Reservoir measurement in natural gas production

Usually a central system of large separator vessels will accept the multiphase product pipeline flows coming from separate wellheads, to produce the separate outputs as single phases of oil, gas and water, plus a slurry of sand or other solid sediments in water. The output of each valuable phase is measured, using Coriolis or ultrasonic custody transfer flowmeters, before transfer to the downstream processing plant or storage reservoirs.

Individual well measurement flow data is required to provide information for reservoir monitoring, and can help optimize well production. To achieve this, individual well flow streams are diverted to a test separator, where flow volume measurements of separated water, oil and gas streams are measured: in the gas stream, a wet gas flow meter is used to compensate for significant water content in the gas. These readings are used for well management, to adjust water injection rates or gas lift pressures, and for allocation measurement. The test flows are then returned to the main production separation systems. An alternative to the test separator for mixed oil, water and gas flows is now available with the introduction of the KROHNE Multiphase well test flowmeter, which can give separate flow data for the two liquid phases and measure the gas void fraction (gvf) from a single meter in the flowline.

Throughout the separation process KROHNE flowmeters and sensors are used to improve process and operational efficiency, for example in using TDR radar level gauges to control the separator interface levels, and in the control of degassing in the final crude oil storage reservoirs.