Drilling with Casing Reduces Cost and Risk

Abstract

Abstract More than 1.2 million ft of hole has been drilled in over 260 wells with retrievable casing-while-drilling tools. These wells have been drilled with seven casing sizes ranging from 4-1/2" to 13-3/8". The drilling system is composed of downhole and surface components that provide the ability to use normal oil field casing as the drillstring so that the well is simultaneously drilled and cased. The casing is rotated from the surface for most operations The experience gained while drilling these wells has led to a better understanding of the advantages of the process. It's most effective applications have been to reduce the cost and risks associated with wells which routinely experience lost circulation when drilled conventionally; wells in which well control is difficult for tripping drillpipe; wells where excessive fluid loss into low pressure reservoirs impairs the production and ultimate recovery; and wells where it is difficult to get the casing shoe as deep as needed.