Abstract.

This paper describes Exxon's experience in drilling conventional oil and gas exploration wells in extremely deep water in several areas of the world. To date, several industry water depth drilling records have been achieved by drilling in water depths ranging from 600 to 1200 m. These wells have been drilled in the Andaman Sea off Thailand, in the Egyptian Red Sea and in the Atlantic Ocean off South America. Drilling in water depths greater than 1200 m is expected in the future. Environmental conditions such as internai waves, high subsea currents, and unusual bottom conditions, encountered in certain deepwater areas, are discussed. The equipment and procedures for drilling under such conditions are reviewed. Innovative techniques and equipment for recovering lost equipment and for re-entry in deep water are included in the discussion.

Résumé.

Cet article décrit l'expérience d'Exxon du forage de puits d'exploration classiques pour le pétrole et le gaz dans les eaux très profondes de différentes régions du monde. Jusqu'à ce jour, on a enregistré des records de forage en eau profonde, allant jusqu'à des profondeurs d'eau de 780 à 1200 mètres environ. Ces forages ont été faits dans la Mer d'Andaman, au large de la Thaïlande, dans la Mer Rouge au large de I'Egypte, et dans l'Océan Atlantique, au large de l'Amérique du Sud. On s'attend dans l'avenir à des forages dans plus de 1200 mètres d'eau. On examine les conditions d'environnement, comme les ondes internes de la mer, les forts courants sous-marins, et les conditions de fond inhabituelles rencontrées dans certaines zones de mer très profonde. On passe en revue l'équipement et les techniques de forage à utiliser dans de telles conditions. On examine égaiement des techniques nouvelles pour la récuperation de l'équipement perdu et la ré-entrée en mer profonde.

1. INTRODUCTION

The first exploration drilling for hydrocarbons in water deeper than 180 m was by Exxon Company, USA in the Santa Barbara Channel off the coast of California in 1965. Since that time, 257 wells have been drilled by industry in water depths greater than 180 m. Table I shows 73, or 28%, of these wells were drilled by Exxon. Table I also reflects that Exxon has drilled 30% of total wells in water deeper than 600 m; this paper will focus on this very deep water experience. TABLE I Industry experience in deep water (November 1978) Wells by Wells by % Water depth Exxon industry by Exxon ~~ Deeper than 180 m 73 257 28 Deeper than 300 m 44 122 36 Deeper than 600 m 8 27 30 Deeper than 900 m 3 8 38 During the period December 1975 to September 1978, Esso Explorati

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