Confirm Cement Integrity Without Zonal Isolation Test

Published: 01/01/2009

Blue hero texture

Fast formations hindering logging

A Canadian operator could not reliably interpret conventional CBLs because of the fast formations near TD. Pulse-echo ultrasonic logs also underestimated the cement in comparison with the results of zonal isolation tests. As a result, the operator was spending USD 200,000 per well conducting zonal isolation tests to confirm the integrity of the cement job.

Evaluating cement in any well environment

By combining classic pulse-echo technology with a new ultrasonic technique—flexural wave imaging—Isolation Scanner cement evaluation service defines the annular material with greater certainty. Low-density solids are readily discriminated from liquids to identify lightweight cements as solids. The azimuthal coverage provides answers around the entire circumference of the casing, determining hydraulic isolation and pinpointing any channels.

Confirming isolation

Isolation Scanner solid-liquid-gas (SLG) maps identified the material in the annulus as solid cement, which in some places had been identified as liquid on conventional acoustic impedance maps. The operator conducted isolation tests to confirm the Isolation Scanner results in 20 intervals within 4 wells. The Isolation Scanner evaluation correctly predicted the test results in 19 of the 20 intervals, with the one conflicting interval identified as lacking isolation whereas the test found isolation over the interval.

Graphic: Confirm Cement Integrity Without Zonal Isolation Test
Isolation Scanner toolstring with subs for logging casing sizes from 41⁄2 in to 95⁄8 in
Graph: Confirm Cement Integrity Without Zonal Isolation Test
The conventional ultrasonic log underestimated the cement, but Isolation Scanner cement evaluation service correctly identified the annular material as solid cement, which was confirmed by zonal isolation tests.

Challenge: Determine cement integrity for deviated wells in fast formations where conventional cement bond logs (CBLs) are inconclusive.

Solution: Conclusively evaluate annulus materials and bond quality by using Isolation Scanner cement evaluation service instead of spending extra time and costs on zonal isolation tests.

Results: Definitively identified well-bonded cement, as confirmed by an isolation test.

Products Used