Abstract
The paper concerns the achievement in separation performance by using a new mixer device for the injection and mixing of the demulsifier into the crude-water flow.
The target for the injection of the demulsifier into the crude-water flow is to modify the surface properties of the crude-water interfaces such that the conditions for droplet-droplet coalescence for the dispersed phase within the two liquid bulk phases are improved. The costs for such production chemicals may become significant at the same time as the impact on the crude-water separability may be non-satisfactory. Facing this, Saudi Aramco has installed and field-tested a new mixer system, denoted ProMix, for more efficiently distributing the demulsifier into the crude-water flow, targeting lower consumption and improved separability.
The operational performance and results for the full scale 20" mixer installation at UGOSP-4 (Uthmaniyah Gas-Oil Separation Plant), normal operating flow rate 275,000 BPD, has been recorded both for winter and summer conditions.
Compared to the existing mixing valve, the ProMix mixer device has served to;
Reduce the demulsifier consumption
Improve the crude oil produced water separation
Reduce the pressure drop across the mixer installation to typical 1-2 psi
Improve operational robustness
The annually averaged reduction in demulsifier consumption has been estimated to 20 %. In addition the oil-inwater content for the water separated from the dehydrator has dropped significantly by the use of the new mixer system, allowing for improved operation of the crude-water interfacial level for the dehydrator. For the operational robustness the introduction of the new mixer system has also served to minimize the dehydrator electrostatic grids failures during the winter conditions.
The reduced pressure drop and improved separability also allows for higher crude flow production in addition to reduced demulsifier consumption. As the ProMix is a compact flange mounted spool piece unit it can easily replace an existing choke or globe valve mixer in order to debottleneck existing separation trains, in addition to serve as mixer units for grass-root installations.
