Abstract
The use of Multiphase Flow Meters (MPFM) has been increasing in the last decades in different well monitoring applications. It is important to extend the working life of this equipment as they have reached the end of life and yet can properly operate before it has to be discarded for technical and obsolescence reasons.
During the early stage of project development, MPFMs are selected and sized based on forecasted well production. At the later production stage of field development, usually flow-rates decline. As a result, the differential pressure through Venturi based MPFM will go below the minimum threshold, to maintain good metrological performances, it then requires to change to a smaller size MPFM.
This paper discusses the design, qualification, and field-test of a new methodology of extending the operating envelope of the MPFM using insert to ensure that the well monitoring data remain accurate and reliable without compromising the safety and integrity of the installation.
The insert venturi application developed is named the LRE "low-rate extender" tool because it reduces the cross-sectional area at the venturi throat, which increases the differential pressure for low flow rates and maintains the measurement accuracy.
The project was launched by first decommissioning one sample MPFM from the wellsite and sending it to the product center to build the customized tool and ensure all mechanical constraints and considerations are tackled on the spot.
Once the insert venturi device has been manufactured and duly inspected, the validation phase started through flow-loop testing. The performance of the MPFM with LRE is expected to be similar to MPFM without it. 328 test points were tested at four pressure levels with a water-liquid ratio (WLR) ranging from 0 to 100 % and a gas-volume fraction (GVF) from 0 to 100 % to prove the accuracy of MPFM with LRE. The validation considered the accuracy in total mass rate, liquid and gas rates, and WLR.
The last phase consisted of field trials, where comparison tests have been performed at different flow regimes between permanent MPFM with LRE and mobile MPFM of smaller Venturi size, the test has been extended for 6 months to monitor the MPFM with LRE long-term reliability.
The article discusses the new development of a retrofittable tool to extend the life of the MPFMs. It is a cost-effective solution and its workflow of design and validation can be applied to other MPFMs using the same measurement methodology facing similar flow measurement challenges.
