Although horizontal filter wells are often chosen for their stable water quality and high yields, they can still suffer from a decline in performance when solids migrate into the filter zone. At the Moers ‘Vinn’ well (commissioned in 1979), the operator reported only minor ochre deposition due to low levels of iron and manganese. However, the main issue was sand intrusion and deposits of silt and fine sand on the screens and within the gravel pack. As the well was conventionally developed during construction, it had not undergone a deep-acting development using the High Pressure Impulse Process®, leaving the system more susceptible to persistent solids accumulation.
For the scheduled mechanical rehabilitation in 2013, the operator, ENNI, cooperated with Robert Plängsken GmbH and Etschel Brunnenservice GmbH, who are HPI-Process® specialists aligned with DVGW W 130 requirements. A key operational constraint was assembling the equipment in the drained well shaft without divers, enabling each of the seven star-shaped horizontal strings to be assessed separately for yield, condition and solids transport. This approach also limited the settling of mobilised solids in the conveying shaft, reducing the effort required for cleaning and disinfection.
In order to fulfil the DVGW requirement of ‘separating, discharging and measuring simultaneously’, a bespoke pipeline design was employed to enable inspection cameras and HPI equipment to be moved into each string, while ensuring the simultaneous pumping of loosened material. The rehabilitation process employed Etschel JET Master® technology featuring high-pressure water nozzles, including a rotating nozzle head (the UNINOZ® system, referenced in the results section), which transmitted pressure impulses through the screen into the gravel pack and the adjacent formation.
Post-rehabilitation documentation confirmed that the discharged material consisted primarily of fine sand and silt, indicating mobilisation from the annular space and the surrounding geology. The report notes that, given the site conditions and gravel-pack dimensioning, the project did not target a ‘technically sand-free’ condition as a termination criterion. Instead, rehabilitation continued until the removal of discharged solids could no longer be achieved. A final comparison of drawdown and operating water levels quantified performance improvements: strings 1, 6 and 7 increased by up to 50%, and a final pumping test showed a 21% increase in specific capacity versus pre-rehabilitation values. The entire job was completed within 14 days, minimising downtime for a highly productive well.
For more detailed information, please click on the PDF button to read the full technical report.
If you wish to evaluate rehabilitation options for your well field, whether due to performance decline, sanding or redevelopment planning, Etschel Brunnenservice GmbH can support you as an experienced specialist in HPI-based well development and rehabilitation. Contact us with your questions to discuss feasibility, process design and documentation strategy.
