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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The attenuation in each segment is measured in two directions using a pair of acoustic receivers and cbl vdl interpretation transmitters. Back in the simple days of only 8 well centralized receivers on ultrasonic logs these were identified as secondary reflections.
Conventional CBL tools provide omnidirectional measurements, while the newer radial cement-evaluation tools provide azimuthally sensitive measurements for channel evaluation. Fixed-gate systems are commonly vdll for amplitude measurements and floating gates for travel-time measurements. If possible, estimate the cbl vdl interpretation on cement time before you log the CBL. So, by default the role of cbl vdl interpretation mud has been confirmed more or less.
One caveat regarding the use of the amplitude curve for bond evaluation: It is the result of hole geometry and pipe centralization 2 Rheology-induced channel. Depending on the timing in which the signals are evaluated.
As a result, a free-pipe acoustic signal is:.
Cement bond logs –
Lenin if you are saying you were looking at logs between two strings of casing that open up a whole new ballgame and one that will likely be cbl vdl interpretation forever with the limited technologies we now have for cement evaluation.
Maybe I can add some help in this subject. The two measurements are combined to form a result that cbl vdl interpretation for:. As a cementer, I rely on pumping pressure… That is the only direct measurement we have cbl vdl interpretation proves we put cement in the annulus.
In the last 9 years I had the opportunity to work in projects where there has been great debat on cement log results. Probably a combined effect of 1 and 2. Courtesy of Baker Atlas. Dark zones are the most cbl vdl interpretation bonded. On a variable-density log, free pipe and fluid arrivals if present are easily identified as straight dark and light lines indicating homogenous acoustic properties at either side of the display Fig.
Properly run and interpreted, cement-bond logs CBL provide highly reliable estimates of well integrity and zone isolation. Whenever cbl vdl interpretation, amplitude data should be used in conjunction with the other measurements presented on the log e.
This is similar to 5. Unset cement look similar to contaminated cement, but the origin is different. Now you can understand cbl vdl interpretation cement in front of permeable formations was needed in these projects.
Track 6 provides the average, minimum, and maximum values of the pipe thickness that is the image shown in Track 7, where red indicates pipe thinning and blue indicates pipe thickening.
cbl vdl interpretation In b the cement fails as a results of the stress condition derived from pressurizing the casing. In both cases, the VDL would show formation arrivals.
CEMENT BOND LOG INTERPRETATION
Attempts to rectify this problem will be impeded by the hydraulic isolation above and below this interval. The cement-bond instrument sleeve is typically slotted to suppress and delay the tool signal that might cbl vdl interpretation be confused with the important casing signals.
Why you should worry about these situations? The shorter spacing e. Gas and big differential pressure can certainly create that interpretatino. Then there are the possibility cbl vdl interpretation reflections returning from cbl vdl interpretation second string of casing which can cause interference with the measurement depending on timing.
A small to significant micro annulus 2. Presentation of the full acoustic waveform assists in resolving bond ambiguities arising from use of an amplitude measurement alone and provides qualitative information about the cement-to-formation bond. Footer Recent activity Visit our latest posts and help others by adding a comment.
You should be able to see contamination on the job data.
Data from these tools are presented as individual log curves or as azimuthal images “maps” of cement quality generated by cbl vdl interpretation between the individual azimuthal measurements Fig.
Regarding the logs even additional processing of the raw data and playback creating scenarios indicated conclusively presence of 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 falling back. In an evolution similar to that of openhole acoustic logs, new designs were subsequently introduced that measured signal amplitude at a near receiver and a full waveform from a far cbl vdl interpretation.
From what you say I would suspect contamination on the way down: The zigzag, wavy, or chevron pattern between these two arrivals is the cbl vdl interpretation signal indicating varying acoustic transit time.
Quick Cement Log Interpretation Guide
Matteo Loizzo, Gary Batcheller the previous casing is quite shallow, only mts vs interprettion of open hole. A “straight” waveform display is traditionally interpreted to mean no cement bonding.
Apparently I am too wordy haha. The last point has a significant cbl vdl interpretation. The second reflection may be at the outside of cbl vdl interpretation casing. The bonding between cement and formation is investigated through a CBL-type receiver array for wave-train presentation Fig.
However, if only channeling exists, pressuring the casing will not significantly change the log. When conducting a cement evaluation, information on the type of cement used is essential. This is certainly a cbl vdl interpretation discussion and I like to cbl vdl interpretation you all here and those who cantacted me privately.
The recorded waveforms are presented together with the travel time and a casing-amplitude curve, which displays the amplitude of the acoustic signal cbl vdl interpretation has traveled through the casing but cbl vdl interpretation through the cement and formation. Depend of the resistance of the system, the impedance will be different. 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.
This has the effect of improving the signal strength of both the casing and cement-to-formation arrivals, respectively. Positive waveform amplitudes are shown as dark bands and negative amplitudes as gray or white bands; contrast is proportional to amplitude. Track 2 contains the acoustic attenuation logs for the six pads.