Cheatham

Globalization of Major SPE Conferences

Historically, two conferences have provided more papers to SPE Drilling & Completion than any other: the annual SPE/IADC Drilling Conference and Exhibition, and the SPE Annual Technical Conference and Exhibition (ATCE). When originally conceived, both were limited to venues in US cities. This was a natural choice because the vast majority of SPE members resided in the US at that time. In recent years, though, SPE has increasingly become a global society. This change is visible in many ways, but it is significant to observe that, for the first time, the most recent occurrence of both conferences was outside the US.

In March 2011, the SPE/IADC Drilling Conference and Exhibition met in Amsterdam, The Netherlands, which has been its home in every odd year starting in 1991. The meeting originated in the early 1980s and still meets in the US in even years. Today, it is considered by many to be the premiere global drilling conference. Over the years, the format has seen some changes. For many years there was no exhibition--only technical and plenary sessions. By contrast, the exhibition at the Rai Congress Center in 2011 was the largest ever for the event. Another change has been the evolution of topics of technical sessions to keep pace with changing technology focus of the industry. But one thing that has not changed in the last twenty years is the host city of Amsterdam every other year.

The idea to convene this conference outside the US was ahead of its time in 1991, or at least leading the trend. Moving this conference to Europe coincided with and supported the globalization of SPE as a society. Initially, the Amsterdam location was a trial to test the level of support outside the US. The new venue was an immediate success, and the rest, as they say, is history. A key benefit is the different cross section of members who attend the Amsterdam conferences compared to those held in the US. Far more attendees in Amsterdam reside outside the US. Such diversification is important to ensure the broadest participation by our society’s members at this prestigious event.

Last year the SPE ATCE met outside the US for the first time. The 2010 SPE ATCE in Florence, Italy was highly successful, in large part because of the diversity of attendees. As the largest attended SPE conference, this event spans all technical disciplines of exploration and production. Consequently, drilling and completions is only one of six technical disciplines represented. Nevertheless, SPE ATCE is an important source of papers to SPE Drilling & Completion.

In conclusion, globalization has been a key focus for SPE in recent years. Diversification of major meeting locations outside the US has been an important element of this strategy because of increased access to SPE members.

Associate Editors

We welcome a new Associate Editor (AE) to our journal: Joe Yunxu Zhou. Joe has been one of our top Technical Editors for some time. As an AE, he will manage reviews in coiled tubing and multiphase flow. This brings our current number of AEs to 11, which represents a new high as we continue to strive to improve quality and reduce cycle time for peer reviews.

The entire roster of AEs currently serving our journal is listed in each issue. Please join me in thanking each of them for their outstanding work. Together, our AEs are responsible for reviewing approximately 200 papers annually. Without their leadership and service, there would be no SPE Drilling & Completion.

Now to the papers. This issue contains 14 papers on the following topics: managed-pressure drilling--three papers; cementing--two papers; completions--four papers; health, safety, and environment--two papers; wellbore stability--one paper; and drilling operations--two papers.

Managed-Pressure Drilling

Constant bottomhole pressure (CBHP) is a commonly used method to implement managed-pressure drilling (MPD). A key question during CBHP operations is what action should be taken when a kick occurs? Should a conventional response be taken to simply shut in the well as soon as possible? Or should advantage be taken of equipment commonly used in MPD to execute some type of continued circulation response to control the kick? Evaluation of Alternative Initial Responses to Kicks Taken During Managed-Pressure Drilling examines results of computer simulation using several methods of initial responses to a kick during CBHP operations. The authors conclude there is no best single response for all situations. The paper provides recommendations and a decision flow chart for the best response under various conditions. The research consortium that conducted the work in this paper intends to provide a basis for comprehensive, reliable well-control procedures for MPD operations equivalent to the industry standard procedures used in conventional drilling. This paper represents a first step in that process. We hope the authors will continue to report their subsequent results in future papers.

A second method of MPD is dual-gradient drilling (DGD), which is the topic of this next paper. As reported in earlier issues of this journal, significant opportunities exist for the convergence of automation and MPD. MPD requires additional equipment compared to conventional drilling, which can include drillstring nonreturn valves, rotating control device, choke manifold, surface separation system, and various pumps. The operational complexity and interaction resulting from these multiple pieces of equipment provides an opportunity for automation. As pointed out in Managed-Pressure Drilling: Using Model Predictive Control To Improve Pressure Control During Dual-Gradient Drilling, the basic principle behind automation is that humans have a critical role in setting system objectives and constraints, while the automation system is tasked to ensure these criteria are met. The paper focuses on one aspect of MPD automation: namely, automated control of bottomhole pressure and hook position in a DGD system. If you are like me, then you had never heard of Model Predictive Control until reading the title of this paper. An Internet search indicated that this method of process control has been used since the 1980s and uses models to represent behavior of complex dynamical systems. Essentially, model predictive control provides a software system to help control MPD hardware. In this paper, model predictive control is applied to control both hook position and bottomhole pressure through coordinated manipulation of mud pump flow rate, subsea pump flow rate, and drillstring velocity in computer simulations.

Our next paper studies a third MPD method--pressurized mud cap closed hole circulation drilling. The common acronym for this method is "PMCD," and it is generally used for cases of massive lost circulation that preclude maintaining circulation back to surface. Managing Circulation Losses in a Harsh Drilling Environment: Conventional Solution vs. CHCD Through a Risk Assessment gives an excellent overview of this version of MPD. It also uses quantitative risk assessment (QRA) to quantify differences between conventional drilling vs. closed hole circulation drilling. To our knowledge, this is the first time QRA has been applied to compare conventional drilling to any MPD technique.

Cementing

Carbon capture and sequestration is an important topic today. A key aspect of designing wells for long-term storage of carbon dioxide is the ability of the cement sheath to withstand the resulting corrosive environment. Another application requiring cement to withstand corrosion is carbon dioxide floods in enhanced oil recovery. Cementing Solutions for Corrosive Well Environments reports results of extensive laboratory tests and field analyses of available data in the literature. The chemistry, mineralogy, and physical properties of conventional American Petroleum Institute (API) cements are studied in the presence of corrosive environments. The main factors responsible for corrosion of the cement sheath in wells are determined. A key finding is that addition of pozzolan to API cement blends showed significantly less corrosion compared to a conventional API cement design. Practical concepts are presented for cement-slurry design, cementing process, and the impact of factors such as temperature and cement admixtures to mitigate cement corrosion. This paper is recommended for anyone involved in designing or executing cementing operations in corrosive environments.

Design of cement systems in deepwater faces challenges from low temperature, weak formations, and shallow water or gas flow. Design and Performance Evaluation of a Unique Deepwater Cement Slurry examines key desirable properties such as short thickening time, fast transition from liquid to solid, rapid development of compressive strength, and environmental friendliness. The paper presents a novel deepwater cement as an alternative to existing cements used in deepwater. The new cement system combines advantages of sulfoaluminate cement and API Class G oilwell cement. In addition, environmentally friendly cement additives for dispersant, fluid-loss control, and accelerator were developed. This paper is recommended to anyone involved in deepwater cementing.

Completions

Gravel packing (GP) is increasingly used in long horizontal wells and challenging environments. Friction Pressure Performance of Commonly Used Viscous Gravel-Packing Fluids investigates an important element of executing a successful gravel pack under such conditions. Specifically it studies the frictional pressure losses during pumping GP fluids for commonly used fluids such as viscoelastic surfactant type, xanthan, and hydroxyethyl cellulose. The problem is particularly important in long horizontal wells in weak formations, as is experienced in many deepwater wells. This paper describes laboratory and yard testing of selected gravel pack carrier fluids to determine their friction pressure gradient under certain conditions. An illustrative example using a commercial GP simulator is presented. These results should be helpful to readers tasked with gravel pack design and the associated fluid selection.

Our second completions paper focuses on openhole gravel packing (OHGP) carrier fluid systems. Openhole Gravel-Pack Case Histories Using Alternative Fluid Displacement for Synthetic-Based Mud provides an excellent review of OHGP fluid systems used in deepwater west Africa, where wells generally require sand control. It also presents a solid case history. This paper should be a useful reference to completions engineers working with OHGP operations.

Completion hardware is often subjected to high differential pressure during frac-pack treatments, for example, during early screenouts. In our third completions paper, the current standard equations are shown to be too conservative when compared to downhole pressure measurements made during actual jobs. Certainly, it is the case that using the standard equations prevents collapse of completions equipment in virtually any job. But the authors point out that many frac-pack treatments are performed in low-pressure reservoirs where use of the overly conservative approach unnecessarily eliminates viable candidates for frac-pack consideration. Deepwater Frac-Pack Maximum Treating Pressure Limits, An Examination Using Bottomhole Pressure Gauges offers an improvement to the current standard equations. Several frac-pack jobs are discussed using post-job bottomhole gauge data to determine the downhole differential pressures and verify accuracy of assumptions used in the improved calculation method. The paper provides valuable insight and recommendations for tool design, fluid properties, and maximum-pressure limitations for frac-pack completions.

Our final completions paper describes case histories for four wells in two gas fields in onshore Algeria. Expandable Completion Liners: A Comparison of Performance With Other Completion Types in the Reg and Teguentour Fields, Algeria describes the reasons for selecting expandable completion liners and their installation. It compares production performance (skin) of the different sand face completions present in these fields. The experiences shared should be helpful to readers responsible for the selection of sand face completions.

Health, Safety, and Environment

Weight materials used in drilling fluids contain traces of heavy metal contaminants. After discharge from drilling operations, drill cuttings with associated mud and weight materials are deposited on the seabed. Metal Partitioning in Ilmenite- and Barite-Based Drill Cuttings on Seabed Sections in a Mesocosm Laboratory reports results from experiments studying the transport of heavy metals from drilling waste (mud and cuttings) deposits on seabed to nearby seawater. Previously, metal toxicity has been addressed in a model developed by several oil companies to predict environmental risks associated with discharges of drill cuttings. Partition coefficients are used to estimate metal concentrations in sediments and interstitial waters. Correct values for these partition coefficients are crucial to the validity of model predictions. This paper improves estimates for partition coefficients to help the industry obtain more accurate estimates for drilling discharges in offshore areas. By the way, if you are a frequent reader of these paper summaries, then you will not be surprised to learn that I had no idea what "mesocosm laboratory" meant when I initially read the title of this paper. An Internet search revealed it is an "experimental water enclosure designed to provide a limited body of water with close to natural conditions, in which environmental factors can be realistically manipulated" (see http://mesocosm.eu/node/16).

Quantitative models of safety allow connecting risk factors and elements of the safety management system to outcomes. But, conventional methods do not account for unreported incidents. Statistical Analysis of Safety Incidents and the Implications of Imperfect Reporting develops and applies a novel statistical method for analyzing safety incident misreporting. The paper demonstrates the value of a more complete model of safety incidence and reporting behavior.

Wellbore Stability

Drilling through natural gas hydrates in deepwater presents significant challenges. In deepwater, gas hydrates occur in shallow formations below the mudline where rock strength is low. If wellbore pressure is sufficiently reduced or temperature sufficiently increased, then hydrates change phase from solid to gas. In this case, maintaining wellbore stability is a key issue because dissociation of the solid hydrate into a gas can cause reduction in rock strength. Further, gasification of the drilling fluid can occur, resulting in further pressure reduction and leading to further dissociation. Because of the industry’s continued push into ever deeper water, Drilling Through Gas-Hydrate Sediments: Managing Wellbore-Stability Risks addresses a very timely subject. The paper describes a 1D semianalytical model for heat and fluid transport in the reservoir that was coupled with a numerical model for temperature distribution along the wellbore. It provides a procedure offering quantitative results of the impact of hydrate dissociation on wellbore stability, which can help design better drilling muds for ultra deepwater operations. Unlike previous studies, this paper includes dissociation of hydrates outside the wellbore. Effects of drilling fluid temperature and bottomhole pressure on hydrate dissociation are considered. Naturally, such a 1D model cannot be expected to fully describe all the complexities of drilling through gas hydrates. But this work represents a significant step forward and is recommended reading for those involved in deepwater drilling operations.

Drilling Operations

Drilling operations centers have existed since the 1980s in several formats with diverse objectives. The first generation of centers was short lived. Real-Time Drilling Operations Centers: A History of Functionality and Organizational Purpose--The Second Generation describes advancements since the early 2000s. The paper discusses foundational capability, data and architecture standards, higher-level work processes, and organizational change management. Several companies now use operations centers on a global basis. The paper presents a summary of the various strategies employed. Associated technologies are mature and proven, but organizational changes required to implement operations centers remain. Opportunities exist for young professionals, who are familiar and comfortable with collaborative technologies. At the other end of the career cycle, operations centers can contribute to more efficient use of scarce specialists or experienced personnel. Several strategies explicitly include knowledge management and stewardship of best practices. For readers who enjoy learning some of the history of our industry, this paper is highly recommended.

Our final paper is the latest in a series by one operator in its quest to implement performance management tools for improving the drilling process. A previous paper described the use of mechanical specific energy, which subsequently has been adopted by the industry as a standard criterion to address bit performance limiters and dysfunction. Borehole-Quality Design and Practices to Maximize Drill-Rate Performance discusses additional practices developed to extend nonbit performance limiters, particularly those related to borehole quality. The paper describes technical models used to understand the major borehole quality limiters, the engineering design, real-time practices, and field results. As in their past papers, the authors bring a different dimension to design and practices for maximizing drilling performance. Although some conclusions are controversial--or at least unexpected--the authors argue their points well and certainly provide great food for thought. This paper is a must read for anyone interested in optimizing drilling performance.

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