Executive Summary

Curtis Cheatham, Weatherford International

SPE Peer-Approved Papers in the Year 2020

How will readers access our journals 8 years from now?

To address this important question, let’s take a look at a brief history ofSPE's peer-reviewed publications, with thanks to Glenda Smith, SPE SeniorManager, Technical Publications.

In the early years of the Society of Petroleum Engineers, the Journal ofPetroleum Technology (JPT) published full-length, peer-approved (PA)papers. In 1961, the SPE Journal (SPEJ) was created to publishmore scientific, fundamental research PA papers, and JPT began handlingonly the more practical PA papers. This format continued for 25 years until1986, when SPE made three major changes in publishing peer-approved papers.First, JPT stopped publishing peer-approved papers of any type. Second,discipline-based journals were launched--including SPE Drilling &Completion. And third, SPEJ was discontinued. In 1996, SPEJwould be reborn to handle PA papers of a more fundamental research nature. Thenext major change occurred in 2005, when online versions of the journals wereadded.

We see there has been significant change over the last 50 years. Today weare in a major revolution in information/communication technology. Therefore,the question is: What changes should SPE make to best serve its members inlight of the ongoing transformation?

As we consider this question, there is a troublesome trend worth noting. Inrecent years, the number of subscribers to SPE journals has essentiallyremained constant despite the large increase in membership. This fact indicatesit is time to reevaluate SPE journals from the ground up. Granted, when oneconsiders this trend, there are some obvious contributing factors. First, thesubscription price has gone up significantly in the past few years as printmedia everywhere have struggled to remain economically viable. Second, there isan increasing usage of the number of papers downloaded from OnePetro (many companieshave corporate memberships) that may be hurting subscriptions.

Both of these factors undoubtedly affect journal subscription, but there isperhaps a more important cause. SPE members are increasingly accessingtechnical papers from mobile devices, such as iPads, other tablets, smartphones, and laptops. Some print media have already ceased to exist, and thethreat to the existence of all remaining print media grows each day.Furthermore, the rate of change of the shift to new and different ways ofaccessing media is accelerating. Remember, 8 years ago SPE had no online accessto its journals. Imagine today how strange it would seem if we were unable toread a technical paper using online access (that may not be your preferredmethod of access, but everyone takes it for granted that it is availabletoday). This shift toward electronic media is affecting journals in allindustries, not just SPE. The revolution in journal access is happening todayright before our eyes, and it is worthwhile to consider how readers will accessour journals 8 years in the future.

The problem is complex. As a society of engineers, we should try to solve itlike a complex problem. First, appropriate and accurate data must be gatheredand analyzed to determine root causes of the problem. Then, options to overcomethese obstacles should be developed and analyzed to determine the optimal wayforward. Finally, changes must be implemented. This is exactly what SPE isdoing. Over the next year, this problem will be addressed at the request of theSPE Board of Directors. During this time, you may be called on to provideinput. But even if you are not contacted, please help your society solve thisimportant problem by providing your thoughts and critical comments! There willprobably be major changes in the way you receive peer-reviewed papers in thenear future and beyond. We need all hands on deck to make sure we get thesechanges right.

Now to the papers. This issue contains 13 papers and a bonus reprint.

  • 1 on drilling-engineering training with directional drilling examples
  • 2 on well control and managed-pressure drilling
  • 1 on drillstring dynamics
  • 1 on casing drilling
  • 4 on completions
  • 1 on formation damage
  • 2 on well integrity
  • 1 on wellbore strengthening
  • 1 classic on horizontal drilling

Drilling Engineering Training With Directional Drilling Examples

Our first paper is a must-read. Simple Engineering Applications Recycledas Effective Training Aids focuses on drilling-engineering training at theintermediate level, which is an important issue as the Big Crew Change movesinto warp speed. Directional drilling examples are used to illustrate keypoints, but the author points out that the method can be applied to otherapplications, such as casing design, hydraulics, and hole cleaning. There ismuch to like about this paper, but what I like most is the author’s passion forengineers to understand the fundamental concepts that underpin sophisticatedsoftware-engineering-analysis models and software. The examples show howengineers can solve simple problems to gain critical insights to more complexproblems and help interpret high-tech (and sometimes even black-box) computerprograms. Simple problems, such as the ones described in this paper, areessential for validation of software-engineering applications because they canbe solved using exact analytical solutions. This leads to a crucialphilosophical point: Advanced engineering software applications are a tool andshould be used accordingly. In the hands of a well-trained, experiencedengineer, these tools are powerful extensions of their own expertise. But thesame software can be useless--or worse, counterproductive--in the hands ofsomeone who uses it as a substitute for engineering skills and experience. Theauthor eloquently explains his philosophy by stating that (1) teaching methodsshould instill curiosity and encourage critical assessment of the models andmethods used, and (2) students should explore the physics in both mathematicaland qualitative terms. Bravo! This philosophy is one that I embrace andfervently try to teach to the bright young engineers with whom I am fortunateto work. I really like this paper and highly recommend it to all readers,particularly YPs!

Well Control and Managed-Pressure Drilling

Managed-pressure drilling (MPD) offers opportunities to improve drillingperformance and safety, which is a highly desirable combination. Our next papertakes a significant stride forward to achieve these goals. A Proposed Methodfor Planning the Best Initial Response to Kicks Taken DuringManaged-Pressure-Drilling Operations is the second paper published inSPE Drilling & Completion from a research consortium focused onproviding the basis for comprehensive, reliable well-control procedures for MPDoperations equivalent to the industry standard procedures used in conventionaldrilling. The first paper published by this research consortium appeared inVolume 26, Number 2, in the June 2011 issue. The current paper proposes amethod for preselecting the best initial response when a kick is taken duringconstant bottomhole pressure MPD operations.

Fundamental research on gas kicks is an important topic. A Dynamic Modelof Percolating Gas in a Wellbore describes a simplified two-phase gasmodel. The authors state that their objective is to model gas percolating up awellbore without resorting to the use of partial differential equations. Theywere motivated by other simplified models, including one published in the lastissue of SPE Drilling & Completion (Kaasa et al., SimplifiedHydraulics Model Used for Intelligent Estimation of Downhole Pressure for aManaged-Pressure-Drilling Control System). The authors show how to usewired drillpipe distributed pressure measurements and an unscented Kalmanfilter with their simplified two-phase gas model to estimate liquid-holdupprofile as a gas kick is circulated out of the well. Performance of the modeland method of estimation are compared with results from a state-of-the-artsimulator (OLGA). Results show it is possible to use noisy wired drillpipemeasurements to successfully estimate liquid-holdup profile.

Future work will augment the model to include fluid compressibility,non-Newtonian fluids, and inclined wells. (Editor's note: liquid holdup is thefraction of the cross-sectional area occupied by the liquid in the pipe orannulus carrying the two-phase gas and liquid flow. Liquid holdup is importantbecause it has a major effect on accurate prediction of pressure losses intwo-phase flow. For more information, see http://geocities.ws/abouelsaoud/productionstorage/liquidholdup.pdf).

Drillstring Dynamics

Our next paper is innovative and practical. Quantification ofDrillstring-Integrity-Failure Risk Using Real-Time Vibration Measurementscombines conventional MWD vibration sensors in a single location in thedrillstring with a new method of data analysis. The new calculation is calledthe characteristic intensity and is derived from seismicground-motion-intensity calculations. It takes into account both the cumulativevibration and the length of the run. The paper provides comparisons to standardmeasures of data analysis, such as RMS acceleration and peak acceleration, forfield runs in 17 ½-in. and 12 ¼-in. hole sizes. For the cases studied, thecharacteristic intensity identified approximately 80% of thedrillstring-integrity failures. The paper concludes that the new method allowsthe differentiation of high-risk scenarios by using only vibration data fromthe run. As the authors state, this result was obtained despite the fact thatfatigue or wear of drillstring components before a run are unknown andvibration sensors were located at a single position in the drillstring. Theyconclude the results seem to indicate that the main contributor to the actualintegrity failures is the fatigue accumulated for any given bit run.

Casing Drilling

The challenges of transferring technology to a new geographical area can beformidable. This paper details an excellent case history for the introductionof casing drilling to a new area. Casing While Drilling (CwD): A NewApproach To Drilling Fiqa Formation in the Sultanate of Oman--A SuccessStory tells the story of how wellbore-instability problems were overcome intwo fields. Critical success factors were appropriate engineering planning,careful selection of casing drilling components and personnel, andimplementation and monitoring of real-time drilling efficiency and optimizationtools. The key performance indicators of reducing overall drill/case time andcost were used to demonstrate the successful implementation of casing drillingin these fields in northern Oman. Readers who are interested in casing drillingor in reading about how technology is effectively transferred to a new field orarea will enjoy this paper.

Completions

The first of four completions papers in this issue presents An ImprovedTechnique for Interpreting Perforating-Flow-Laboratory Results: HonoringObserved Cleanup Mechanisms. It discusses traditional perforatinglaboratory experiments (API RP-19B, Section 4) that yield key results that arerequired inputs to downhole flow simulators. The paper develops new methods formeasuring and interpreting coreflow efficiency. The new method enables morerealistic treatment of effective tunnel flowing length, diameter, crushed-zonethickness, and crushed-zone permeability. This work accepts the existingconventional skin and downhole-inflow models as a valid framework for the timebeing. The authors present a coherent methodology of interpreting laboratorydata for the purpose of generating the required inputs to the skin models. Inaddition to improving the treatment of perforation damage within the existingframework, the discussions in this paper also pave the way to develop newmodels that will extend beyond the current 1D radial inflow simplification. Theauthors recommend this workflow should be considered for inclusion in anyrevisions to Section 4 testing protocol.

Many casing- and screen-damage incidents have been reported in deepwater oiland gas fields in the Gulf of Mexico and other locations around the world.Casing- and Screen-Failure Analysis in Highly Compacting SandstoneFields reviews historical casing/well-failure events in five wells in ahighly compacting sandstone field and performs a comprehensive geomechanicsanalysis of various casing-damage mechanisms (tension, axial compression,shear, and bending) related to large reservoir depletion. A 3D nonlinearfinite-element model is developed for simulating stress changes in theoverburden and the reservoir intervals and evaluating the effect oflithological anomalies on casing stability. The numerical-analysis resultspresented in this work help engineers understand possible casing and screendeformation and failure mechanisms experienced in highly compacting sandstonefields. On the basis of the study findings, completion design guidelines arepresented to avoid or mitigate compaction-induced casing damage in both theoverburden and reservoir intervals.

Sand-control technology commands much attention in our journal, and it isthe subject of our next paper that offers a highly innovative solution to anold problem. Pumping a gravel slurry between a downhole screen and the rockmatrix has been used to prevent production of undesirable solids or sand fromthe formation in traditional oil and gas completions. Recently developedexpandable technology attempts to eliminate this operation by expandingmetallic sand-control screens against the wellbore. However, a problem withthis process is borehole irregularity. It is desirable to have a smart downholescreen structure that is capable of self-expanding and conforming to theborehole surfaces in certain downhole conditions. In-Situ Mechanical andFunctional-Behavior Characterization of a Shape-Memory Polymer for Sand-ControlApplications documents development and extensive laboratory testing of anadvanced shape memory polymer structure that offers breakthrough performancefor sand-control applications. This study used a high-pressure/high-temperaturein-situ mechanical-test system and test method to characterize the in-situhot-wet mechanical and functional behavior of the shape memory polymer foam,including deployment and contact-pressure development functional properties,and compressive and time-dependent stress-relaxation and creep mechanicalproperties. Study results are used to establish the operational window ofshaped memory polymer screen as a sand-control solution. The new technologyreported in this paper is certainly exciting. Presumably, the next step isfield trials.

Knowing the exact flow allocation for each controlled zone is important forwell optimization and the management of an intelligent well system (IWS).Transferring Intelligent Well System Triple-Gauge Data Into Real-Time FlowAllocation develops a comprehensive hydraulics model to address this topic.This paper discusses a recent application of the model to estimate the flowallocations of an existing two-zone deepwater IWS oil producer that beganproduction in 2007. A total of 1,362 daily triple-gauge data points areavailable for this study, where pressure and temperature data indicate that thewell was flowed in multiphase downhole conditions for a large percentage of itsproduction life. Verification was completed by comparing the predictedflow-allocation results with this well’s measured total rates and dailyallocation rates. These comparisons showed a good match between the predictedresults, measured data, and the available reservoir study results. This paperis very interesting and recommended to readers who are considering use ofintelligent wells or who want to stay abreast of the latest developments inthis area.

Formation Damage

Most filter-cake models in the literature assume homogeneity in the radialdirection. Characterization of Filter Cake Generated by Water-Based DrillingFluids Using CT Scan shows that the filter cake is not homogeneous, butinstead consists of two layers of different properties. The results obtainedfrom the computed tomography scan showed that the filter cake in theselaboratory studies contained two layers with different properties. One layerwas close to the drilling fluid, which had an average thickness of 0.1 in.,while the second layer close to the rock surface had an average thickness of0.06 in. Both the porosity and permeability of the layer close to the drillingfluid were zero, while the porosity of the layer close to the rock surfaceranged from 10 to 20 vol% and the permeability of this layer was nearly 0.087μd. Scanning electron microscopy results showed that the two layers containedlarge and small particles, but there was very poor sorting in the layer closeto the drilling fluid, and led to zero porosity in this layer. Previous modelsunderestimated the thickness of the filter cake by almost 50%. A new method wasdeveloped to measure the thickness of the filter cake, and various models werescreened to identify the best model that can predict our permeabilitymeasurements.

Well Integrity

In the post-Macondo world, well integrity has received much attention. Butwhat exactly does "well integrity" mean? One definition of well integrity is"the application of technical, operational, and organizational solutions toreduce the risk of an uncontrolled release and/or unintended movement of wellfluids throughout the life-cycle of a well" (NORSOK Standard D-010, Rev 3,August 2004). Our next paper, Assessing Well-Integrity Risk: A QualitativeModel, describes a well-integrity risk-assessment model that has proven tobe successful for indentifying and ranking well-barrier-failure risk in a well,a group of similar wells, or an entire well portfolio. The results from theassessment allow the risks to be ranked so that areas of highest risk areidentified and can be monitored and/or mitigated properly with limitedresources. The asset can use the risk-assessment results as a reference for awell-integrity program to reduce risk from well operations and potentialwell-integrity problems on a routine basis.

Cement sheath is a key element for maintaining well integrity. In our nextpaper, the authors develop a mechanistic model to simulate the various modes ofloss of cement-sheath integrity after the cement has been placed in the well.Use of a Mechanistic Model To Forecast Cement-Sheath Integrity aims toevaluate the risk that cement sheaths could represent to leakage pathwaysbecause of the cement becoming damaged or debonding at one of the boundaries.This paper first summarizes cement behavior as a solid, and then uses datapresented in the first part to show that loss of cement-sheath integrity notonly depends on cement properties but also on the well architecture and wellhistory. The model presented here is thoroughly explained and is of interest toother researchers focused on cementing or well integrity.

Wellbore Strengthening

Twenty years ago, the first paper was published on wellbore strengthening.Fortunately for readers of SPE Drilling & Completion, our next paperwas written by two of the same authors as that pioneering work. In recentyears, various methods of wellbore strengthening have been proposed, such aswell cooling, stress cage, and tip screenout of induced fractures.Parametric Analysis of Wellbore-Strengthening Methods From Basic RockMechanics presents a set of analytical equations developed for these threewell-known wellbore-strengthening methods. It also provides information aboutthe strengths and limitations of each method. Finally, an updated set ofequations based on previous works by the authors are provided to make analysisof wellbore-strengthening methods easier to implement.

Classic SPE Drilling & Completion Paper

This issue closes with the reprinting of a classic paper that helped changeour industry. In this issue, we have chosen Drilling the Cold LakeHorizontal Well Pilot No. 2 by R.R. MacDonald. This paper first appeared inSPE Drilling Engineering Vol. 2, No. 3, in September 1987. (SPEDrilling Engineering was the precursor of SPE Drilling &Completion.) It was the first paper on horizontal drilling published in ourjournal.

Since this paper was published 25 years ago, horizontal drilling has becomea mainstay technology. The recent boom in unconventional reservoirs, such asshale gas and liquids, would have been impossible without horizontal drilling.Nowadays, it is routine to drill dozens or even hundreds of horizontal wells inan unconventional field. How far the industry has come in a quarter of acentury!

This paper is important for the historical achievement it documents. Inaddition, the story itself is worth reading by today's engineers, both youngand old. It clearly describes the extensive engineering work performed toidentify and address the key problems that were anticipated: hole drag (andassociated drillstring buckling) and directional-surveying accuracy (andwellbore placement). Then, a comprehensive account of the drilling of the wellis presented, including significant changes to the plan during drilling. Forsomeone like me who entered the industry a decade before horizontal wells firstappeared on the scene, it is fascinating to read how such a disruptivetechnology overcame limitations not only of equipment but also of people'sthinking. I encourage you to read this prime example of superb drillingengineering--it will be worth it. Enjoy.

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