Losing annular integrity is one of the most dangerous and potentially damaging types of well failure. Contaminated ground water and annular blowouts at surface are among the most feared potential outcomes. Despite advances in cementing, unwanted annular flow and sustained annulus pressure due to poor cement sealing is a prevailing concern for many operators. Diagnosing tubing and casing thickness condition can catch the early signs of corrosion, with implementation of remedial action to ensure annular integrity at an effective cost.
The MID/S4 is primarily run through tubing, with the ability to simultaneously inspect the tubing and the casing strings behind it. The MID/S4 combines twin centralisers, an internal gamma ray sensor, a temperature probe and two axial coils in order to measure casing corrosion and defects up to the 4th string.
Using a pulsed eddy current technique with increased pulse duration and recording times a depth of investigation of 20” is achieved with a total metal thickness evaluation limit of 1.9”.
|Outside diameter, in [mm]||1 11/16 |
|Length, in [cm] (with Centralizers)||144.5 [367.2]|
|Weight, lb [kg]||30.8 |
|Maximum pressure, psi [MPa]||14,500 |
|Maximum temperature, DegF [DegC]||350 |
|Maximum Depth of Investigation, in [mm]||20 |
|Maximum combined wall thickness, in [mm]||1.90 [48.3]|
|Measurement Accuracy of 1st / 2nd / 3rd / 4th Strings||5%/10%/15%/20% of nominal wall thickness|
|Defect ‘crack’ resolution detection along pipe axis|
|1st / 2nd / 3rd / 4th Strings||11% / 25% / 33% / 50% of the perimeter|
|Defect ‘transversal crack’ minimum length required for detection||16.7% of the perimeter|
|Recommended logging speed, ft/min [m/min]||10-15 [3-4.5]|
|Logging mode||Real time|
|Fluid||Water, brine, production fluid|
|Minimum casing size, in [mm]||2.5 [63.5]|
|Maximum casing size, in [mm]||18 5/8 |