The Drilling Fluid Inhibition Properties Effect on Hole Quality - A Well Survey

摘要

Shale inhibition is considered to be the most important factorto prevent hole problems when drilling with water baseddrilling fluid (WBM). Some components are believed to bevital for well bore inhibition like KCl, glycols and designedpolymers. The effect of the products is largely based on thecuttings quality seen in the return flow at the rig. When newsystems are introduced they are often tested in relativelysimple wells and performance are evaluated based on resultsform that well.Some incidental observations where systems not regardedas inhibitive outperformed the state of the art water baseddrilling fluid systems. This observation trigged of a largersurvey on drilling efficiency with respect to water baseddrilling fluid system. Water based drilling fluid systems usedin Statoil's operations over the last 15 years in the North Seawere compared with respect to hole quality. Data from thesurvey shows that today’s highly inhibitive systems do notperform any better than systems used for 15 years ago. Thesurvey raises a question around the way drilling fluid systemsare designed today. Are we using the right methods fordesigning the drilling fluids?The paper describes the result from the survey. In thepaper a method using different "indicators" to measure thehole quality is used. Such indicators include: stuck pipefrequency, tripping time, drilling progress, caliper data andcuttings quality. As a result of the first part of the survey, thedrilling fluid chemical composition was altered both whendrilling through non-reactive and reactive formations in aseries of wells. An increased drilling efficiency was observed.The paper describes how the drilling fluid composition couldbe optimized dependent on the smectite content ofthe formation.