Executive Summary

Carl Thaemlitz, Aramco Services Company

Greetings and welcome to the December edition of SPE Drilling & Completion. While recently attending the SPE’s Annual Technical Conference and Exhibition, I was deeply impressed by two things. First, the dedication to high-quality science and engineering reflected in the papers and posters at the event. Second, the dedication expressed through the volunteer efforts put forth by so many fellow professionals to make possible not only this particular event, but to ensure that the SPE organization as a whole maintains its stature as an outstanding professional organization worldwide. As you renew your SPE membership this year, please remember to consider how you can participate in the volunteer efforts of our great organization, which can be accessed at http://www.spe.org/volunteer.

And now, on to the papers.

Completions

The challenge of mitigating sustained casing pressure is a long-standing priority in the well construction industry. Our first paper is Casing Expansion as a Promising Solution for Microannular Gas Migration, which presents a bench-scale research investigation apparatus and its capability of being representative of the real-world mitigation challenges associated with sustained casing pressure. Flow-through experiments are used to show the effectiveness of the casing expansion technique in the sealing of microannular gas leakage pathways.

Buckling of Buoyancy-Assisted Tubulars addresses the challenges of the Euler representation for buckling of pipes under buoyant conditions. The authors present that a certain amount of axial load is still required for both buckling initiation and formation of first helix, even for weightless pipes. We are presented with new models that also consider the influence of buoyancy for each mode of buckling, including how they were developed and verified.

Drilling

Real-Time Casing-Design Optimization: A Case Study in the Use of Managed-Pressure Drilling To Develop an Adaptive Well Design and Eliminate Casing Strings on a Deepwater Exploration Well presents to us how the enhanced drilling and pressure-management capabilities of managed pressure drilling (MPD) can bring significant reductions in both cost and risk, if they are embraced during the well-design process. The work presented in this paper demonstrates that by using MPD, it is possible to not only safely reduce kick-tolerance criteria, but also to navigate narrow drilling pressure windows, allowing us to reach far deeper-section depths than are possible with conventional design methods.

Drillstring Mechanics Model for Surveillance, Root Cause Analysis, and Mitigation of Torsional Vibrations illustrates a methodology used to develop practical workflows for torsional-vibration surveillance, root-cause analysis, and mitigation by means of redesign. The workflows were validated in the field against direct downhole measurements. The model provides a robust research platform to monitor, analyze, and mitigate most common vibrational dysfunctions, while remaining accessible to operations personnel.

Our next paper presents techniques applicable to any exploration, appraisal, or early development well that has a potential for encountering geopressured formations in high-angle well sections. Integrated Predrill Pore-Pressure and Borehole-Stability Prediction for Prelude Development shows how enhanced safety, optimized well and casing designs, and reduction of nonproductive drilling time by the use of integrated borehole stability and pore pressure/fracture-gradient models can result in higher minimum-required mud weights and narrower drilling windows than would be suggested from the pore pressure/ fracture-gradient models by themselves. The predrill studies can be extended to provide integrated real-time pore pressure and borehole stability while drilling, and the models can be recalibrated following each well to provide updated predictions for subsequent nearby wells.

The Use of Modeling To Enhance the Analysis of Formation-Pressure Integrity Tests presents a model for predicting early pressure buildup (prefracture) behavior and how the model can be used to improve the interpretation of formation-pressure-integrity tests. The model takes into account the effects of mud compressibility, casing expansion, cement compressibility, air-in-lines, channel volume, formation compressibility, and permeability losses, which results in simplifying the need to separately treat the compressibilities for mud, casing expansion, and cement before drilling out the casing shoe.

The technical challenges encountered when drilling fractured and vugular, calcareous lithologies is characteristic of the Middle East region. Air drilling, foam drilling, and managed pressure drilling are all techniques used to address the drilling challenges. Mathematical Modeling of Drilling Operations by Use of Nitrogen-Enriched Mud: A Case Study by Use of a Recorded Drilling Data-Set describes a model to calculate a foam’s physical characteristics as a function of pressure and temperature. A method to calculate the pressure in the annulus and in the drillstring is described, as well as necessary principles to calculate heat exchange during the drilling process.

The problem of heave-induced pressure fluctuation during drilling is considered in Modeling and Avoidance of Heave-Induced Resonances in Offshore Drilling. The surge and swab pressures created by the vertical motion of the drillpipe can induce resonances, which may amplify downhole-pressure oscillations by a factor of 10. The locations of the resonant frequencies may be avoided because they depend upon effects from the topside choke opening. Techniques to avoid resonances are discussed; we are presented with detailed appendices.

Threat-and-Error Management: The Connection Between Process Safety and Practical Action at the Worksite summarizes the principles of high-reliability organizations and their contribution to process safety in the context of drilling operations. Threat and error management is described, which evolved from aviation-based crew-resource management to produce the levels of safety that we accept as normal today. Operational risk management in drilling is introduced as the analogous link with aviation. The paper concludes by illustrating how these concepts can be used in drilling operations to enhance routine risk-management activities, along with describing the tools and techniques involved.

Landing horizontal wells in a reservoir is a critical task, and the accuracy of the result drives the economics of a well. The deep directional resistivity, logging-while-drilling solution brings new methods to mitigate risks in difficult or critical landings. Rather than relying solely on well-to-well correlations or pilot-hole data, Avoid Pilot Holes, Land Wells, and Optimize Well Placement and Production With Deep Directional Resistivity Logging While Drilling supplements with a more-direct observation of the reservoir top approaching, from approximately 15 m below the tool in field applications. The case study of a recent well landing in the North Sea shows how effective the deep directional resistivity solution has been in low-tolerance-landing scenarios.