Abstract

Casing wear caused by rotating drill strings can lead to reduced well life, failed or burst casing strings, and expensive non-productive time (NPT) for remedial actions. In Alaska's Alpine Development field, where logistics are challenging, regulations are strict, and the operational window is small, drilling increasingly long laterals has vastly increased the cost and risk of casing wear, necessitating effective mitigation.

After detailed analyses of Alpine field wells, one operator successfully implemented a casing wear mitigation plan combining new tools, modeling techniques and analyses. The plan required strategic placement of Non-Rotating Protectors (NRPs) based on predicted casing wear, analyzed side forces, and lateral length. Additionally, the operations group wanted to simultaneously improve computer modeling for both casing wear and torque and drag (T&D) analysis.

One major challenge was predicting appropriate wear factors for casing wear modeling. Operational challenges included how to deploy the plan in managed pressure drilling (MPD) operations, where preventing premature wear on rotating control device (RCD) sealing elements had to be considered.

Implementing this casing wear mitigation plan allowed the operator to successfully drill extended reach multilateral wells to planned total depth while keeping wear below maximum allowable thresholds. The paper describes the challenges and approach to predict casing wear, as well as successful mitigation strategies and lessons learned from an extensive offset database. Included are comparisons to field results from casing logs, and several wells that deployed the casing wear mitigation plan, versus an offset well that was drilled without a plan.

The paper describes new techniques for predicting and modeling casing wear which, in combination with utilization of specific tools, results in a readily-applicable approach to wear mitigation in extended-reach drilling (ERD).

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