Process Instruments, LLC implemented the first well test validation system in 1998. The first system did not
have the ability to separate gas and liquid phases. It was used downstream of an automatic well system.
The system was useful for improving well test system accuracies. In order to use this system for portable well
testing and validation, we added the patented Accuflow separator.
We apply API Chapter 8, Sec. 2 – Standard Practice for Automatic Sampling of Liquid Petroleum for our sampling and handling.
Principal #1 – Measure the flow with an accurate repeatable non mechanical meter.
The flow meter uses a Coriolis mass flow meter manufactured by Endress+Hauser. Coriolis meters have no wearing parts and
are extremely accurate. The meter is selected for its compact design and stable zero.
Principal #2 – Condition the flow stream prior to sampling.
A multi-vane static mixer is used upstream of the isokinetic sampler to ensure oil and water are reduced to small droplets
and dispersed evenly across the cross section of the flow stream.
Principal #3 – Take a sample proportional to the flow-rate.
For a representative sample, the sample is taken proportional to the flowrate. The PLC monitors flowrate and sends signals
to actuate sampling. Faster flow means faster sampling.
Principal #4 – Take an isokinetic sample.
An isokinetic positive-displacement sampler grabs the sample from the center of the flow stream at fluid velocity, isolates it,
and discharges by a positive displacement piston to reduce sample escaping.
Principal #5 – Handle the sample properly.
Water cut is determined by weight instead of volume. This helps reduce variables that can cause error and improves accuracy in high water cut ranges.
Conclusion
Well testing is difficult due to well dynamics and variation in flowrates. High water cut wells are among the most difficult to measure.
Accurate physical sampling helps validate automated systems and improve confidence.
- The sample must be properly conditioned.
- The sample should be taken using an isokinetic sampler.
- The sample should not be divided once it has been taken.
- The sample must be analyzed properly.
Validation of New Technology
Any new technology for well testing should always be validated with an accurate and proven system. Process Instruments has the experience and knowledge required for validation needs.