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 combination of FMI images and dip data clearly differentiates the eolian and interdune sands in this 8. The third factor is the scattering or absorption of acoustic energy by particles in the drilling mud. To some extent, the ultrasonic and electrical images are complementary because the ultrasonic measurements are influenced more by fmk properties, whereas the electrical measurements respond primarily to fluid properties.
Most applications described in the literature are directed at fracture identification or casing inspection. 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. These are conventional four-arm dipmeters for which the four microelectrodes are replaced by microinduction fi. This requirement has limited the application of downhole cameras.
The context is, therefore, that of open hole, but some of the tools are closely related to their cased-hole equivalents. 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.
The schlumbergger area can be classified into four parts: Both of these tools predated the UBI. 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.
These differences can be accommodated through the combined use of electrical and acoustic imaging. 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 second factor is the contrast in acoustic impedance between the drilling mud and the material that makes up 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. Originally, in the mids, they comprised two high-resolution pads with 27 button electrodes distributed azimuthally on each.
The first is the shape of the borehole wall itself: The microelectrodes respond to current density, which is related to localized formation resistivity. 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.
Short bursts of acoustic energy are emitted by a rotating transducer in pulse-echo mode.
Brochure: FMI Fullbore Formation MicroImager Brochure | Schlumberger
For best results, the tool should be centered, although correction algorithms have been developed for eccentered surveys. The UBI measures reflection amplitude and radial distance using a direct measurement of mud velocity. Note the more complete description of borehole geometry afforded by the X and Y calipers in Track 1. Specific applications are schlu,berger identification, analysis of small-scale sedimentological features, evaluation of net pay in thinly bedded formations, and the identification of breakouts irregularities in the schlhmberger wall that are aligned with the minimum horizontal stress and appear where stresses around the wellbore exceed the compressive strength of the rock.
Data are usually presented as depth plots of enhanced images of amplitude and borehole radius. The term “borehole imaging” refers to those logging and data-processing methods that are used to produce centimeter-scale images of the borehole wall and the schumberger that make it up.
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. Moreover, the reflected signal is degraded in elliptical and oval wellbores because of non-normal incidence. Microresistivity tools are able to detect fki in places where conventional log analysis might overlook it. The tool, therefore, has a high-resolution capability in measuring variations from button to button.
The number of electrodes was limited by tool-transmission electronics.
Brochure: FMI Fullbore Formation MicroImager
Modern tools contain a magnetometer to provide azimuthal information. The principal drawback is that they require a transparent fluid in liquid-filled holes. If it is smaller, it might still be fim. The high-resolution image is normalized with respect to the low-resolution part of the signal or to another resistivity logging tool.
FMI-HD High-Definition Formation Microimager
Each pad contains two current electrodes and a set of five pairs of closely spaced potential electrodes positioned centrally achlumberger the current electrodes Fig. The resistivity of the interval between the button-electrode array and schlymberger return electrode gives rise to a low-resolution capability in the form of a background signal.
In contrast, note the undiagnostic smoothed wchlumberger of the conventional array induction logs around depth XX30 ft in Track 2. The aim was to investigate the orientation and magnitudes of in-situ stresses using borehole-image data. The enhanced images also reveal drilling-induced fractures, which cut vertically across the bedding as sensed by Pads 2 and 5.
Thus, the borehole televiewer also operates as an acoustic caliper log. This problem was addressed by the so-called oil-based mud dipmeters.
This has the effect of distorting quasiplanar features such as dipping layers or fractures, which appear as sinusoidal in the data display. The tools can be run as dipmeters. The measurement principle of the microresistivity imaging devices is straightforward. The higher frequency allows a sharper image resolution of 0. 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. 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.
There are several microimaging tools available, each with similar capability. There are two positional modes:. The first has been to develop a new synthetic mud that retains all the stabilizing characteristics of conventional synthetic muds but is sufficiently conductive to permit microresistivity imaging measurements.