Technical Session 18 – Tubulars

Editor’s note: These abstracts have been edited for space and clarity. This program is current as of 15 January 2013. Additions, withdrawals and other changes to the conference program after this date may not be reflected. Click here for the most updated program.

TECHNICAL SESSION 18: TUBULARS

Dynamic Model for Stiff String Torque and Drag, V. Tikhonov, K. Valiullin, Aquatic Company; A. Nurgaliev, R.A. Gandikota, L. Ring, P. Chaguine, C.A. Cheatham, Weatherford International

A stiff string torque and drag model is presented that uses steady state dynamic equilibrium of the drill string as its basis for calculations. Results are compared to previously published torque and drag models that are based on static equilibrium. The novelty of the new dynamic model is in the ability to solve torque and drag operations of the entire drill string in reasonable time using standard engineering computers. The new approach is based on a 3D-transient dynamic model of drill string and BHA in an elastic borehole.

Safely Exceeding Buckling Loads in Long Horizontal Wells: Case Study in Shale Plays, S. Menand, Drillscan; D. Chen, Hess Corp

This paper shows a case study in shale gas wells for which helical buckling load has been exceeded without compromising the success of the operations.

Drilling data from long horizontal wells in US shale plays have been gathered, analyzed and compared to an advanced drill string mechanics model that enables to calculate simultaneously torque, drag and buckling.

Drill Pipe Riser Intervention System Successful Experience in Offshore West Africa, C. Rohart, H. De Fonvielle, VAM Drilling; W. Campbell, TOTAL

While offshore intervention on subsea equipment is quite common, the increasingly deeper water operations require light weight intervention systems, while meeting safe and stringent operating specifications. For these new deep offshore challenges, the conventional risers are becoming a more costly and less desirable solution.

The solutions that were used by TOTAL in Angola are drill pipe risers with a proprietary double shoulder connection and featuring a Teflon seal ring close to the external shoulder. Intensively used in West Africa since 1999, the solution has shown robustness and reliability on several projects such as Girrasol and Rosa and now GirRI. The paper draws a summary of these operations and field use feedback, as well as maintenance costs and the financial benefits of using this product.

Brittle Failures of Oilfield Components Due to Improper Testing Methods, S.R. Koneti, S.R. Gokhale, T.H. Hill Associates

Oilfield tubular components can fail through brittle cracking due to poor fracture toughness of the material. For heat treated material, most vendor and user manufacturing specifications, including API, require the mechanical test specimen to be removed from either a sacrificial production part, a prolongation removed from a production part, or from a quality test coupon (QTC) from the same heat.

In certain cases, manufacturers prefer to perform all mechanical testing on a QTC. However, case studies indicate that material test results on the QTC, especially Charpy V-notch impact energy values, which point to the fracture toughness of the material, may not accurately represent the material properties of the actual component.

This paper presents case studies and lessons learned from the analysis of failures that were found to be related to this discrepancy.

The Stability of a Pipe Stand Racked in a Derrick, Part 2 – A General Pipe Stand Model, S.J. Sawaryn, P. Pattillo, BP Exploration

This paper builds on the information contained in Part 1 and presents a general pipe-stand model. The model is based on the Fourier series solution of the energy equation for calculating the deflection and buckling condition of an inclined, non-uniform pipe stand with an arbitrary number of intermediate loads and stick-up above the top racking board. Full details of the derivation and algorithms are included in the paper. This flexible approach is used to examine more complex, practical situations, including the buckling sensitivity to the position of the upper support and added loads, such as tool joints or running tools racked with the stand.

Analysis of Torsional Shock During Drilling, T. Collins, E.M. Elhassan, Schlumberger

Recent developments in drilling techniques such as rotary steerable tools, aggressive diamond drill bits and dual-diameter drilling tools have greatly improved the speed of drilling wells and have allowed efficient drilling in very difficult environments. These have created a new set of conditions that the bottomhole assembly must withstand: a combination of high rotary speed and high, unsteady reactive torque, which have given new importance to an understanding of drill string dynamics.

Dynamic loading of drill strings has previously been studied using application-specific models and numerical methods. This paper demonstrates the application of some simple methods borrowed from acoustics, which allow approximate but very general solutions to the dynamic effects of torsional shock loading.

The results are illustrated with a case study from a well where unexpected geological features led to very high torsional shock, which caused severe equipment damage. The dynamic loading was shown to be well beyond the accepted design parameters. The new methodology can account for this loading as well as providing the design tools to withstand it.

E-POSTERS:

The Stability of a Pipe Stand Racked in a Derrick, Part 1 – Foundation, S.J. Sawaryn, BP Exploration

The paper presents an exact analytical solution using higher order functions for the deflection and buckling of a simple pipe stand in a derrick, modeled as an inclined slender column, with self-weight and pinned at both ends.

The results are consistent with industry practice where an intermediate finger board is used to support 93 ft stands of both 2 ³/8-in. and 2 ⁷/8-in. steel pipe but is not required for 3 ½-in. pipe. These observations suggest a suitable safety factor for application in other cases.

Analytical Model to Estimate the Drag Forces for Micro-hole Coiled-Tubing Drilling, Y. Zhang, Y. Hao, University of Houston; R. Samuel, Halliburton

Micro-hole coiled-tubing drilling is a new technology that provides added advantages while posing numerous operational challenges. This manifests in a number of ways, all adversely affecting the efficiency of the drilling process.

The problems include increased wellbore friction, poor hole cleaning, tubular failures and associated problems during tripping operations. Presently, conventional torque-and-drag models are used to calculate the drag forces and surface loads. Estimates of surface loads predicted using conventional torque-and-drag models are under-conservative as a result of the residual bend in the small-size coiled tubing on the reel and gooseneck. In such circumstances, an improved model and more comprehensive analysis is required.

This paper documents the comparison between the predicted mathematical simulation results with the actual well data from wells describing the accuracy and applicability of the model. The analysis results and comparison are presented along with three examples.