Microresistivity Tool

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Accurate flushed zone (Rxo) resistivity

Applications

  • In microspherically focused laterolog (MSFL) mode, the MRT provides excellent high-vertical resolution and  flushed-zone resistivity (RXO) measurements.
  • With a pad change, the MRT can also provide a high-quality permeability indication with anmicrolog (MEL) measurement.

Features and Benefits

  • The borehole-corrected MSFL provides accurate Rxo measurements necessary to estimate moveable-hydrocarbon volumes, which reducesing estimation errors and associated costs.
  • High-resolution measurements from the MSFL and MEL improve bed-boundary delineation in narrow beds, which increasesing accuracy in determination of hydrocarbon reserves.
  • The uncomplicated MEL measurement provides an efficient indication of permeability, which enablesing timely selection of zones for testing or potential completion.

Tool Description

The Weatherford microresistivity tool (MRT) measures flushed-zone resistivity (Rxo). An interchangeable pad allows this versatile tool to function either as a microspherically focused laterolog (MSFL) or a microlog (MEL) device.

The MSFL measures flushed-zone resistivity (Rxo), which can be used to calculate flushed-zone water saturation (Sxo). The difference between undisturbed water saturation and flushed-zone water saturation indicates the volume of hydrocarbons flushed during the invasion process.

This pad-type microresistivity device uses a concentric arrangement of five electrodes to force the tool’s measurement current into a hemispherical pattern. This arrangement helps to eliminate errors generated by wellbore conditions such as mudcake on the borehole wall.

The three-electrode array on the MEL pad provides the shallow-reading micro inverse (m. inverse) and deeper-reading micro normal (m.normal) measurements. The amount of mudcake present on the borehole wall can be indicative of permeability in the adjacent zone, with the variation in mudcake thickness primarily affecting the response of the shallow-measuring m. inverse curve. Positive separation between the curves (m. inverse > m. normal) denotes the presence of mudcake, which providesing a high-resolution permeability indicator.