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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Traditionally, they have required a conductive borehole fluid, but it will be seen later that this requirement has been obviated by oil-based-mud imaging tools.
The direction of rotation of the subassembly governs the orientation of the transducer. The principal drawback is that they require a transparent fluid in liquid-filled holes. Examples of microresistivity image displays are shown in Figs.
There are several microimaging tools available, each with similar capability. Today they furnish a true high-resolution color image of the wellbore.
For best results, the tool should be centered, although correction algorithms have been developed for eccentered surveys. The term “borehole imaging” refers to those logging and data-processing methods that scblumberger used to produce centimeter-scale images of the borehole wall and the rocks that make it up. Examples of these irregularities are fractures, vugs, and breakouts. The borehole televiewer operates with pulsed acoustic energy so that it can image the borehole wall in the presence of opaque drilling muds.
FMI-HD High-Definition Formation Microimager
Unless transparent fluid can be injected ahead of the lens, the method fails. Although the caliper can reveal the orientation of breakouts, the tool provides little information about their size and, more generally, about the overall shape of the borehole wall. Ultrasonic measurements can be made using the same tool in all types of drilling mud, and this can facilitate interwell comparisons. The resolution of electrical microimaging tools is governed by the size of the buttons, usually a fraction of an inch.
FMI-HD High-Definition Formation Microimager | Schlumberger
There are two positional modes:. To some extent, the ultrasonic and electrical images are complementary because the ultrasonic fi are influenced more by rock properties, whereas the electrical measurements respond primarily to fluid properties. The resistivity of the interval between the button-electrode array and the return electrode gives rise to a low-resolution capability in the form of a background signal.
The arrangement is reminiscent of the Schlumberger electrode array that is still used for surface resistivity sounding in geoelectrical prospecting.
The other major historic limitation, the need to wait until the camera is recovered before the images can be seen, has fallen away with cmi introduction of digital schlhmberger. 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 upper part of the tool. Breakouts are indicated by the low acoustic amplitude of the reflected signal, shown here as darker areas. The pads and flaps contain an schlumbergerr of button electrodes at constant potential Fig.
On the other hand, most microresistivity imaging devices require a water-based mud; otherwise, schlumbberger alternative tool, such as the OBMI, has to be used. Use this section to provide links to relevant material on websites other than PetroWiki and OnePetro. The buttons have a diameter of 0. These amplitudes are governed by several factors.
These differences can be accommodated through the combined use of electrical and acoustic imaging. The FMI tool is able to detect laminations as thin as 0.
Borehole imaging –
The tool does not provide an absolute measurement of formation resistivity but rather a record of changes in resistivity. They are especially useful for net-sand definition in thinly laminated fluvial and turbidite depositional environments. The third factor is the scattering or absorption of acoustic energy schlumberged particles in the drilling mud. 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.
Sdhlumberger subject area can be classified into four parts: Data are usually presented as depth plots of enhanced images of amplitude and borehole radius. The enhanced images also reveal drilling-induced fractures, which cut vertically across the bedding as sensed by Pads 2 and 5.
Current is focused into the formation, where a depth xchlumberger investigation of several tens of centimeters is claimed. Acoustic impedance provides an acoustic measure of the relative firmness of the formations penetrated by the wellbore material and, thus, it has the capability of discriminating between different lithologies, with high acoustic impedance giving rise to high reflected amplitudes.
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.
Each pad contains two current electrodes and a set of five pairs of closely spaced potential electrodes positioned centrally between the current electrodes Fig.
The first is the shape of the borehole sclhumberger itself: These are conventional four-arm dipmeters for which the four microelectrodes are replaced by microinduction sensors.
Borehole imaging has been one of the most rapidly advancing technologies in wireline well logging.