Friction Load Redistribution for Robust and Cost Efficient Design of Extended Reach and Horizontal Well Completions
| Autor: | Ruggero Trevisan, Albert R. McSpadden |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Engineering
Cost efficiency business.industry 02 engineering and technology Redistribution (cultural anthropology) Structural engineering 010502 geochemistry & geophysics 01 natural sciences Stress (mechanics) 020401 chemical engineering Load redistribution 0204 chemical engineering business 0105 earth and related environmental sciences |
| Zdroj: | Day 1 Tue, March 01, 2016. |
| DOI: | 10.2118/178905-ms |
| Popis: | In horizontal and extended reach wells where long completions are run into highly deviated or lateral zones, large compression loads arise due to running friction. These loads remain locked in the string when the packer or cement sets. Dissipation of friction during life service due to string vibrations and movements redistributes these friction loads between the wellhead and packer or top of cement. A numerical approach is presented to calculate the redistributed friction load so that an accurate initial tubing load is implemented in the tubular stress analysis. The proposed methodology offers an opportunity for design optimization via accurate prediction of tubing loads when the locked-in friction loads may be a determining factor in the balance between marginal tension limits near surface and marginal compression loads downhole. The numerical approach is a simple 1D finite element model in which incremental frictional loads are decomposed and redistributed based on relative stiffness of the string uphole and downhole of each local node. Essentially each portion of the string is represented as a series spring. The methodology requires input of the estimated friction load for each incremental element during running from a standard torque-drag analysis. The results are particularly relevant for ERD, multistage completion and shale-type multizonal lateral wells, where overestimation of in-service compression above the packer or cement may pose considerable design challenges for tubular components including connections. The common assumption to ignore friction in tubing analysis is non-conservative in that it may underestimate friction loads, especially downhole at the packer. However, applying the full slackoff load downhole is also unrealistic and overestimates compression above the packer leading to costly component selection. Results from the numerical model wherein post-dissipation friction loads are redistributed show that only a part of the friction induced compression migrates to the packer. Some of the redistributed friction load results in additional tension at the wellhead. The type of trajectory, kick off depth and deviation angle are important factors for the load redistribution. The methodology presented in this work provides an approach to calculate the proportion of friction load transferred to the surface compared to the packer or cement top. The redistributed result which divides the running friction load between hanger tension and downhole compression is not always intuitive. This approach is critical for correct modelling of the initial conditions in the tubing stress analysis with significant impact on tubular cost efficiency and fit-for-purpose design and well integrity. |
| Databáze: | OpenAIRE |
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