Executive Summary

Curtis Cheatham, Weatherford International

It is my honor to introduce the next Executive Editor (EE) of SPEDrilling & Completion to you, Carl Thaemlitz. Carl has a strongcommitment to our journal and we are fortunate to have someone so passionatefor peer review at the helm for the next 3 years. Please join me incongratulating Carl and giving him our full support in his new and excitingjob.

SPE Drilling & Completion published 163 papers during the last 3years--a slight increase over the previous 3 years. We increased the ranks ofour Technical Editors (TEs) from 110 to more than 200 during this period, andour Associate Editors (AEs) grew in number from eight to 12. A majorimprovement was achieved in reducing time required from paper submission todecision. These results were achieved through lots of hard work--not only byTEs and AEs, but also by authors and SPE staff. My heartfelt thanks go out toall.

The 200 TEs are too many to mention by name (but all TEs who reviewed atleast one paper in each calendar year are named in the following March issue).However, I would like to recognize the 16 AEs with whom I was privileged towork with over the last 3 years. Each is a recognized industry expert whodevotes massive time and energy in managing paper reviews. Four AEs served theentire 3 years with me and I am amazed they were able to put up with me for solong! Seriously, I am humbled by their commitment and contributions to ourjournal.

  • Carl Thaemlitz
  • Christoph Zerbst
  • John Thorogood
  • Fionn Iversen

Six AEs ended their terms during my tenure. I am grateful for their serviceand dedication to our journal.

  • Max Medina
  • Pål Skalle
  • João Carlos Plácido
  • Dan Stone
  • Deepak Gala
  • David Kulakofsky

Six AEs began their terms in the last 3 years. I am proud of their superbaccomplishments and look for each of them to continue to excel in their pivotalroles in peer review.

  • Kaibin Qiu
  • Shilin Chen
  • John Mason
  • Joe Yunxu Zhou
  • Steve Nas
  • Bernard Piot

I would also like to thank two folks who served as my informal advisers--myfather, John Cheatham, and another close friend, DeBow Freed II. Their guidanceand counsel helped me tremendously through these 3 wonderful years and wasespecially useful for the really tough stuff.

When I became EE, I read the executive summaries of many of my predecessors.I noted that, in their final issue, they always thanked the SPE professionalstaff. At the time, I thought--well, isn’t that nice! Now, I realize howcrucial these outstanding individuals are to the success of SPE journals. I hadthe great pleasure to work with Glenda Smith, Chris Carpenter,Mattie Tanner, Rebekah Stacha, Adam Wilson, VictoriaPreston, Meghann Mays, and Leah Miller. Readers typically donot meet or interact with them, so it is hard to convey the significance ofwhat SPE staff does behind the scenes. Trust me, it is top-notch work they doto the benefit of all of us. And there is one person who deserves to be singledout--Stacie Hughes. Before I became EE, I worked with Stacie when I wasan AE. I thought she was the Peer Review Administrator for only one SPEjournal--SPE Drilling & Completion. I believed this because she isso efficient, responsive, and on top of everything. When I became EE, I learnedStacie is Peer Review Administrator for all seven SPE journals! So, to me, shedoes the work of seven people, and represents the best in SPE peerreview--dedication, service, technical excellence, and good old-fashioned hardwork.

Now, to the papers. This issue contains 14 papers.

• 4 on tubulars
• 2 case histories
• 1 on Pore Pressure in Shale
• 4 on drilling operations and optimization
• 1 on cementing
• 2 on completions

Tubulars

Multistage fracturing in horizontal shale wells is one of the most importantnew technologies in recent years. A key question is: Should we designproduction casing for such wells using the same procedure that we use forconventional wells? Special Considerations in the Design Optimization of theProduction Casing in High-Rate, Multistage-Fractured Shale Wells shows thatthermal effects during cooling create both bending stress magnification andannular pressure reduction caused by cement contraction in trapped cementvoids. The result is increased loads and new modes of failure that should beconsidered in design. The paper provides acceptable design options forshale-well production casing. It is recommended to engineers responsible formanaging integrity of production casing in shale development wells. This paperalso provides a derivation of bending stress magnification factor (BSMF) thatdiffers slightly from the Paslay and Cernocky BSMF, which is commonly used fordrillstring design.

A common assumption in designing casing for burst is that the fluid isfilled with fluid in the annulus. What if hard cement fills the annulus?Casing Burst Stresses in Particulate-Filled Annuli: Where Is the Cement?uses numerical finite element analysis to compare casing burst resistanceassuming various backup profiles, including fluid hydrostatics, solid cement(both elastic and plastic), and cement as loose particles. Guidelines areprovided to calculate the enhanced casing burst resistance. This paper is afascinating treatise on the subject and is highly recommended to engineersresponsible for casing design.

Our next paper extends the analysis of two well-known papers that are oftencited for buckling considerations--Lubinski (1962), whose analysis consideredthe casing to be perfectly rigid, and Christman (1976), whose analysispostulated a composite pipe on the basis of the summed properties of the twotubular strings. Buckling of Tubing Inside Casing shows the 1976 paperled to incorrect predictions concerning buckling. The new paper presents morerealistic bucking configurations for the various methods that two concentricpipes can interact when one or both pipes are in compression and would have atendency to buckle. The contact forces between the pipes and with the externalwellbore are explicitly calculated and contact or noncontact conditions arediscussed. New insights describing tubing buckling tendency are given, whichchallenge the typical assumptions of rigid casing. For example, it is predictedthat a surprising amount of shear and bending is transferred to the casing bythe buckled tubing, which is not normally considered in casing design. Thiseffect was not known previously, and can be significant. All results areanalytical so that they can be easily used in spreadsheets or handcalculations. Several example calculations are presented to illustrate howthese results might be used. This is an important paper that is highlyrecommended to any readers responsible for designing casing or tubing or toanyone interested in the topic of buckling.

Numerous methods are available to determine fatigue life from either elasticor plastic-bending cycling. However, few data are available within the industryon how fatigue damage is affected by the combination of elastic and plasticbending cycles. Combining Elastic and Plastic Fatigue Damage in SteelPipelines, Risers, and Coiled Tubing presents the experimental workconducted to measure combined fatigue life. The tests were conducted on notchedsamples of flat steel used to manufacture coiled tubing that has beenplastically and elastically cycled. The work shows that the combined fatiguedamage from plastic and elastic cycle is higher than the linear summation ofthe fatigue damage from both sources. Experimental work confirms that plasticand elastic cycles can be combined by use of a nonlinear relationship. Apower-law-damage rule provides an appropriate method to determine the overallfatigue damage.

Case Histories

Our next paper provides a thorough case history showing how unconventionalmethods were used to successfully drill challenging, shallow, extended-reachwells on the north slope of Alaska. Nikaitchuq Extended-Reach Drilling:Designing for Success on the North Slope of Alaska describes the technicalchallenges, well design solutions, and operational practices that were trialedand implemented to enable extended reach wells to be successfully drilled onthe edge of the industry experience envelope (the famous "nose plot"). Twotechnical challenges for this project were management of equivalent circulatingdensity (ECD) and torque and drag. Two key solutions were application ofhydraulics and torque and drag modeling software.

A redevelopment campaign in the Netherlands required new techniques toensure long-term cement integrity in thermal wells to permit use of steaminjection. Contemporary Approach Coupled With Traditional Techniques TacklesExtreme Wellbore Environment in Schoonebeek Heavy Oil Field offers timelyinformation for the industry. The paper contains a number of areas such asmicro-CT scans of foam that have not been explored previously. Thecomprehensive case history of the rejuvenation of a complete field tells thecomplete story, from the selection of design criteria, to the logistics,operational and economical constraints, and finally implementation in thefield.

Pore Pressure in Shale

An Innovative Approach for Pore Pressure Prediction and DrillingOptimization in an Abnormally Subpressured Basin develops a drillingoptimization procedure that simultaneously allows improved penetration ratesand good quality of cuttings. The paper describes the challenging drilling ofsubpressured zones in western Canada that will serve as a good model forothers. Five previously drilled wells were used in the study of the proposedoptimization procedure. Presumably the next step is to test the method on newwells.

Drilling Operations and Optimization

Nonproductive time (NPT) in drilling operations has been a major focus ofdrilling optimization for many years. Lost circulation, kicks and otherwell-control incidents, stuck pipe, and unstable wellbores are prime examplesof NPT that the industry continues to attempt to solve, or at least reduce. Ournext four papers deal with new methods to reduce NPT.

After an NPT event has occurred, we are often able to look back and detectkey data that could have foretold the likelihood of trouble. But, much morevalue would be obtained if the NPT event could be detected beforehand andprevented. Early Symptom Detection on the Basis of Real-Time Evaluation ofDownhole Conditions: Principles and Results From Several North Sea DrillingOperations proposes a method for predicting NPT events before they happen.The method comprises (1) computing various physical forces using models; (2)calibrating these models using real-time data (surface and downhole); (3)analyzing deviations between model and measured values; (4) estimating thecurrent state of the well; and (5) predicting root causes of changes in wellcondition to provide early warning of deteriorating well conditions. Themonitoring system has been used on 15 wells in five fields. The paper providessolid case studies to demonstrate the method. The point is well made that itcan be difficult for rig crews to trust such technology if there are no othersigns that trouble is imminent. But, to be worthwhile, a confidence level inthe technology must be established and if corrective action is preemptivelytaken, then how can one be assured the NPT was really going to occur? Falsewarnings can also be problematic. All these soft issues are discussed withgreat insight. This paper provides some real food for thought.

Drilling automation has the potential to provide significant improvements inefficiency and safety because it already has been achieved in other industries.To help ensure drilling automation systems work properly in all circumstances,Advanced Drilling Simulation Environment for Testing New Drilling AutomationTechniques and Practices offers a means to enable testing automationtechniques, equipment, and work processes under a wide range of simulatedconditions. This paper details the application of an advanced drillingsimulation environment called hardware in the loop to verify real-timeperformance of automation systems without putting an actual well at risk.Complex drilling situations can be simulated, including deteriorating downholeconditions. The authors expect the new testing environment for drillingautomation technologies and associated work processes can be regarded as a stepforward for enabling safe introduction of automation at the rig site and indaily drilling operations.

Lost circulation and well control problems can cause major NPT. Accurateprediction of downhole pressures is vitally important to avoid such events.Predicting optimum tripping speeds for drillstring, casing, and liners(particularly in narrow annular clearance conditions) is essential to avoidlost circulation by tripping in too fast or to avoid swabbing in a kick bytripping out too fast. Surge-and-Swab Pressure Predictions forYield-Power-Law Drilling Fluids presents a new steady-state numerical modelthat accounts for fluid and formation compressibility and pipe elasticity usingthe industry preferred yield power law rheological model. Comparisons withpublished theoretical models and laboratory and field measurements arepresented to validate the model.

Another major cause of NPT is differential pressure sticking. The fourthpaper on drilling operations and optimization addresses methods to diagnosedifferential sticking in the Persian Gulf, where the problem occurs frequently.Intelligent Prediction of Differential Pipe Sticking by Support VectorMachine Compared With Conventional Artificial Neural Networks: An Example ofIranian Offshore Oil Fields compares two methods using artificial neuralnetworks for diagnosing differentially stuck pipe. Results indicate that thesupport vector machine (SVM) method works better than a conventional artificialneural network applying a particular transfer function. This paper is aninteresting contribution to the literature, representing a first use of SVMs indrilling,

Cementing

Displacing fluids in downhole conditions over long distances can bedifficult. A key problem can be mixing of fluids in the annulus, such ascement, with drilling fluid or spacer. A common assumption for hydraulicsmodels is that fluids are immiscible, and therefore do not mix. AComprehensive Theoretical and Experimental Study on Fluid Displacement forOilwell-Cementing Operations presents a numerical model using lubricationtheory that accounts for annular mixing of fluids. Model results are validatedin an experimental vertical well. Future enhancements to the model are planned,including simulating pipe movement. This paper should be worthwhile toengineers involved in cementing operations.

Completions

Multilateral wells have been used extensively since the early 1990s toaccess multiple reservoirs from a single mother bore. North Sea World RecordInstallation--Deepest Sealed Multilateral System presents a case historywith emphasis on operational challenges. This paper should benefit drilling andcompletion engineers involved in application of high end multilateraltechnology.

Our last paper is definitely cutting edge and the topic of sand control indeepwater has a huge impact on reservoir economics. UltralightweightProppants: An Effective Approach To Address Problems in Long Horizontal GravelPacks Offshore Brazil provides innovative ideas on deepwater gravelpacking. Completion engineers involved in deepwater completions requiring sandcontrol will find this paper worth reading.

That wraps up this issue. On behalf of your entire Editorial ReviewCommittee, thank you for your continued support of SPE Drilling &Completion.

Curtis Cheatham
cheatham@spemail.org