The tubular program of the ultra-deep well represents a major portion of the initial well costs, relates directly to probability of economically reaching projected depths and plays a continuous role in determining profitability during the well's productive life. productive life. This paper reviews, in general terms, tubular safety factor considerations, compatibility of tubular material and end finish with well environments, and hole and pipe size combinations.
The ultra-deep well is defined as one which is 18,000 to 28,000 feet deep. Drilling and completion technology for each well varies according to projected depth and anticipated downhole environment, such as high pressures, sour gas, clearance problems, etc. A particular set of conditions dictates tubular design considerations, and similar conditions found in like wells of various fields and basins; therefore, there can be a deign relationship between ultradeep wells of two different fields (Buffalo Wallow and Washita) or two different basins (Delaware and Anadarko). For this reason, a general review of leading tubular designs for areas of ultra-deep drilling should be informative.