Curry

This issue of SPEDC is my last as editor. Nowadays, a farewell performance is often called a swan song, but I rather hope this editorial is not my swan song. In Elizabethan times, it was believed that a swan would be silent throughout its life until singing delightfully in its dying moments. Orlando Gibbons’ madrigal “The Silver Swan” is perhaps the best known, and almost certainly the most beautiful, expression of this belief:

The silver swan, who living had no note,
When death approach'd, unlock'd her silent throat;
Leaning her breast against the reedy shore,
Thus sung her first and last, and sung no more.
Farewell, all joys; O Death, come close mine eyes;
More geese than swans now live, more fools than wise.

Apparently, this romantic legend had its origins in ancient Greece. Socrates himself (particularly missed as he is according to Monty Pythons’ philosophers’ song) declared that swans, having sung loudly and long all their lives, would sing more loudly and more sweetly as their death approached in happiness at going to meet the gods Orpheus and Apollo. As Socrates recognized, the reality is that most swans are not silent; rather, they whistle and honk loudly but tunelessly. Anyone who has heard me try to sing will recognize the similarity there. When the presiding vicar led my wife and me up to the altar for our marriage—and driven more by concern for his own ears than my embarrassment, I fear—he let me know that the congregation could no longer hear us, and I could stop singing if I wished. 

So, perhaps this can be my last bow. In an earlier editorial, I cited the Sherlock Holmes approach to problem diagnosis: when Holmes made “His Last Bow,“ he had long since retired from 221B Baker Street to the English South Downs and a life of philosophy and agriculture, mostly beekeeping punctuated by occasional crippling bouts of rheumatism. Sir Arthur Conan Doyle may have intended “His Last Bow” to have been just that; however, he went on to write a further 12 stories chronicling previously unpublished incidents from the fictional great detective’s earlier life. Doyle maintained it was public clamour for more Holmes adventures that persuaded him to change his mind; he made no mention of royalty payments from sales of those later, earlier stories. I do not imagine there will be any clamour for more of my editorials, and, as I am sure readers will be relieved to hear, there is no financial inducement to tempt me into returning from editorial retirement.  Sadly, I will not be retiring to the South Downs or to beehives any time soon—my day job beckons.

Interviewed immediately after winning gold at his fourth consecutive Olympic games and asked about the prospect of him competing in the next games, Sir Steve Redgrave, the great British oarsman, and arguably the greatest British Olympian ever, said, “Anyone who sees me go anywhere near a boat again, ever, you’ve got my permission to shoot me.” Despite this, Redgrave did go near a rowing boat again and went on to win gold in his fifth Olympic games. He was rightly and wildly applauded, not shot. Perhaps I should heed this warning of the danger of giving a public commitment not to return. When younger, I spent much time rowing competitively, or perhaps it would be more accurate to say rowing in competitions. I still remember briefly feeling what, for me, was all too rare: the satisfaction of winning my division in a sculling race on the River Thames—only to have my smugness shattered by discovering that a 16-year old called Redgrave, competing in the junior division, had beaten me by so much that, if we had started at the same time, he could have taken his boat out of the water, put it on the trailer, and been showering in the changing room before I crossed the finishing line.

Two issues ago, I worried about whether or not we would be able to find replacements for the Review Chairpersons retiring along with me. I need not have worried. An old Yorkshire adage reassures that “cometh the hour, cometh the man.” I rather doubt its optimism always justified, but it has been for the SPEDC Review Committee. Peringandoor Hariharan, Geoff Weighell, and Carl Thaemlitz have all agreed to become Review Chairpersons with the next issue. Of the current Review Chairpersons, Albertus Retnanto has nobly agreed to stay in post for a third year, and Robert Mitchell has at least another year of his term of office to run; thanks go to them all, and to Mark Shemaria and Jose (JC) Cunha, who both join me in retirement. Cunha deserves special mention, not only for serving 3, rather than the statutory 2, years as a Review Chairperson, but also for so doing while being Chairperson of SPE’s Drilling Technical Interest Groups. That is true dedication to SPE. 

I am particularly pleased to be able to tell you that, after being a Review Chairperson for 3 years, John Mason has agreed to replace me as Executive Editor. Looking back, I see that John makes it five British SPEDC editors in a row, which, perhaps, says as much about our national gullibility as it does about our willingness to help SPEDC. 

The recipients of this year’s Outstanding Technical Editor Awards are listed elsewhere in this issue; congratulations to each and every one! Serving on the review committee of an SPE peer-reviewed journal is not the easiest of tasks, but I firmly believe it to be a valuable one. Archiving and sharing technology and knowledge that has been validated by the rigorous process of peer review are, for me, the most important functions of SPE. Thanks for all their hard work are due, not only to the Outstanding Technical Editors, but also to the Review Chairpersons and all the other members of the Review Committee. 

And with that, it is time for me to introduce the papers in this issue. The first three papers all relate to deepwater drilling. One characteristic of the offshore environment that has never appealed to me is that it does not stay put. The water goes up and down repeatedly, and with it, up and down repeatedly goes the rig. When the rig starts heaving, so do I. Long casing strings offshore mean high loads on the drillpipe used to run and to land the casing in the wellhead. Once the rig heave motion becomes significant, the dynamic loads on a long deepwater landing string can erode safety margins.  Evaluation of Heave-Induced Dynamic Loading on Deepwater Landing Strings describes a model to calculate the impact of periodic vertical rig motion on the dynamic loads in the landing string. The authors present some calculations and draw a number of interesting conclusions directly relevant to deepwater casing-running operations.

Blowout-preventer testing is a necessary but ultimately unproductive operation.  It ties up rig time that could otherwise be spent making hole.  Deepwater BOP tests with synthetic drilling fluids can be protracted affairs.  The surface-pressure reading typically decays for some time after pumping stops. U.S. regulations require the target pressure to be held steady for at least 5 minutes before the test can be considered valid. The shut-in phase can often last 45 minutes before the pressure stabilizes sufficiently to give a valid test. With 10 or more individual components to be tested, the shut-in periods can easily add up to more than 4 hours of rig time. Anything that can be done to speed BOP testing, without reducing confidence in the stack’s ability to hold pressure if called upon to shut in the well, has to be welcome.  Advanced Analysis Identifies Greater Efficiency for Testing BOPs in Deep Water presents an investigation of pressure buildup and decay during deepwater BOP testing. The authors give sample pressure and temperature calculations for both low- and high-pressure tests. They use their analyses to propose a way of detecting BOP leaks with a synthetic drilling fluid much more rapidly than can be done by the current method. 

Deep seawater is cold wherever you are in the world—usually only a few degrees above freezing. When drilling in deep water, the cold seawater surrounding the long marine riser effectively cools the drilling fluid, giving much lower fluid temperatures in a significant proportion of the well-circulation path than exist in more conventional drilling environments. The authors of the third of our deepwater papers anticipated that these conditions could lead to substantial departures from the hydraulic behaviors seen when drilling less extreme wells. A joint industry project they set up took the opportunity of exploring a well drilled at 2741 m (nearly 9,000 ft!) water depth offshore Brazil to collect high-frequency pressure and temperature data during a variety of drilling operations.  Ultradeepwater Hydraulics and Well-Control Tests With Extensive Instrumentation: Field Tests and Data Analysis gives details of the measurements that were made, and compares predictions from a transient thermohydraulics model and a transient well-control simulator with the experimental data. They draw several interesting conclusions, not the least of which is that a simple single-bubble model of a gas kick may be very conservative.

Our next paper also deals with unusual drilling hydraulics. This time it is the fluid, not the environment, that is unusual. Foam makes an attractive drilling fluid for drilling underbalanced in formations that tolerate or demand very low wellbore pressures. It has high viscosity—far, far higher than those of mists or dry gases—giving good cuttings transport and formation-fluid lifting capacity. Conventional drilling-hydraulics calculations assume an incompressible drilling fluid. Foam is anything but incompressible. Increase the pressure, and the gas volume fraction (the quality) goes down, and with it, down goes the viscosity.  Hydraulic Optimization of Foam Drilling For Maximum Drilling Rate in Vertical Wells uses a recently developed model of cuttings transport with foam to investigate hydraulic optimization in foam drilling. The authors propose a new method for selecting the combination of foam-flow rate and nozzle sizes that gives the best bit hydraulics while, at the same time, ensuring effective hole cleaning.

Having talked about underbalanced drilling, we return to conventional overbalanced operations for our next paper. In conventional drilling, we do not want hydrocarbons to flow into the well while drilling, but we do want them to flow when we produce the well. Keeping the well overbalanced keeps the formation fluids in the formations, but it also raises the risk of filtrate entering the reservoir and impairing subsequent productivity. The authors of Predicting and Monitoring Fluid Invasion in Exploratory Drilling contend that proper fluid design, reliable filtration testing, and attentive rigsite monitoring are needed to minimize invasion. They propose a fluid-design method that uses simple flow models to predict field behavior from laboratory-test results, and they support their analyses with laboratory and field data.

Geosteering is now a widely understood term. Geostopping was new to me until I read the next paper. Development plans for a gas field offshore Malaysia called for two long horizontal wells. Unfortunately, the karstic limestone reservoir in the area is overlain by a thick interval of soft shale that needs to be cased off before entering the reservoir, to avoid borehole collapse. To make things difficult, there are no geological markers in the shale to indicate that the well is approaching the reservoir top. Other fields in this area had set the casing well above the reservoir, leaving as much as 300 ft of potentially unstable shale exposed to the low mud weight used to minimize losses in the reservoir. This often necessitates installation of an expandable liner to support the shale. The authors of Geostopping With Resistivity-Forward Modeling To Prevent Drilling Into The Lost-Circulation Zone of a Prolific Carbonate Reservoir realized that a logging-while-drilling deep-resistivity sensor that looks out radially from the wellbore effectively looks down in a near-horizontal hole. That is, in certain circumstances, it can be made to investigate geologically deeper rock than that at the bit. They describe how they exploited this to detect the approaching reservoir top, allowing drilling to stop, and the problematic shale to be cased off just above the reservoir; in other words, using geological information to stop drilling—geostopping.

Gas bubbles at surface indicated problems subsurface in another gas field offshore Malaysia. Gas channelling through microannuli in the cement behind casing was identified as the culprit. Workover options were evaluated, and it was decided to try to block the gas by perforating and squeezing fresh cement into the faulty zone. Historically, block-squeeze jobs do not have a good record of success, particularly in low-injectivity situations.  Innovative Remedial-Cementing Solution Provides Annular Isolation in Duyong B-4 describes what the authors did to maximize the probability of achieving a gastight squeeze in this case. Key factors in their success were the use of both sonic and ultrasonic cement-evaluation logs to locate the problem and a cement slurry designed specifically for low-injectivity remedial cementing to seal it off.

Beyond knowing that the “smart” in smart wells was not a human resources acronym to describe good objectives, I was not entirely sure what constituted a smart well, let alone where they might be useful, until I read our last paper.  Reservoir Management Employing Smart Wells: A Review explains that a smart well typically contains downhole equipment intended to perform three functions: monitor operating conditions downhole, image reservoir attributes away from the well, and control fluid inflow and outflow rates.  There have been plenty of papers that describe the field application of specific smart wells. This review focuses instead on where they are most likely to be cost-effective. The author identifies 15 different, mostly high-cost, applications for smart wells and, for each, explains why he thinks they would benefit from a smart well.

Much has changed in my 2 years as editor. SPE’s online journals have advanced to the point of reality. When you renew your subscription this year, you will be given the choice of receiving your SPEDC online only or online and in hard copy. If you have not already done so, I would suggest you go to www.spe.org/web/ejournals/DC/index.html, where you can experience a preview of the online journal functionality coming at the start of 2006. 

Society’s increasing demand for hydrocarbons has risen to match the current production capacity, driving oil and natural gas prices dramatically higher to levels from which, short of economic collapse, there seems little immediate prospect of significant retreat. It is imperative that we as an industry make and operate the wells needed to supply mankind’s demand for the hydrocarbons that fuel our civilizations. I am confident that you, the professional drilling and completion engineers who read SPEDC, will rise to that challenge. And I hope that the new technologies and knowledge this journal presents, and will continue to present, will help you do that.

In closing, I must express my gratitude to all who I have had the pleasure to work with on SPEDC over the past 2 years: the Review Committee and the SPE staff, particularly Stacie Hughes and Shashana Pearson-Hormillosa, and before Shashana, Becca Walters. They have been enormously helpful, diligent, and tolerant. I am sure my job as Executive Editor would have been much more difficult without them.

Finally, my family have been given their visas to join me in Texas. With that and with the relief of no more editorials to write, things are looking up: david.curry@bakerhughes.com.