ABSTRACT

Deep drilling poses major problems when high temperatures, high pressures, and acid gases Are encountered below 17,000'. A combination of these items usually requires Extensive planning, exotic materials, long drilling times, and result in high costs. This paper discusses some of industry's accomplishments, current technology, and challenges associated with deep drilling And is conducted in water depths greater than 5,000'.

INTRODUCTION

America?s first oil well, drilled in 1859 by 'Colonel' Edwin L. Drake. Was a deep drilling Challenge to those involved. Although Drake reportedly said that they were prepared to drill to a thousand feet if necessary, oil was found at a depth of 69', approximately four months after the well was started in April, 1859. The Oil and Gas industry has continued to set depth record reaching the 10,000' mark in 193, the 15,000' mark in 1938 and the 20,000 mark was reached in 1972. Only two wells have been drilled below 30,000' in the United States. The first, a 30,050-footer in 1972, and the second , a 31 441-foot hole in 1974, were both drilled by lone star Production Company in Oklahoma's Anadarko Basin.

The deepest well in the world is reported to be in the Soviet Union and recently drilled below 34,448'. The target depth of this well is 49212' (15,000 meters). This well, the USSR's SG-3 wildcat on the Kola Peninsula, west of Murmansk, was spudded in May, 1970, reached a depth of 31, 725' in July, 1979, and a depth of 32, 808' in May 1980. The Soviet's have reportedly said that improved technology probably will be required if the hole is to achieve target depth.

The depth of well is not the main item to measure when determining the complexity of a deep well. Any time we stretch the capability of men, equipment, and technology, it is a challenge. For purposes of this review, a deep well will physically be referred to as being deeper than 17,000'. This depth has been selected to include a majority of the wells in the Tuscaloosa Trend of South Louisiana where many deep drilling challenges exist. If acid gases (H2S or CO) are produced at bottom hole temperatures above 300 ° F, continuous corrosion inhibitor circulation may be required, and the well will be defined as a deep sour Gas Well( DSGW). Some companies have developed their own DSGW specifications for metallurgical control on deep, critical, acid gas wells since some requirement exceed API specifications.4. Deep drilling in certain geological areas is not new. As can be seen in Figure 1, the 20,000' drilling depth was reached over 30 years ago and the 30,000 foot depth was reached over 8 years ago. The industry has had rigs capable of drilling to 30,000' for several years. However, if the well is to be an economical success, it must be safety completed to allow long term sustained production. Therefore, for evaluation, completion, stimulation, and initial production.

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