred in water depths greater than 7,500 ft (2,286 m). It is interesting to note that, in November 2003, the first well began drilling in over 10,000 ft (3,050 m) of water and more are anticipated.

Figures 34 and 35 further break down the deepwater well counts into exploratory and development wells, respectively.

Figure 34. All deepwater exploratory wells drilled in the Gulf of Mexico by water depth. (Click the image to enlarge)
Figure 34. All deepwater exploratory wells drilled in the Gulf of Mexico by water depth. (Click the image to enlarge)

Figure 35. Deepwater development wells drilled in the Gulf of Mexico, divided by water depth. (Click the image to enlarge)
Figure 35. Deepwater development wells drilled in the Gulf of Mexico, divided by water depth. (Click the image to enlarge)

This report uses the designation of exploratory and development wells provided by the operators.

The data reflect the variations among operators in classifying wells as either development or exploratory.

In the past two years, there has been a decrease in the number of exploratory wells drilled. This is best illustrated by looking at the number of wells drilled in the 1,500- to 4,999-ft (457- to 1,524-m) water-depth range. While exploratory drilling at this depth is decreasing, drilling in the 5,000- to 7,499-ft (1,524- to 2,286-m) and the >7,500 ft (2,286 m) water-depth ranges is increasing.

There has also been a decrease in the number of development wells drilled in the last year.

Possible reasons for the recent decrease may be the method by which wells are categorized in this report (exploratory versus development), the retention of exploratory wells for production purposes, and the lag from exploration to first production.

The complexity of the deepest water developments may also be a factor, requiring operators to spend more time in planning and design.


Most development drilling was in the 1,500- to 4,999-ft (457- to 1,524-m) water-depth range; there are no development wells in water depths exceeding 7,500 ft (2,286 m).


Figure 36 illustrates the geographic distribution of deepwater exploratory wells. Note the progression into the western GOM and into deeper water through time.

Figure 36. Deepwater exploratory wells drilled in the Gulf of Mexico 1992-1997. (Click the image to enlarge)
Figure 36. Deepwater exploratory wells drilled in the Gulf of Mexico 1998-2003. (Click the image to enlarge)
Figure 36. Deepwater exploratory wells drilled in the Gulf of Mexico. (Click the image to enlarge)

Figure 37 depicts the locations of deepwater development wells.

Figure 37. Deepwater development wells drilled in the Gulf of Mexico 1992-1997. (Click the image to enlarge)
Figure 37. Deepwater development wells drilled in the Gulf of Mexico 1998-2003. (Click the image to enlarge)
Figure 37. Deepwater development wells drilled in the Gulf of Mexico. (Click the image to enlarge)

Once again, the data reveal a general increase in activity as well as a trend toward increasing water depth with time.

One indicator that MMS has found useful in projecting activity levels is the number of plans received.

Although the order of plan submission and drilling activities can vary with projects, operators generally proceed as follows:

  • file an Exploration Plan (EP),
  • drill exploratory wells,
  • file a Conceptual Deep Water Operations Plan (DWOP),
  • file a Development Operations Coordination Document (DOCD),
  • file a Preliminary DWOP,
  • drill development wells, then
  • begin production.
Figure 38 shows the number of deepwater EP’s, deepwater DOCD’s, and DWOP’s received each year since 1992 (DWOP’s were not required until 1995).

Figure 38. Deepwater EP's, DOCD's, and DWOP's received in the Gulf of Mexico since 1992. (Click the image to enlarge)
Figure 38. Deepwater EP's, DOCD's, and DWOP's received in the Gulf of Mexico since 1992. (Click the image to enlarge)

The count of EP’s and DOCD’s includes initial, supplemental, and revised plans; only the initial submittals (Conceptual Part) of the DWOP’s are shown.

Some shallow-water activities are included in the DWOP data because DWOP’s must be filed and approved for developments in greater than 1,000-ft (305 m) water depths and for all subsea developments regardless of water depth.

The discussion of subsea wells later in this report will address the significance of shallow-water subsea tiebacks—the effective use of deepwater technologies in shallow-water marginal developments.

There was a marked increase in EP’s, DOCD’s, and DWOP’s beginning in 1996. In recent years, however, there has been a moderate decrease in these plans.

Until recently there had been a gradual increase of drilling depth (as measured in true vertical depth [TVD]). Since 1996 the maximum drilling depth has increased rapidly, reaching depths below 30,000 ft (9,144 m) in 2002.

Figure 39 shows the maximum TVD of wells drilled each year since 1965.

Figure 39. Maximum wellbore true vertical depth (TVD) drilled in the total Gulf of Mexico each year. (Click the image to enlarge)
Figure 39. Maximum wellbore true vertical depth (TVD) drilled in the total Gulf of Mexico each year. (Click the image to enlarge)

The maximum TVD increased gradually from 17,500 ft (5,334 m) in 1965 to 26,978 ft (8,223 m) in 1998.

The recent dramatic increase in TVD to a record 31,824 ft (9,700 m), reached in 2003, may be attributed to several factors, including enhanced rig capabilities, deeper exploration targets, and the general trend toward greater water depths.

Figure 40 shows the maximum water depth drilled in the entire GOM each year since 1965.

Figure 40. Maximum water depth drilled each year. (Click the image to enlarge)
Figure 40. Maximum water depth drilled each year. (Click the image to enlarge)

The progression into greater water depths has been very rapid. Deepwater drilling began in 1975; significant water depth records occurred in 1976 (1,986 ft or 605 m), 1983 (3,530 ft or 1,076 m), and 1987 (7,500 ft or 2,286 m).

In November 2003, ChevronTexaco set a world record – drilling in 10,011 ft (3,051 m) of water at its Toledo prospect in Alaminos Canyon Block 951.



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Cover and Title Page

PREFACE

INTRODUCTION

BACKGROUND

LEASING DRILLING AND DEVELOPMENT RESERVES AND PRODUCTION SUMMARY AND CONCLUSIONS . . . Feedback