Reduction of Drill String Torque and Casing Wear in Extended Reach Wells Using Non-Rotating Drill Pipe Protectors
Authors: Moore N.B. , Mock P.W. , Krueger R.E. 
Published: December 2007

1. Abstract
Extended Reach Drilling (ERD) is increasingly becoming the means of expanding production of aging oil fields. With ERD also come problems associated with high drilling torque and excessive casing wear. This paper addresses the issues of casing wear protection and drill string torque reduction with the use of Non-rotating Drill Pipe Protectors (NRDPP). The design principle of operation, and operational limitations of NRDPP are discussed. Analysis methods for placement and typical applications are discussed. Analysis results typically include the determination of contact loads of the drill string to the casing and application of loading criterion based on design performance. Placement recommendations limit the side wall contact loads to an experimentally determined criterion for safe NRDPP operation. Four operational experiences are discussed to allow comparison of various types of applications and field problems. Operational experiences include cases in Alaska, Gulf of Mexico, North Sea and New Zealand. Other related considerations associated with the use of NRDPP include drill string vibration and hot hole environments. This report concludes that properly placed NRDPP can substantially reduce drill string torque by 10-30% and that casing wear is prevented where the protectors are applied.

2. Introduction
ERD is critical for optimizing development of many fields in the North Sea. the Gulf of Mexico, Alaska, and other locations throughout the world. ERD is increasingly important because it offers the potential of reduction of location footprint or platform size, access to restricted areas, and greater utilization of existing facilities. These benefits result in lower cost.
However, ERD also imposes additional technical problems. Teel discusses technologies for successful ERD wells. These problems include drill string capacity and BHA design, bore hole stability, hole cleaning, solids control, casing placement as well as high drill string torque and increased casing wear.
High drill string torque and excessive casing wear are frequently serious problems in ERD wells. High drill string torque can threaten well completion by exceeding the capacity of Top Drive systems or drill string. Casing wear can necessitate the use of casing patches, liners, and entire casing string replacements. These procedures increase well completion times and costs.
One approach to reducing drill string torque and preventing excessive casing wear is the use of Non-Rotating Drill Pipe Protectors (NRDPP). For example in the Bass Strait, NRDPPs were used successfully as part of the changes implemented to reduce torque and prevent casing wear. Over the last six years NRDPPs have been used successfully in hundreds of ERD wells world wide for torque reduction and casing wear prevention.

3. Purpose
This effort examines the use of Non-Rotating Drill Pipe Protectors in Extended Reach Drilling specifically with respect to torque reduction and casing wear prevention and related considerations.
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