Water Well inspections using wireline geophysical techniques

June 22, 2026

The Situation

Wellington Water are currently assessing their aging well-fields that provide drinking water across the city of Wellington. As part of this assessment, Geophysics Ltd was asked to undertake an internal condition assessment on a number of its water wells using a variety of wireline geophysical techniques.

Figure 1 - Aerial view of Water Well Scanning operation.

Technical Approach

Geophysics Ltd deployed a variety of wireline tools (typically used in the Geotechnical and Mining industries) that provided depth accurate, repeatable, digital and physical measurements inside the wells.

These included;

· Acoustic Televiewer deployment using a special “Very Large Bore” ALT ABI tool

· Optical Televiewer including UV.

· Downhole 360° camera (DGRT)

· Fluid Temperature and Conductivity

· Mechanical Calliper

· A 500 m Mount Sopris Wireline Winch.

To undertake the well condition assessments, all well pumps, stuffing boxes and top hat’s / casing lids were removed by crane. Once the water well was cleared, wireline geophysical logging could take place using a sheave block suspended off the crane.

Large specialised centralisers were installed on all tooling to ensure all imagery data was well centralised within the water well’s (which had a diameter of 800-950 mm).

Figure 2 - Large specialised centralisers for the televiewer probes.

Utilising these advanced probes provided insight into the condition of these water wells, including;

· Fluid conductivity

· Screen quality assessments

· Metal loss

· Casing thickness

· Verification of construction records

No other tooling bar physically removing and inspecting the Water Well casing would be able to provide such an accurate and comprehensive assessment of casing condition.

Figure 3 – Screen Join as observed on the downhole camera and optical & acoustic televiewer imagery.

Outcomes

A comprehensive, high resolution data-set was able to be collected with clear depth and casing integrity information.

Defects within the water wells were able be to be identified with a mm accuracy using predominantly the 360° acoustic and optical televiewers, with a typical vertical sample interval of 1-2 mm.

J-latches, casing joins and screen condition were able to be assessed for condition based on age, and casing separations observed could be highlighted.

Calcific build-up was also observed on the well wall. Using the acoustic calliper measurements, the thickness of the build-up was able to be calculated, with some being upto 60 mm thick! These areas highlighted to the client the areas that required to be scrubbed.

Figure 4- Calcific concretions as seen on both the downhole camera and the optical & acoustic televiewer (with apparent metal loss)

Apparent metal loss was calculated from the inside of the well using the acoustic calliper data. This is particularly useful information for the client to allow them to make an informed decision on condition of the well as it reaches its operational end life.

Summary

Using wireline geophysical tooling outside of their usual environment (in this case to inspect existing assets) can provide essential information to help key utility providers to monitor and manage their ageing assets.

Applying this advanced technology provides far greater in-sight into water well inspections in comparison to a standard camera survey.

As population growth places increasing pressure on water resource infrastructure, extending the service life of water wells is becoming more important than ever. Wireline geophysical surveying plays a key role in this process, providing critical information on well condition and integrity to support effective asset management and long-term water security.