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Dielectric Scanner Multifrequency dielectric dispersion service R A4 R A3 R A2 R A1 P A P B T A T B R B1 R B2 R B3 R B4 Measurements that speak volumes Dielectric Scanner service is the first in the industry to employ multifrequency dielectric dispersion science to accurately quantify residual hydrocarbon volume, the Archie mn exponent, and formation CEC. Parameters available previously only through core analysis or estimation are now delivered as continuous logs at the wellsite. The di
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  Dielectric Scanner Multifrequency dielectric dispersion service  R A4 R A3 R A2 R A1 P A P B T A T B R B1 R B2 R B3 R B4 Measurements  that speak volumes Dielectric Scanner service is the first in the industry to employ multifrequency dielectric dispersion science to accurately quantify residual hydrocarbon volume, the Archie mn   exponent, and formation CEC. Parameters available previously only through core analysis or estimation are now delivered as continuous logs at the wellsite. The dielectric dispersion measurement constructs an accurate radial profile of the close-borehole region, providing new and unique information on rock properties and fluid distribution for advanced petrophysical interpretation. Used in conjunction with  traditional logging measurements, Dielectric Scanner dielectric dispersion measurement enables developing a more accurate reservoir description for reservoir evaluation and management. Multispacing Operation The heart of Dielectric Scanner service lies in its short, multispac-ing antenna array pad. Each of the cross-dipole antennas has collocated magnetic dipoles. The transmitters (T A  and T B ) are in the center and the receivers (R A1–4  and R B1–4 ) are placed symmetri-cally around them for optimal measurement accuracy and borehole compensation. To minimize environmental effects, the short, fully articulated antenna pad is applied firmly against the borehole wall by a hydraulically operated eccentering caliper to enable optimal pad contact, even in rugose boreholes. Electromagnetic waves are propagated into the formation at four frequencies and two polariza- tions for high-resolution, high-accuracy measurements of reservoir properties at up to 4 in from the borehole wall. The conventional approach to determining oil volume requires weeks or months for laboratory core analysis or accepting the uncertainty inherent in estimated Archie parameters. With Dielectric Scanner* measurements direct from your reservoir, the wait for accurate formation evaluation answers is over. APPLICATIONS ■  Direct measurement of water volume independent of water resistivity ( R  w  ) at a depth of investigation to 4 in [10 cm], solving for ã  Residual hydrocarbon volume in produced reservoirs ã  Hydrocarbon volume in low-resistivity or low-contrast shaly and laminated sand formations ã  Hydrocarbon volume and mobility in heavy oil reservoirs ã  Water salinity ■  Continuous Archie mn   exponent log from rock texture measurements in carbonates for determining saturations beyond the invaded zone ■  Cation exchange capacity (CEC) to account for effect of clay volume in siliciclastics ■  High-resolution water-filled porosity for  thin-bed analysis Dielectric Scanner pad antenna con- figuration. The blue dipoles define the longitudinal polarization and the red ones are the transverse polarization. The two coaxial electrical probes (P  A  and P  B  ) are used for quality control of pad application and for determining the mud and mudcake dielectric proper- ties at the frequencies of interest.  One of the revolutionary advances provided by  the Dielectric Scanner tool is the continuous measurement of dielectric dispersion, which is  the variation of formation dielectric properties as a function of the frequency. High-resolution measurements obtained with the different array spacings, each with two polarizations at four frequencies, are radially interpreted  to obtain permittivity and conductivity at each frequency. Conventional dielectric tools make only a single-frequency measurement with limited applications, and its interpretation can-not account for textural effects, invasion, and unknown or variable water salinities. The Dielectric Scanner permittivity and con-ductivity measurements at each frequency are interpreted using a petrophysical model. The output parameters of the model are water-filled porosity (hence water saturation if the  total porosity is known), water salinity, and  textural effects in carbonates or CEC in shaly sands. Simultaneously fitting the permittivity and conductivity dispersions frees the water-filled porosity from salinity effects. Rather, water salinity is an additional output of the analysis. For a well drilled with oil-base mud (OBM), the calculated water salinity is the formation water salinity.In carbonate reservoirs, the dielectric disper-sion is driven mainly by the rock texture. In  turn, Dielectric Scanner analysis provides a continuous in situ measurement of rock tex- ture, presented as an mn   exponent log. In shaly sand reservoirs, processing provides a continuous log of the CEC. In heavy oil reservoirs or in shallow-invasion situations, Dielectric Scanner measurements are made in both the invaded and non-invaded zones,  to determine moveable hydrocarbon content. Previous-generation single- frequency electromagnetic propa- gation tools, emulated in the log on the left by single-frequency pro- cessing, cannot account for textural variation, resulting in the overesti- mation of invaded zone resistivity R xo  (Track 2). In the log on the right, Dielectric Scanner multifre- quency mixing analysis correctly matches the water-filled porosity to the total porosity in this water- filled sand in Track 3, as confirmed by the matching R xo  values of the Dielectric Scanner and resistivity tools in Track 2. Dielectric dispersion science Dispersion plots of the measured permittivity and conductivity at four frequencies and the fit to the petrophysical model with the estimated parameters. X,050X,100X,150X,200X,300X,350X,400X,450X,550X,600X,000X,500X,250i i i I i i i i ....I i i i.i l i I i i i.il ii l i ill i..li ii l ili iResistivity2-ft Array Induction Resistivity A90ohm.m0.2 2,0000.2 2,0000.2 2,000Invaded Zone Resistivityohm.mDielectric Scanner Invaded Zone Resistivityohm.mPorosityHydrocarbonTotal Porosityy.yx.x ft 3  /ft 3 Dielectric Scanner Water-Filled PorositySalinityDielectricScannerSalinityppt0 100..y.yx.x ft 3  /ft 3   X,050X,100X,150X,200X,300X,350X,400X,450X,550X,600X,000X,500X,250Resistivity2-ft Array Induction Resistivity A90ohm.m0.2 2,0000.2 2,0000.2 2,000Invaded Zone Resistivityohm.mDielectric Scanner Invaded Zone Resistivityohm.mPorosityHydrocarbonTotal PorosityDielectric Scanner Water-Filled Porosityy.yx.x ft 3  /ft 3 SalinityDielectricScannerSalinityppt0 100i i i I i i i i ....I i i i.i l i I i i i.il i..i l i ill ili ii l ili iy.yx.x ft 3  /ft 3 ..  An operator in the Middle East wanted to improve understanding of the fluid saturations in a high-porosity carbonate reservoir where variability in the Archie m   and n   exponents increased the uncertainty in conventional log interpretation. The measurements were also ambiguous because the mud filtrate salinity was approximately 180,000-ppm [-ug/g] NaCl.The carbonate textural information provided by Dielectric Scanner service enabled accurate mn   determination instead of relying on potentially incorrect estimations from conventional log analysis or waiting for laboratory core analysis. Having accurate values of the Archie exponents is important because they are the basis for calculating saturation values from resistivity.As shown by the porosity curves in Track 5, the significant difference between Dielectric Scanner water-filled porosity (blue curve) and the total porosity calculated from standard porosity measurements indicates a large volume of residual hydrocarbon in the formation. In Track 2 the Dielectric Scanner hydrocarbon saturation accounts for variation in the Archie exponents across  the reservoir and confirms up to 95% residual hydrocarbon. Conventional saturation determination using constant values of the Archie mn   exponents does not account for their variation, as shown by  the difference shaded red where the conventional and Dielectric Scanner residual oil saturations do not match. Confirmation of the high residual saturation is in Track 4, where the R  xo   measurements from Dielectric Scanner and conventional resistivity logging closely match each other. Dielectric Scanner measurements confirm   95% residual hydrocarbon saturation It Speaks Volumes about Carbonates Accurate hydrocarbon volume in carbonates from salinity-insensitive determination of water-filled porosity and rock texture factors Case studies
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