Impacts of Oriented Perforating on Fracture Stimulation Treatments: Kuparuk River Field, Alaska
Authors: Pospisil G. , Carpenter C.C. , Pearson C.M. 
Published: December 2007

G. Pospisil, C. C. Carpenter, and C. M. Pearson

SPE Members

This paper summarizes the results of stress oriented aligned perforating based on fracture treatments on over 200 wells In the Kuparuk River Field. Stress aligned oriented perforating is one method used for enhancing fracture stimulations in wells with deviations averaging 40 from vertical.

Comparisons between oriented and non-oriented perforating strategies show a reduction in near wellbore pressure loss and an increase in proppant placement within the fracture. Additionally, wells treated after oriented perforating techniques show higher productivity for comparable treatments. These results support the continued use of oriented and aligned perforating techniques for deviated wells to be fracture stimulated.

The clear trend In drilling is towards more non-conventional, high angle, and horizontal completions to promote productivity, facility, and reservoir management opportunities. Stress oriented aligned perforating techniques present a cost effective method to enhance stimulation potential of non-vertical wells.

Introduction

During the Kuparuk River Field history, fracture stimulation has been a critical component in the effective completion and economic operation of over 600 wells. This study was initiated in 1993 to determine the Impacts of oriented perforating techniques on fracture treatments and well productivity.

Located in the Alaskan Arctic, the Kuparuk River Field is one of the United States' largest producing oil fields (300,000 barrels oil per day), covering an area of approximately 115,000 acres. The field was discovered in 1969, but was not deemed economic for development until 1977, after completion of the Trans Alaska Pipeline. Figure 1 shows the site of the field location on the North Slope of Alaska. Field development was started in 1979 using gravel pads as central drill sites from which deviated wells were drilled to drain a four section area (4 square miles). Initial development was on 160 acre well spacing with some 80 acre infill locations.

The Kuparuk reservoir is a moderate permeability sandstone at approximately 6000 feet subsea depth. After a short period of primary production, the majority of the field is under secondary recovery receiving pressure support through a combination of waterflood and water alternating immiscible gas Injection. Previous reports have documented both the geological description and the reservoir mechanisms of the field.

Production occurs from two horizons within the Kuparuk sandstone. This study focuses on the lower horizon, the A Sand. The deeper producing zone is present throughout the field and contains 65% of recoverable oil in place. The average net thickness is typically less than 30 feet, with permeability ranging from 20 to 100 md. it is a fine to very fine grained sandstone Interbedded with shale and cemented with quartz and varying amounts of ankerite.

The A Sand unit can be further divided into six distinct subzones. Each of these subzones has variable reservoir quality across the field and typically one or two of these subzones dominate the A Sand productivity in any given area.

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