S T R E T C H I N G C E M E N T I N G T E C H

IN MEXICO, DRILLING in increasing-ly challenging environments is taking thecementing industry into uncharted areasand stretching the limits of current tech-nology. Current technology can’t ensuresuccessful circulation and an effectiveseal. Failure to achieve a seal can have alarge impact on the cost of drilling a welland its productive life.

Traditionally, the industry has relied ontwo very different technologies for thecreation of ultra-light cement slurries —either using nitrogen or via the additionof low specific gravity microspheres intothe cement. While both technologies arecapable of producing very light cementslurries, neither have been used in an oil-well to form an effective seal at densitiesbelow 7.5 lb/gal. In these most difficultMexican formations where fracture gra-dients range from 7.5 to 6 lb/gal, currentcement densities have reduced chancesof successful circulation.

This paper presents case histories show-ing a melding of the two technologies.Lab data and guidelines are provided forhow to best use these technologies atdensities down to 5 lb/gal (a worldrecord).

Ultralightweight Cementing Technolo-gy Sets World's Record for LinerCementing With a 5.4 lb/gal SlurryDensity (IADC/SPE 98124) DS Kulakof-sky, R Bonifacio, O Araujo, Halliburton; IRamirez, Petroleos Mexicanos.

L A R G E C E M E N T V O L U M E S

With deep wells being drilled in the Gulfof Mexico, the volume required to cementa larger casing back to the surface canexceed 20,000 sacks. The conventionaljackup rigs used to drill these deep gaswells are generally limited to less than10,000 cu ft of bulk storage. This bulkstorage is generally divided betweenbarite, bentonite and cement.

If liquid pre-mix cement slurry could bemaintained in boat tanks during mar-itime conditions for extended periods oftime, it would be possible to perform a30,000-sack cement job from an offshoresupply vessel.

For the liquid pre-mix cement slurry tobe considered a viable alternative to con-

ventional cementing technology, it’s nec-essary to determine: Is the agitation sys-tem in the liquid mud tanks sufficient tomaintain large quantities of premixedcement slurry? Can slurry maintenancebe performed on the slurry while it’s inthe liquid mud tanks? What are the per-sonnel requirements for liquid slurrymaintenance while at sea? Can the boattransfer liquid cement fast enough tomeet the job requirements? Could thedensity of the original premixed slurrybe increased or decreased in the boattanks?

This paper will outline the 10-day slur-ry stability test that was undertakenaboard an offshore supply vessel. Thistest duplicated the anticipated storageconditions of 650 bbls of pre-mixedcement slurry stored in the liquid mudtanks of a working offshore supplyvessel.

Large Scale Feasibility Determinationof Storing and Transporting a LiquidPremixed Cement Slurry Below DeckUnder Maritime Conditions (IADC/SPE98894) CJ Fanguy, DR Doherty, DTMueller, BJ Services.

F L U I D D I S P L A C E M E N T

The need for an efficient displacement ofdrilling fluids from cased wells prior toinstallation of completion equipment hasbeen relatively undisputed in the past.

Several different fluid systems have beenapplied, as well as a variety of differentmechanical tools, to achieve what is con-sidered to be a clean well in order tosafely run advanced completion equip-ment in the well. In contradiction to therequirements related to running moreadvanced equipment in the wells is the

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Innovative cementing meets increasing needs

IADC/SPE DRILLING CONFERENCE: CASE HISTORIES

98124: To adapt for drilling operations in Mexico, melding of foam and microspheres technologiesstretched current lower slurry density limits—down to a 5 lb/gal cement that set a world record.

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fact that several of the fields on the Nor-wegian shelf are entering the maturephase and tail end production. For thesefields, the margins are less, and a signif-icant focus is put on cost-efficient solu-tions. In many cases, the need for casingcleaning in conjunction with displace-ment of drilling fluids is questioned.

This paper reviews the results fromdrilling fluids displacement and casedhole cleaning operations performed on190 wells on the Norwegian continentalshelf over the past five years.

These wells cover a variety of differentcompletion scenarios where both water-based and oil-based drilling fluids havebeen used.

The results from the survey are present-ed with a focus on the requirementstoward a clean well and the ability tomeasure the efficiency of the differentfluid systems and operational proce-dures used. The paper discuss differentcasing cleaning requirements versuswell completion scenarios and displace-ment techniques.

Displacement of Drilling Fluids andCased Hole Cleaning: What Is Suffi-cient Cleaning? (IADC/SPE 99104) EBerg, S Sedberg, H Kaarigstad, BJ Ser-vices; T Omland, K Svanes, Statoil.

P R E V E N T I N G S T U C K P I P E

Comparatively little research has beendone to predict stuck pipe, and there arefew references for quantifying estimatesof force needed to free stuck pipe. If therisks that lead to stuck pipe are identi-fied in advance, procedures can be setup to reduce the possibility of theiroccurrence.

This paper presents an application ofneural network methods for understand-ing the causes of differentially stuckpipe. The method enables drilling indus-try personnel to estimate the risk ofoccurrence of stuck pipe during wellplanning procedure and during drilling.A feed forward error and learning rulesare used. The convolutional analysis ofthe model is based on the constraints ofdifferent drilling variables. The trainedneural net is shown to be able to auto-matically detect variables of concern.

The paper also includes field case stud-ies of stuck pipe incidents from the Gulfof Mexico where the neural networkmethodology successfully predicted pipesticking.

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Stuck Pipe Prediction and Avoidance:A Convolutional Neural NetworkApproach (IADC/SPE 98378) R Samuel,Halliburton; S Nagarakanti, C Siruvuri,University of Houston; KK Bharucha,Landmark Graphics Corp.

D O W N H O L E P R E D I C T I O N S

This paper will explain how design dataand real-time simulation of cementingjobs can be used to make detailed predic-tions of well parameters and provideinformation so that adjustments can bemade during the cementing operation.The tools allow a more accurate predic-tion on cement tops, changing casing pro-grams, controlling flowback rates andpressures, monitoring equivalent circu-lating density (ECD) on specific zones, orenabling personnel to create a betterdesign for the next well in the field.

Computer simulations that model sur-face and downhole conditions can pre-vent cementing failures both before theactual cementing operation and duringthe operation. Maintaining control andpredicting problems can be determinedby taking into account all the monitoredand calculated variables on a real-timemode and comparing the outputted pre-dictions with the pre-job design and theactual ongoing job.

Demonstrated by examples and casestudies, the simulation process performssteps needed to give precision to predic-tions in placement calculations. Multipledesign program runs may be taken with-out actually jeopardizing the integrity ofthe well.

Study Comparing Computer Simulat-ed and Monitored Real Time Cement-ing Designs vs. Actual Jobs in Progress(IADC/SPE 98079) PG Creel, MR Briney,H Pipes, DD McKenzie, Halliburton.

C A S I N G / L I N E R D R I L L I N G

Recent technological advances are driv-ing casing and liner drilling from a nichemarket into the mainstream environ-ment. Improved connections, tubulars,advances in rig technology and pipe han-dling have enabled operators to considerdrilling with casing/liner as an option onmany new wells.

In a mature South Texas field, an opera-tor discovered the difficulties of drillinginto formations with weak matrixstrengths, loss circulation zones, andtight pore pressure/fracture gradientwindows. These issues have deemed the

field sensitive to aggressive drilling tech-niques, and the operator has been forcedinto a conservative drilling program withreduced flow rates and lower weight onbit capacity.

A service company introduced a newliner drilling system engineered so theoperator can ream and drill liner to bot-tom. It is comprised of a robust fixed cut-ter casing bit and a drill in liner assem-bly designed to handle rotation andtorque.

The liner system utilizes a running toolthat allows the liner to be pushed, pulledand rotated without fear of release. Onceat desired setting depth, the hydraulicbalancing tool is released with a settingball. The casing bit is manufactured froma specialized steel alloy that allows tech-nicians to braze PDC cutters directly tothe one-piece bit, ensuring a robust cut-ting structure capable of efficientlydrilling new formation, as well as ream-ing existing hole. Even with less thanoptimal drilling parameters, the systemallows the operator to run the liner tosection TD, cement, and then drill outwith no damage to the BHA.

To date, seven intervals have beendrilled with this system.

Managing Uncertainty and ReducingRisk: Liner Drilling Operations inSouth Texas (IADC/SPE 99110) LI Clark,EE McClain, Hughes Christensen; KEvans, Baker Oil Tools.

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IADC/SPE DRILLING CONFERENCE: CASE HISTORIES

98079: A designer plans a cement job that will be monitored in real-time. Design data and real-timesimulation of cementing jobs can be used to make detailed predictions of many well parameters andprovide information so adjustments can be made during the cemeting operation.

99110: In aSouth Texas field,a liner drillingsystem was usedto allow the oper-ator to ream anddrill liner to bot-tom. The systemincludes a robustfixed cutter and adrill in linerassemblydesigned to han-dle rotation andtorque.

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