GB2549365A

GB2549365A - Improved lift system for use in the production of fluid from a well bore

Info

Publication number: GB2549365A
Application number: GB1701699.9A
Authority: GB
Inventors: Najam Ali Beg Mirza
Original assignee: Caltec Ltd
Current assignee: Caltec Ltd
Priority date: 2016-04-14
Filing date: 2017-02-02
Publication date: 2017-10-18
Anticipated expiration: 2037-02-02
Also published as: GB2549365B; GB201701699D0

Abstract

A lift system for use in the production of fluid from a well bore 13. The system includes the well bore 13 and a surface jet pump 10. Where the surface jet pump 10 receives fluid from the well bore to a low pressure input 15 of the jet pump and a high pressure fluid source 11 provides motive flow to a high pressure input of the surface jet pump. The system also features an artificial lift apparatus 14 located at or near the bottom of the well bore 13. Optionally, artificial lift apparatus is electrical submersible pump, plunger lift, velocity string, soap injection and/or downhole jet pump. Optionally, the high pressure fluid source is provided by the electrical submersible pump. Where the low pressure input of the surface jet pump is used to draw casing gas from the well bore, thus lowering casing pressure and enabling a liquid level in the well bore to rise and cover the electrical submersible pump for pumping.

Description

Improved Lift System for use in the Production of Fluid from a Well Bore

The present invention relates to an improved lift system for improving production from oil or gas wells, particularly those that incorporate artificial lift methods.

Background to the Invention

The use of artificial lift, to improve the rise of fluid from an oil or gas well is known, however, sometimes such systems fail or are put under excessive strain because of inadequacy of the system, which could cause them to be less effective in boosting production. The present invention seeks to propose improvements to such systems.

There are many ways for reducing wellhead pressure, such as using multiphase pumps, but each solution is different and has its own unique features. The only common factor is that all boosting systems reduce the flowing wellhead pressure. For example, WO 2011/025590 relates to the use of jet pumps downhole and is particularly suited for improving the production of heavy oil. In this case, by using light oil or diluents as the motive flow, the viscosity of the heavy oil is reduced which helps to reduce pressure losses along the well bore. The system is downhole, i.e. with no use of a surface apparatus to reduce wellhead pressure.

Surface jet pumps are well known. For example, EP0717818 relates to the use of surface jet pump where flow from a high pressure oil well is used to reduce the back pressure on low pressure wells. However, in this document the source of motive flow is a high pressure well and the low pressure well is not gas lifted.

Summary of the Invention

The present invention herein is an extension and/or development upon the system described by WO2013124625 (corresponding to the granted UK Patent No. 2499473). For example, in the present invention an artificial lift method such as ESP (electrical submersible pump), plunger lift, velocity string, soap injection and downhole jet pump can be placed at or near the bottom of a well to help weak wells to flow. If a surface jet pump (such as described by EP0717818) is used at the topside level to reduce back pressure on the wellhead, a similar benefit as WO2013124625 is expected.

In one broad aspect of the invention there is provided an improved lift system according to claim 1.

In principle the gas lift system is intended for use in the production of fluid from a well bore and includes an artificial lift apparatus located at or near the bottom of a well bore; a surface jet pump receives fluid from the well bore and a high pressure fluid source provides fluid power to a surface jet pump in order to reduce back pressure on the well.

Preferably the artificial lift apparatus is selected from an electrical submersible pump, plunger lift, velocity string, soap injection and/or downhole jet pump, depending on a number of factors such as well depth, well profiles, well inflow characteristics and the gas volume fraction (GVF) of produced fluids.

The use of a surface jet pump (SJP) is a cost effective and simple solution and, particularly, by implementing the invention, the flow regime improves within the well bore because the produced fluids flow at a lower pressure and therefore at a higher apparent velocity and volumetric flow rate.

Preferably, the motive HP flow for the SJP could be one of the following: HP gas; HP oil or gas from one or more HP wells; HP liquid phase (oil or water). This HP liquid may be from an available HP source such as injection water or export oil, the pressure of which has been boosted for other reasons.

Brief Description of the Drawings

Figure 1 illustrates a general schematic view of a surface lift system implemented according to a first embodiment of the invention;

Figure 2 illustrates a second embodiment of a surface lift system implemented according to the invention;

Figure 3 illustrates a third embodiment of a surface lift system implemented according to the invention;

Figure 4 illustrates a fourth embodiment of a surface lift system implemented according to the invention;

Figure 5 illustrates a fifth embodiment of a surface lift system implemented according to the invention;

Figure 6 illustrates a sixth embodiment of a surface lift system implemented according to the invention; and

Figure 7 illustrates a seventh embodiment of a surface lift system implemented according to the invention.

Detailed Description of the Invention A SJP (Surface Jet Pump) has been used to reduce back pressure on wells, manifold, and separators. Referring to Figure 1, it is now proposed to use a surface jet pump 10 in combination with a well 13 which produces with the aid of an artificial lift method 14; e.g. ESP, plunger, jet pump, hydraulic pump, soap injection, chemicals, etc. A fluid source 11 provides fluid power to a surface jet pump which is used to further optimise output production 12. The SJP10 is used to pull the wellhead/separator pressure down on the well(s) 13 via its low pressure line 15, to allow the well to produce and also to reduce the duty of the artificial lift method 14.

Fig. 2 illustrates an artificial lift system in the form of a downhole jet pump 14 powered by a gas line 16 output from a compressor 17, to lift fluids from the well bore 13. In this arrangement a surface jet pump 10 is used to pull the pressure down on the wells, powered by liquid 11, i.e. there are two jet pumps working together, thereby reducing the amount of HP gas 16 needed for the downhole jet pump. The reduced amount of gas for feeding the downhole jet pump could be as a result of shortage of as on a site.

Fig. 3 illustrates a downhole jet pump 14 powered by a liquid line 16 from a pump 18. A surface jet pump 10 is used to pull the pressure down on the well(s) 13, powered by either gas or liquid 11. Again, this configuration features two jet pumps working together, thereby reducing the amount of HP liquid 16 needed for downhole jet pump 14.

Fig. 4 illustrates a first series (one or more) of downhole ESPs 19 providing high pressure fluid power 11 to a surface jet pump 10 which is connected, by its low pressure line 15, to another well where the ESP 20 is not performing or broken down. The SJP 10 is used to pull the wellhead pressure down on the well(s) 13, to allow the well 13 to produce.

Fig. 5 illustrates a configuration where another surface fluid source provides fluid power 11 to a surface jet pump 10 which is used on at least one well 13 where an ESP 20 is not performing or broken down. The SJP 10 is used to pull the wellhead pressure down on the well(s) 13, to allow a well to produce and also to reduce the duty of ESP 19.

Fig. 6 illustrates a configuration where a downhole ESP 19 provides fluid power 11 to the high pressure input of a surface jet pump 10, which is used to draw casing gas into its low pressure input 15 from the same well 13, thus lowering casing pressure. This in turn allows liquid level in the wellbore to rise to help ESP 19 for pumping. The SJP also enables the casing gas pressure to be commingled with the fluids from well 13.

In a further embodiment, Fig. 7 illustrates a first downhole ESP 19 in a first well 13 providing fluid power 11 to a surface jet pump 10 which is used on a second well 21 to draw its casing gas via the low pressure input 15 thus lowering casing pressure. The other well 21 may or may not have an ESP.

It will be apparent that the system of the invention can be assembled from available oil production components at a well site. Alternatively, the components can be manufactured for specific compatibility, i.e. tuned to cooperate with each other for best performance.

In all cases, where reference is made to an ESP downhole, the ESP can be other types of downhole boosting system such as progressive cavity pumps (PCP) or other artificial lift systems.

Claims

Claims:

1. Improved lift system for use in the production of fluid from a well bore, including: a well bore; a surface jet pump receiving fluid from the well bore to a low pressure input of the jet pump; a high pressure fluid source for providing motive flow to a high pressure input of the surface jet pump; an artificial lift apparatus located at or near the bottom of the well bore.

2. The improved lift system of claim 1 wherein the artificial left apparatus is selected from: an electrical submersible pump, plunger lift, velocity string, soap injection and/or downhole jet pump.

3. The improved lift system of claim 1 or 2 wherein the motive flow for the high pressure input is selected from: HP gas; HP oil or gas from one or more HP wells; HP liquid phase (oil or water).

4. The improved lift system of any preceding claim wherein the artificial left apparatus is a downhole jet pump.

5. The improved lift system of claim 4 wherein a high pressure motive flow to the downhole jet pump is provided by a compressor or pump.

6. The improved lift system of any preceding claim 1 to 3 wherein the artificial left apparatus is an electrical submersible pump.

7. The improved lift system of claim 6 wherein there is a first series of downhole electrical submersible pumps providing the high pressure fluid source, and wherein the low pressure input is connectable to a well bore where an electrical submersible pump is not performing or broken down.

8. The improved lift system of claim 6 wherein the surface jet pump is connectable at the low pressure input to a plurality of well bores, wherein at least one of the well bores includes an electrical submersible pump that is not performing or broken down.

9. The improved lift system of claim 6 wherein the high pressure fluid source is provided by the electrical submersible pump and the low pressure input of the surface jet pump is used to draw casing gas from the well bore, thus lowering casing pressure and enabling a liquid level in the well bore to rise and cover the electrical submersible pump for pumping.

10. The improved lift system of claim 6 wherein the high pressure fluid source is provided by an electrical submersible pump from a second well bore and the low pressure input of the surface jet pump is used on the (first) well bore to draw its casing gas, thus lowering casing pressure.