3,788 wells over four years show average drilling periods, depths
James K. Dodson
James K. Dodson Company
- A linear regression curve shown above depicts the average number of days required to drill US Gulf Federal OCS wells against total well depth for 3,788 wells drilled in the 1990-1994 period. Plotted on the chart are the time-depth averages of 30 selected operators.
- A linear regression curve for the year 1994 depicts the average number of days required to drill US Gulf Federal OCS wells against total well depth for 866 wells. The average time-depth positions of 30 selected operators are plotted with respect to the overall average.
A comparison of wells drilled by 30 selected operators over the past five years suggests that Newfield Exploration, Amoco, and Marathon are among the most efficient drillers in the US Gulf of Mexico. The comparison benchmarked operators at respective average drilling depths with the number of days required to reach total depth.
A total of 3,788 wells drilled by all operators in the Federal OCS region of the US Gulf of Mexico was used to develop average drilling periods versus well depths over a five-year period. The average depth for all wells during that period was 10,816 ft. The average drilling time for all wells was 29 days. Sidetrack, re-entry, and re-completed wells were not included in the well count.
Other leaders over the past five years include McMoran, Murphy Oil & Gas, Walter Oil & Gas, Mobil, Chevron, Vastar, BP, Unocal, and Brooklyn Union.
While the comparison shows average drilling days at various depths, extenuating circumstances may lead to longer than average drilling periods over several years for some of the operators. These include:
- Drilling as many frontier or exploratory wells as offset or infill wells.
- Drilling a number of wells in ultra-deep water.
- Drilling a large number of deep wells, such as in Mobile Bay.
- Drilling many wells with mobil salt sections or sub-salt wells.
- Drilling areas with hard rock intervals, high temperatures and pressures, or complex geology.
- Drilling many wells with long offsets (TD to surface).
Operators that focus activity heavily on shallow water plays where wellbore logs are available for many wells find drilling more predictable and faster.
On the opposite side are operators drilling frontier exploratory wells where little is known of the geology or downhole conditions. Even development drilling in frontier regions brings many surprises for drilling crews trying to reduce time on the hole.
A one-year comparison (1994) tends to reveal a great deal about operators' short term drilling focus, while a five-year comparison (1990-1994) tells more about an operator's philosophy and approach to drilling.
The amount of time spent by rigs and crews on a series of wells is a rough gauge of producer costs for drilling. What does not appear in the accompanying charts are the results.
In the end, what has been found and produced at what cost is the true evaluator of a producer's capabilities and worth.
At the same time, benchmarking the drilling phase serves as an important efficiency guidepost.
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