Subsea barrier fluid system

Abstract

The invention provides an autonomous subsea barrier fluid system for a subsea pressure booster, the subsea pressure booster comprising a process fluid compartment, a motor compartment and a rotor assembly extending from the motor compartment into the process fluid compartment with one or several shaft seals separating the process fluid from the barrier fluid in the motor compartment. The subsea barrier fluid system is distinguished in that it comprises: a subsea barrier fluid pump, a barrier fluid delivery line, arranged between the barrier fluid pump and the motor compartment, a pressure controlled regulator, operatively arranged to at least one of the barrier fluid delivery line and the subsea barrier fluid pump, a subsea barrier fluid storage, and a barrier fluid suction line arranged from the subsea barrier fluid storage to the subsea barrier fluid pump.

Claims

1. A subsea barrier fluid system for a subsea pressure booster, the subsea pressure booster comprising a subsea pressure booster process fluid compartment, a motor compartment and a rotor assembly extending from the motor compartment into the subsea pressure booster process fluid compartment with one or several shaft seals separating a process fluid from a barrier fluid in the motor compartment, the subsea barrier fluid system comprising: a subsea barrier fluid pump; a barrier fluid delivery line that is arranged between the subsea barrier fluid pump and the motor compartment; a pressure-controlled regulator, wherein the pressure-controlled regulator is operatively arranged to one of: the barrier fluid delivery line that controls a delivery of the barrier fluid to the motor compartment; and the subsea barrier fluid pump; a subsea barrier fluid storage; a barrier fluid suction line arranged from the subsea barrier fluid storage to the subsea barrier fluid pump; wherein the subsea barrier fluid system is autonomous in that it consists merely of subsea barrier fluid equipment without topsides equipment for barrier fluid supply and without a barrier fluid delivery bore in an umbilical from topsides to the subsea barrier fluid system; a reference pressure line or device that controls the pressure-controlled regulator and is operatively arranged between the subsea pressure booster process fluid compartment and the pressure-controlled regulator; a barrier fluid return line coupled to the pressure-controlled regulator or the barrier fluid delivery line; and wherein the subsea barrier fluid storage is coupled to receive the barrier fluid from the barrier fluid return line.

2. The subsea barrier fluid system according to claim 1, wherein the pressure-controlled regulator is a PVR.

3. The subsea barrier fluid system according to claim 1, wherein the pressure-controlled regulator is an electromechanical device.

4. The subsea barrier fluid system according to claim 1, wherein the pressure-controlled regulator is set to provide an overpressure in the motor compartment over the subsea pressure booster process fluid compartment.

5. The subsea barrier fluid system according to claim 1, wherein the subsea barrier fluid storage comprises a pressure compensation arrangement.

6. The subsea barrier fluid system according to claim 4, wherein: the subsea barrier fluid storage comprises a pressure compensation arrangement, wherein the pressure compensation arrangement adjusts the pressure of the subsea barrier fluid system; and the pressure compensation arrangement adjusts a pressure of the subsea barrier fluid storage to be equal to the lowest pressure of the subsea pressure booster process fluid compartment or the ambient subsea pressure.

7. The subsea barrier fluid system according to claim 4, wherein the overpressure is 5-50 bar overpressure.

Description

FIGURE

(1) FIG. 1 illustrates an embodiment of a subsea barrier fluid system of the invention.

(2) FIG. 1A1 illustrates a further detail of the system illustrated on FIG. 1.

(3) FIG. 1A2 illustrates an alternative or additional further detail of the system illustrated on FIG. 1.

(4) FIG. 2 illustrates a simpler embodiment of a subsea barrier fluid system of the invention.

(5) FIG. 2A1 illustrates a further detail of the system illustrated on FIG. 2.

DETAILED DESCRIPTION

(6) With reference to FIG. 1, a subsea barrier fluid system 1 for a subsea pressure booster 2 is illustrated, the subsea pressure booster comprising a process fluid compartment 3 and a motor compartment 4. Further, the system comprises a subsea barrier fluid pump 5 (Subsea HPU); a barrier fluid delivery line 6, arranged between the barrier fluid pump 5 and the pressure booster motor compartment. A pressure controlled regulator 7a is operatively arranged in or to the subsea barrier fluid pump 5. A reference pressure line 9a or device is operatively arranged between the barrier fluid delivery line and the pressure controlled regulator 7a. A pressure controlled regulator 7b is operatively arranged in the barrier fluid delivery line. An accumulator bank 8 is operatively arranged to the subsea barrier fluid delivery line; a reference pressure line 9b or device is operatively arranged between the subsea pressure booster process fluid compartment and the pressure controlled regulator. A barrier fluid return line 10 is coupled to the pressure controlled regulator and a subsea barrier fluid storage 11, is arranged to return barrier fluid from the barrier fluid delivery line at excessive overpressure. A barrier fluid suction line 12 is arranged from the subsea barrier fluid storage to the subsea barrier fluid pump.

(7) FIG. 1A1 illustrates a further detail of the system illustrated on FIG. 1, namely a pressure compensator 13 to sea, arranged to the subsea barrier storage 11. FIG. 1A2 illustrates an alternative or additional further detail of the system illustrated on FIG. 1, namely a pressure compensator 13 arranged between the subsea barrier fluid storage 11 and the reference pressure line 9b or the pressure booster process compartment.

(8) Reference is made to FIG. 2, illustrating a simpler embodiment of the system of the invention, feasible for less demanding subsea pressure booster arrangements, such as water injection systems or other systems with relatively stationary pressure conditions. Identical or similar features have the same reference numerical as for FIG. 1. The simplified system illustrated on FIG. 2 has no barrier fluid return line and no reference pressure line or device 9b. In FIG. 2A1 a pressure compensator 13 to sea is illustrated, as arranged to the subsea barrier fluid storage 11.