Emerson’s Laura Schafer described how diagnostics in a Micro Motion Coriolis flow measurement in oil & gas production.
Laura opened with the objective for oil & gas producers to maximize the return on investment. One way to do this is to take advantage of the diagnostics in their measurement equipment.
Some challenges include putting separators on every single well and these separators are poorly sized, given the the variable production rates from shale formations. To deal with the large number of wells being drilled, design is “cookie cutter” where design usually errs on the side of smaller separators and larger valves. This results in problems with separation–gas blowby and liquid carryover.
Companies are short on experienced people and environmental concerns caused by gas venting.
Traditional measurements in tanks are done by manual tank gauging which has health & safety concerns, uncertainty, and error. Turbine meters have been used for flow measurement but have issues with mechanical failure caused by sediment in the flow, gas flashing, and other flow effects.
Laura described the Coriolis effect that measures mass flow, density flow, and volumetric flow. Coriolis meters are tolerant of sand, debris, and gas coming out of solution. One diagnostic is device drive gain which indicates a change in the the oil liquid compostion. Drive gain also spots entrained gas in the production flow.
In the first diagnostics scenario Laura described, density was rising between dump cycles. Water in the oil was causing overreadings. By adding separation residence time to the process, the oil readings became more accurate avoiding the “missing oil”.
The second example was a volumetric flow spike as density drops to zero. The drive gain spiked indicating gas in the stream. The problem was identified as a vortex being created in the separator dump sucking gas into the liquid stream. The level was changes and more frequent dump cycles performed to eliminate the problem.
Laura shared additional examples around temperature control for the separator where the drive gain diagnostics identified conditions where the temperature was too high and too flow. The drive diagnostic can even spot paraffin buildup, common in many shale formations.
