What is Multi-finger Caliper (24 finger) Log?

The Multi-finger Caliper (24 finger) is a professional logging device used to detect the geometric shape changes of the inner walls of downhole casing or tubing. It achieves high-resolution and all-round measurement of the inner diameter of the casing through 24 independent mechanical detection arms (or "fingers") evenly distributed around the instrument's circumference, and generates an inner diameter imaging map to evaluate the deformation, corrosion, cracks, misalignment and other damage conditions of the casing.

In short, this is a logging technology used to perform a "CT scan" on the wellbore or casing. It is not merely about measuring an average diameter, but rather obtaining radius values in 24 directions at each depth point, thereby precisely depicting the actual shape and size of the cross-section at that depth.

◆ Measurement information–Records radius in up to 24 directions to reconstruct the full cross-sectional profile.

◆ Data output–24 radius curves, cross-sectional images, and derived curves such as max/min diameter, average diameter, and eccentricity.

◆ Detection capability–It can accurately identify complex damages such as elliptical deformation, bending, local depressions/protrusions, corrosion pits, perforations and cracks of the casing.

◆ Application–Advanced, high-precision tool dedicated to detailed casing-integrity evaluation and advanced engineering analysis.

 

A-One Oil Multi-finger Caliper (24 finger)

 

The core purpose of Multi-finger Caliper (24 finger) is "diagnosis", which is mainly applied to casing wells to solve the following key problems:

Evaluate Mechanical Damage & Deformation of Casing
◆ Detect ovality / bending– Accurately compute casing ovality (ratio of major to minor axes) to determine whether squeezing or deformation has occurred due to formation creep, salt/gypsum-layer extrusion, or operational incidents.
◆ Locate & quantify local damage–Identify and measure depth, length, and azimuth of pits, grooves, or holes caused by perforating, tool drag, or corrosion.
◆ Monitor damage evolution–Run logs at different times and compare results to track progression of damage such as corrosion.

Evaluate Perforation Quality

Evaluate whether the shape and size of the perforation holes meet the design requirements.

Check the perforated interval for any unintended casing deformation or fractures induced by the perforating operation.

Provide Key Input for Workover & Stimulation Operations
◆ Before running casing patches, milling, sidetracking, or fishing assemblies, obtain the exact ID and deformation profile to guarantee tool passage.

◆ Evaluate whether it is suitable to carry out fracturing, acidification and other stimulation measures, and determine whether the casing strength is sufficient.

Support Other Log Interpretations
◆ Supply accurate casing-geometry data for cement-bond evaluation (e.g., sector-bond logs), because casing shape strongly influences acoustic measurements.

◆ Combined with the results of the electromagnetic thickness tool, it is possible to comprehensively determine whether the damage is caused by external compression (significant change in well diameter) or internal corrosion (thinning of wall thickness but possible little change in well diameter).

◆ High resolution–24-Fingers provide full-360° coverage with minimal inter-arm spacing, resolving millimeter-scale changes.

◆ All-round measurement–It can detect local small-scale damage and avoid missed detection.

◆ Intuitive imaging– Three-dimensional images facilitate engineers to quickly determine the type and severity of problems.

◆ Well-adapted–It can be applied to various pipe diameters such as oil pipes and casing pipes, and is suitable for inclined shafts in combination with centralizers.

The Multi-finger Caliper (24 finger) is a state-of-the-art casing-damage evaluation tool. Through combining high-density mechanical fingers, precision displacement sensors, and imaging processing, it delivers full-coverage, high-resolution measurements of the inner casing wall. Its purpose is to detect and quantify any casing impairment in real time, furnishing the critical data needed for safe and efficient field development. Moving far beyond simple diameter readings, the tool provides a 3-D, visual diagnosis of casing geometric health-an indispensable technology for managing mature assets, geologically complex reservoirs, and any downhole intervention campaign.

Welcome to contact us to learn more about our tools via e-mail info@a-oneoil.com