Proper hole conditioning means to establish a hole that is free of cuttings, debris, etc., and that has a mud in a fully "displaceable" or "circulatable" condition to allow the spacer and cement slurries to effectively displace the mud out of the hole.
During this research project, several parameters that influence hole conditioning were investigated using large scale well models. Resistivity probes were used to detect the travel time of "tagged" slugs as they traveled through the models. This allowed measurements of the circulation efficiency or "circulatable hole" (portion of the mud circulating at a given time) to be made during the tests. Resistivity probes were used since currently available "tagging" techniques (liquid calipers normally used in the field) lacked the accuracy that was needed for the research experiments. To simulate hole conditioning across areas of good permeability, for example across pay zones and even partially depleted zones, circulatable hole measurements were made across man-made sandstone cores. Measurements were also made in pipe-in-pipe (impermeable) sections. Different types of mud were used.
This paper discusses the impact of hole conditioning on the outcome of a cementing operation. The paper also includes, based on the data collected, a compilation of practical recommendations for improving hole conditioning and therefore cement job displacement efficiency in actual field application.