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Abstract

Prudhoe Bay Field is the largest producing field in North America. Prudhoe Bay is currently expected to yield at least 25% more reserves than estimated at field start up. This paper briefly describes the history of the field and some of the key developments that have taken place which have contributed to improved recovery efficiency. These incremental developments have resulted from a process of continuous surveillance, interpretation of field performance, management of multiple reservoir mechanisms, efficient utilization of the gas resource, and exploitation of the existing field infrastructure.

There are four dominant recovery processes currently at work in Prudhoe Bay; Gas Cap Expansion/Gravity Drainage, Waterflood, Miscible Flood, and Gas Cycling. Continuous management of these processes and analysis of field performance leads to identification of attractive targets for further development. Major components of the current field development plan are described in this paper.

Prudhoe Bay is seen by many as a mature oil field on an inevitable and irreversible decline. The major Owners in Prudhoe Bay continue to pursue incremental developments to mitigate decline and supplement proved reserves. Unit technical studies are typically done in multi-company, multi-disciplinary work teams. The pooling of resources in this manner has enabled efficiency gains and has promoted the sharing of ideas and best practices. The current view of potential future development targets and some of the opportunities under consideration for development of these targets are discussed.

Introduction

Prudhoe Bay field was discovered in early 1968 by ARCO and Exxon with the drilling of the Prudhoe Bay State #1 well. A confirmation well was drilled by BP Exploration in 1969. The next 8 years saw frenetic activity as ARCO, BP, Exxon and other companies with lease holdings in the vicinity worked to delineate the reservoir, resolve equity participation, put together an initial plan of development, and design and construct the initial infrastructure.

Prudhoe Bay came on stream in June of 1977, rapidly ramping up production until the field's maximum allowable rate was reached in 1979 at 1.5 MMSTB/D. This plateau rate was maintained until 1988. The current production rate from the field is approximately 1.15 MMSTB/D.

In late 1992 the 8 billionth barrel of liquids was produced from Prudhoe Bay. Pertinent Prudhoe Bay facts are listed in Table 1.

GEOLOGICAL SETTING

The Prudhoe Bay Field is a combination structural and stratigraphic trap. A regional cross section representative of the Alaskan North Slope is shown in Figure 1. (Ref 1). The Unitized intervals are of Triassic age and include the Sag River Formation, Shublik Formation, and the Sadlerochit Group.

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