CARBON DIOXIDE FROM GREAT PLAINS PLANT FLOWING INTO CANADA

On September 14, 2000, carbon dioxide began flowing from the Great Plains Synfuels Plant near Beulah, North Dakota, north to an oil field near Weyburn, Saskatchewan, Canada. A 205-mile pipeline connects the Synfuels Plant and the oil field (see Figure 1).

Figure 1

Free flow and water flooding have already been used by PanCanadian Resources in the Weyburn Field. Now the third (tertiary) method--CO2 miscible flooding--will be used in the years ahead.

Pan Canadian reports that CO2 miscible flooding will extend the life of the Weyburn Field by about 25 years.

The CO2 project represents another new byproduct for the Synfuels Plant, which is owned and operated by Dakota Gasification Company (DGC), a subsidiary of Basin Electric Power Cooperative. With CO2 the Synfuels Plant now has eight byproducts on its production list, along with about 135 million cubic feet of synthetic natural gas per day, which is the primary product.

PanCanadian will use up to 95 million standard cubic feet of CO2 daily--about 40 percent of the Synfuels Plant’s capacity. At the plant, CO2 is produced from the Rectisol unit in the gas cleanup train.

The pipeline project is the result of a CO2 sales contract signed in July 1997 between DGC and PanCanadian. Following almost 2 years of engineering and design work, groundbreaking ceremonies were held May 12, 1999. On December 1, 1999, the final weld connecting the United States and Canadian portions of the $100-million pipeline project was made.

The Weyburn oil field covers 52,000 acres southeast of Weyburn, just north of the North Dakota border. Production consists primarily of medium-gravity crude oil with a low gas-to-oil ratio.

The Weyburn oil field was discovered in December 1954 by Central Del Rio Oils Limited, a predecessor company that became part of PanCanadian in 1971. The actual Weyburn Unit was established in 1962. The 50 companies and individuals then producing from the field pooled their interests into one unit and initiated a water-flood project to increase the reservoir pressure, thus boosting production.

By the end of 1996, about 328 million barrels of oil had been produced from the Weyburn oil field, representing about 25 percent of the 1.28 billion barrels of oil originally in place. The CO2 flood project will extract at least another 122 million barrels of oil at a cost of C$1.1 billion.

The Weyburn Field has 963 wells, including 534 vertical wells, 115 horizontal wells, 171 injector wells and 146 abandoned wells. The reservoir lies at an average depth of 4,655 feet. Production averages about 22,600 barrels per day, down from a high of 45,000 barrels per day in the mid-1960s.

PanCanadian holds the largest share of the current 37 partners in the field and is operator of the oil field.

The Weyburn Unit is an ideal candidate for miscible flood technology because of the crude oil quality and the reservoir average depth of 4,655 feet.

Other CO2 miscible floods are currently operating at Midale, Saskatchewan, Canada, located 28 miles to the southeast of Weyburn and at Joffre in Alberta. PanCanadian has been investigating the potential of enhanced oil recovery techniques at the Weyburn Unit for several years.

There are two huge compressors that push CO2 through the pipeline. Each compressor is driven by a 20,000-horsepower electric motor and weighs 105 tons. Should additional demand for CO2 arise, more compressors and a booster station would be required.

During normal operations, CO2 will be carried in the pipeline as a gas, but in a state called supercritical--meaning it acts much like a liquid. During the pipe-filling process, the CO2 is in a gaseous state. As the pipeline fills and its pressure increases, CO2 does become liquid. Then as the pressure continues to increase, the CO2 returns to the gas phase and enters the supercritical state.

The first additional barrels of oil from the Weyburn Field will start to flow in 2001.

The CO2 project adds about $30 million of gross revenue to the gasification plant’s cash flow each year, and is not subject to outside forces or commodity prices. The sale is for a set quantity (of product) at a set rate over a long period of time--15 years.

DGC will be participating in an international research project associated with piping CO2 from the Great Plains Plant to the Weyburn oil field. The study is called the International Energy Administration (IEA) Weyburn CO2 Monitoring Project. The C$23-million multiyear project is designed to demonstrate an effective method of CO2 sequestration while at the same time expanding the understanding of enhanced oil recovery. The Canadian Petroleum Technology Research Centre, Regina, Saskatchewan, is conducting the study for the IEA.

DGC directors approved participating in the study, as one of several corporate sponsors, during the next 4 years at a cost of $50,000 annually. Additional funding is expected to be provided by the United States Department of Energy (DOE), the Federal Government of Canada and the provincial Governments of Saskatchewan and Alberta.

DGC filed an application for a grant of $4 million with the DOE in August 2000 seeking partial funding for the project.

DGC’s K. Ganzer said collection of baseline data for the study began last May. "A database of this type of knowledge would serve to enhance the understanding of CO2 sequestration in oil fields and promote the use of CO2 for enhanced oil recovery," Ganzer said. "This knowledge would be valuable to DGC in analyzing future sales of CO2 to other oil field operations."