GB2526820A

GB2526820A - System and process for pumping fluids

Info

Publication number: GB2526820A
Application number: GB1409859.4A
Authority: GB
Inventors: Mirza Najam Ali Beg; Mir Mahmood Sarshar
Original assignee: Caltec Ltd
Current assignee: Caltec Ltd
Priority date: 2014-06-03
Filing date: 2014-06-03
Publication date: 2015-12-09
Anticipated expiration: 2034-06-03
Also published as: GB2526820B; GB201409859D0

Abstract

A system for pumping fluids comprises a fluid separator 24 having an inlet for a mixture of HP (high pressure) fluids, a first outlet for gas-rich HP fluid, and a second outlet for liquid-rich HP fluid. A booster pump 26 is connected to receive liquid-rich HP fluid from the separator and increase the pressure of the fluid. A jet pump 28 has a HP inlet connected to receive liquid-rich VHP (very high pressure) fluid from the booster pump, a LP (low pressure) inlet configured to receive a mixture of LP fluids, and an outlet for a second mixture of HP fluids. The jet pump 28 is configured to combine the liquid-rich VHP fluid with the mixture of LP fluids, so that the second mixture of HP fluids is at a pressure between the pressure of the liquid-rich VHP fluid and the mixture of LP fluids.

Description

SYSTEM AND PROCESS FOR PUMPING FLUIDS

The present invention relates to a system and process for pumping fluids, and in particular but not exclusively to a system and process for sustainable oil production boosting.

Under previous patents by Caltec for a pumping system known as the WELLCOMTM system, energy from one or more high pressure wells is used to lower the back pressure on one or more low pressure wells. This system is covered under patent number US 6162021.

A further system is known in which gas and liquids from selected low pressure (LP) wells are separated and a single phase booster pump is installed on the LP liquid outlet line of the system in order to boost its pressure to higher values, and feed the boosted liquid phase to a surface jet pump as the motive flow. The jet pump in this case boosts the pressure of the separated LP gas to that demanded by the downstream system. This solution, which uses both a jet pump and a booster pump, has the trade name of W[LLCOM BOOSTTM and is described as prior art in patent number US 8257055.

Both systems, whilst being effective and very cost effective, and offering a number of advantages, also suffer from weaknesses. In the case of the WELLCOMTM system, the pressure of the high pressure (HP) well is not sustainable for ever and after a period it will not be as effective as it was in the early days of its application when the wellhead pressure of the HP well was high and typically at least twice to three times the pressure of the LP wells. In the case of the WELLCOM BOOSTTM system, the liquid flow rate of the LP well could drop significantly with time, thus restricting the motive liquid flow rate.

There are also cases where from day one the production pressure of the HP well is not high enough and is below the desired value for successful operation of the WELLCOMTM system, which should typically be above twice that of the LP well in order to achieve an acceptable level of boost in the pressure of the LP fluids.

It is an object of the present invention to provide a system and process for pumping fluids that mitigates one or more of the aforesaid problems.

According to one aspect of the present invention there is provided a system for pumping fluids comprising: a. a fluid separator having a separator inlet configured to receive a first mixture of HP (high pressure) fluids, a first separator outlet for gas-rich HP fluid, and a second separator outlet for liquid-rich HP fluid; b. a booster pump having a pump inlet connected to the second separator outlet to receive liquid-rich HP fluid from the fluid separator, and a pump outlet for liquid-rich VHP (very high pressure) fluid, the booster pump being configured to increase the pressure of the liquid-rich fluid such that the pressure of the liquid-rich VHP fluid at the pump outlet is greater than the pressure of the liquid-rich HP fluid at the pump inlet; and c. a jet pump having a HP jet pump inlet connected to the booster pump outlet to receive liquid-rich VHP fluid from the booster pump, a LP jet pump inlet configured to receive a mixture of LP (low pressure) fluids, and a jet pump outlet for a second mixture of HP fluids, the jet pump being configured to combine the liquid-rich VHP fluid with the mixture of LP fluids, such that the second mixture of HP fluids at the jet pump outlet is at a pressure between the pressure of the liquid-rich VHP fluid and the mixture of LP fluids.

The booster pump is preferably configured such that the pressure of the liquid-rich VHP fluid at the pump outlet is significantly greater than the pressure of the liquid-rich HP fluid at the pump inlet. Typically, the pressure of the liquid-rich VHP fluid at the pump outlet is at least twice the pressure of the liquid-rich HP fluid at the pump inlet, and may be three or more times that pressure. For example the pressure difference between the outlet and the inlet fluids may be greater than 20 bar and preferably greater than 30 bar, and is typically about 40 bar.

The system makes it possible to maintain production from LPwells, even lithe pressure of the high pressure (HP) well is not sustainable and falls below the value required to maintain production from the LP well, which is typically at least twice to three times the pressure of the LP wells. The system also allows production from the LP well to continue, S even if the liquid flow rate of the LP well falls significantly. The flow rate of the liquid-rich HP fluid is usually greater than the flow rate of the LP fluids and is typically approximately twice as great.

Advantageously, the booster pump is a positive displacement pump. Alternatively, any other suitable pump that can tolerate the presence of some gas in the liquid rich fluid may be used.

Advantageously, the fluid separator is a cyclonic separator, preferably a uniaxial cyclonic separator. However, it may alternatively be any other suitable kind of separator including, for example, a test separator, a production separator or a gravity separator.

Advantageously, the system includes a commingling device having a first inlet configured to receive the gas-rich HP fluid from first separator outlet, a second inlet configured to receive the second mixture of HP fluids from the jet pump outlet, and an outlet for a third mixture of HP fluids, wherein the commingling device is configured to combine the gas-rich HP fluid with the second mixture of HP fluids to form the third mixture of HP fluids. Any suitable type of commingling device may be used.

As an example, the first mixture of HP fluids may have a pressure of at least 30 barg, preferably about 40 barg.

Typically, the liquid-rich VHP fluid has a pressure of at least 70 barg, preferably about barg.

The mixture of LP fluids may have a pressure of less than 30 barg, preferably about 20 barg.

As an example, the pressure of the liquid-rich VHP fluid may be at least twice, preferably at least three times, the pressure of the mixture of LP fluids The second mixture of HP fluids may have a pressure of at least 25 barg, preferably about 30 barg.

As an example, the discharge pressure of the jet pump may be higher than the pressure of the LPfluids by at least 10 bar, preferably at least 20 bar.

Advantageously, the system is part of an oil/gas production installation, the first mixture of HP fluids is produced by one or more HP wells and the mixture of LP fluids is produced by one or more LP wells.

According to another aspect of the invention there is provided a process for pumping fluids comprising: a. receiving a first mixture of HP (high pressure) fluids and separating the first mixture of HP fluids into a gas-rich HP fluid and a liquid-rich HP fluid; b. increasing the pressure of the liquid-rich fluid using a booster pump to provide a liquid-rich VHP (very high pressure) fluid having a pressure greater than the pressure of the liquid-rich HP fluid; and c. supplying the liquid-rich VHP fluid to a HP jet pump inlet of a jet pump, d. supplying a mixture of LP (low pressure) fluids to a LP jet pump inlet of the jet pump, and e. combining the liquid-rich VHP fluid with the mixture of LP fluids in the jet pump, to form a second mixture of HP fluids at an outlet of the jet pump outlet, wherein the second mixture of HP fluids is at a pressure between the pressure of the liquid-rich VHP fluid and the mixture of LP fluids.

Advantageously, the process includes combining the gas-rich HP fluid with the second mixture of HP fluids in a commingling device, to form a third mixture of HP fluids.

Advantageously, the first mixture of HP fluids has a pressure of at least 30 barg, preferably about 40 barg.

Advantageously, the liquid-rich VHP fluid has a pressure of at least 70 barg, preferably about 80 barg.

Advantageously, the mixture of LP fluids has a pressure of less than 30 barg, preferably about 20 barg.

Advantageously, the second mixture of HP fluids at the outlet of the jet pump has a pressure of at least 25 barg, preferably about 30 barg.

Advantageously, the process is part of an oil/gas production process, the first mixture of HP fluids is produced by one or more HP wells and the mixture of LP fluids is produced by one or more LP wells.

To overcome the shortcomings described above, a novel solution is adopted, which is the subject of this patent. In this case the flow from the selected HP wells is first passed through a gas-liquid separator to separate HP gas and liquids. The separator can be of any type, but advantageously can be the patented lSEPTM compact separator (patent no. US 6398973), which has a number of advantages such as compactness and requiring no level control or active pressure control, which is ideal for remote areas or unmanned platforms or subsea applications.

The separated HP liquid phase is then boosted further by a single phase pump. The boosted liquid phase is then fed to the jet pump as the motive flow. The jet pump in this case can receive the entire [P flow from the selected LP wells. The pressure of the [P flow is then boosted to a higher pressure demanded by the downstream production and processing system.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 (Case 1) is a schematic representation of a pumping system according to an embodiment of the invention, and Figure 2 (Case 2) is a schematic representation of a prior art pumping system of the WELLCOM BOOSTTM type, as described as prior art in patent number US 8257055.

Referring first to the prior art pumping system of the WELLCOM BOOSTTM type that is shown in Figure 2, this is configured to receive a LP multiphase gas and oil mixture from one or more [P wells through an inlet line 2. The mixture is supplied to a separator 4, which in this case is a compact cyclonic type separator of the type sold under the trade name lSEPTM, which is the subject of patent no. US 6398973). The gas and liquid phases are separated by the separator 4 and a booster pump 6 is used to boost the pressure of the LP liquid phase. This boosted liquid phase is fed to the HP inlet ofajet pump 8 and S is used as the motive flow. The separated LP gas is fed through a bypass line 10 to the LP inlet of the jet pump 8. The pressure of the LP gas is boosted by the jet pump 8 to deliver a gas/liquid mixture into a pipeline 12 at the required discharge pressure.

Referring now to the new pumping system shown in Figure 1, this is configured to receive a first HP multiphase gas and oil mixture from one or more HP wells through a manifold 20 and an inlet line 22. The mixture is supplied to a separator 24, which in this case is a unidirectional compact cyclonic separator of the type sold under the trade name lSEPTM and described in patent no. US 6398973). Alternatively, the separator may be a reverse flow cyclonic separator or a gravity separator. The gas and liquid phases are separated by the separator 24 and supplied to a first separator outlet 25a for gas-rich HP fluid, and a second separator outlet 25b for liquid-rich HP fluid.

A booster pump 26 is used to boost the liquid phase to a higher pressure, which we call a very high pressure (VHP). This boosted VHP liquid phase is fed to the HP inlet 27a of a jet pump 28 and is used as the motive flow. The LP inlet 27b of the jet pump 28 is configured to receive a LP multiphase gas and oil mixture from one or more LP wells through an inlet line 30. The pressure of the LPgasJliquid mixture is boosted by the jet pump 28 to deliver at jet pump outlet 31 a second HP gas/liquid mixture, which is discharged into a pipeline 32 at the required discharge pressure. The HP gas separated by the separator 24 is optionallyfed from the first separator outlet 25a through a bypass line 34 to a commingling device 36, where it is combined with the second HP gas/liquid mixture to form a third HP gas/liquid mixture in outlet line 38, downstream of the outlet 31 of the jet pump 28. Alternatively, the HP gas separated by the separator 24 may be delivered from the first separator outlet 25a to a separate HP gas outlet (not shown).

To demonstrate the benefit of the solution provided by the present invention, Table 1 below shows two cases where a booster pump is used. Case 2 relates to the earlier WELLCOM BOOSTTM system as shown in Fig. 2, which can boost the pressure of [P fluids from 20 barg to 30 barg. In this case the booster pump 6 boosts the pressure of the LP liquid phase from 20 barg to9S barg.

In case 1, comprising an embodiment of the invention as shown in Fig. 1 the separated HP liquid phase is further boosted by booster pump 26 from 40 bar to 80 barg and as a result the jet pump 28 can boost the pressure of the entire LP flow from 20 to 30 barg.

In both cases the power requirement of the booster pump 6,26 is similar. However, if the booster pump 26 in case 1 boosts the pressure of the liquid phase to 90 barg instead of 80 barg the system can drop the back pressure on the [P wells further below 20 barg, which helps to increase production further. The system described in the present patent application therefore has a major advantage of prolonging the use of the production boosting system, even if the pressures of both the HP and the LP sources are not sustainable in the long term.

A further benefit of this solution is that sometimes in case 2 (Fig. 2) the LP well cannot produce initially and is shut in, and therefore there are no LP liquids available to feed the booster pump 6. However, in case 1 (Fig. 1) this problem does not arise, as the HP liquids are drawn from producing HP wells.

The flow rate of the liquid-rich HP fluid, which is used as the motive fluid in the jet pump, is usually greater than the flow rate of the LP fluids. In Case 1, shown in Table 1, the flow rate of the liquid-rich HP fluid is S000bbl/d, which is twice the flow rate of the LP fluids (2500bb1/d).

Claims

CLAIMS1. A system for pumping fluids comprising: a. a fluid separator having a separator inlet configured to receive a first mixture of HP (high pressure) fluids, a first separator outlet for gas-rich HP fluid, and a second separator outlet for liquid-rich HP fluid; b. a booster pump having a pump inlet connected to the second separator outlet to receive liquid-rich HP fluid from the fluid separator, and a pump outlet for liquid-rich VHP (very high pressure) fluid, the booster pump being configured to increase the pressure of the liquid-rich fluid such that the pressure of the liquid-rich VHP fluid at the pump outlet is greater than the pressure of the liquid-rich HP fluid at the pump inlet; and c. a jet pump having a HP jet pump inlet connected to the booster pump outlet to receive liquid-rich VHP fluid from the booster pump, a LP jet pump inlet configured to receive a mixture of LP (low pressure) fluids, and a jet pump outlet for a second mixture of HP fluids, the jet pump being configured to combine the liquid-rich VHP fluid with the mixture of LP fluids, such that the second mixture of HP fluids at the jet pump outlet is at a pressure between the pressure of the liquid-rich VHP fluid and the mixture of LP fluids.
2. A system according to claim 1, wherein the booster pump is a positive displacement pump.
3. A system according to claim 1 or claim 2, wherein the fluid separator is a cyclonic separator.
4. A system according to claim 3, wherein the fluid separator is a uniaxial cyclonic separator.
5. A system according to any one of claims ito 4, including a commingling device having a first inlet configured to receive the gas-rich HP fluid from first separator outlet, a second inlet configured to receive the second mixture of HP fluids from the jet pump outlet, and an outlet for a third mixture of HP fluids, wherein the commingling device is configured to combine the gas-rich HP fluid with the second mixture of HP fluids to form the third mixture of HP fluids.
6. A system according to any one of claims ito 5, wherein the first mixture of HP fluids has a pressure of at least 30 barg, preferably about 40 barg.
7. A system according to any one of claims ito 6, wherein the liquid-rich VHP fluid has a pressure of at least 70 barg, preferably about 80 barg.
8. A system according to any one of claims ito 7, wherein the mixture of LP fluids has a pressure of less than 30 barg, preferably about 20 barg.
9. A system according to any one of claims ito 8, wherein the pressure of the liquid-rich VHP fluid is at least twice, preferably at least three times, the pressure of the mixture of LP fluids.
10. A system according to any one of claims 1 to 9, wherein the second mixture of HP fluids has a pressure of at least 25 barg, preferably about 30 barg.
11. A system according to any one of claims i to 10, wherein the system is part of an oil/gas production installation, the first mixture of HP fluids is produced by one or more HP wells and the mixture of LP fluids is produced by one or more LP wells.
12. A process for pumping fluids comprising: a. receiving a first mixture of HP (high pressure) fluids and separating the first mixture of HP fluids into a gas-rich HP fluid and a liquid-rich HP fluid; b. increasing the pressure of the liquid-rich fluid using a booster pump to provide a liquid-rich VHP (very high pressure) fluid having a pressure greater than the pressure of the liquid-rich HP fluid; and c. supplying the liquid-rich VHP fluid to a HP jet pump inlet ofajet pump, d. supplying a mixture of LP (low pressure) fluids to a LPjet pump inlet of the jet pump, and e. combining the liquid-rich VHP fluid with the mixture of LP fluids in the jet pump, to form a second mixture of HP fluids at an outlet of the jet pump outlet, wherein the second mixture of HP fluids is at a pressure between the pressure of the liquid-rich VHP fluid and the mixture of LP fluids.
13. A process according to claim 12, including combining the gas-rich HP fluid with the second mixture of HP fluids in a commingling device, to form a third mixture of HP fluids.
14. A process according to any one of claims 12 to 13, wherein the first mixture of HP fluids has a pressure of at least 30 barg, preferably about 40 barg.
15. A process according to any one of claims 12 to 14, wherein the liquid-rich VHP fluid has a pressure of at least 70 barg, preferably about 80 barg.
16. A process according to any one of claims 12 to 15, wherein the mixture of LP fluids has a pressure of less than 30 barg, preferably about 20 barg.
17. A process according to any one of claims 12 to 16, wherein the second mixture of HP fluids has a pressure of at least 25 barg, preferably about 30 barg.
18. A process according to any one of claims 12 to 17, wherein the process is part of an oil/gas production process, the first mixture of HP fluids is produced by one or more HP wells and the mixture of [P fluids is produced by one or more [P wells.