A 1,500 ft municipal sandstone well: capacity nearly doubled — and sand production cut below 1 ppm

The problem

Two problems, actually — and they usually travel together in deep sandstone wells. The well's specific capacity had fallen to 10.1 gpm/ft, and it was pumping sand at 1.8–5.0 ppm — enough to wear pump bowls and shorten equipment life. In an open borehole well there is no screen or gravel pack: the water enters through the rock face itself, and the plugging develops in the fractures and pores of the near-wellbore zone, where surface cleaning methods cannot reach.

The treatment

The rehabilitation was staged, and honestly reported here as it was performed:

1. Downhole video survey and diagnostics to map the producing intervals and confirm mechanical condition.
2. Block-shot treatment of selected intervals, followed by bailing to total depth.
3. AirShock® rehabilitation of the producing intervals across roughly 550–1,500 ft, using 6" and 8" air impulse generators at 1,900–3,000 psi — pressure stepped to the well's response. 82.5 total hours of impulse treatment.
4. Bailing to total depth, then development by pumping and surging, with a final step-drawdown performance test.

A deep municipal rehabilitation is a staged engineering project, not a single visit — and the impulse phase is planned around the well's own producing intervals, not run blindly top to bottom.

The result

Post-treatment testing at over 2,400 GPM ran clear with only a very slight trace of sand. The permanent pumping assembly was reinstalled and passing bacteriological samples were obtained before return to service.

The sand result deserves the emphasis: impulse treatment did not just restore capacity — it reduced sand production. By cleaning fines out of the near-wellbore zone in a controlled way during treatment and development, the material that would otherwise have been pumped out slowly through the bowls (wearing them as it went) was removed deliberately, up front.

Why it matters

Deep open-borehole sandstone wells are among the hardest rehabilitation cases: the plugging is in the rock itself, the depths put high hydrostatic pressure above the tool, and sand production threatens the pumping equipment even when yield is acceptable. This case shows the pattern a utility should expect from a properly staged rehabilitation — diagnostics first, energy methods matched to the intervals, controlled development after — and the two numbers that define success: restored specific capacity, and sand at less than 1 ppm.

Results depend on well construction, geology, degree and type of plugging, and correct system configuration. Every recommendation begins with the well's records and test data.