Tallgrass announces open seasons for Pony Express, Seahorse pipeline capacity

Midstream player Tallgrass released separate announcements last week about open seasons on two of its pipelines. Both of the binding joint tariff open seasons – on the Seahorse and Pony Express pipelines – are seeking shipper commitments for oil transportation from Bridger Pipeline’s Guernsey Hub.

Tallgrass operates both pipelines, in which Bridger is also a partner. Both open seasons will run for 30 days from August 21 and cover existing capacity on the two pipelines.

Pony Express has a capacity of roughly 400,000 barrels per day (bpd) and covers a distance of around 900 miles (1,448 km), extending from Wyoming and southeast Colorado to the Cushing oil hub in Oklahoma. The system carries oil from the Powder River and Denver-Julesburg (DJ) basins and Williston Basin volumes coming out of North Dakota can also connect to the pipeline. Tallgrass held a separate 30-day open season for capacity on a separate section of Pony Express, from the pipeline’s Colorado origins, from June 8, building on earlier open seasons on both Pony Express and Seahorse.

The originally planned Seahorse pipeline would have connected to Louisiana, with a capacity of up to 800,000 bpd. However, the project was cancelled and replaced by a different scheme, under which Tallgrass is using existing infrastructure connecting to the Guernsey Hub to transport crude and market capacity together with Bridger.

Now, Guernsey is becoming a chokepoint, which has prompted the development of new capacity connecting to the hub. Indeed, in late June, Bridger and Canada’s South Bow said they would jointly develop a new pipeline from Guernsey to Cushing. The companies told Reuters that the project would be developed along a corridor that had been acquired from another company. This pipeline is expected to be the third leg of a larger project to transport oil from Alberta to Cushing, according to that Reuters report.

The story cited a JP Morgan research report from earlier in June, according to which a joint venture between South Bow and Bridger had acquired the right-of-way of the cancelled Liberty pipeline from Tallgrass. However, none of the companies have publicly confirmed this.

Separately, South Bow and Bridger have also proposed an Alberta-to-Guernsey oil pipeline known as the Prairie Connector. A final investment decision (FID) on that project is being targeted for mid-2027.