Downhole fluid separator design in multilateral well

A system, comprising

• a lower completion disposed in a main bore of a multilateral well in a position downhole from a junction of the multilateral well;
• a fluid separator configured to receive formation fluid flowing from the lower completion, wherein the formation fluid includes oil and water, wherein the fluid separator is configured to at least partially separate the formation fluid into formation oil and formation water, wherein the fluid separator is configured to output the formation oil, via a separator oil outlet, to flow uphole, and wherein the fluid separator is configured to output the formation water, via a separator outlet to flow toward a lateral bore of the multilateral well;
• water cut sensor disposed uphole from the fluid separator, wherein the water cut sensor is configured to measure the percentage of water in the formation oil;
• and
• a tubular swivel having an upper portion and a lower portion, wherein the lower portion is rotatable with respect to the upper portion, wherein the fluid separator is connected to the lower portion, and wherein the fluid separator is configured to rotate to a gravitationally up position via rotation of the lower portion of the tubular swivel.

A system, comprising:

• a lower completion disposed in a main bore of a multilateral well in a position downhole from a junction of the multilateral well;
• a fluid separator configured to receive formation fluid flowing from the lower completion, wherein the formation fluid includes oil and water, wherein the fluid separator is configured to at least partially separate the formation fluid into formation oil and formation water, wherein the fluid separator is configured to output the formation oil, via a separator oil outlet, to flow uphole, and wherein the fluid separator is configured to output the formation water, via a separator water outlet to flow toward a lateral bore of the multilateral well;
• a water cut sensor disposed uphole from the fluid separator, wherein the water cut sensor is configured to measure the percentage of water in the formation oil;
• and
• a sampler having an upper valve and a lower valve, wherein the sampler is disposed between the fluid separator and an upper completion packer, wherein the lower valve is configured to selectively block flow of the formation oil through an upper production tubing, wherein the upper valve is disposed between the lower valve and the upper completion packer, and wherein the upper valve is configured to open a flow path from a junction annulus to the upper production tubing in response to the lower valve blocking flow of the formation oil through the upper production tubing such that the formation water may flow to the surface via the upper production tubing for sampling.

A system comprising:

• an orienting liner hanger disposed in a main bore of a multilateral well in a position downhole from a junction of the multilateral well;
• a lower completion assembly secured to a downhole end of the orienting liner hanger;
• a fluid separator configured to receive formation fluid flowing from the lower completion assembly, wherein the formation fluid includes oil and water, wherein the fluid separator is configured to at least partially separate the formation fluid into formation oil and formation water, wherein the fluid separator is configured to output formation oil into a separator annulus via a separator oil outlet, and wherein the fluid separator is configured to output the formation water, via a separator water outlet, to flow toward a lateral bore of the multilateral well;
• a dual string packer secured within the main bore in a position between the fluid separator and the junction of the multilateral well;
• an upper completion packer secured within the main bore in a position uphole from the junction;
• an upper production tubing extending at least from the separator annulus, through the dual string packer, and to the upper completion packer, wherein the upper production tubing is configured to direct the formation oil from the separator annulus to flow uphole through the upper completion packer;
• a lower production tubing having a downhole end coupled to the separator water outlet, wherein the lower production tubing extends through the dual string packer and into the junction annulus to direct the formation water into the junction annulus, wherein the junction annulus is formed in the main bore about the upper production tubing between the dual string packer and the upper completion packer, wherein the junction annulus is fluidly coupled to the lateral bore such that formation water output into the junction annulus is directed to flow into the lateral bore from the junction annulus;
• and
• a water cut sensor disposed uphole from the fluid separator, wherein the water cut sensor is configured to measure the percentage of water in the formation oil flowing through the upper production tubing.