Methods and systems for processing crude oil using cross-flow filtration

1. A method of processing crude oil comprising:

adding water to the crude oil to produce oil and brine and a rag layer including an emulsion comprising brine and oil and solids;

separating oil from brine including producing brine comprising the rag layer;

separating the rag layer into a hydrocarbon emulsion having finer solids and brine comprising larger solids; and

passing the hydrocarbon emulsion and finer solids along a cross-flow filter to produce a retentate comprising brine and solids and a permeate comprising hydrocarbon.

2. The method according to claim 1 , further comprising separating brine from the brine comprising the rag layer.

3. The method according to claim 2 , wherein separating brine from the brine comprising the rag layer comprises passing the brine comprising the rag layer through a settling tank, gravity separator, or a coalescing plate interceptor (CPI) separator.

4. The method according to claim 1 , further comprising adding one or more of additional hydrocarbon, a demulsifier, a reverse demulsifier, a coagulant, and a flocculant to the rag layer.

5. A method of processing crude oil comprising:

passing the crude oil through a desalter, including separating oil from brine comprising a rag layer and removing the brine comprising a rag layer from the desalter via a first port and removing the oil via a second port;

passing the brine comprising the rag layer through a separator including separating the rag layer into a hydrocarbon emulsion having finer solids and brine comprising larger solids, including removing the brine comprising larger solids from the separator via a third port and removing the hydrocarbon emulsion and finer solids from the separator via a fourth port; and

filtering the hydrocarbon emulsion and finer solids using a cross-flow filter to produce a retentate comprising brine and solids and a permeate comprising hydrocarbon, including removing the retentate from the cross-flow filter via a fifth port and removing the permeate from the cross-flow filter via a sixth port.

6. The method according to claim 5 , further comprising adding one or more of additional hydrocarbon, a demulsifier, a reverse demulsifier, a coagulant, and a flocculant to the rag layer.

7. The method according to claim 6 , further comprising mixing the rag layer and the one or more of the additional hydrocarbon, the demulsifier, the reverse demulsifier, the coagulant, and the flocculant in a mixer.

8. The method according to claim 5 , wherein separating the rag layer into a hydrocarbon emulsion having finer solids and brine comprising larger solids comprises passing the rag layer through a settling tank or a mixing tank.

9. The method according to claim 1 , further comprising recirculating the retentate to the cross-flow filter.

10. The method according to claim 9 , further comprising directing the hydrocarbon emulsion and finer solids from the separator to a working tank and recirculating the hydrocarbon emulsion to the cross-flow filter via the working tank.