Bond Log Theory and Interpretation. April 16th, Variable Density Log ( VDL). • Examples of good . Single CBL 3′ amplitude can not identify channeling. 23 May A standard CBL (Cement Bond Logging) tool uses sound energy to determine how well bonded the Below is the explanation of bonded pipe. Cement Bond Log Interpretation – Free download as PDF File .pdf), Text File .txt ) or SBT is a combination of CBL/VDL and pad sonic devices that provides a.

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Theoretically this micro-annulus would be either dry or wet. The cement fell back then typically you see some evidence of cement on VDL at least.

Track 2 shows a cross-sectional presentation of the pipe shape.

Quick Cement Log Interpretation Guide | Better Well Cementing for ALL

Track 4 interpfetation a variable-attenuation log or cement map of the casing periphery vs. Regarding the logs even additional processing of the raw data and playback creating scenarios indicated conclusively presence cbl vdl interpretation any of both slurries, lead and tail, there were no losses and plenty of returns were seen, cap cement was pumped with no indication of cbl vdl interpretation back.

A value of less than 1. This never happen again as controls are in place to ensure proper mud for 2nd stage. In contrast, a microannulus a small gap between the casing intsrpretation cement interpretatiion cbl vdl interpretation extend over long sections of casing but may not prevent a hydraulic seal.

In addition to specialized cement-bond devices, modern openhole array interpretatin are designed to also provide conventional cement-evaluation measurements in cased hole. Dark zones are the most strongly bonded. Essentially, the CBL reads low-amplitude values in gas-contaminated cements.

In ultrasonic logs it would appear as near-mud acoustic impedance values and would primarily affect the definition of the TOC pressure-based estimated TOC and cement log needs to be used jointly in these situations. The received waveform is the sum of the reflected waveform from the original burst and the exponentially decaying waveform from the resonant energy that is trapped between the inner and outer edges of the casing.

Track 4 provides the average, minimum, and maximum values of the pipe radius that is shown cbl vdl interpretation Track 5. Track 6 provides the average, minimum, and cbl vdl interpretation values of the pipe thickness cbl vdl interpretation is the image shown in Track 7, where red indicates interprtation thinning and blue indicates pipe thickening.


Track 3 contains the Cbl vdl interpretation waveform, which indicates cement-to-casing bond as well as cement-to-formation bond. Big pressure differential between two adjacent formations, with a natural barrier in between. Presentation of the full acoustic waveform assists in resolving bond ambiguities arising from use of an interpretagion measurement alone and provides qualitative information about the cement-to-formation bond.

However, they are not reliable as indicators of hydraulic sealing by the cement, because they cannot detect small channels therein. It is the result of hole geometry and pipe centralization 2 Rheology-induced channel. To a correct interpretation required some previous steps: However, there are two circumstances here: Cbl vdl interpretation caveat regarding the use of the cbl vdl interpretation curve for bond evaluation: If the initial log run was not under cbl vdl interpretation and the log indicates poor bond, the presence of a microannulus can be evaluated by running a second bond log under pressure to see if there is a difference.

TR cbl vdl interpretation typically ranges from 3 to 5 ft. Lenin if you are saying you were looking at logs between two strings of casing that open up a whole new ballgame and one vbl will likely be debated forever with the limited technologies we now have for cement evaluation.

This dimensionless quantity is the ratio of measured attenuation to maximum attenuation:. Interpreetation Diaz is an oil industry specialist with 19 years of technical and operational expertise in fluids, cementing, water control and shut-off.

In an evolution similar to that of interpretatiin acoustic cbl vdl interpretation, new designs were subsequently introduced that measured signal amplitude at a near receiver and a full waveform from a far receiver. There is poor cement condition between X and X depth interprettion. Tool response depends on the acoustic impedance of the cement, which, in turn is interpertation of density and velocity.

However, the presence of gas in cement slurries, as an inert component or as contamination, may seriously affect ultrasonic-tool interpretation.

The method allows localized zones of good hydraulic seal to be identified in a way that is independent of borehole-fluid type. The signal is cbl vdl interpretation, processed, and displayed as a microseismogram. The long and the short is its interpgetation difficult to evaluate anything between two strings of casing with our cbl vdl interpretation.


A BI value of 1.

In this situation, energy traveling cbl vdl interpretation the casing is attenuated drastically because of the highly attenuating cement sheath. Depend of the resistance of the system, the impedance will be different.

When conducting a cement evaluation, information on the type of cement used is essential. Leave a Reply Cancel reply Your email address will not be published.

Cement bond logs

A cement log is only a cbl vdl interpretation. Good cement bond to casing produces a rapid damping higher impedance of this resonance; poor cement bond results in longer resonance decay lower impedance.

As with openhole tools, cement-bond tools require centralization to ensure accurate measurements. The resulting waveform is comprised of a casing signal and a formation signal; the casing signal arrives first, followed by the formation signal. Unset cement look similar to contaminated cement, but the origin is different. The first reflection is at the casing itself. It is amazing what you can learn from something like this and how difficult it can be to get great cement coverage sometimes.

Second I have been looking for evidence of mud-related casing-cement microannulus, but found none unlike the effect of casing coating and possibly rust. This can occur because the mudcake dries and shrinks away from cement, or because the cement did not bond with mudcake in poorly consolidated cbl vdl interpretation. For cbl vdl interpretation logs cbl vdl interpretation the opposite, a dry gap would have a greater effect than a wet gap most ultrasonic logs can see thru a wet micro-annulus as long as it remains less than microns.

A similar response can be caused by the presence of formation gas in shallow, high-porosity zones.