Abstract

This paper describes the development of a completion method for a well in Offshore, Louisiana. This completion was designed and built to handle a corrosive gas up to 20,000 psi at 400 degrees F from depths below 20,000 ft.

Though this well was never completed, all of the equipment was manufactured and the testing completed prior to the well being temporarily plugged and prior to the well being temporarily plugged and abandoned. This completion method resulted in new tools and techniques which will be necessary for similar wells in the future.

Introduction

There are several methods for completing deep, hot, high pressure, corrosive gas wells. 1 Each method has its advantages and disadvantages. The preferred completion method should be simple enough to minimize the amount of anticipated problems, yet be flexible enough to also handle the unexpected problems. The majority of completion problems can problems. The majority of completion problems can be eliminated by a thorough understanding of the various completion components and how they relate to the total completion plan. This includes a thorough testing of each component prior to running the completion.

This South Timbalier well and the proposed completion presented some unique challenges. The well had 20,000 psi gas at 400 degrees F with CO2- To complete this well, problems had to be overcome, such as: well depth, the weight of the tubulars, the piston effects due to pressure changes, buckling of piston effects due to pressure changes, buckling of the tubing, the minimal use of rotation, a time limit and oil-based mud with suspended barites. This completion resulted in new technology. New products such as the Casing Bore Receptacle (CBR), products such as the Casing Bore Receptacle (CBR), high pressure safety valve and a special subsurface tubing hanger were designed, built and tested for this well.

HISTORY

In December, 1979, Tenneco, et al embarked on drilling a deep, corrosive, high pressure gas well in the Gulf of Mexico. Intermediate casing was set at 17,500 ft. and drilling commenced to 20,000 ft. At this point, a 4.0 ppg kick was encountered and handled with the, surface equipment; however, the drill pipe became stuck and the hole was lost in late March of 1980. It was decided to side track the hole at 17,500 ft. and start drilling again. The sidetrack was drilled to 20,000 ft. to the top of the transition zone which was encountered early, and a 7–5/8" liner was run and set. In July of 1980, the drilling depth was 20,200 ft. The well was logged, the hole was temporarily abandoned, and the rig was released. The total time for this phase was 192 days.

Near the end of December, 1980, plans were formulated to re-enter the well bore. The operating agreement called for a well to a depth of 23,000 ft. A task force was organized and planning begun utilizing industry experience and technology in 20,000 psi equipment. The planning group covered numerous study areas in an effort to successfully complete the well in a safe and economic manner.

Major topics of study were:

  1. Drilling and completion fluids behavior

  2. Drilling and production tubular design

  3. Surface and subsurface completion hardware

  4. Re-evaluation of reservoir potential with economics

  5. Platform vs. caisson concept

  6. Drilling rig design

  7. Projected formation pressures and temperatures with impact on:

    • Maximum safe drilling depth

    • Hydraulics

    • well control

    • Potential production problems

    • Design of 20,000 psi blowout preventors

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