Executive Summary

Curtis Cheatham, Weatherford International

SPE ATCE and DSATS

The 2011 SPE Annual Technology Conference and Exhibition (ATCE) will convenein Denver from 31 October through 2 November. This event offers many wonderfulopportunities for members to learn about technology and make valuable industrycontacts. From technical sessions to plenary sessions to the exhibits, thereare ample avenues for curious minds to stretch their boundaries. There are alsoactivities even before ATCE officially starts, including training courses, aworkshop for Technical Editors of SPE journals (including SPE Drilling &Completion, of course), and meetings of some SPE Technical Sections.

If you are like me, then you may be wondering what exactly a TechnicalSection is. How many are there? And what do they do? Some research on the SPECommunities website revealed the following information.

First, what is a Technical Section? "A Technical Section is a group of SPEmembers with a common interest in a technical area who join together to shareideas, promote competence, and develop projects related to their technicalinterest."

Second, how many are there? Currently SPE has six Technical Sections:

  • Digital Energy
  • Research & Development
  • Wellbore Positioning
  • Drilling Systems Automation
  • Production & Operations
  • Well Integrity

Third, what do they do? Technical Sections generally meet "virtually" butalso hold face-to-face meetings once a year. They are global, self-operatinggroups with officers and members who publicize their section’s technicalinterest and develop projects to advance the state of the art. They are open toany SPE member to join at no charge.

The newest SPE Technical Section dedicated to drilling or completionsactivity is the Drilling Systems Automation Technical Section (DSATS).According to its website, "The objective of this group is to accelerate theuptake of drilling systems automation by supporting initiatives thatcommunicate the technology, standardize its nomenclature, promote lessonslearned/best practices, and help define its value proposition."

DSATS has had numerous meetings since its inception in 2007. This year,there are two meetings planned, both in conjunction with major SPE conferences.The first meeting was held in Amsterdam in conjunction with the SPE/IADCDrilling Conference and Exhibition last February. The turnout was 270attendees, which indicated keen interest in the technical area.

The second DSATS meeting in 2011 will be held on 30 October in conjunctionwith ATCE. The event will include a panel discussion on the expansion of wellconstruction automation beyond drilling into completions and interventions.Heretofore, DSATS has focused on drilling systems, as one would expect from thename. Broadening the discussion to nondrilling activities is expected to draw alarge audience from the multidiscipline audience that attends ATCE. Who knowswhere this meeting might lead the industry? Perhaps one result could be aseventh Technical Section. The meeting site will be the Colorado ConventionCenter, which is also the site of ATCE. There is no charge to attend thismeeting, but you must register to attend because of limited seating.

DSATS has seen strong growth, as demonstrated by its current size of 187members. Another sign of growth has been the recent formation of a Europeansubcommittee for DSATS. Its purpose is to support and participate in meetingactivities in Europe. This geographic expansion indicates the growing globalinterest in automation.

I encourage you to go to the following website and consider joining one ormore Technical Sections: http://communities.spe.org/TechSections/default.aspx.

Now to the papers. Continuing our custom since March 2010, this issuecontains 14 papers.

  • Carbon capture and storage, two papers
  • Cementing/zonal isolation, two papers
  • Well control and blowouts, one paper
  • Drilling operations, one paper
  • Inflow-control devices, two papers
  • Deepwater completions, one paper
  • Tubulars, five papers

Carbon Capture and Storage

Carbon capture and storage (CCS) aims to reduce the amount of carbon dioxidein our atmosphere. Our first two papers examine the sealing ability of cementedwellbore sections to contain carbon dioxide injected into underground storage.The last issue of SPE Drilling & Completion (June 2011) alsoincluded a paper on CCS, so this is clearly a hot topic.

Leakage through new or existing wellbores is considered a major risk forcarbon dioxide geological storage. Long-term effective containment is required;but, reliable data about long-term containment of CO2 is almostnonexistent. The authors of our first paper, Quantifying the Risk ofCO2 Leakage Through Wellbores, used steam and methane injectionwells as analogs to assess failure rates and consequences for cementedwellbores in CO2 wells. Statistical data about occurrence of leaksand their consequences are analyzed to determine the risk profile ofCO2 leaks. A smaller sample of data about leak rates is alsoanalyzed. Rates and consequences are then compared to try to assess the orderof magnitude of major and catastrophic leaks. The paper concludes that cementedwellbores appear very effective at controlling leak rates and they will likelybe as effective with CO2 as they currently are with the steam andmethane analog wells.

Our second paper also examines long-term sealing ability of cemented sectionin wellbores penetrating CO2-storage reservoirs. A key concern isthat microfractures inside wellbore cement or microannuluses are possiblepathways for CO2 leakage. The Effect of CO2-SaturatedBrine on the Conductivity of Wellbore-Cement Fractures presents anexperimental study that investigates the changes inside the cement internalstructure when exposed to acidic brine through an artificial fracture. Computedtomography scans and mercury intrusion porosimetry tests were conducted toassess changes in pore-size distribution. Environmental scanning electronmicrosopy was used to further investigate the nature of altered zones withinthe cement at a much finer scale. The impact of CO2-rich brine onwell cements under dynamic conditions appears to have dual effects on porosityof cement matrix. Low-pressure experiments showed porosity reduction for smallpore sizes, while high-pressure experiments appear to cause increased porosityfor large size pores. The authors conclude that, in terms of the behavior ofwellbore cements under CCS conditions, it is possible that cements will undergoboth dissolution and precipitation of new minerals. Further work is ongoing toquantify the change in permeability of cement with longer-term acidic brineexposure.

Cementing and Zonal Isolation

Dynamic Aspects Governing Cement-Plug Placement in Deepwater Wellsreports a parametric study based on computational fluid dynamics to determinethe influence of rheological properties of fluids (drilling fluid, spacers, andcement slurries), string rotation, and flow rates (including free-fall effects)on the quality of cement plugs. Guidelines and recommended procedures areprovided for displacing cement plugs in vertical, inclined, and horizontaloffshore wells. Fluid conditioning, spacer design, and pumping scheduleprocedures are highlighted.

In recent years, exploration activities in Kuwait have focused on Jurassic,Triassic, and Permian formations at depths between 15,500 and 20,000 ft.Cementing operations have presented major challenges because ofhigh-pressure/high-temperature (HPHT) conditions, large casing sizes, oil-basedmud, the presence of H2S/CO2, and narrow pore/fracture pressure window. Since2003, work has been carried out to employ changes to technologies beingdeveloped in HPHT wells around the globe, especially in the North Sea. Theresult was a notable improvement in cementing performance. OngoingDevelopment of Cementing Practices and Technologies for Kuwait Oil Company’sDeep High-Pressure/High-Temperature Exploration and Gas Wells: Case Historyexamines application of these technologies, materials, and practices over an8-year period. This paper breaks down the many design elements of extremelychallenging cementing operations. This solid case history provides excellentdetails comparing early and recent casing and cementing programs.

Well Control and Blowouts

Rotating control devices (RCDs) are used to provide a closed circulatingsystem. Conventional wisdom suggests that drilling with RCDs improves kickdetection and, thus, that fewer blowouts should occur when this equipment andrelated practices are deployed. Is conventional wisdom correct in this case?Yes, says The Impact of Rotating Control Devices on the Incidence ofBlowouts: A Case Study for Onshore Texas, USA as it finds consistentstatistical evidence that the use of RCDs decreases the incidence of blowoutsusing a sample of wells from onshore Texas from 2001 to 2007.Interestingly--perhaps even surprisingly--the paper concludes there is noconsistent evidence to suggest that oil wells have more or fewer blowouts thangas wells. (It is more difficult to provide gas-tight casing connections thanit is to provide oil-tight connections. Therefore, conventional wisdom mighthave said there should be more gaswell blowouts than oilwell blowouts.)

Drilling Operations

Traditional plug and abandonment (P&A) of exploration wells isaccomplished by setting a series of cement plugs and mechanical retainersystems to isolate zones from each other and from surface. PermanentAbandonment of a North Sea Well Using Unconsolidated Well-Plugging Materialdescribes a North Sea P&A field case study using an alternative method. Anunconsolidated plugging material with high solids concentration was used toprovide a gas-tight barrier. The authors claim the method avoids problems withwell integrity that might be caused by cement shrinkage or fracture. The methodrequires a solid foundation; it cannot be placed on top of a liquid. Thematerial is also not suitable as a foundation for a kick-off plug or behindstructural (weight-/load-bearing) because of its relatively low shear strength.The paper shows how the fast and efficient placement of the plug contributed tooverall cost reduction. It also explains how the well-barrier element complieswith requirements in both the Norwegian and UK sectors of the North Sea.Operational procedures are presented.

Inflow-Control Devices

Inflow-control devices (ICDs) are completion hardware designed to distributeflow evenly in the reservoir. With a more-evenly distributed flow profile,production is less likely to suffer problems related to water or gas coning,sand production, and other drawdown-related issues. Understanding the Rolesof the Inflow-Control Devices in Optimizing Horizontal-Well Performanceinvestigates when and how ICDs should be used. An integrated analysis method ofinflow (reservoir) and outflow (wellbore) is used to generate the flow profileof a horizontal well. Two conditions that result in productionproblems--wellbore pressure drop and reservoir heterogeneity--are addressed.Examples illustrate key points. The paper concludes that three productionproblems can be corrected by proper design and use of ICDs--the heel-toeproblem, heterogeneous permeability distribution, and thin oil formation.

Our second paper on inflow control also addresses nonequalized productioninflux along a horizontal well. Multinode Intelligent-Well Technology forActive Inflow Control in Horizontal Wells describes a new technology toequalize production influx and delay water breakthrough more effectively thanconventional, passive ICDs (as described in the preceding paper). The newsystem provides full electric remote actuation of downhole flow control formultiple valves with a single control line. This paper compares production andwater-saturation profiles using the new technology to conventional ICDs in ahorizontal-well simulation. The system is still under development; and, as theauthors conclude, field data are required to prove the concept for productionoptimization and better reservoir management.

Deepwater Completions

Planning and Execution of Highly Overbalanced Completions From a FloatingRig: The Ursa-Princess Waterflood Project is a compelling story of adeepwater reservoir that has been on production since 1999 and is nowundergoing a waterflood to increase and stabilize reservoir pressure andimprove sweep efficiency. As more deepwater reservoirs approach depletion,specialized tools and procedures will be required to continue to deliver safeand effective sandface completions from floating rigs. This paper details manyof these considerations and summarizes the execution and results from the mainreservoir in the Mars-Ursa basin in the Gulf of Mexico. It is a must-read foranyone involved with or interested in deepwater fields.

Tubulars

We wrap up this issue with five papers related to tubulars. The first paperprovides lessons learned from the past 20 years of successful application oftorque-position makeup technology. Whether you are an expert in connections orsomeone who wants to know what LTC, STC, and BTC mean, you will benefit fromreading Continuing Application of Torque-Position Assembly Technology forAPI Connections. This paper is an easy read that clearly details a criticaland sometimes overlooked aspect of well construction.

Solid expandable liner systems were introduced approximately 15 years ago.My first exposure to expandables occurred at an SPE forum around 1995 when avideo of the process was shown (yes, we used video in the 20th Century!). Irecall thinking to myself "no, no, no" because intentionally inducing plasticdeformation into a structural member conflicted with all my mechanicalengineering training. Obviously, I was wrong because expandable systems werehere to stay. Today, expandables provide viable options for dealing with majordrilling hazards such as massive lost circulation or depleted zones. MajorAdvancement in Expandable Connection Performance, Enabling Reliable GastightExpandable Connections asserts that, despite the progress, connectionperformance remains a problem. This paper details new cone-expansion technologythat the authors claim eliminates the majority of damage to connections whenexpanded with traditional cones. Finite-element analyses and physical testingverification are provided to show how the new technology leaves connectionswith minimal visible damage to threads and metal seals after expansion. Thepaper concludes by stating developments of advanced connection designs areunderway to provide enhanced pressure sealing and mechanical performance duringand after expansion.

No standard procedure has been adopted by the industry to qualify casingconnections for high temperatures up to 350°C. New Standard for EvaluatingCasing Connections for Thermal-Well Applications introduces a new protocolfor evaluating casing connections for thermal applications. The protocol, whichwas developed jointly by several operators and connection manufacturers,employs both analytical and experimental procedures. Adoption and use of thenew protocol is expected to increase reliability and reduce failures of casingstrings in thermal wells.

Our last two papers are courtesy of the same lead author. Dr. Rob Mitchellpulls off the rare double by publishing two papers in the same journal issue(and not a two-part series). His first paper points out that designcalculations for casing and tubing forces and displacements are traditionallyperformed assuming the fluids are static. Obviously, this could be asignificantly limiting assumption because casing must also withstand flowingfluid forces. Casing Design With Flowing Fluids adds the effects offluid dynamics to the pipe equilibrium problem. The general equations forbalance of fluid momentum are combined with the equilibrium equation for pipe.The effective forces emerge as a natural combination of pipe force andfluid-force terms. This mathematical tour de force is power packed anddefinitely worth a read for readers responsible for casing or tubingdesign.

Our final paper challenges conventional wisdom about how pipe buckles. Theaccepted paradigm has existed for more than 30 years, which is that bucklingoccurs first into a sinusoid and then into a helix. Torque and drag softwareprograms calculate the onset of these buckling limits as well as the additionalside force caused by the helix that leads to a condition known as lockup, whichmeans that the pipe cannot be moved deeper into a wellbore. LateralBuckling--The Key to Lockup analyzes the field data presented in animportant paper (SPE-115930-PA) that was published in the December 2009 issueof SPE Drilling & Completion. In this prior paper, high-qualityfield data were obtained in a 2020-m research well known as Ullrigg U2. Readersmay recall this paper concluded that current industry-standard calculations ofthe onset of sinusoidal and helical buckling did not match well with thesefield data. (Subscribers of SPE Drilling & Completion can downloadthis paper from online archives.) The results of the new analysis show thatconnectors appeared to have primary importance in the buckling behavior ofdrillpipe. More important, this paper concludes that lateral buckling was theprimary mode of behavior in these tests, not helical buckling. Neither of theseresults was expected. The authors state that conventional buckling models willrequire significant revision to account for these effects. Only time will tell,but this paper could represent a major transformation in buckling analysis.

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