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Image Log Interpretation March 29, 2012

Posted by ugmsc in Course and Workshop Summary.

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On March 20th 2012, AAPG UGM-SC organize a free guest lecture with Mr, Amudra Prabantara B.Sc from Weatherford as the speaker.  The title that Mr. Amudra Prabantara presented is “Borehole Imaging Tech Review and Application”, with several main topic, those are evolution of resistivity imaging tools, advantage and benefit of image log analysis, application of image analysis, bortex-porospect image petrophysic (IPP).

Images log have resistivity which called microscanner or FMS or FMI logs, actually carry an array of electrodes on pads used to produce an electrical image of the formations seen on the borehole wall. Acoustic image logs, also called televiewer or CBIL logs, use a rotating transducer to measure acoustic impedance images over the entire borehole wall, as well as an acoustic caliper. Microscanners have better vertical resolution and dynamic range than televiewers, but televiewers see the entire wellbore while microscanners usually see less than 100%.

On earlier microscanner tools, the image arrays were on only two of the four pads, so several logging passes of the tool had to be merged together for better borehole coverage. Using this technique, from forty to eighty percent wellbore coverage could be achieved. Newer tools now have four or eight active imaging pads, reducing the need for repeat passes to obtain 100% coverage of the borehole wall.

In addition to the array electrodes, the tool also has ten standard dipmeter electrodes (8 measure electrodes plus 2 speed buttons) as well as a directional cartridge containing accelerometers and magnetometers for orientation input to the standard dip computations.

Flowchart of image log usually using GPIT LQC-with 3 axis that related with magnetometers with another feature such as acccelerometers,thermometer,magnetometer which really influentby magnet indignation. And as information that PAD 1 azimuth that 1800  is looking down when tool is vertical tool and relative bearing (RB) is from up on a vertical plane.Before try the analysis there preparation stage inclluding outlier removed,destriping pad, summering reduction,fixing bad dad.

In 90 minutes of lecturing, Mr. Amudra Prabantara also tell that the method of Dipping is auto and manual dipping which separated by functional treatment. CMI also have some application that is to know detailed interactive structural analysis and sedimentological and statigraphy.

Another explanation is about methodology dip classification generally,send separation/shale preparation and the example of dip classification, those are sedimentary features,stuctural features,in situ stress indocator.By using ImageLog software we also can interpret for fractures, in-situ stress indicators and lithofacies,  producing results which underpin fracture models or support operational activities such as selection of perforation or testing intervals. Other well data can be loaded alongside the image for identification of fracture porosity and fracture flow properties.

Natural fracture attributes are true orientation,open or closed,spacing, intersections, clustering,lithological or structural controls. Induced fractures (geomechanics indicators) are breakout orientations and widths,xial tension fracture orientations,enhanced natural fractures,borehole shape.Sedimentology are Image facies,dipmeter analysis for structural tilt,bedform types and geometries,

At all the image log interpretation have advantage and weakness,it help us to compile data from image log data from another source as like from bore, but because of that we have to be carefull on making the decision.So, the interpretation of log analysis is so important cause without a detailed and careful analysis of this data from a company’s web server logs, a company will be more or less blind and oblivious both to threats and opportunities.



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