Cheatham

It is my honor to introduce the next Executive Editor (EE) of SPE Drilling & Completion to you, Carl Thaemlitz. Carl has a strong commitment to our journal and we are fortunate to have someone so passionate for peer review at the helm for the next 3 years. Please join me in congratulating Carl and giving him our full support in his new and exciting job.

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

The 200 TEs are too many to mention by name (but all TEs who reviewed at least 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 to work with over the last 3 years. Each is a recognized industry expert who devotes massive time and energy in managing paper reviews. Four AEs served the entire 3 years with me and I am amazed they were able to put up with me for so long! Seriously, I am humbled by their commitment and contributions to our journal.

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

Six AEs ended their terms during my tenure. I am grateful for their service and 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 superb accomplishments and look for each of them to continue to excel in their pivotal roles 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--my father, John Cheatham, and another close friend, DeBow Freed II. Their guidance and counsel helped me tremendously through these 3 wonderful years and was especially 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 professional staff. At the time, I thought--well, isn’t that nice! Now, I realize how crucial these outstanding individuals are to the success of SPE journals. I had the great pleasure to work with Glenda Smith, Chris Carpenter, Mattie Tanner, Rebekah Stacha, Adam Wilson, Victoria Preston, Meghann Mays, and Leah Miller. Readers typically do not meet or interact with them, so it is hard to convey the significance of what SPE staff does behind the scenes. Trust me, it is top-notch work they do to the benefit of all of us. And there is one person who deserves to be singled out--Stacie Hughes. Before I became EE, I worked with Stacie when I was an AE. I thought she was the Peer Review Administrator for only one SPE journal--SPE Drilling & Completion. I believed this because she is so efficient, responsive, and on top of everything. When I became EE, I learned Stacie is Peer Review Administrator for all seven SPE journals! So, to me, she does the work of seven people, and represents the best in SPE peer review--dedication, service, technical excellence, and good old-fashioned hard work.

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 important new technologies in recent years. A key question is: Should we design production casing for such wells using the same procedure that we use for conventional wells? Special Considerations in the Design Optimization of the Production Casing in High-Rate, Multistage-Fractured Shale Wells shows that thermal effects during cooling create both bending stress magnification and annular pressure reduction caused by cement contraction in trapped cement voids. The result is increased loads and new modes of failure that should be considered in design. The paper provides acceptable design options for shale-well production casing. It is recommended to engineers responsible for managing integrity of production casing in shale development wells. This paper also provides a derivation of bending stress magnification factor (BSMF) that differs slightly from the Paslay and Cernocky BSMF, which is commonly used for drillstring design.

A common assumption in designing casing for burst is that the fluid is filled 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 resistance assuming various backup profiles, including fluid hydrostatics, solid cement (both elastic and plastic), and cement as loose particles. Guidelines are provided to calculate the enhanced casing burst resistance. This paper is a fascinating treatise on the subject and is highly recommended to engineers responsible for casing design.

Our next paper extends the analysis of two well-known papers that are often cited for buckling considerations--Lubinski (1962), whose analysis considered the casing to be perfectly rigid, and Christman (1976), whose analysis postulated a composite pipe on the basis of the summed properties of the two tubular strings. Buckling of Tubing Inside Casing shows the 1976 paper led to incorrect predictions concerning buckling. The new paper presents more realistic bucking configurations for the various methods that two concentric pipes can interact when one or both pipes are in compression and would have a tendency to buckle. The contact forces between the pipes and with the external wellbore are explicitly calculated and contact or noncontact conditions are discussed. New insights describing tubing buckling tendency are given, which challenge the typical assumptions of rigid casing. For example, it is predicted that a surprising amount of shear and bending is transferred to the casing by the buckled tubing, which is not normally considered in casing design. This effect was not known previously, and can be significant. All results are analytical so that they can be easily used in spreadsheets or hand calculations. Several example calculations are presented to illustrate how these results might be used. This is an important paper that is highly recommended to any readers responsible for designing casing or tubing or to anyone interested in the topic of buckling.

Numerous methods are available to determine fatigue life from either elastic or plastic-bending cycling. However, few data are available within the industry on how fatigue damage is affected by the combination of elastic and plastic bending cycles. Combining Elastic and Plastic Fatigue Damage in Steel Pipelines, Risers, and Coiled Tubing presents the experimental work conducted to measure combined fatigue life. The tests were conducted on notched samples of flat steel used to manufacture coiled tubing that has been plastically and elastically cycled. The work shows that the combined fatigue damage from plastic and elastic cycle is higher than the linear summation of the fatigue damage from both sources. Experimental work confirms that plastic and elastic cycles can be combined by use of a nonlinear relationship. A power-law-damage rule provides an appropriate method to determine the overall fatigue damage.

Case Histories

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

A redevelopment campaign in the Netherlands required new techniques to ensure long-term cement integrity in thermal wells to permit use of steam injection. Contemporary Approach Coupled With Traditional Techniques Tackles Extreme Wellbore Environment in Schoonebeek Heavy Oil Field offers timely information for the industry. The paper contains a number of areas such as micro-CT scans of foam that have not been explored previously. The comprehensive case history of the rejuvenation of a complete field tells the complete story, from the selection of design criteria, to the logistics, operational and economical constraints, and finally implementation in the field.

Pore Pressure in Shale

An Innovative Approach for Pore Pressure Prediction and Drilling Optimization in an Abnormally Subpressured Basin develops a drilling optimization procedure that simultaneously allows improved penetration rates and good quality of cuttings. The paper describes the challenging drilling of subpressured zones in western Canada that will serve as a good model for others. Five previously drilled wells were used in the study of the proposed optimization procedure. Presumably the next step is to test the method on new wells.

Drilling Operations and Optimization

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

After an NPT event has occurred, we are often able to look back and detect key data that could have foretold the likelihood of trouble. But, much more value would be obtained if the NPT event could be detected beforehand and prevented. Early Symptom Detection on the Basis of Real-Time Evaluation of Downhole Conditions: Principles and Results From Several North Sea Drilling Operations 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 the current state of the well; and (5) predicting root causes of changes in well condition to provide early warning of deteriorating well conditions. The monitoring system has been used on 15 wells in five fields. The paper provides solid case studies to demonstrate the method. The point is well made that it can be difficult for rig crews to trust such technology if there are no other signs that trouble is imminent. But, to be worthwhile, a confidence level in the technology must be established and if corrective action is preemptively taken, then how can one be assured the NPT was really going to occur? False warnings can also be problematic. All these soft issues are discussed with great insight. This paper provides some real food for thought.

Drilling automation has the potential to provide significant improvements in efficiency 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 Automation Techniques and Practices offers a means to enable testing automation techniques, equipment, and work processes under a wide range of simulated conditions. This paper details the application of an advanced drilling simulation environment called hardware in the loop to verify real-time performance of automation systems without putting an actual well at risk. Complex drilling situations can be simulated, including deteriorating downhole conditions. The authors expect the new testing environment for drilling automation technologies and associated work processes can be regarded as a step forward for enabling safe introduction of automation at the rig site and in daily drilling operations.

Lost circulation and well control problems can cause major NPT. Accurate prediction 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 avoid lost circulation by tripping in too fast or to avoid swabbing in a kick by tripping out too fast. Surge-and-Swab Pressure Predictions for Yield-Power-Law Drilling Fluids presents a new steady-state numerical model that accounts for fluid and formation compressibility and pipe elasticity using the industry preferred yield power law rheological model. Comparisons with published theoretical models and laboratory and field measurements are presented to validate the model.

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

Cementing

Displacing fluids in downhole conditions over long distances can be difficult. A key problem can be mixing of fluids in the annulus, such as cement, with drilling fluid or spacer. A common assumption for hydraulics models is that fluids are immiscible, and therefore do not mix. A Comprehensive Theoretical and Experimental Study on Fluid Displacement for Oilwell-Cementing Operations presents a numerical model using lubrication theory that accounts for annular mixing of fluids. Model results are validated in an experimental vertical well. Future enhancements to the model are planned, including simulating pipe movement. This paper should be worthwhile to engineers involved in cementing operations.

Completions

Multilateral wells have been used extensively since the early 1990s to access multiple reservoirs from a single mother bore. North Sea World Record Installation--Deepest Sealed Multilateral System presents a case history with emphasis on operational challenges. This paper should benefit drilling and completion engineers involved in application of high end multilateral technology.

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

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

Curtis Cheatham
cheatham@spemail.org