Directional Drilling, Drill Bits, andDrillstring Dynamics
Completion Planning, Design, and Installation;Sand Control, Intelligent Completions, and Gravel Packing
Real-Time Operations, Drilling Automation,Drilling Process Control and Modeling, and Well Control
Completion and Intervention Operations,Well Design, and Construction
Geomechanics, Wellbore Stability, andPore Pressure
Hydraulics, Coiled Tubing, MultiphaseFlow, and Rheology
Drilling Fluids, Fluids Handling, Processing,and Treatment; Rock/Fluid Interactions, and Cuttings Transport
JournalPerformance Statistics. SPEDCcontinues to show generally favorable performances through increases inmanuscripts submitted and a wide readership. The following are highlights ofperformance statistics for the period July 2013 to June 2014:
And now, on to the papers…
A new model for predicting the torque and drag behavior of drillstrings is presented in Drillstring Analysis With a Discrete Torque/Drag Model, which improves upon the evaluation of drillstring integrity through the provision of bending moments and shear forces. For simple trajectories, the new model gives similar results to those of the model by Dawson and Morehead; however, for complicated trajectories, the new model allows for better representation of the contact forces occurring within the wellbore. The improved contact force prediction allows for better friction factor predictions.
Combined Rate of Penetration and Pressure Regulation for Drilling Optimization by Use of High-Speed Telemetry makes use of wired-drillpipe technology to consider multiple variables when attempting to control complex processes (e.g, drilling in deepwater wells). A case is made for how the application of a comprehensive multivariate controller for both the rate of penetration and the well pressure is superior to that of the common method, where separate controllers are used, allowing for the shift to anticipatory decision-making responses rather than feedback-based responses.
The authors of our next paper, A New Approach To Estimate Invasion Radius of Water-Based-Drilling-Fluid Filtrate To Evaluate Formation Damage Caused by Overbalanced Drilling, propose a practical model to determine the depth of mud-ﬁltrate invasion near the wellbore when drilled using a water-based mud. The model handles multiphase flow issues, which results in a better representation of the drilling-fluid filtrate and formation-fluid-displacement process, allowing for improved wellbore skin predictions.
Finite-Element Studies of Hoop-Stress Enhancement for Wellbore Strengthening discusses the mechanism of wellbore strengthening by focusing on hoop stresses at and near the wellbore through the application of the ﬁnite-element method. Wellbore and near-wellbore stresses are evaluated during the processes of fracture creation, propagation, and after plugging with lost circulation materials. This better understanding of the several interacting events local to the wellbore and near-wellbore regions can result in improved operational practices related to lost-circulation management.
Large accumulations of methane hydrates are known to exist in the deepwater Nankai Trough off the southern coast of Japan. Because of its enormous potential as an energy source, there is growing interest in the production of methane gas from these deposits. Well-Integrity Evaluation for Methane-Hydrate Production in the Deepwater Nankai Trough presents a study that provided critical information to assist in preparation for, and execution of, a work ﬂow and methodology applicable to well-integrity evaluations for wells constructed within methane hydrate-bearing formations. As large amounts of compaction and subsidence may be anticipated for such wells, methods to mitigate reductions in well integrity are important to prevent losses of zonal isolation caused by overburden pressures.
Sustained casing pressure and gas migration problems caused by thermal and stress loading may occur as a result of temperature and pressure induced stresses, which can be created by well events such as hydraulic fracturing, cyclic steam injection, steam assisted gravity drainage (SAGD), production, completion, and other remedial treatments. Using Fatigue-Failure Envelope for Cement-Sheath-Integrity Evaluation presents a method for evaluation cement sheath integrity on the basis of the effects of fatigue on cement samples at simulated downhole conditions. The experimental process is discussed in detail.
Coalbed methane is one of the major clean-burning gas resources. The southern Qinshui basin of China is rich in coalbed methane and is the ﬁrst area in China to show good commercial production. The Use of a Novel Spacer and Ultralow-Density Cement System To Control Lost Circulation in Coalbed-Methane Wells presents how the application of a spacer fluid containing a hydrophilic ﬁber, when used along with ultralow-density cement slurries, can be used to mitigate losses. Details are provided describing the slurry design, its ﬁeld application, and the cement-bond evaluations that verify the conclusions.
The authors of our final paper introduce worst case discharge as a relatively new term given to a hypothetical event that is deemed to be of low probability but of high impact. Assessment of Fracture Containment and Broaching Resulting From Worst-Case-Discharge Events addresses the circumstances that lead to such events and the occurrences’ subsequent impacts upon the subsurface well structures. The paper reviews and discusses design changes targeted at mitigating and remediating potentially negative impacts for a variety of scenarios.