A Comparison of Cementation Logging Tools in a Full-Scale Simulator

Abstract

Acoustic cementation logging tools have been run in a full-scale cement flow loop and the logs compared to a physical examination of the cement in the annulus. In the flow loop the complete cycle of cementing operations -mud and spacer circulation, and cement placement -was carried out. The flow loop included artificial formation and double string sections.Three tools were used in the flow loop: a sonic tool and two ultrasonic pulse-echo tools. The sonic tool measures the attenuation of sonic waves along the casing and is sensitive to shear coupling between casing and cement. The ultrasonic tools measure the damping of a thickness-mode resonance and the acoustic impedance. One ultrasonic tool samples every 45 degrees in azimuth; the other provides complete coverage using a rotating probe.Conditions such as channeling, good and contaminated cement, mud and water were created in the flow loop. The logs were consistent with the subsequent physical examination, within the resolution limits of each tool. Very thin annulus and highly contaminated cement posed interpretation problems. Of the tools investigated, the rotating ultrasonic tool provided the most accurate predictions of cement distribution and quality.The results illustrate the advantages and limitations of the different types of tools, and will be a useful aid in the interpretation of cementation logs.

Ultrasonic Well Integrity Logging Using Phased Array Technology

“…We have processed the waveforms similarly to the T 3 pro-cessing algorithm [2,29] to derive the estimated impedance 𝑍 𝐴 behind the plate (Fig. 5b) from the group delay curve of the measured signals.…”

“…5b) from the group delay curve of the measured signals. We have modified this impedance using a linear trend as in [2], normalised to the values for air and water with normal incidence, respectively. This is a fair first approximation according to our experience.…”

“…Here, 'single element' refers to transducers with only one active element. In cased-hole logging, waves are typically transmitted through the borehole fluid into the surrounding pipe and the responses are recorded [1][2][3][4][5]. The obtained signals can be used to reconstruct the pipe thickness, if any damage has occurred to the pipes by drill bits, and whether cement is sufficiently bonded to the outside of the innermost pipe.…”

A calculation approach for acoustic impedance and time-of-flight of an embedded elastic thin layer by ultrasound

“…Taking the cased well in acoustic logging [4] for instance, we investigate error functions for equations (2.5) as shown in figures 2(a)-(c). Acoustic and geometrical parameters of the constituent materials are listed in table 1.…”

“…In the actual applications, for a thin layer the thickness-to-wavelength ratio usually satisfies h/λ < 2.5 = 3 [1]. Various ultrasonic technologies including acoustic microscopy, ultrasonic spectroscopy and Lame waves technique have been developed for the determination of acoustic and geometrical properties of the thin layer [1][2][3][4][5][6][7][8][9][10][11].…”