The call came in from a drilling company WellJet® has worked with many times on successful rehabilitation projects. Good people. Experienced. Resourceful. Reliable. They had just finished drilling a new municipal well in rural Nevada. The town was nestled at the base of the Snake Mountain Range, between Granite Peak and Mt. Moriah. Residents, farmers and ranchers all depended on local groundwater.
The new well was 258’ deep, 8” ID, with Stainless Steel Wire-Wrapped Screen perforations from 150-200’. Static water level was 53’. Pump setting was 150’. The well was designed to produce 50 gpm with 50’ of drawdown, at a Specific Capacity of 1.0 gal/ft. Upon completion of development, initial pump testing produced only 25 gpm, with 100’ of drawdown, for a Specific Capacity of 0.25 gal/ft – and the pump was breaking suction, so no sustained step testing could be conducted.
Downhole video revealed that something had gone very wrong during construction of the well. Somehow, cement that was supposed to form the sanitary seal outside the casing had migrated around the bentonite plug at the top of the gravel pack – gotten inside the casing – and completely plugged and occluded the entire perforated area of the well.
Efforts to remove the cement and redevelop the well with chemicals, swabbing, airlifting and over-pumping didn’t work. The driller was unhappy. The engineers were unhappy. The client was unhappy. There was talk of abandoning the well, moving to a different nearby site, and drilling a new well. There was also talk, as there always is in this most litigious society in the world, of lawsuits. The whole project was looking like a looming catastrophe.
In a last-ditch, Hail Mary attempt to avert disaster, the driller called WellJet®. Could the patented high-pressure hydrojetting process remove the cement and make the well produce water? Had WellJet® ever done something like this before?
It turns out, yes. In the Middle East. In Southern Jordan. On the Disi-Mudawarra Water System Conveyance project. Local Bedouins, unhappy that the wells were going to take “their” water over a hundred miles away by pipeline to the capital city of Amman, decided to sabotage one of the wells by hurling chunks of concrete and construction lumber downhole. Rendering it inoperable. Or so they thought. But WellJet® demonstrated that it was able to pulverize the concrete into sand and pebbles, and the lumber into sawdust. Sabotage thwarted. Well saved.
Could the same approach work here? Fifteen years of experience, on more a thousand successful well development and rehabilitation projects worldwide, said yes.
Could WellJet® guarantee success? No. There are no guarantees in the water well industry. But it was worth a try.
WellJet® performed three separate passes at 18,500 psi, with exit velocities around 2,000 fps. During the jetting process, water overtopped the standpipe and was diverted to a designated runoff area. This discharge was thick with cement slurry and fine sand.
Upon completion of jetting, approximately 32’ of fill had accumulated in the bottom of the well – along with however much had been discharged during the process.
The driller followed jetting with swabbing and airlifting, evacuating the accumulated fill.
Post-jetting downhole video showed a remarkable transformation:
97% of the cement had been removed by the jetting process. So the inside of the well looked much better. But well development and rehabilitation is not a beauty contest. The proof of the pudding is in the tasting.
How did the well perform?
90 gpm. 50’ drawdown. Specific Capacity 1.8.
Production improved by 260%.
Efficiency improved by 620%.
There was no more talk of abandoning the well. No more threats of legal action.
The driller was understandably pleased: “This well has turned out about as well as we could have hoped… We couldn’t have done it without WellJet.”
The client was very happy: “We can hardly believe it.”
WellJet® is the world’s most powerful tool for water well development and rehabilitation. Nothing can match its ability to deliver energy downhole, remove obstructions, open plugged perforations, and restore free water flow.
Happy Labor Day, America!