Tests of the HEPP tool on pipes and plates coated with scale, chemical encrustation, and marine life have demonstrated significant removal of fouling without damaging the underlying pipe and structures.
A field test was performed in May 2006 on an existing well located on the Mohave Resort Golf Course property in Laughlin, Nev. Since the 133-foot-deep, 18-inch-diameter well was drilled in 1997, the flow had decreased to 250 gallons per minute (gpm) from 1,000 gpm. Conventional acid and brushing treatments had increased the flow to 650 gpm, but a significant problem remained with the pumping level, which at 115 feet was almost to the bottom of the screens. The HEPP test was to be the last effort before drilling another well.
Because of the age of the well and mild-steel construction of the spiral screens, the HEPP device was operated at the low power levels that had been successful for the 10-inch test pipe. The flow rose to 775 gpm and the pumping level near the top of the screens to 94 feet. This single application dramatically improved the specific yield of the well and prevented its abandonment.
In addition, restoration of the pumping level to its original level reduced electrical costs for pumping. Eighteen months after the first treatment, Mohave reported data confirming that the treated well had maintained the same level of performance. This period included a summer of extreme heat during which the pumps ran 24 hours for six days a week without any pump letdown.
This test also confirmed the HEPP process did not force the debris and fouling into the well formation or cause damage to the gravel pack. This concern was the reason other impulse shock-wave generation methods were rejected for this application.
— Ayers is technical director of Advanced Conversion Technologies Inc. (ACTIX), Spring Valley, Calif.; Vivona is senior project manager with Jacobs Engineering Group Inc., Houston.Water well treatment capabilities
Performance standards for commercial-use HEPP tools fall into four categories.PRODUCTION CAPACITY
- Well-specific capacity returned to 90% of original
- Well flow rate returned to original
- Maintain above levels for a period of not less than one year.VISUAL INSPECTION
- All scale removed from the perforations and casings
- No structural damage to the well.WATER QUALITY
- All water quality, including bacteriological, returned to background quality
- Disinfection behind the screens
- No sand production above American Water Works Association standards
- Water quality parameters sustained for a period of not less than one year.OPERATIONAL PERFORMANCE
- Depths of up to 1,500 feet and diameter of 10 inches or more
- Ability to run on any 240 VAC, single-phase, 20-amp output generator or power source
- Treatment rate of 1 foot/four seconds
- Ability to adjust power levels via topside controls
- Telemetry and controls provided via separate wire line
- In-situ debris cleaning during treatment
- Ability to mount camera forward of spark head.