Michels Directional Crossings successfully completed a nearly 1.6 km horizontal directionally drilled bore on an approximately 235 km natural gas pipeline that now runs underneath the Atchafalaya River and the accompanying levee system in central Louisiana, United States.
The nearly 1.6 km Atchafalaya drill was one of the last of a total of 15 horizontally directional drilled (HDD) installations that Michels Directional Crossings completed on the Acadian Haynesville Extension Project, a pipeline that originates in the Haynesville Shale in Red River Parish, Louisiana, and terminates near Donaldsonville, Louisiana.
The Haynesville Extension Project will extend the existing 705 km Acadian Gas Pipeline System, which is owned by Acadian Gas LLC, a jointly owned subsidiary of Enterprise Products Partners L.P. and Duncan Energy Partners L.P. The project will increase market share for existing customers, connect the service to new markets, and add more than 200 MMcf/d of new customers along the route. Michels Directional Crossings completed the Atchafalaya River drill for Michels Pipeline Construction, which was the prime contractor for spreads 3 and 4 of the Acadian Haynesville Extension Project. Michels Directional Crossings completed a total of seven drills for Michels Pipeline Construction and a total of ten drills for Willbros Group, Inc., the prime contractor for spreads 1 and 2.
Willbros was contracted to construct spread 1, which included a 171 km section of 42 inch diameter pipe, a 4 km section of 36 inch diameter pipe, and a 4 km section of 20 inch diameter pipe.
The Atchafalaya River is classified as a navigable channel of the Mississippi River and has been a significant project of the US Army Corps of Engineers for over a century. As a primary industrial shipping channel and the cultural heart of Cajun Country, maintaining the integrity of Atchafalaya, the levee system, and the surrounding environment has been a primary issue for the Corps.
Because of this, any utility lines designed for crossing the waterway and levee system must undergo significant planning. Any state-of-the art equipment and methods must be submitted to and approved by the Corps of Engineers.
A difficult challenge overcome
A controversial opening delayed the Atchafalaya installation and put the project on an extremely tight timeline. This made an already difficult challenge – previous attempts to drill and place utility lines underneath the Atchafalaya have encountered failures due mostly to difficulty with hole stability in the sandy, silty soils – even more difficult.
With that setting as the backdrop, and evidence of the past failed HDD attempts visible in the form of pipe bridges spanning over the river, Michels Directional Crossings began work in mid-July 2011 using Corps-approved technology and methods, which included pilot hole intersect technology and annular pressure monitoring through sensitive zones designated beneath the levee areas on either side of the Atchafalaya. It did not take much more than a week for the two sides to meet 32 m below the riverbed.
Michels Directional Crossings’ vast experience with the conditions helped the project team hold the hole open during larger reaming passes, which is where others had failed.
“People ask me, “÷What’s the difference between you guys and them?'” Michels Project Manager Larry Shilman said. “You don’t want it to come off the wrong way, but it’s our people. It’s our experience. We’ve seen this stuff before and we know how to deal with it.”
The 36 inch diameter Atchafalaya drill ultimately spanned 1,522 m feet and was one of four drills Michels Directional Crossings completed on spread 4. Michels completed one drill on spread 3 – a 42 inch crossing – and nine more 42 inch crossings on spreads 1 and 2. Michels completed one other 36 inch crossing on spread 1.
While the Atchafalaya drill was the most technically difficult of the 15 drills, Michels Directional Crossings broke the 1.6 km mark on two other occasions: once in Kingston, Louisiana, while drilling under the Kansas City Railroad (1,623 m), and once in Boyce, Louisiana, while bypassing the Boise Cascade (1,628 m). All told, Michels Directional Crossings’ 15 HDD installations spanned more than 16.4 km.