Automatic evaluation of drilling fluid properties

Abstract

This thesis is structured in two main parts. First part covers the fundamental role of drilling fluid in the drilling process. It provides a description of the mud circulating system for conventional drilling operations, outlines the basic composition of drilling fluids, and describes the main functions and properties of drilling fluids. Furthermore it describes the current testing procedures and equipment and illustrates how testing is used in the evaluation of drilling fluid properties. The thesis also covers the fundamentals of drilling fluid hydrodynamics, including drilling fluid rheology and the three most commonly used rheological models for characterizing drilling fluid flow in conjunction with frictional pressure loss calculations. Some of the weaknesses and limitations of the current testing regime will also be discussed. The second part will present a description of a new concept “Instrumented standpipe” enabling automated measurements of important drilling fluid parameters during drilling operations. The Instrumented Standpipe concept is based on continuous pressure monitoring of the flow path between the mud pump and the swivel. These pressure measurements can provide valuable real time information about the fluid density, frictional parameters and rheological parameters. The major part of this chapter is related to the practical installation and implementation of a small scale Instrumented Standpipe set up on an existing flow loop, and validation of its performance through experimental testing.