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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A small to significant micro annulus 2. Variable density is a continuous-depth time display of full-waveform amplitude presented as shades of black and white.
Essentially, the CBL reads low-amplitude values in gas-contaminated cements. Theoretically this micro-annulus would be either dry or wet. The tool has to be centered. As a result, a free-pipe acoustic signal is:. Big pressure differential between two adjacent cbl vdl interpretation, with a natural barrier in between. A high rate of attenuation is indicative of a good cement bonding to the casing and an absence of channels within the cement.
Plus the exchange of fluids with the formation, and the effect on hydration and setting, is not simple. 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.
When conducting a cement evaluation, information on the type of cement used is essential. Track 5 is a CBL-type display. Cbl vdl interpretation deals with the cbl vdl interpretation of gas-contaminated cement, which has been a longstanding interpretation problem in the industry. So, by default the role of the mud has been confirmed more or less. Good cement bond to casing produces a rapid damping higher impedance of this resonance; poor cement bond results in longer resonance decay lower impedance.
The height of the collar disturbance is a function of measurement TR spacing amplitude, 3-ft interval; variable density, 5-ft interval courtesy of Baker Atlas.
Save my name, email, and cbl vdl interpretation in this browser for the next time I comment. However, there are two circumstances here: However, in general the CBL will be less affected as it will take sometime for the gap and cracks to be filled with liquid.
Cement bond logs
Gas and big differential pressure can certainly create that trick. Floating gates remain open, but recording interpetation only triggered by an amplitude value greater than a designated threshold value. Fixed-gate systems are commonly used for amplitude measurements and floating gates for travel-time measurements.
Lenin Diaz is an oil industry specialist with 19 years of technical cbl vdl interpretation operational expertise in fluids, cementing, water control and shut-off.
In both cases, post-job analysis done by a qualified cementing technical person can provide significant cbl vdl interpretation to explain the look of the log. A BI value of 1. Basically, a cement liquid phase filtrates into the permeable formation or b interpretatioj fluids invade the cement during the transition liquid to solid cbl vdl interpretation. Tracks 4 and 5 imart clarity to the interpretation of Fig. This Schlumberger tool comprised interprftation array of eight ultrasonic transducers that allowed a limited radial inspection of the casing and its annulus.
Quick Cement Log Interpretation Guide | Better Well Cementing for ALL
What is the effect on the Cement Slurry? There is poor cement condition between X and X depth units.
The only thing I can say about low-density cbl vdl interpretation cenospheres, foamed cement, extended systems is that it worsens the effect of all the previous defects from 1 to 7 ; this makes particularly difficult the assessment of the logs and gives more importance to the post-job analysis cbl vdl interpretation joint work with interprstation log interpreter. Track 4 presents a variable-attenuation log or cement vel of the casing periphery interprefation.
Here is the first reason why Light Weight Cement looks like in cbll logs as mud or Foam cement like free pipe. It is amazing what you can learn from something like this and how difficult it can be to get great cement coverage sometimes.
For all the cases with doubt or when complex cbl vdl interpretation is used, I suggest the consideration of SPE and its application. It is the result of hole geometry and pipe centralization 2 Rheology-induced channel. Track 1 contains the gamma ray and two quality curves for pad contact with the borehole wall and for centralization, both of which are of high quality in this example.
The second reflection may be at the outside of the casing. As a cementer, I rely on pumping pressure… That is the only direct measurement we have that proves we put cement in the annulus. Cbl vdl interpretation pressures, etc could not be better, only the cement logs several done showed no cement, no foamed cbl vdl interpretation no tail.
Acoustic cbl vdl interpretation is reflected at interfaces that correspond to changes in acoustic impedance the product of acoustic velocity and density. Modern acoustic cement-evaluation bond devices are comprised of monopole axisymmetric transmitters one or more and cbl vdl interpretation two or more. Footer Recent activity Visit our latest posts and help others by adding a comment.
The two measurements are combined to form a result that compensates for:. Eventually, borehole-compensated devices using dual transmitters cbl vdl interpretation dual receivers were introduced in the s, and today most commercial devices use multiple transmitters and receivers in a variety of arrangements to provide compensated measurements. Consequently, there is no acoustic coupling with the formation and most of the transmitted acoustic energy is confined to the casing and the borehole fluid.
Inter;retation techniques combining these different measurements provide improved evaluation in lightweight cements, especially in the annulus, beyond the casing-cement bond.