TX 75083-3836, U.S.A., fax 01-972-952-9435. Abstract

Deviated wells pose an inherent risk to down-hole tubulars via increased bending and contact loads. Deviation is a "necessary evil" when it comes to directional wells as periodic well path corrections are often needed to stay on course for a planned trajectory. These intrinsic deviations generate bends and kinks in the wellbore, effectively reducing the "pass through" diameter of a given well section and making it more difficult to move a tool string through the well. Understanding this tortuosity limitation is instrumental in helping engineers to better place completion components for mitigating risks associated with high stress environments; such as fatigue, premature wear, and difficulty running-in-hole. A new analysis software has been developed that analyzes the geometry of the wellbore and its effect on the mechanical loading of down-hole tools by utilizing a combination of gyro-based high-density surveys and ID measurements from multi-finger caliper logs. Using a specified tool length, (i.e. the length of a pump) this methodology allows for a determination of an effective tool OD or length that can be run so as to avoid any bending in the tool. This approach also allows for a quick comparison of multiple tool assembly lengths in order to aid in the tool selection and decision process. The results are supported with enhanced 3D visualizations, which help to effectively describe the tortuosity present in a wellbore and estimate the allowable pass-through ID ("Effective ID") for a specified tool length. Some real-world applications of this technology are presented in detail. The OD and lengths of components placed in the wellbore can now be considered; determining if completion tools will experience bending while being run down-hole, if a holdup while running-in-hole is probable, or if operating at a certain setting depth is likely to result in premature failure. These results may then be used to optimize the completion string, artificial lift setting depth, or allowable tubular size for subsequent casing or tubing strings. Similarly, non productive time (NPT) associated with problems running other completion devices (perforation guns, plugs/packers, tubing, liners, etc.) in the well can be avoided by utilizing this analysis. Now, completion and production engineers can have a better understanding of the tortuosity in the wellbore and its effects on the production or completion equipment to be run in the wellbore. This study provides insight into the practical application and utility of high-density surveying, caliper-logging, and estimating tortuosity while considering tool lengths and ODs. Comparing the results obtained with both standard measurement while drilling (MWD) surveys and short interval surveys, it is shown that standard dog-leg severity (DLS) measurements lack the required resolution to properly model the effective diameter of the wellbore. Utilizing the new approach has proven to be more valuable for artificial lift placement optimization, identifying wellbore access issues, and quantifying wellbore tortuosity.