Method and system for preventing clathrate hydrate blockage formation in flow lines by enhancing water cut

Abstract

The present invention includes a method for inhibiting hydrate formation blockage in a flow line used to transport hydrocarbon containing fluids. Water is added to a hydrocarbon containing fluid to produce a water cut enhanced hydrocarbon containing fluid. Salt may be added to the hydrocarbon containing fluids as well. Hydrate formation blockage is inhibited from forming within the flow line by the addition of the water and / or the salt. Sufficient water may be added such that the hydrocarbon containing fluid is converted from a water in oil emulsion to a water continuous emulsion. A system for preventing the formation of hydrate blockage in conduits is also provided. The system includes a flow line for transporting a hydrocarbon containing fluid and a water injection conduit fluidly connected to the flow line to add water to the flow line to increase the water cut of a hydrocarbon containing fluid flowing through the flow line. A salt dispenser may also be included which is used to increase the salinity of the hydrocarbon containing fluid. The system may further include a water separator to separate hydrocarbons from water which receives fluids from the flow line. The flow line, water separator and water injection conduit may cooperate to form a loop wherein water from the flow line may be separated by the water separator and a portion of the separated water is delivered back to the water injection conduit to be reinjected into the flow line.

Description

TECHNICAL FIELD [0001] The present invention relates to preventing the formation of clathrate hydrate blockages in flow lines or conduits carrying hydrocarbons. BACKGROUND OF THE INVENTION [0002] Clathrate hydrate plug formation in oil and gas pipelines is a severe problem for the petroleum industry. When water is produced along with gas, oil, or mixtures of both, under the right pressure and temperature conditions, there is a potential to form a solid hydrate phase. Pressure-temperature conditions favorable for hydrate formation are commonly encountered during the winter in fields onshore and in shallow water depths offshore, and regularly in deepwater (>1,500 feet water depth) fields offshore. As a rule of thumb, at a seafloor temperature of about 40° F. for water depths greater than 3,000 feet, hydrates can form in a typical natural gas pipeline at pressures as low as 250 psi. As solid hydrates form, the hydrates can deposit on the pipe walls or agglomerate into larger solid m...

AI Technical Summary

Benefits of technology

[0007] Preferably, the resulting water cut enhanced hydrocarbon containing fluid is water continuous. Sufficient water may be added such that the hydrocarbon containing fluid is inverted from a water in oil emulsion to a water continuous emulsion state thereby decreasing emulsion viscosity and reducing pressure drop in the flow line.

[0012] The system may further include a water separator to separate water from hydrocarbons received from the flow line. The flow line, water separator and water injection conduit may cooperate to form a partially closed loop wherein water from the flow line may be separated by the water separator and delivered back to the water injection conduit to be reinjected into the flow line to enhance the water cut of the hydrocarbon containing fluid.

[0013] It is an object of the present invention to provide a method and system to address multiple flow assurance issues (hydrate inhibition, emulsion viscosity / stability, system thermal performance, and system hydraulic performance) through a simple, cost-effective, and environmentally friendly strategy.

[0014] It is another object to provide a method for multiphase production of crude oil and natural gas wherein hydrocarbon containing fluids are transported through a flow line at unconventionally high water cuts to thereby reduce hydrate blockages in the flow line relative to using hydrocarbon containing fluids having a lower water cut.

Problems solved by technology

Further, sufficient water may be added to the original hydrocarbon containing fluid such that there is an excess of the water phase relative to the hydrocarbon phase such that hydrate formation is self limiting.

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