Several new procedures for completing oil wells have been developed inrecent years. Each method when used where properly applicable promises to be adefinite aid to operators in lowering development or operating costs, or indeveloping the full potentialities of the oil well. Multiple-zone completionsare now frequently used, in contrast to the older practice of setting a solidwater string over each zone to be produced. Gravel packing in unconsolidatedformations often prevents sand troubles formerly experienced where aconventional perforated liner was used. Light-weight bentonitic clay muds andoil-base drilling fluids are definite steps toward eliminating mudding damage, which occurs when heavy rotary mud is used.

Since in each case the new procedure developed is an alternate of olderconventional methods, a problem of selection is presented. The purpose of thispaper is to suggest methods of arriving at these choices and to presentpractical observations that may be of aid in their application.

Introduction

Discovery of deep and prolific oil-producing zones in the San Joaquin Valleyof California during the years 1936, 1937 and 1938 directed attention to meansof improving rates of penetration in drilling. In these years rapid advanceswere made in hole-making technique, and as a result the investment required fordeep development projects was substantially reduced. Improvements introducedduring this period included:

  1. larger drilling machinery, with fasterhoisting speeds, higher rotary speeds, and larger circulation volumes

  2. better mud control

  3. increased use of alloy steels.

This increasedefficiency of operation has been maintained but further improvement in deepdrilling practice has been less marked in the years 1939, 1940 and 1941. Thediscovery and intensive development of the Wilmington field, in the Los AngelesBasin, which reached its peak in 1938, was influential in shifting the emphasisfrom hole making to completion procedure. Since 1938, California operators havedevoted an increased amount of study to programs for drilling in and completingwells. This new emphasis on completion procedure has, led to the development oftechniques that represent the first successful departures from conventionalmethods to be introduced in many years.

T.P. 1465

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