Abstract

This paper focuses on the unique problems that were confronted in the process of formulating and implementing a field redevelopment strategy for the Piper field, located in Block 15/17 of the UK North Piper field, located in Block 15/17 of the UK North Sea continental shelf. The original Piper A development, including 56 directionally-drilled wells, was lost on 6 July 1988.

The process of selecting a site for the Piper B drilling template is reviewed in the context of:

  1. the proximity of oil and gas pipeline networks serving the Tartan and Clay more platforms;

  2. the proximity to subsea wells and debris at the Piper A site;

  3. the presence of shallow gas hazards in are as adjacent to the Piper A site;

  4. the requirement for directing some replacement wells to the original Piper A targets;

  5. the requirement for directing other replacement wells to revised targets.

The drilling of Piper B redevelopment wells in close proximity to the Piper A well cluster requires an proximity to the Piper A well cluster requires an unusually rigorous and comprehensive approach to collision avoidance, as the possibility for deep intersection with existing wellbores poses a substantial drilling hazard. Key considerations in the planning and execution of Piper B directional drilling include:

  1. the QC of survey records for the original Piper A wells;

  2. the quantification of survey errors in the original Piper A surveys;

  3. the assignment of error models for the calculation of positional uncertainty;

  4. the generation and maintenance of clearance reports.

To date, six directional wells and two sidetracks have been safely drilled through the Piper B template. Strategic site selection and the highest standards of directional well planning and collision avoidance surveillance have been key ingredients of the ongoing and successful redevelopment of the Piper field.

Introduction

The Piper field, located in block 15/17 of the United Kingdom Continental Shelf, 125 miles north-east of Aberdeen, was discovered in 1973, and was developed from a single fixed platform, Piper A, with first oil produced in 1976.

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