Drilling-fluids cleanup of casing is achieved by either turbulent flow, contact time, rotation or reciprocation across the casing waif, but combination of all gives excellent result.

The paper presents an enhanced casing welfbore cleanup methodology of combining detergents, drill-string rotation and reciprocation to clean casing and achieve a solids­ free completion fluid of less than 30NTU's (Nephelometric Turbidity Units). The method has successfully in some field applications displaced and cleaned up wells completion fluid NTU levels of less than 20 NTUs within some 2 hours of pumping time.

Cleanup was carried out in one phase as the chemical-pi/1-train is formulated to be capable of displacing the mud and cleaning the wellbore simultaneously. A one-trip consideration was given for provision of adequate spaces for the backload of mud and the containment of contaminated fluids. A one-trip phase, with rotation and reciprocation was combined with scraper-run and displacement of welfbore to creek or industrial water, thereby saving considerable rig-time. An engineered pumping design generated the required rates and turbulent flow necessary to optimally clean-up the casing.

This paper presents the successful cleanout of drilling mud in five trial wells in a Niger Delta field (referred to as Niger field).

Keywords:
drilling fluids and materials, reciprocation, operation, detergent, drilling fluid formulation, drilling fluid chemistry, rotation, drill-string rotation, drilling fluid selection and formulation, cleanup
Subjects:
Drilling Operations, Drilling Fluids and Materials, Drilling fluid selection and formulation (chemistry, properties), Drilling fluid management & disposal, Completion Installation and Operations
Copyright 2003, Society of Petroleum Engineers
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