The acoustic determination of the pump intake pressure in wells producing viscous low API gravity crude is presented in this paper. These wells have liquid above the pump and the pump is set above the formation and gas flowing upward through the gaseous liquid column. The method to determine the pump intake pressure involves the acoustic measurement of the liquid level and the casing-pressure buildup rate when the casing head valve is closed. When these data are used with this paper's new empirically derived correlation for viscous crudes, then an accurate gradient of the gaseous liquid column in the annulus is obtained. This new correlation provides a more accurate correction of the gaseous gradient of the fluid above the pump intake for wells producing viscous crudes.
Results are presented from field testing of numerous wells where the actual gradients of gaseous liquid columns were measured is wells having a variety of gas flow rates and an oil gravity in the range of 10 degrees API. A back pressure valve is used to increase and stabilize the casing head pressure and the valve is used to depress and to stabilize the liquid level at different depths while the well is produced at a constant rate. Over a period of many days the acoustic measurements to the stabilized liquid levels are acquired. The gradient of the gaseous liquid column is then calculated and the pressures are extrapolated to the pump intake depth. Development of a new correlation from the analysis of this field data improves the accuracy of pump intake pressure determination in wells producing viscous low API gravity crude.