Improved Out-of-Slip Casing Running Efficiency in A Shale ERD Application Combining Fixed Casing Centralization and Rotation to Reduce Openhole Running Friction
Authors: Dall'Acqua Daniel , Taubner Spencer , Miller Samantha M. , Clark John , Gladney Mark 
Published: September 2022

The prevalence of longer extended-reach drilling (ERD) wells as a means of more efficiently recovering reserves in a variety of upstream oil and gas applications has led to heightened focus on overcoming related drilling and casing running challenges. The case study presented in this paper demonstrates that for ERD wells, the use of fixed casing centralizers is a simple and effective solution for overcoming casing running friction and extending lateral reach while preserving casing standoff.

Merit in casing running optimization in this Marcellus application was established in prior challenging but shorter runs, where string rotation did not provide anticipated benefits with respect to hook load recovery and running efficiency in the lateral prior to installation of a floatation sub. After earlier runs were assessed relative to torque and drag (T&D) predictions, it was postulated the free-rotating casing centralizers on the strings were not rotating as quickly as the pipe, limiting rotation effectiveness. Given increased lateral length of future wells, the operator analyzed the benefits of applying field-tested fixed centralizers that rotate with the pipe to reduce running resistance to forward motion.

As part of the planning process for future longer wells, predictive torque and drag analysis was used to compare various equipment configurations and running scenarios, and to provide an indication of the torque demand relative to casing connection limitations. This also revealed the merit in using metrics of downhole axial load transfer efficiency and downhole obstruction capacity (among others) to compare the scenarios. This showed that the field behavior seen during earlier runs with floating centralizers aligned with running mechanics that can be predicted by an appropriate centralizer-aware torque and drag model. Fixed centralizers were efficiently installed in the pipe yard and transported to site. Armed with pre-run T&D predictions and a mechanism for rapidly calibrating T&D with rig measurements to adapt plans in real-time, the operator’s next casing runs were monitored and revealed very clear alignment with T&D predictions and much higher out-of-slip running efficiency. Hook load recovered considerably upon rotation, and faster running was achieved during the intermediate part of the lateral run prior to installation of the floatation sub. Target depth (TD) was reached without interruption in longer wells, and relative to a representative earlier well, about 10 hours of rig time was saved.

This paper demonstrates, using two remarkably clear operator-provided casing running datasets, that a fixed centralization strategy can be a powerful reach extension mechanism and can increase out-of-slip running efficiency, provided associated torque demands are managed in the casing system design.

Furthermore, the paper introduces simple metrics that can be used to compare candidate running configurations in the context of downhole load transfer effectiveness.