Abstract

Optimal wellbore placement and collision avoidance requires accurate real-time steering of directional wells. Uncertainties in the wellbore position are accounted for by industry standard error models. However, these error models are only valid if the directional surveys are quality controlled and gross error is prevented by appropriate procedures. Particularly effective quality control is achieved by independent validation. A novel real-time web application was developed for the transfer of directional survey data between the rig site and a remote operations center. Surveying professionals at the rig site upload or import survey data into the web application in real-time. The survey measurements are then automatically validated through independent quality checks to identify gross error. Remote survey analysts can access the pre-qualified survey data and evaluate it for systematic or random error that would indicate non-compliance with the instrument performance model. Surveys can also be corrected in real-time when systematic error is identified and provided back to the rig site personnel for accurate steering and wellbore placement. This web service has been implemented and refined on over 50 rigs in North America. Examples for common types of errors that were prevented and/or corrected are incorrect magnetic declination, wrong north reference, excessive drillstring interference, poor instrument calibration, sensors misaligned with the wellbore and incorrect survey order. The impact of these errors if not prevented could easily cause 100 ft. or more in positional error at the bottom hole location. Real-time survey quality analysis provides higher confidence in wellbore placement, reduces risk of collision, and maximizes reservoir drainage.

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