Abstract

In late 1997, Millenia Resource Consulting Ltd. was commissioned by PanCanadian Resources Ltd. (formerly CS Resources Ltd.) to design and construct a 2000 m3/d production gathering system for 15 API oil in the Sandy Lake region of Alberta. The system consists of 27 km of 273.1 mm (10 in.) and 168.3 mm (6 in.) line over hilly terrain and through muskeg. The line was originally designed to operate as a hot oil line with a minimum flow rate of 700 m3/d; however, a drop in the price of heavy crude in late 1998 resulted in a drop in the expected production to a maximum of 450 m3/d. This flowrate was insufficient to provide heat for the entire line, and a corresponding rise in viscosity resulted in excessive pressure drop. The most effective solution to the pressure drop problem was determined to be a push water system, where produced water was recycled from the Wabasca battery via a 88.9 mm (3 in.) line, and injected into the 273.1 mm (10 in.) production line at Sandy Lake.

This paper discusses the commissioning, start up and operations of this heavy crude push water system, up until the end of the first year of operation. Some of the advantages and disadvantages of coaxial flow lines and push water systems over other heavy crude push water systems are also discussed.

Introduction

In late 1997, PanCanadian Resources Ltd. (formerly CS Resources Ltd.) commissioned Millenia Resource Consulting Ltd. to design and construct a 2000 m3/d production gathering system for 15 API oil in the Sandy Lake region of Alberta. The design specifications for the system required it to operate as a hot oil line with a minimum flow of 700 m3/d.

During 1998, the price of heavy crude fell from $25 (US)/bbl to $12 (US)/bbl, resulting in the suspension of drilling and completion of 54 wells and nine production pads in the field serviced by the gathering system. These cuts in production meant that the projected maximum rates for the system were only 350 to 450 m3/d for the winter of 1998 and 1999. This flowrate would be insufficient to provide heat for the entire line, and the corresponding rise in viscosity would result in excessive pressure drop.

A push water system was selected as the most effective solution to maintain flow through the gathering system. Produced water would be recycled from the Wabasca battery via a 88.9 mm (3 in.) line, and injected into the 273.1 mm (10 in.) production line at Sandy Lake.

This paper provides a discussion of the commissioning, start up and operating issues of this push water system. It is the intent of the authors to provide other heavy crude producers with enough information so that, if and when economics or operations dictate, coaxial flow lines and push water systems may be considered over other heavy crude transportation methods.

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