Advanced Electrical Resistivity

700-520

Introduction

Formation Factor and Resistivity Index are values calculated from core resistivity measurements at overburden and partial-saturation conditions. The brine-saturated sample is held in a non-conducting (insulated) hydrostatic core holder with two electrodes at each end of the sample and a porous plate at the downstream end. Confining pressure is applied to the sample and resistivity of the sample is measured at 1 kHz using a four-electrode LRC meter. Saturation is reduced incrementally by applying gas pressure and measuring the volume of displaced brine when equilibrium is achieved. Sample resistivity is measured at each equilibrium condition.

Description

The resistivity of the core sample is measured multiple times. The first measurement is made while the sample is saturated with a reservoir-matching brine at overburden pressure. The Formation Factor can be calculated with this data.

After the first measurement, the core sample is desaturated. The resistivity is measured again at each equilibrium condition. The Data Saturation Exponent can then be calculated from this data.

The Single-Cell unit includes one quick-access cell with four electrodes. It can accept core samples measuring 1.5" in diameter and 2" long. The Multi-Cell unit includes a cell with a nominal 4" internal diameter and 18" length. It has a maximum pressure of 10,000 PSI (69 MPa) and accepts up to five samples measuring 1.5" in diameter and 2" long.

Both units include the following:

• Annulus Supply: manual pump, gauge, valves, plumbing, and small vacuum pump for 10,000 PSI annulus supply
• Gas Supply Control: low-pressure regulator, gauge, valves, and plumbing for desaturating the sample with separator and pipettes for measuring expressed pore fluid
• Pore Fluid System: 316 transfer cell, gauges, Nitrogen regulator, valves, and plumbing for saturating samples and measurement of permeability

Optional Equipment

• Automated Data Gathering: PC with software for controlling the unit, recording resistivity and temperature, and fitting data for early determination of equilibration
• Transfer Cell with Floating Piston: Prevents gas from going into solution and allows for easier operation
• Additional sample cells and end pieces with a range of porous plate permeabilities are available.

For more information about this product or to request a quote, contact us.