Cementing is a critical process in oil and gas well construction. But how do you assess the quality and seal of the cement job? That’s where cement bond evaluation and integrity logs come in. If you’re involved in drilling operations, it’s key to understand these tests. Here’s your guide to everything you need to know about cement bond integrity.
Why Cement Bond Integrity Matters
Properly cemented well casings are vital for safe, efficient drilling. Cement provides structural integrity to the wellbore and zonal isolation between formations. It also protects the casing from corrosion. Poor cement bonding can lead to leaks, instability, and other major issues. That’s why cement evaluations are so important.
When To Perform Evaluations?
Before you move on to the Evaluation processes, Please make sure to visit some online blog articles to know better about performing such tasks. Top A Mag can help in this regards.Cement bond logs (CBLs) should be run after each cementing stage, as well as later in the life of the well. Immediate CBLs verify the integrity of the initial bond. Later tests check for issues like bonded casing failure. Most operators perform CBLs on surface, intermediate, and production casings.
Different Evaluation Methods
There are several techniques for evaluating cement integrity:
- Cement Bond Logs – the most common acoustic method using a sonic tool.
- Ultrasonic Imager Tools – newer technology using ultrasonic imaging.
- Temperature Logs – identify irregular cooling that indicates voids.
- Radial Bond Tools – uses a radioactive source.
Each has pros and cons to consider. Work with your wireline provider to determine the best method for each situation.
Log Components
A typical cement bond log has two curves – the amplitude curve and variable density log (VDL) curve. The amplitude shows bond strength based on sound dampening. The VDL provides a visual reference to depth. The analysis combines these elements.
Interpreting Results
Understanding cement bond log results is key. The ideal log shows consistent full bonding. But there are several responses that can indicate problems:
- Little or no bonding – free pipe, micro annuli, voids.
- Poor bonding – channels, poor cement.
- Gas cut mud contaminated cement.
- Casing collars.
- Shoulder beds indicate partial bonding.
Remedial Actions
If a CBL indicates poor bonding, remedial cementing is required to achieve zonal isolation. Common solutions include:
- Squeeze cementing – pumping cement through perforations.
- Plugback and abandonment – plugging a bad section.
- Stage cementing – re-cementing problem zones.
The specific remedy depends on the situation. A CBL provides critical data to determine the best path forward.
Factors that Affect Integrity
Many variables impact cement bonding and quality:
- Casing centralization and pipe standoff.
- Hole stability and mud conditioning.
- Cement slurry design and placement.
- Waiting-on-cement time.
- Fluid loss control.
- Cement curing conditions.
Advanced Evaluation Technologies
New techniques are enhancing cement evaluation:
- Digital CBLs provide clearer data on acoustic impedance.
- 3D radial CBLs give 360-degree imaging.
- Ultrasonic imaging tools can “see through the casing.”
- Casing corrosion tools detect unseen issues.
Partnering with Experts
Cement evaluation requires specialized tools and expert analysis. Work closely with your wireline provider’s cement bond logging specialists to deploy the right solutions and interpret results accurately. Their insights can save time and money while optimizing cementing programs.
Cement bond log data provides invaluable information on the integrity of wellbores. Understand these concepts, tests, and methods to optimize cementing operations, reduce risks, and remedy issues. With a sound cement bond evaluation program, such as those offered by Renegade Wireline, you’ll have confidence in your wells from spud to abandonment.
