Abstract

The "systems approach" when used in developing a well completion system for producing wells through deep permafrost demonstrated producing wells through deep permafrost demonstrated its value in adapting well operations to unique circumstances and environments. This method of problem solving, often used by aerospace and problem solving, often used by aerospace and defense industries, provides the discipline for an integrated group of specialists in considering the effects of the modification of specific equipment and components on the total system.

The completion system for North Slope wells uses 700 ft of 2-1/2-in. thick polyurethane insulation around 7-in. OD casing to keep the upper 500 ft of permafrost from thawing while the well is producing at high rates for more than 20 years. Additional insulation can be added at a later date from 700 ft to the bottom of the permafrost if it is necessary to further protect the well by limiting the thaw radius. protect the well by limiting the thaw radius. The weight of all the casing strings is transferred down hole rather than through the wellhead. A packing gland-type wellhead allows the production casing to "grow" due to thermal expansion.

Illustrations depict three different approaches considered for completion systems of North Slope wells, a schematic of Mobil's completion system, thaw profiles for insulation to 700 ft and for insulation to 2,000 ft and an arrow diagram showing the interrelations of drilling and production problems which must be considered when adapting a completion system to a unique environment.

Introduction

With exploratory efforts increasing in remote areas and unusual environments, well completion systems are becoming more complicated to adapt to these environments. Altering a conventional completion procedure or piece of completion equipment to cope with a specific problem can often create unforeseen problems in problem can often create unforeseen problems in other parts of the procedure. When conventional procedures are changed to solve a particular procedures are changed to solve a particular problem, a technique is needed which will help problem, a technique is needed which will help view the well as a complete system. One such technique, the "systems approach", used recently by space- and defense-oriented industries to help organize and coordinate problem-solving assignments, was used by Mobil to develop a well completion system for North Slope wells.

At first glance one may think this is what is done subconsciously - or may ask what is the difference in the systems approach and the tried and proven scientific method.

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