Electrical Properties System (Overburden)

The Electrical Properties System (Overburden), model CT-RCA-EPO, measures the resistivity of rock core plugs and of brine while the plug is held under overburden pressure. It is used on fully and partially brine-saturated samples to obtain formation factor and resistivity index at stress, the inputs behind the cementation and saturation exponents used in Archie-based log analysis. The reference overburden pressure is 700 bar (10,000 psi). Measurements are made at room temperature.

How it works

A core plug of 1 in or 1.5 in diameter and up to 3 in length is loaded into the system and overburden pressure is applied. An electrical excitation is passed through the sample and its resistance is read by a 2-electrode or a 4-electrode method, as selected for the test. Brine resistivity is measured as well, so formation factor can be computed for the fully saturated plug and resistivity index for each partially saturated state.

The controlled variables are overburden pressure, the saturation state of the plug and the electrical excitation. The reported result is the resistivity index at stress, together with the formation factor at each pressure step. The unit runs from 110-220 VAC, 50 or 60 Hz, and requires a 150 psi air supply. A companion ambient-pressure system and calibrated resistivity check plugs are listed in the same category.

What is included

• Resistivity measurement in 2-electrode and 4-electrode configuration
• Overburden pressure capability to 700 bar (10,000 psi), room temperature operation
• Sample capacity: 1 in and 1.5 in diameter plugs, up to 3 in long
• Power 110-220 VAC, 50 or 60 Hz; air supply 150 psi

Specify for your project

• Plug diameter (1 in or 1.5 in) and maximum plug length
• Maximum overburden pressure required for the reservoir under study
• Electrode configuration: 2-electrode, 4-electrode or both
• Brine composition and the saturation states to be tested (fully and partially saturated)
• Wetted materials and instrumentation, which are configured per project
• Site power and compressed air available

This description defines the product family. Guaranteed performance, included hardware, exclusions, interfaces and acceptance criteria are stated only in the project-specific technical proposal and approved datasheet.

Features

• Core diameter: 1" and 1.5"
• Core Length: up to 3"
• Resistivity measurement: 2 and 4 electrodes
• Overburden pressure: 700 bar (10,000 psi)
• Temperature: Room condition
• Power supply: 110-220 VAC, 50 or 60 Hz
• Air: 150 psi