The FMI fullbore formation microimager gives you microresistivity formation images and dip data in water-base mud, differentiating the structures and. UltraTRAC all-terrain wireline tractor conveys FMI microimager ft in carbonate reservoir lateral in only 7 h, New Mexico. The FMI-HD high-definition formation micro-imager employs the well-proven microresistivity imaging approach of the industry-standard FMI fullbore formation .
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The FMI tool is able to detect laminations as thin as 0. The higher frequency allows a sharper image resolution of 0. An applied voltage causes an alternating current to flow from each electrode into the formation and then to be received at a return electrode on the schlumbdrger part of the tool. The third factor is the scattering or absorption of acoustic energy by particles in the drilling mud. The pads and flaps contain an array of button electrodes at constant potential Fig.
In contrast, note the undiagnostic smoothed form of the conventional array induction logs around depth XX30 ft in Track 2. Thus, the borehole televiewer also operates as an acoustic caliper log. Downhole cameras were the first borehole-imaging devices.
For best results, the tool should be centered, although correction algorithms have been developed for eccentered surveys. This problem is more serious in heavily weighted muds, which are the most opaque acoustically, and it gives rise to a loss of image resolution. Borehole televiewers work best where the borehole walls are smooth and the contrast in acoustic impedance is high.
Specific applications are fracture identification, analysis of small-scale sedimentological features, evaluation of net pay in thinly bedded formations, and the identification of breakouts irregularities in the borehole wall that are aligned with the minimum horizontal stress and appear where stresses around the wellbore exceed the compressive strength of the rock.
Examples of microresistivity image displays are shown in Figs. Both of these tools predated the UBI. The amplitudes of the reflected pulses form the basis of the acoustic image of the borehole wall. The travel time for the acoustic pulse depends on the distance between the transducer and the borehole wall, as well as the mud velocity.
Use this section for citation of items referenced in the text to show your sources. There are several microimaging tools available, each with similar capability. The resolution of electrical microimaging tools is governed by the size of the buttons, usually a fraction of an inch.
The combined tool is 86 ft [ The principal drawback is that they require a transparent fluid in liquid-filled holes. Microresistivity imaging devices were developed as an advancement on dipmeter technology, which they have mostly superseded.
The tool delivers a more complete data set than is achievable schlumbreger either of the components separately. On the other hand, most microresistivity imaging devices require a water-based mud; otherwise, an alternative tool, such as the OBMI, has to be used. The microelectrodes respond to current density, which is related to localized formation resistivity.
Prensky  has provided an excellent review of this important subject.
Brochure: FMI Fullbore Formation MicroImager Brochure | Schlumberger
The measurement principle of the microresistivity imaging devices is straightforward. This problem was addressed by the so-called oil-based mud dipmeters. The tool, therefore, has a high-resolution capability in measuring variations from button to button. However, the image probably relates to a depth of investigation of no more than 0. To some extent, the ultrasonic and electrical images are complementary because the ultrasonic measurements are influenced more by rock properties, whereas the electrical measurements respond primarily to fluid properties.
Current is focused into the formation, where a depth of investigation of several tens of centimeters is claimed. The conventional microresistivity imaging devices require a conductive mud in which to function.
Optical imaging Acoustic imaging Electrical imaging Methods that draw on both acoustic and electrical imaging techniques using the same logging tool Prensky  has provided an excellent review of this important subject.
FMI Fullbore Formation Microimager
The tool can also be used for investigating the geometry of the inner surface of casing where it is not desired to measure resonant ringing as an indicator of cement integrity.
The enhanced images also reveal drilling-induced fractures, which cut vertically across the bedding as sensed by Pads 2 and 5. Electrical microimaging tools have proved superior to the ultrasonic televiewers in the identification of sedimentary characteristics and some structural features such as natural fractures in sedimentary rocks. Breakouts are indicated by the low acoustic amplitude of the reflected signal, shown here as darker areas. The principal application of downhole video has been in air-filled holes in which acoustic and contact electrical images cannot be obtained.
Acoustic borehole-imaging devices are known as “borehole televiewers. Ultrasonic measurements can be made using the same tool in all types of drilling mud, and this can facilitate interwell comparisons.
FMI-HD High-Definition Formation Microimager
Use this section to provide links to relevant material on websites other than PetroWiki and OnePetro. The combination of FMI images and dip data clearly differentiates the eolian and interdune sands in this 8.
The second factor is the contrast in acoustic impedance between the drilling mud and the material that makes up the borehole wall. The tool does not provide an absolute measurement of formation resistivity but rather a record of changes in resistivity.
Originally, in the mids, they comprised two high-resolution pads with 27 button electrodes distributed azimuthally on each.
They are especially useful for net-sand definition in thinly laminated fluvial and turbidite depositional environments. Reflected pulses are received by the transducer. Data are usually presented as depth plots of enhanced images of schlumbrger and borehole radius.
Unless transparent fluid can be injected ahead of the lens, the method fails. These differences can be accommodated through the combined use of electrical and acoustic imaging.
Modern tools contain a magnetometer to provide azimuthal information. The aim was to investigate the orientation and magnitudes of in-situ stresses using borehole-image data. However, drilling with oil-based or synthetic muds has increased because of the improved drilling efficiency and greater borehole stability relative to water-based muds. The televiewer has superseded multiarm dipmeter calipers for these applications.