What is CBL VDL log?

What is CBL VDL log?

Cement bond logs (CBL) and variable density log (VDL) are one of the vital logging techniques used to evaluate cement-casing-formation bonds before the well testing or execution of the production operation in the well. These logs are also crucial during the workover operation to maintain the integrity of the well.

What does CBL measure?

They indicate how good the cement bond is. A cement bond log (CBL) documents an evaluation of the integrity of cement job performed on an oil well. It is basically a sonic tool which is run on wireline. Similar to a ringing bell, when no cement is bonded to the casing, pipe is free to vibrate (loud sound).

What is the purpose of a cement bond log?

A cement bond log documents the evaluation of the integrity of cement work performed on an oil well. In the process of drilling and completing a well, cement is injected through the wellbore and rises up the annulus between the steel casing and the formation.

What is VDL in drilling?

VDL is the top view of the cut away of upper part of acoustic wave that represents how cement bond from casing to wellbore. Caliper: Caliper measures wellbore diameter.

What is CBL construction?

A cement bond log (CBL) is a means to determine the integrity and quality of a cement bond.

What is a good VLDL cholesterol level?

Normal VLDL cholesterol level is between 2 and 30 mg/dL. Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results. The examples above show the common measurements for results for these tests.

What is VDL in blood test?

Very-low-density lipoprotein (VLDL) cholesterol is produced in the liver and released into the bloodstream to supply body tissues with a type of fat (triglycerides). There are several types of cholesterol, each made up of lipoproteins and fats.

How does a CBL-VDL log work?

When the casing is bonded to hard cement, casing vibrations are attenuated proportionally to bonded surface. The basic tool configuration of CBL-VDL log is composed by One Transmitter and Two Receivers: the first Receiver is located 3 ft. from the Transmitter and is used for CBL Measurement.

What is the difference between CBL/VDL and ultrasonic logs?

In the ultrasonic log, because all gaps and cracks are filled with fluid, the image is erratic or patchy with intermittent highs and lows acoustic impedance; the average, however, will be closer to good cement value. In b) the setting process is delayed showing a similar pattern to 3) and 4) in the CBL/VDL and ultrasonic logs.

How does the amplitude affect the CBL log?

It would affect the CBL log with amplitude values ranging 10 to 30 mV, but lower than free-pipe value. In ultrasonic logs, it would appear as areas/spots with lower acoustic impedance values. A cement log is only a snapshot.

What is variable density log (VDL)?

The wave train can be displayed as a Variable Density Log (VDL) where the positive and negative cycles of the wave train are shaded black and white respecticvely. CEMENT BOND LOG INTERPERTATION MODELS: 1) GOOD CEMENT · “Amplitude” low. · “VDL” formation signals are strong.