It's unlikely that an echo-meter can be used to reliably detect the static interface level between API gravity 22 heavy oil and 9 ppg brine in a wellbore. Here's why:

• Echo-meters rely on sound waves: Echo-meters work by sending sound waves down the wellbore and measuring the time it takes for the echo to return. This method is effective for detecting changes in acoustic impedance, which is a measure of how sound waves travel through a material.

• Density differences: The difference in density between heavy oil (API gravity 22) and 9 ppg brine is relatively small. This difference may not be significant enough to create a clear acoustic impedance contrast that the echo-meter can detect.

• Fluid mixing: Even if there is a slight difference in acoustic impedance, it's possible that mixing between the oil and brine at the interface could blur the signal, making it difficult to accurately determine the interface level.

• Wellbore conditions: The presence of other factors like gas, scale, or corrosion in the wellbore can further complicate the acoustic signal, making it less reliable for detecting the interface.

Alternative methods:

• Pressure gradient logging: Measuring the pressure gradient across the interface using a pressure gauge can provide a more accurate determination of the interface level.

• Electrical conductivity logging: Using an electrical conductivity logging tool, you can identify the boundary between the conductive brine and the less conductive oil.

• Gamma ray logging: This technique can identify the boundary between the two fluids, especially if the oil and brine have different radioactive properties.

Important Considerations:

• The specific characteristics of the oil and brine (density, viscosity, and composition) can affect the effectiveness of any measurement technique.

• The wellbore conditions (depth, diameter, and presence of other fluids) also play a role in the accuracy of the interface level determination.

Conclusion: While an echo-meter might theoretically be used to attempt to detect the interface, it's not a reliable or recommended method due to the limitations discussed above. Other more suitable logging tools are available for this purpose.