Contaminacion De Fluidos De Perforacion

SPE 163023
Effect of Cement Contamination on Some Properties of Drilling Mud

Joel O. F, Ndubuisi, E. C, and Ikeh, L., University of Port Harcourt, Nigeria
Copyright 2012, Society of Petroleum Engineers

This paper was prepared for presentation at the 2012 SPE Nigerian Annual International Conference and Exhibition held in Abuja, Nigeria, 6-8 August 2012.
This paper was selected forpresentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have
not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum
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ABSTRACT

Drilling of oil well is a capital intensive project;hence, the importance of selection of proper
mud system that is free from contamination
cannot be overemphasized. A poor design and
contaminated drilling fluid can be very costly in
the life of any well. Therefore, during drilling
operations care must be taken to avoid
contamination of mud with cement among
others. This project details experimental work
and findings associated with mudcontamination
with cement. Also, solutions were proffered on
how to manage contaminated mud systems with
cement during drilling operations. The result of
this work will in no small way help not only the
operators but Engineers to manage this concern
with dispatch when it arises, thereby minimizing
down time and associated costs which affect
drilling operations negatively.
INTRODUCTION
Drillingfluids are usually formulated to meet
certain properties to enable the mud carry out its
basic functions. A properly designed drilling
fluid should be able to perform some major
functions
to
meet
up
with
design
objectives.Thus, higher concentration of
contaminants in a drilling mud system causes

detrimental effect on its performance.
(Broughton, 1938).
In general, a contaminant isany material that
causes undesirable changes in drilling fluid
properties. Solids are by far the most prevalent
contaminants. Excessive solids, whether
commercial or from the formation, lead to high
rheological properties and slow the drilling rate.
While there are specific treatments for each
contaminant, it is not always possible to remove
the contaminant from the system.
Pretreatmentcan be advantageous as long as it
is not excessive and does not adversely affect
mud properties (Medermont, 1973).
The instability in the drilling mud properties is
as a result of various contaminants incorporated
in the mud system(Luminus, 1980).
Generally, a good drilling fluid is simple and
contains a minimum number of additives. This
allows easier maintenance and control of
propertieseven at elevated temperature and
pressure. It is desirable to have a mud system
that is flexible enough to allow changes to be
made to meet changing requirements as they
occur. Each change in mud should be planned
well in advance of the time it is required. This

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will allow current treatment of the mud
consistent
with
future
requirements.
Contaminants are encountered on everyphase
of the drilling operation. They also exist in
drilled formations, water supply and in materials
used in formulating and maintaining the drilling
fluid properties. They can rapidly alter the
physical and chemical characteristic of the
drilling mud. The severity of the problems
experienced depends on the type of drilling mud
used(Medermonth,1973,BaroidTraining
Manual, 1997).
Though the...