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. P. 161

The M field development involves one of the largest drilling projects in Saudi Arabia, targeting various carbonate reservoirs, and with an extraordinary amount of extended reach wells (ERWs) requires meeting the expected oil production rate, at the lowest development cost possible. More than two-thirds of the wells fall under the extended reach drilling classification, and the majority of the wells have measured depths (MDs) between 24,000 ft and 31,000 ft. These wells are open hole completions where acid stimulation is highly needed to overcome reservoir damage and improve the well's performance after drilling operations terminate.The placement of the treatment fluids requires a uniform distribution along the open hole section. Among the different techniques considered, namely bullheading, using the rig drill pipe and coiled tubing (CT), the last one offered the soundest technical and cost option. However, the CT technique alone did not show the ability in reaching the maximum depth in most ERWs of this field. Therefore, the tractor 1 was required to provide the significant amount of pull force needed to operate inside these long distances, not seen before in open hole completions.The first eight well campaigns, using a combination of CT, a hydraulic tractor and friction reducer fluids, have achieved the main objectives. Moreover, a new intervention world record 2 was set when the CT bottom-hole assembly (BHA) reached the maximum depth of 28,257 ft inside open hole in two different occasions, to place the stimulation fluids, and to record an injection profile. During the campaign, a total of 41,774 ft accumulated footage has been operated with the tractor, allowing over 3,400 bbls of acid to be placed in direct contact with the formation. As a result, the average injection rate has increased more than tenfold, reducing the drilling requirements for injection wells originally projected.The job preparation, technology, results, learning curve experience and best practices are discussed in this paper, including proposed operational enhancements. This experience demonstrates the feasibility of the operations with CT required for full zone coverage, yielding optimum water injection rates at the lowest development cost.

Summary Buckling and its effects are topics of economic and technical interest as extended reach drilling (ERD) and horizontal wells become critical to maximizing recoverable reserves, particularly in the continental United States and Alaska. Previous work has resulted in important discoveries about drillstring buckling, but to date, little testing has been performed on actual drillpipe in a controlled manner, particularly in measuring drillstring whirl. As a result, there can be disparities between theoretical predictions of buckling effects vs. actual field results. These disparities can result in unrealistically high friction factors required to bring calculated values close to actual data, or in many cases, operational difficulties can result such as high torque, low rate of penetration (ROP), drillstring failures, inability to maintain directional control, or inability to reach the planned depth. To learn more about drillstring behavior in buckling conditions, a full-scale buckling test fixture was developed to evaluate the effects of buckling on 2⅞-, 3½-, and 4-in. drillpipe while sliding and rotating inside 7-in. casing. The test fixture incorporated a variety of sensors and cameras to characterize torque, drag, vibration, and drillstring deformation under buckling loads. As part of the test program, low-friction nonrotating protectors were also tested to measure performance under buckling conditions. The test results show that drillstring buckling occurs at far lower loads than predicted by current models, possibly caused by minor deformations inherent in real drillpipe. The results also show that for a given amount of torque or drag, protectors increased the available compressive load by 20 to 30% and substantially reduced vibration caused by drillstring whirl. The test results were used to develop a new semiempirical buckling model that predicts contact forces resulting from drill-drag modeling software in which it was compared against actual data from a large number and variety of wells. The results show an ability to more accurately predict torque, drag, and vibration caused by buckling and whirl.

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For coiled tubing stimulations each CT size offers various advantages and limitations, including but not limited to; maximum pump rate, logistics, fatigue life and cost. In extended reach (ERD) wells CT Tractors can be utilized to improve coiled tubing (CT) access of the horizontal section of the well-bore. The objective of this study was to compare the performance of a slim CT tractor with various sizes of CT, namely 2" and 2-3/8". Tubing Force Analyses (TFA) were performed for a group of wells using CT modeling software with friction coefficients back modeled from previous CT interventions in the same field. Three similar candidate wells were chosen where CT was predicted to lockup prior to reaching Total Depth (TD) without the use of a tractor, and where TD was able to be reached with the use of a tractor for both 2" and 2-3/8" CT. During field operations down-hole pressure sensors and tension compression sub were included in the BHA to verify the effectiveness of the CT tractor with live readings. The field operations demonstrated that 2-3/8" CT reached further in the wellbore prior to activating the tractor. The operations confirmed that the slim hydraulic CT Tractor was able to pull both 2" and 2-3/8" CT a significant distance past CT lockup depth. Matrix stimulations were successfully performed on each of the 3 wells. The study concludes that both 2" and 2-3/8" CT combined with a hydraulic slim tractor were both appropriate solutions to access extended reach open hole for Matrix stimulation operations. Production engineers have case study results to show the effectiveness of using 2" vs 2-3/8" CT with a slim hydraulic tractor to access ERD wells for stimulation operations.