Drill Cutting Transport in Full Scale Vertical Annuli
Authors: Sifferman Thomas R. , Myers George M. , Haden Elard L. , Wahl Harry A. 
Published: December 2007

This paper was prepared for the 48th Annual Fall Meeting of theSociety of Petroleum Engineers of AIME, to be held in Las Vegas, Nev., Sept. 30-Oct. 3, 1973. Permission to copy is restricted toan abstract of not more than 300 words. Illustrations may not be copied.The abstract should contain conspicuous acknowledgement of where and bywhom the paper is presented. Publication elsewhere after publication inthe JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERSJOURNAL is usually granted upon request to the Editor of the appropriatejournal provided agreement to give proper credit is made.
Discussion of this paper is invited. Three copies of any discussionshould be sent to the Society of Petroleum Engineers Office. Suchdiscussion may be presented at the above meeting and, with the paper, maybe considered for publication in one of the two SPE magazines.

Abstract
The absence of the basic data needed tofully evaluate present field practices andcurrent concepts on drill cutting transportprompted this full scale study. Several drill prompted this full scale study. Several drill pipe and casing sizes were used in a 140-ft pipe and casing sizes were used in a 140-ft vertical flow system to define the variablesaffecting drill cutting transport under steadystate conditions.
Variables evaluated were annular velocity(4 to 200 ft/min), fluid rheologicalproperties (mud, water, oils), cutting size (3-6 properties (mud, water, oils), cutting size (3-6 mesh), fluid weight (12-15 ppg), rotary speed(0-200 rpm), drilling rate (cutting feedconcentration), drill pipe position(centered-eccentric), and annular size. Annularvelocity and fluid rheological properties werethe most significant variables. Annularvelocities well below the 120 ft/min used in mosthydraulic programs were found adequate toclean the hole. Increasing apparent viscositydramatically improved cutting transport. Theother variables showed 2nd and 3rd ordereffects. Terminal slip velocities were a goodindicator for the velocities required toinitiate transport, but observed transport was75 to 90% of the theoretical values.These findings should destroy many mythson drill cutting transport and provide afactual basis for improving drillinghydraulics.

Introduction
The drilling literature does not answeror else gives conflicting answers to many ofthe questions asked about drilling hydraulics.Some of these unresolved questions are:
Should mud viscosity be raised or loweredto clean the hole? What velocity is requiredto prevent excessive cutting buildup in theannulus? Can the annular velocity be lowerin slow drilling areas? As mud weightincreases, can annular velocity be decreased?How does drill pipe rotation, position(centered or eccentric) and annular clearancesaffect cutting transport and pressure drops?Is an annular velocity of 100-120 ft/minneeded to keep the hole clean? If not, whatvelocity is required? What are the "ideal"mud properties? Are our current hydraulicprograms a technical and economic "overkill"? programs a technical and economic "overkill"?