Drilling Aspects of the Deepest Well in California

Abstract

Abstract On May 30, 1985, an Exploratory Well 934-29R was spudded in the Elk Hills Naval Petroleum Reserve #1 at Tupman, California. Bechtel Petroleum Operations, Inc. and the Petroleum Operations, Inc. and the Department of Energy cooperated in a joint effort to drill a 25,000 foot well and determine whether or not hydrocarbons are present at the deeper depths. Several zones present at the deeper depths. Several zones of interest had been drilled through when the well reached a final T.D. of 24,426 feet (Figure #1). This paper will reveal some of the more significant drilling technology used and also problems encountered while drilling the deepest well in California. Points to be covered will include the Points to be covered will include the following:Casing Design to Accommodate 5" Drill PipeLVT Oil Base MudDiamond Bit DesignUtilization of TurbodrillsCementing Introduction In 1975, a decision was made by DOE to drill three deep test wells at Elk Hills (Figure #2). The first well was spudded in 1977. It was drilled to 18,270 feet and curtailed due to hole problems. The second well was spudded in 1978 and drilled to basement at 18,761 feet. These two wells were evaluated prior to designing a drilling program for prior to designing a drilling program for 934-29R. In the past, major hole problems were encountered due to the length of time reactive shales were exposed to a water base mud system. Sloughing would result and casing strings were run sooner than planned. Smaller drilling assemblies would then have to be run, giving rise to mechanical problems such as twist-offs and parted pipe. problems such as twist-offs and parted pipe. To alleviate this problem, one of the goals of 934-29R was to design the well with an adequate sized casing to permit the drilling of the entire well with 5" drill pipe. Casing Design The conductor pipe was 36" line pipe which was cemented at 71' prior to the rig moving on. The well was spudded with a 17-1/2" bit and drilled to 323 feet. A hole opener was then run and the hole was opened to 23 inches from 71 feet to 323 feet. A second larger hole opener was run, increasing the hole size to 32 inches for the same interval. At that time, 26", 278#/ft line pipe was run in 40' sections with welded pipe was run in 40' sections with welded connections and cemented in place at 323 feet. Drilling out the shoe of the 26" casing was done with a 14-3/4" bit and the hole was drilled to 2,836 feet. A hole opener was run and enlarged the hole to 23 inches. P. 453