Elbe crossing near Hamburg: 1,400 m gas pipeline under the river

The bore ran 1,400 metres under the Elbe at 28 metres below the riverbed. The contractor drilled with a 250 tonne rig and a 36 inch product pipe, which meant a fluid demand of up to 3,000 litres per minute during the reaming passes. Trucking that volume in was not an option on a site with one access road.

One mixing unit, one recycler, two tanks

We placed a MudForce 2500 next to the rig, fed by a recycling unit that returned 70 percent of the fluid to the mixing tank. Two 30 m3 storage units gave the crew a buffer of 60 m3, enough for four hours of reaming without fresh water. The whole setup was commissioned in one day.

Result

Eleven drilling days, zero fluid stops and 40 percent less water hauled compared to the contractor’s previous river crossing. The recycler alone saved 38 truck movements.

Why the fluid setup decided the schedule

On a river crossing the rig is rarely the bottleneck. Fluid is. Every hour the mixing unit cannot keep up, the reamer waits. So we sized the fluid side first and let the rig follow.

Numbers from the site

• Peak demand: 3,000 l/min during the 36 inch reaming pass
• Recycled share: 70 percent of return flow
• Buffer: 60 m3 in two storage units
• Water hauled: 40 percent less than on the previous crossing