The Pioneer design included the transportation of the captured, dehydrated and compressed CO2 800 meters from the Keephills 3 plant site to the CO2 metering station at the head of the pipeline legs to the EOR oilfield and the sequestration site. In order to provide maximum operational flexibility, each pipeline leg was designed to be able to accept 100% of the instantaneous CCF CO2 output.
The pipeline diameter selected was NPS 10 (nominal pipe size of 10 inches or 273.1 mm outside diameter). The pipeline was designed to accept 99.5% pure dense-phase CO2 compressed to 14 MPa. A metering station was to be constructed at the oilfield receiving terminal where product custody would have been transferred to the oil producer. CO2 is an acid gas that will react with water to form carbonic acid which will cause corrosion challenges. Thus, it is crucial that CO2 accepted for pipeline transportation meet stringent quality specification, particularly for contamination by water. Proper dehydration of the CO2 stream is important in order to avoid the critical dew point temperature that may be encountered due to line shut-in or exposed pipe in contact with ambient temperature conditions. The Pioneer CO2 specification for water content was maximum 50 ppmv (parts per million by volume).
While CO2 is non-toxic, at high enough concentrations it can be an asphyxiant and a major CO2 release could potentially have serious consequences. The design of the CO2 pipelines must reflect the potential risks involved, particularly block-valve spacing.
Several pipeline routing alternatives for the EOR pipeline were considered based on environmental, social, economic, and geotechnical analysis. Although shorter routes were technically feasible, the selected route utilized existing right-of-way (ROW) for about one quarter of its length, and was determined to be more acceptable to landowners and local communities. The selected pipeline route was 74 km long and crossed minor waterways and three highways. The largest urban area close to the pipeline route was the Town of Drayton Valley located 5.6 km east of the pipeline.
The pipeline to the sequestration site was designed to the same technical characteristics as the EOR pipeline because it was also designed to be capable of handling the same CO2 volumetric rate, which is 100% of the CCF output. As with the EOR pipeline, the sequestration pipeline would have originated from the Keephills CO2 metering station.
The sequestration pipeline was to be approximately 6 to 8 km long and was to terminate at a metering station located at the sequestration site, which was to be located to the southeast of the Keephills site. The routing utilized existing ROW for 80% of its length.
The two pipeline routes are shown in Figure 4.