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A Fully Completed Solution With Zonal Isolation in Norway

This paper describes the design, testing, installation, and performance of the first fully completed well using an intelligent inner completion inside an uncemented liner with openhole packers for zonal isolation. The term “fully completed” implies full reservoir access along the pay length for production and high-rate matrix acid stimulation using limited entry for fluid diversion within well segments. The well-design concept evolved from technical challenges associated with completing long cased-and-cemented laterals in the mature Ekofisk waterflood.

Introduction

To improve acid stimulation and reduce casing deformation and well failures in the Ekofisk field, a new class of wells was introduced to the field (please see the complete paper for a discussion of field characteristics and associated challenges). These new fully completed wells were perforated along the entire horizontal section and used limited-entry techniques to distribute acid more evenly over the reservoir intervals. Perforations were generally spaced at one hole every 10 ft of reservoir net pay along the horizontal section, with stimulation volumes on the order of 20 bbl of 28% hydrochloric acid (HCl) per perforation. These new completion techniques proved successful in providing high-productivity completions with low well-failure rates. Post-stimulation skin values have been found to be in the –4 to –4.5 range, while liner deformation and well failures have decreased.

The new fully completed designs were first implemented in horizontal wells with cemented liners, but as confidence in the designs increased, conceptual planning moved to openhole designs with uncemented liners. To improve the fully completed well designs further, it was desired to combine the benefits of a surface-operated intelligent-well system (IWS) for downhole flow control with limited-entry diversion to provide uniform acid distribution along pay intervals in an uncemented liner. This led to the Ekofisk 2/4-B-19C (hereafter referred to as the B-19C) well design. For a discussion of the functional requirements, design features, and modeling and testing of the uncemented-liner completion and all of its components, please see the complete paper.

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 166209, “Intelligent Completions and Uncemented Liners Combine To Provide a Fully Completed Solution With Zonal Isolation in Norway,” by A.W. Kent, D.W. Burkhead, R.C. Burton, K. Furui, S.C. Actis, K. Bjornen, J.J. Constantine, W.W. Gilbert, R.M. Hodge, L.B. Ledlow, M. Nozaki, A. Vasshus, and T. Zhang, ConocoPhillips, prepared for the 2013 SPE Annual Technical Conference and Exhibition, New Orleans, 30 September–2 October. The paper has not been peer reviewed.
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A Fully Completed Solution With Zonal Isolation in Norway

01 May 2014

Volume: 66 | Issue: 5

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