Assessment of Acoustic Reservoir Pressure Measurements at the Well-Head

Summary A conventional pressure/static gradient survey is performed with downhole pressure gauges. Pressure gradient surveys require a full wireline crew and a gauge specialist. The cost associated with this type of survey can be significant and there are noticeable risks and time involved. An alternative approach is to measure pressure gradients using an acoustic surveillance technique, which requires no wireline intervention, only portable instruments with a minimal footprint. The survey can be completed in a few hours, reducing cost/risk and minimizes production losses. The innovation is related to how the gas and liquid gradients are determined. By using the measured acoustic response combined with wellhead measurements and onsite analysis, it is possible to determine both the gas and liquid gradients, that can be used to determine Top Perforation pressures, with good accuracy and documented results. The benefits included the lower costs, less POB required, intervention-less nature of the campaign and the lack of extended shut-in period requirements.