This is the 25th anniversary issue of SPE Drilling & Completion(SPEDC). So many changes have occurred since SPEDC Volume 1Number 1 was published in February 1986. Technology that we take for grantedtoday either did not exist then or was just emerging.
Major advances in communication and information technology have played a keyrole in our industry. Imagine what it was like in 1986 when wells were drilledand completed without the Internet, mobile phones, personal computers, email,search engines, texting, broadband, webinars, and smart phones. True, some ofthese technologies may be merely nice to have, but others are essentialcornerstones of well construction.
Significant improvements have also occurred in drilling and completiontechnology--such as horizontal wells, 3D/4D seismic,polycrystalline-diamond-compact bits, measuring-while drilling/logging-whiledrilling, rotary steerable systems, top drives, real-time operations centers,expandable pipe, multilateral wells, intelligent wells, underbalanced drilling,managed-pressure drilling, casing drilling, synthetic-based fluids, hydraulicfracturing, rig mechanization and automation, and many more.
As we mark this anniversary, it seemed appropriate to examine changes inSPEDC over the years. To this end, Chris Carpenter, SPE Managing Editorof Journals, supplied the table of contents for every issue from 1986 to thepresent. These TOCs are available at http://www.spe.org/go/spedc and providethe basis for the following reflections.
When it was established in 1986, the journal was called SPE DrillingEngineering. During this inaugural year, 47 papers were published in sixbimonthly issues. Domestic subscriptions for SPE members cost USD 17.50. Volume1 Number 1 contained seven papers on the following topics: reducing cost perfoot in drilling deep, hard rock; clear brine drilling fluids; polymer drillingfluids for improved shale stability; cuttings transport experiments indirectional wells; air drilling in the Black Warrior Basin to address lostcirculation; casing wear; and drilling using foam/mist combination. Itsurprised me to realize that the topics themselves are still relevant today. Ofcourse, the specific technology discussed today would be quite different.Nevertheless, it is noteworthy that the same general categories of problemsstill exist 25 years later. In 1986, the first discussion of papers by readersappeared in Volume 1 Number 5; it contained four discussions and one reply byan author.
In 2010, 56 papers were published in four quarterly issues in SPEDrilling & Completion. (The journal format changed to quarterly in1987, and the journal name changed in March 1993.) Subscriptions for SPEmembers cost USD 70 for print + online and USD 45 for online only.Unfortunately, there are no discussions of any papers published in 2010. Infact, such discussion is rare in recent years. Why is this? Debate of importantand controversial issues in a public forum can accelerate progress. At aminimum, such debates can stimulate interest. Do readers today use other meansto discuss papers? Or is everyone simply too busy? A convenient method alreadyexists online at the SPEDC website to submit a discussion for eachpaper. If readers began submitting online discussions in sufficient quantity,then SPE would look into a type of notification system that would updatesubscribers on new discussions. Write to let me know your thoughts ondiscussions of papers.
From 1986 to 2010, approximately 1,000 papers were published inSPEDC. Starting with the March 2005 issue, all papers are available tosubscribers in online archives, so you can access them for free. However,papers published from 1986 to 2004 are available only through OnePetro and arenot free. Therefore, to get a sense of when SPEDC first published paperson important technologies, I scanned through the tables of contents from 1986to 2004 that Chris provided. The following 35 papers seem especially noteworthyin relation to industry firsts:
Clearly this highly unscientific selection is biased towards my ownexperiences and interests. I would be interested in reading your list if youcare to share it.
The marking of our journals 25th anniversary represents a major achievement.Many people have contributed over the last quarter century, including authors,subscribers, reviewers, and SPE staff.
Currently, SPEDC has over 150 technical editors (TEs) who reviewpapers submitted for peer review. (Since 2009, the SPE peer-review systemallows all seven peer-reviewed journals to use each other’s TEs. While this isa good thing, it does make it difficult to obtain a precise count of TEs forSPEDC.) We salute their devotion and service. Each year, associateeditors (AEs) select the Outstanding TEs based on quality, timeliness, andnumber of reviews. Our Outstanding TEs for 2010 are recognized elsewhere inthis issue.
In the November 2010 issue of Journal of Petroleum Technology, SPEPresident Labastie discussed peer review in his article titled "En Route." Henoted the significant improvement for all SPE journals in average time toreturn an initial decision to authors--from 225 days in 2006 to 98 dayscurrently. SPEDC has achieved a similar improvement over this period.Presently, our average time for returning an initial decision to authors is 86days.
The primary reason for the improved decision time is the hard work andcommitment by our reviewers. Special recognition goes to our ten AEs, who areall experts in their field. Each AE is responsible for specific subjects asshown below, with some overlap to accommodate potential conflicts of interestand work load (after all, each one is a volunteer!): CarlThaemlitz--drilling fluids, completion fluids, and chemistry; ChristophZerbst--completions planning, design, and installation, sand control,hydraulic fracturing, gravel packing, cuttings re-injection, safety in designand engineering, intelligent completions, and multiphase flow in wells; JohnThorogood--directional drilling and surveying, drilling project management,wellbore design/construction, human factors in health, safety, security,environment and social responsibility, deep water, harsh environment, andArctic operations; Max Medina--hydraulic fracturing, advancedtubing/casing design, completion design and planning, sand control,perforating, thermal completion design, steam-assisted gravity-drainageproduction and well construction, and intelligent completions; FionnIversen--real-time drilling applications, drilling automation, drillingprocess control and modeling, flow modeling, information systems and data use,measurement and control, well control, and multiphase flow in wells; KaibinQiu--wellbore stability, geomechanics, sanding, compaction and subsidence,and pore pressure; Shilin Chen--drill bits, drilling dynamics, downholetools and equipment, and directional drilling; David Kulakofsky--cement,cementing, and zonal isolation; John Mason--completion equipment,planning, design and installation, perforating, hydraulic fracturing,intelligent completions, and completion and intervention operations; andDeepak Gala--managed-pressure drilling, underbalanced drilling, airdrilling, casing and liner drilling, well control, blowout preventers, andblowout control.
Equally essential to SPEDC is the SPE staff, whose skills andcommitment are first class. On behalf of the TEs, AEs, and our readers, weexpress our heartfelt thanks to each of them. Special thanks go to StacieHughes, Mattie Tanner, Glenda Smith, Chris Carpenter,and Victoria Preston.
Carl Sagan famously said, "We live in a society exquisitely dependent onscience and technology, in which hardly anyone knows anything about science andtechnology." The truth of this statement is worth pondering. How can oursociety improve our collective ability to understand the ever-changingtechnology that underpins not only our daily existence but also our industrialprogress?
Journals such as ours that use peer review are a key tool in this quest forunderstanding technology. These journals provide a level of quality controlwhile ensuring that an industry’s technology is written, disseminated, shared,and preserved for future generations. We are grateful to our predecessors forhaving started SPEDC to publish the best papers on drilling andcompleting oil and gas wells. We humbly carry on their hard work, noble vision,and dedication to excellence so that future generations will continue to enjoythe same benefits we derived from the first 25 years of SPEDC.
What does the next twenty-five years and beyond hold for SPEDC?Again, we quote President Labastie from his "En Route" article in the November2010 J. Pet Tech: "In closing, I would say that peer-reviewed journalsare one strong element of the distinctive character of SPE. They have done alot in the past for the prestige of our Society. They will do a lot in thefuture, as our industry will certainly become more technology intensive andwill need more efficient ways to exchange high-quality technicalknowledge."
Now to the papers. This issue contains fourteen papers on the followingtopics: general drilling--six papers, wellbore stability, geomechanics, anddrilling fluids--five papers, hydraulic fracturing--one paper, andmanaged-pressure drilling--two papers.
Automation has had enormous impact on safety, efficiency, and risk reductionin other industries such as aviation. Similar opportunity exists today fordrilling automation. Recently both SPE and IADC formed technical sections ondrilling automation. How are these two industry committees different in theirobjectives, goals, and activities? Our first paper answers these questions andmore. Drilling Automation: Technologies, Terminology, and Parallels WithOther Industries describes concepts for drilling automation that arealready in operation or under development. It also proposes a classificationscheme for key categories. Automation in the aviation industry is described inrelation to drilling automation. Potential pitfalls are discussed that relateto ergonomics, human factors, and avoiding "overautomation" ("Dave? … Just whatare you doing, Dave?" from HAL in 2001: A Space Odyssey). The paperconcludes that early adoption of standardization is critical for rapiddevelopment of drilling automation. This paper comes at a crucial time becausesuch standards are currently under development for terminology, data, andinterfaces. The authors invite all interested companies and individuals to jointhe effort.
Cementing across salt zones was done as early as the late 1940s around saltdomes in the Gulf of Mexico. More recently, subsalt reservoirs have beendiscovered in basins around the world, such as the Gulf of Mexico, the NorthSea, West Africa, eastern Canada, and Brazil. Field development in thesesubsalt reservoirs requires successful cementation of casing strings thatcontact thousands of feet of salt. Cementing Casing Strings Across SaltZones: An Overview of Global Best Practices explores the issues andsolutions associated with cementing casing strings across extensive saltsections. Key concerns are salt movement (creep and flow), salt dissolution andits impact on cement strength, and determination of safe mud weight whendrilling through and immediately below salt. This paper is essential readingfor anyone interested in the state of the art on this topic.
High-Integrity Wellbore Surveying proposes a new set of minimumrequirements for survey validation. It is a product of collaborative work bythe SPE Wellbore Positioning Technical Section. The paper documents weaknessesin conventional directional-surveying quality control (QC) procedures.Theoretical considerations, statistical analyses of real survey data, andactual examples of failed surveys that passed conventional QC procedureswithout detection are presented. The need for survey QC tests that validatesurvey accuracy claims has been previously described by several authors, butthis paper provides the first comprehensive study of the contribution that suchtests make to directional-survey reliability. This paper systematicallyevaluates each of the QC tests and tabulates which error terms are controlledby which tests. The results point out weaknesses in current common practice anddemonstrate the significant effort required to achieve appropriate control.This paper also deals with error-model validation. Error models are usuallybased initially on manufacturing tolerances and estimates of referencetolerances and environmental effects. QC tests derived from models may under-or overestimate actual system performance. As statistically significantquantities of field survey data are accumulated, it is possible to reverse theQC process and test the model's compliance with the data. This practice hasalso been previously proposed, but it is not commonplace and rarely extended tothe global applicability of tool-error models. This paper describes two methodsof validating error models using cumulated QC data.
Multiwell thermal interaction will alter the wellbore temperatures as wellas formation temperatures in the interwell zones and also farther out from thewell template. The change in temperature profile relative to a single well canbe significant. Multiwell Thermal Interaction: Predicting Wellbore andFormation Temperatures for Closely Spaced Wells presents a methodologybased on standard industry thermal/hydraulic-modeling software and afinite-element model (FEM) in a loosely coupled, iterative analysis thatassumes steady-state conditions. A case study forhigh-pressure/high-temperature offshore field development is presented. Themultiwell disturbance on formation and wellbore temperatures affects welldesign, facilities planning, and operations. Annular pressure buildup, wellheadmovement, tubular-stress design, cement-slurry design, subsidence/compactioneffects, and facilities health and safety issues can all be affected. Ifmultiwell thermal interaction is not taken into account, then load events, suchas annular pressure buildup, wellhead movement, and thermal-induced stressesmay be underestimated. In developing this model of multiwell thermalinteraction, the objective was to provide a practical, robust method thatincorporates standard industry tools and established analytical models. Theproposed method can be used to predict both the wellbore temperatures andsurrounding formation temperatures.
Managing Drilling Vibrations Through BHA Design Optimization employsa bottomhole assembly (BHA) design evaluation process based on afrequency-domain lateral-dynamic model in both predrill and post-drill hindcastmodes. The method conducts a comparative analysis of several specific BHAdesigns. BHA lateral vibrations are characterized such that alternative BHAconfigurations may be developed and compared directly with a proposed baselineassembly. In the hindcast mode, the BHA model can be operated at the recordedweight on bit and rotary speed to generate corresponding model results in timeor depth, and these values can be compared with the measured performance data.A case study of a BHA with a motor and roller reamer is described, withcorresponding field date for four original BHAs and four redesigned assemblies.A second case study shows model and field results for two rotary steerableassemblies. The model employs two vibration modes for each candidateBHA--lateral bending and "twirl," or BHA whirl. In the lateral bending mode, aconstant reference side bit force is applied, and the magnitudes of theresponse are compared along each BHA. In the twirl mode, a reference masseccentricity is applied. Index values have been developed to summarize dynamicperformance to indicate which BHA design is preferred and identify operatingsweet spots. The authors have found that the relative performance assessmentbased on use of this model is a good predictor of field results.
Probabilistic estimation of well duration has been common practice for morethan a decade. This paper asserts that it is not possible to use these previousstate-of-the-art methods to obtain sufficiently accurate predictions. InProbabilistic Well-Time Estimation Revisited, a database of 118 centralNorth Sea wells was analyzed for nonproductive time (NPT) from the originaldaily drilling reports. Results showed the data actually underestimated NPT by19.7% on average. Train wrecks (mechanical NPT more than 2.5 days long) wereonly 4% by number but represented 50% by duration. It was found that "ordinary"mechanical NPT, train wrecks, waiting on weather in open water, and waiting onweather with riser connected are all statistically distinct, with verydifferent occurrence frequencies and probability distribution functions.Earlier models did not observe this important distinction. The authors claimtheir analysis technique is accurate and that it may be applied as a templateto other areas after proper local calibration. They have published their entiredata set and the full technical basis of their method because they believe lackof such information has held back progress in this area by hindering the debateessential to bring the subject to a mature level. Publishing full details ofall steps in the analysis makes the paper a little long, but we agree with theauthors that it is essential to stimulate debate.
Wellbore strengthening has been a hot topic in recent years. CaseHistory: Successful Wellbore Strengthening Approach in a Depleted and HighlyUnconsolidated Sand in Deepwater Gulf of Mexico discusses drilling throughthe depleted formations at Total's Matterhorn tension-leg platform in deepwaterGulf of Mexico using a flat-rheology synthetic-based fluid engineered with ahigh concentration of bridging particles to impart a strengthening effect onthe formation. A drill-ahead method of applying the treatment to the formationwas used (rather than a pill spotting method) because the risk of fracturingthe reservoir existed with the mud weight needed to control the caprock. Thepaper describes the laboratory approach to fluid design and the operationalpractices to apply the treatment on location. A post mortem analysis comparesformation breakdown pressures taken from fracturing operations to actualwellbore pressures experienced while drilling and cementing to demonstrate thata strengthening effect was realized. The results imply that using such adesigner fluid can have a strengthening effect on depleted/unconsolidatedformations, in which some operators have had limited success in applyingwellbore strengthening techniques.
Significant fluid loss while drilling through fractured formations is amajor problem. A common method of dealing with massive losses is to apply lostcirculation material (LCM). The authors are convinced that use of LCMs is notthe only way of reducing mud losses. In some cases, LCMs may result inpermanent damage of productive fractured zones. Field experience shows thattype and rheological parameters of the drilling fluid have a strong impact ofthe rate and volume of losses while drilling through fractured formations. Thisobservation led to the work that is documented in Quantitative Analysis ofMud Losses in Naturally Fractured Reservoirs: The Effect of Rheology, whichdevelops a mathematical model for Herschel-Bulkley (yield-power law) drillingfluid losses in naturally fractured formations. It investigates effects ofrheological properties such as yield stress and flow behavior index on mudlosses. Results indicate that yield stress can control the ultimate volume oflosses while the shear-thinning effect can tremendously affect the rate oflosses. Therefore, mud losses in fractures can be minimized by optimizing therheology of the drilling fluid. The model allows for quantitative analysis oflosses that take into account fluid rheology to characterize the fractures.Hydraulic aperture of conductive fractures can be obtained by continuouslymonitoring mud losses and fitting field records of mud losses to the model.Estimates of fracture width is valuable for designing sealing treatments andother potential cures for lost circulation. The proposed model is useful fordrilling and completion design. A practical application of the proposedtechnique is demonstrated through a field example of mud loss measurements in afractured well in the Gulf of Mexico. The paper concludes that use of LCM inconjunction with rheology adjustment is recommended as a better way ofmitigating fluid losses than the use of LCM alone.
Previously the theory of rock failure based on planes of weakness has beenapplied primarily for layered rocks. Here it is extended to significantlyweaker mudstones showing strength anisotropy. Wellbore-InstabilityPredictions Within the Cretaceous Mudstones, Clair Field, West of Shetlandsdescribes a study conducted to address problems in earlier high-inclinationwells that experienced unstable wellbores in Cretaceous mudstones overlying theClair oilfield. Results of this study were used to plan an ERD well, which wassuccessfully drilled, cased, and brought on stream using the plane of weaknessmodeling of wellbore instability. Although the magnitude of the mechanicalanisotropy in mildly compacted mudstones is small compared to that in the hard,brittle rocks such as slates and schists for which the weak-plane model wasdeveloped, the inherent weakness of these mudstones means that even a smalladditional weakening can have a critical impact on wellbore stability anddrilling success. The characteristic signature of the weak plane failure modeis a pronounced increase in the mud weight required for wellbore stability atmedium inclinations and a small additional increase in the mud weight requiredfor stability at high inclinations. Indications of unexpected instability at(say) 20 to 40° should be closely investigated and not dismissed as aconsequence of drilling practices. They may be an early indicator of trouble atmoderate to high inclinations; conversely, trouble at moderate inclinationsneed not imply that there is no drilling window at high inclinations. A similarfailure mechanism may occur in other parts of the world. Therefore, the methoddeveloped here for the Clair field may also be useful elsewhere.
Numerous casing and production-liner deformation/failure problems have beenreported in high-porosity chalk formations in both the overburden and thereservoir sections, causing costly operations problems that prevent workoversand recompletions. A Comprehensive Modeling Analysis of Borehole Stabilityand Production-Liner Deformation for Inclined/Horizontal Wells Completed in aHighly Compacting Chalk Formation presents the results of studies performedto investigate stability of an openhole, cemented liner, and uncemented-linercompletions in a highly compacting chalk formation. The effects of criticalcavity dimensions caused by various acid stimulation techniques were alsoinvestigated. Analytical and numerical models were developed for evaluatingcavity-induced axial compression collapse of production liners. Model resultsindicate that the risk of the cavity-induced axial compression collapsesubstantially increases for short perforated intervals stimulated with largeacid treatments. Increasing the perforation-interval lengths along the entireliner axis results in more uniform acid distribution and will greatly reducedthe chance of axial compression collapse caused by localized cavitydeformation. Key completion design criteria and stimulation strategies weredeveloped for wells completed in highly compacting chalk reservoirs to reducerisk of casing and liner mechanical problems.
Drilling in depleted and compacted fields can cause costly problems. TheValhall field in the Norwegian sector of the North Sea has experiencedsignificant reservoir compaction in weak chalks, exceeding 10 m in some places.Sixty Days Ahead of Schedule: Reducing Drilling Risk at Valhall UsingComputational Geomechanics presents a novel approach for predicting localstress changes in the overburden induced by reservoir compaction andsubsidence, whereas previous work has often focused on depletion-inducedfracture gradient changes in the reservoir itself. The new technology is basedon a history-matched full-field FEM geomechanics model to calculate stresses,strains, and displacements. Results are exported from the FEM to geologicalmodeling software to perform wellbore stability calculations. In thisenvironment, users can incorporate 4D seismic from the permanent life-of-fieldseismic array at Valhall. By calculating the operational mud weight window overa high-risk interval in the overburden, a good correlation to historical NPTwas found. The method is used in detailed well planning where moving the well50 m in one direction can be the difference between problem-free drilling andhuge drilling challenges. The paper presents application of the technology on anew water injector delivered 60 days ahead of schedule with reduced costs ofapproximately USD 20 million. The application potential for this technology issignificant even in reservoirs with less compaction than Valhall, as inhigh-pressure/high-temperature fields and highly deforming reservoirs.
A Crosslinkable Synthetic-Polymer System for High-TemperatureHydraulic-Fracturing Applications describes a new hydraulic fracturingfluid capable of service temperature up to 232°C. The fluid uses a syntheticpolymer that is crosslinkable to metal ions to generate high viscosity. Thesynthetic polymer fracturing gel overcomes thermal limitations of traditionalguar and derivatized guar-based fracturing fluids. Several advancements havebeen made in the development of this technology to maximize the efficiency ofcrosslinking and to give an effective breaking profile, resulting in goodlaboratory gel cleanup in proppant pack. Research efforts have yielded afracturing fluid with good fluid stability at high temperatures to createbetter proppant transport and placement. The crosslinking system can be tunedfor crosslinking onset as a function of temperature, thereby allowingoptimization to specific wellbore conditions. The system has been applied insouth Texas at temperatures approaching 232°C.
Solid case histories are highly useful instruments to transfer knowledgefrom one area to another. Managed-Pressure Drilling Using a ParasiteAerating String is such a case history that chronicles drilling in Piceancebasin in western United States. The basin presents significant challenges forlost circulation and stuck pipe. This paper describes a new technique for thisbasin that involves acquiring real-time equivalent-circulating-density data andcontrol of annulus mud weight through air injection in a parasite string. Themethod was successful in achieving the desired major reduction in fluid lossesduring drilling by controlling equivalent-circulating density.
Pressure maintenance within safe bounds and minimization of influx of fluidsfrom the formation during a kick are basic concerns of well control.Managed-pressure drilling (MPD) offers improved capabilities over conventionalwell-control methods to address these concerns. Improved Kick ManagementDuring MPD by Real-Time Pore-Pressure Estimation asserts that the issue ofdeveloping an appropriate process to control flow during MPD operations has notbeen thoroughly addressed yet. By definition, MPD does not encourage influxinto the wellbore. Nevertheless, in some cases an influx will occur. When akick is taken, obtaining an accurate estimate of the pore pressure at theinflux zone as quickly as possible will assist regaining control of the well.The proposed method estimates formation pore pressure automatically on basis ofreal-time measurements when a gas kick is taken during MPD. It relies oncharacteristics of the pressure-buildup curve. A North Sea well is used as testcase geometry, and an advanced hydraulics model is used in a virtual well incomputer simulations for presented results. The method is demonstrated tomaintain pressure within desired bounds and reduce formation fluid influx,thereby reducing the risk of hole-stability problems and the cost associatedwith NPT.
That wraps up this issue. On behalf of your entire Editorial ReviewCommittee, thank you for your continued support of SPE Drilling &Completion.