Schlumberger

Case Study: Multiphase Flow Meter Captures Single-Phase Surface Samples for Accurate Onsite Analysis

PhaseTester equipment with Vx technology enables constructing reliable production history for future performance forecasting, Middle East

Challenge: Quantify current and future well performance by accurately measuring condensate, water, and gas flow rates from retrograde gas condensate reservoirs with commingling production.

Solution: Use PhaseTester portable multiphase well testing equipment with Vx multiphase well testing technology, operating in gas mode, to measure flow rates without phase separation and to collect surface samples.

Result: Captured surface samples for onsite compositional analysis for fluid characterization and equation-of-state (EOS) modeling; performed more than 800 production tests with an excess of 1,900 flow periods recorded.

Verify gas and condensate production for accurate forecasting

An operator in the Middle East was beginning production well test operations in a commingling retrograde gas condensate field, and its objectives included evaluating well performance, monitoring reservoir behavior, measuring flow rate, analyzing surface fluid composition to verify commingling and production, and constructing an accurate production history for future performance forecasting. Commingling retrograde gas condensate reservoirs results in significant variation of the producing condensate/gas ratios between wells and flow periods. These gas condensate reservoirs produce at very high gas‑volume fractions, averaging typically above 99%.

Further, the operator needed to both meter the total commingled flow rate at the surface and allocate surface production to individual reservoir units. Operations also called for capturing fluid samples for gas well testing to verify the production of gas and condensates.

To meet these objectives, the operator elected to use well test equipment and techniques that enabled flow rates to be metered with high accuracy and repeatability while testing numerous wells in a given time frame.

Perform multiphase flow metering with onsite analysis

PhaseTester equipment with Vx technology was selected to test the retrograde gas condensate reservoirs in the field. The reliable and previously unobtainable measurements recorded through the use of this technology proved to be invaluable to the EOS modeling process. Schlumberger developed a gas well testing workflow for the operator that consisted of nine steps.

 1. Collaborate with reservoir and production teams to define and agree on well test objectives.

 2. Mobilize the well test equipment to the wellsite, rig up the equipment, and ccheck the well status to ensure the hardware is functioning properly to retrieve well information.

 3. Execute well testing according to the well test program.

 4. Capture pressurized fluid samples for PVT analysis as well as stock-tank samples for onsite verification.

 5. Analyze fluid samples in the field PVT laboratory.

 6. Generate EOS-based fluid model for each flow period.

 7. Postprocess the initially recorded raw data.

 8. Conduct QC of the flow rate measurement data. 

 9. Generate the final report and deliver to end users.

Production well testing was performed to optimize hydrocarbon production, compare the actual production with the nodal analysis and single-well predictive models, and decide whether to intervene to enhance well production.

Analyze fluid composition onsite and forecast future production

The dynamic response of PhaseTester equipment with Vx technology made it possible to quickly and accurately estimate well performance, even during short flowing periods, as well as analyze multirate testing to quantify deliverability.

Well testing with Vx technology delivered substantial benefits: the operator was able to continuously update reservoir models with well test results, improving the history match and future production forecast; production decline has been monitored well by well; production impairment caused by condensate banking has been determined; and a comprehensive flow rate measurement database was constructed, easing the tracking and analysis of the results. To date, more than 800 gas well tests have been performed, totaling more than 1,900 flow periods.


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Accurate Flow Rate Measurement for Optimal Production Forecasting

Well test results. The condensate, gas, and water flow rates were measured at high frequency.Flowing fractions of three-rate flow test.Recombined fluid compositions for three flow periods in gas condensate well.
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