Torque and Drag Modeling: Advanced Techniques and Troubleshooting
- John McCormick (Halliburton) | Gefei Liu (Pegasus Vertex Inc)
- Document ID
- Society of Petroleum Engineers
- SPE Annual Technical Conference and Exhibition, 8-10 October, San Antonio, Texas, USA
- Publication Date
- Document Type
- Conference Paper
- 2012. Society of Petroleum Engineers
- 1.1 Well Planning, 3 Production and Well Operations, 1.12.6 Drilling Data Management and Standards, 1.6 Drilling Operations, 1.6.1 Drilling Operation Management, 1.10.1 Drill string components and drilling tools (tubulars, jars, subs, stabilisers, reamers, etc), 1.6.10 Running and Setting Casing, 1.10 Drilling Equipment
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Extreme torque and drag (T&D), especially when unplanned, is a primary limiter to the reach of horizontal and extended-reach wells. Many engineers use T&D software models without a thorough understanding of how the input affects the calculations in the program. This paper describes best practices in complicated T&D modeling applications.
The discussion in this paper is applicable to wells with horizontal laterals, extended-reach wells, wells with difficult geometries, and all complicated well operations that require T&D models for planning and troubleshooting. Specifically applicable are operations that T&D programs have difficulty handling, such as running dual strings, expandable casing operations, drilling with casing, and jarring operations.
Most engineers involved in downhole operations from operators to service companies run either T&D models or base decisions related to their wells and operations on reports from these programs. Many of the engineers and managers in the oilfield can benefit from this guide on best practices for a commonly executed, but little understood, component to well planning.
Few papers address the practical application side of T&D modeling, and most engineers and managers have only a basic understanding of how to create a model or interpret the results. This paper disseminates technical information to increase global competence in a vital part of any challenging well drilled. Drilling extreme and challenging wells is becoming more common, and increased knowledge for T&D modeling and interpretation is needed.
This paper is written with the assumption that its readers are familiar with T&D software modeling. Based on the authors' experience working with everyday T&D users, various aspects of T&D modeling that may not be immediately apparent to the user will be explained. Descriptions of how to use the history/surface graphs, calibrate a model to field data, and when and how to apply tortuosity are explained. Some troubleshooting scenarios are explained and solutions offered. Limitations of other programs are also discussed.
The input necessary to build a T&D model is often learned from options that are commonly selected within organizations to produce required graphs. Without a thorough understanding of how the software calculates results or the impact the results have on them, the confidence and the ability of the T&D software user is limited. Simple methods for learning more about T&D programs and the ability to determine the impact the input has on the model output are also explored in this paper.
Surface vs. String Graphs
There are two main modes used in T&D software programs: surface and string graphs. The surface graph shows the hookload and surface torque values that are familiar to the drillers. The string graphs show the forces within the string from the bit or shoe to the top of the string. An excellent analogy that is often used is that of an iceberg (Figure 1), where ? of the mass is hidden beneath the water surface. Surface values are useful, but the string graphs provide the true value of T&D models by predicting the forces within the string that are virtually invisible on the rig floor.
|File Size||421 KB||Number of Pages||16|