WO2015123736A1

WO2015123736A1 - Subsea system for injection of seawater by means of a submerged centrifugal pump

Info

Publication number: WO2015123736A1
Application number: PCT/BR2014/000052
Authority: WO
Inventors: Carlos Eduardo MAIA DE SOUZA; Rene Thiago CAPELARI ORLOWSK
Original assignee: Petróleo Brasileiro S.A. - Petrobras
Priority date: 2014-02-19
Filing date: 2014-02-19
Publication date: 2015-08-27

Abstract

Subsea system for injection of seawater by means of a submerged centrifugal pump, more especially relating to a subsea system for injection of water into aquifers of petroleum or gas reservoirs requiring a secondary recovery method using water injection. The system is formed by a capture tube (2) that includes and keeps longitudinally aligned the pumping unit formed by a submerged centrifugal pump (1), a motor (11), a screen (3) or filters (6) and (8) or (9) and a flow measuring device (14). The stream of water is filtered through the screen (3) or filter (6) and then through the filter (8) or (9), and then flows towards the suction side of the submerged centrifugal pump (1). The suction side of the submerged centrifugal pump (1) is isolated from the discharge by means of a discharge pipe (12) or by means of a jacket (10). The capture tube (2) is able to float by means of a flotation device (4) and tethers (7) or is connected to/mounted directly onto the subsea tree (22); an ROV panel (19) is provided for connection of power cables and hoses for injection of chemicals, where necessary, and also comprises interfaces for valve operation. The speed of the motor (11), and consequently the flow and discharge pressure thereof are controlled by means of a speed-varying device (20) arranged externally to the capture tube (2). The present invention is mainly intended for use in injector wells where the injection of untreated seawater does not cause undesirable damage to the formation. The application thereof is directly linked to a reduction in water-injection plants installed on floating units.

Description

SUBMARINE SEA WATER INJECTION SYSTEM BY SUBMERSE CENTRIFUGAL PUMP FIELD OF THE INVENTION

The present invention relates to subsea seawater injection system by means of specially developed equipment employing submerged centrifugal pump. This technology is intended for the area of oil exploration and production and the like, specifically in the production of new fields, as a method of injecting water into oil or gas reservoir aquifers that require a secondary recovery method through water injection. Its full use is mainly intended for injection wells where the injection of untreated seawater does not cause undesired formation damage. Its application is directly linked to the reduction of water injection plants installed in floating units. BACKGROUND OF THE INVENTION

It is well known that during the operating time of a hydrocarbon production well pressure drop is common, ie at some point there will be insufficient underground pressure to force the oil to the surface. To assist in maintaining the extraction pressure secondary recovery methods are applied. They rely on external power supply to the reservoir in the form of fluid injection to increase reservoir pressure, thus replacing or increasing the reservoir's natural impeller with an artificial medium. To this end, pumps such as electric submersible pumps (ESP), submerged centrifugal pumping (BCS) and others are used to bring oil to the surface.

There are several techniques to make better use of oil reservoirs, which can increasingly increase the recovery of oil from the reservoir. One of these techniques is secondary recovery, used to maintain or increase reservoir pressure. There are virtually two types of secondary recovery: water injection and gas injection. In particular, for the present invention it is stated that the water to be injected may be water taken up or water produced together with the oil. In either case it should be treated. Water can be injected into the oil itself or into the aquifer.

Water injection into the reservoir must be selectively so that water enters the intervals of different permeability which, in this case, is controlled by flow regulators acting independently by interval. In applying secondary recovery it is necessary to determine the injection flow rate of each interval as very high values may fracture the formation.

TECHNICAL STATE ANALYSIS

PI 0904009-9 (Weatherford) refers to a downhole water injection regulator installed in a side pocket chuck to regulate fluid flow in a water injection completion. The regulator is fitted with an internal piston and may be fitted with a retaining dart. The piston and retention dart regulate the flow of fluid within the regulator housing. The seals in the regulator housing block the spindle holes that communicate with a surrounding ring. When initially installed in the mandrel, the blind plug on the regulator lock prevents fluid flow through the regulator so that the regulator acts as a fake valve and allows operators to adjust and test the shutters or perform other operations. To initiate the water injection operation, operators use a cable and winch to remove the blind plug disposed in the lock. With the plug removed, fluid communication from the tubing column can pass through the perforated lock and the regulator where the piston and retention dart regulate fluid flow out of the ring. PI 0708920-1 (Shell) relates to a water injection system and method comprising a well drilled within a subsurface formation; a production facility on one end of the well; a water production facility connected with the production facility; wherein the water production facility produces water by removing some ions and adding an agent that increases water viscosity and / or enhances hydrocarbon recovery from formation and injects water into the well.

Document PI 0404603 (PETROBRAS) deals with a system for capturing and injecting underground aquifer water into hydrocarbon reservoirs, specifically a system for capturing aquifer water wells and injector wells in oil reservoir (petroleum) and one or more bombs.

Document BR PI 0400926 (PETROBRAS) comprises a well drilled in a subsurface formation, a production facility on the upper side of the well with a water production facility connected to the production facility, where the water production facility produces water. by removing some ions and adding an agent that increases water viscosity and / or enhances hydrocarbon recovery from formation by injecting water into the well.

Other documents illustrate BCS applied to tubular equipment, such as in US6382320 (MCDERMOTT MARINE) which deals with the method and system for the offshore production of fluid hydrocarbons, or in GB2347156 (BAKER HUGHES) and others not specifically devoted to the object of this invention. which, however, serve as an example of the state of the art.

CURRENT PROBLEMS

Submerged centrifugal pumping systems - BCS - are not new and have been widely employed within dry completion wells, offshore and onshore, where they are very effective. In these In these cases, its replacement cost is considered cheap in the industry. But a defective pump at the bottom of a wet-completed well can be a production and logistical problem. In addition to pump replacement costs, reliance on resources such as a marine rig, which are not always readily available, can mean production shutdown. The challenge is to increase the reliability of these pumps and to seek alternative arrangements that facilitate intervention when they fail, such as installing the pumps in seabed hosts rather than the producing well.

On the other hand, subsea water injection systems near the seabed capture have several drawbacks and difficulties due to their current configuration. The main difficulty is associated with the complexity of the system and the amount of equipment that needs to be installed. Starting with the first component to install, known as the flowbase. This is responsible for receiving and supporting all other equipment that makes up the submarine pumping station. The flowbase is designed to be accommodated on the seabed and therefore has a geometry foundation structure designed and constructed to maintain the correct leveling of all equipment regardless of the inclines or slopes of the ground. As it is a fixed metal structure, if there is any unforeseen level difference or even a need for relocation of the pumping station, the base structure will need to be modified to adjust to the new ground conditions. This causes major impacts on the project, with delays and increased costs. Another foundation option for the base is to use a torpedo sub-base instead of a fixed base. However, this solution also has other drawbacks as it requires one more installation step prior to launching the flowbase, which entails increased costs. In addition, there is the added cost due to the torpedo structure. After installing the flowbase, the other equipment modules are installed on it, each requiring an installation step. The pump module that houses the powertrain assembly and other equipment has more stringent installation requirements, requiring installation using heave compensators.

Vessels with this type of trim are considered more critical features, having lower availability and higher daily cost. In addition, upon connection, this module requires a series of interconnections with other equipment, which are made through individual cables or hoses and require Remote Operated Vehicle (ROV) assistance for their connections. In addition to the installation cost, the motorcycle pump unit is itself a large piece of equipment that is costly compared to BCS (Submersible Centrifugal Pump) pumps.

Due to the currently adopted configuration for the pumping station, at least five other equipment modules are required, four of which are installed in the flow base and one in the Wet Christmas Tree - ANM. To connect the suction and discharge lines to the pump, three connection modules (either vertical or horizontal) are required, two modules for the line that connects the pump discharge to ANM and the other one that connects the intake line to the suction. of the bomb. These modules are also wired and, due to their size, present difficulties during installation. In addition to the three connection modules, there are two more umbilical termination modules, one for the umbilical power, which takes electrical power from the Floating Unit to the pump and the other to supply hydraulic power required for valve actuation in the subsea station and also barrier fluid supply. Today, barrier fluid represents a major operational and logistical problem. Hoses carrying this fluid in the hydraulic umbilical must be of a special type and require several cleaning steps to preserve fluid quality. In addition, during installation there should be no contamination with water, which makes operation more difficult.

Barrier fluid also requires a supply unit installed in the Floating Unit which also requires more stringent care with regard to the risk of water contamination. The fluid, when restricted to specification, can often be supplied by only one manufacturer, representing a supply problem.

In order to better specify the current situation, below is the list of equipment used to perform water injection with capture near the underwater bed. As already stated, this water injection is made through subsea pumping systems installed in the seabed near the injection AN. The main components for the proper functioning of these systems are:

• Flowbase - Positioned on the seabed, you can use a mud mat type structure designed to accommodate the slope of the ground or even be installed on a torpedo type subbase, which must be pre-nailed. The flow base serves as a guide and housing for the other equipment that makes up the subsea pumping station. There are also pipes that connect the suction and discharge of the pump to the respective connectors of the water collection line to the flow base and the flow base injection line to the ANM.

• Pump module - is the module in which the pump assembly resides, recoverable filter module with backwash system, ROV panel, receptacles with supply, valves, flowmeter and choke. The pump used for water injection is a rotary type centrifugal pump. Connection Modules - Lines that connect the pump station to the ANM and pickup utilize connection modules to connect to the flowbase. These modules can be horizontal or vertical. Traditionally PETROBRAS, now requesting this application, uses hydraulic locking vertical connection modules. At the end of each line is a connection module. The modules that make the line connection between the ANM and the flow base are the pump discharge modules. The module installed at the end of the water intake line connects the latter to the pump suction through the flow base tubing. Umbilical Termination Module (MTU) - To bring the power required to power the electric motor from the motor pump assembly, a power umbilical is required from the Floating Unit to the pump. This umbilical connects to the flowbase through an MTU. Likewise, to bring hydraulic power to actuate and control subsea valves, there is an umbilical that connects a Hydraulic Power Unit (UPH) installed in the Floating Unit to the flow base. This umbilical also has hydraulic lines for the transportation of barrier fluid needed to protect the electric motor. This umbilical is connected to the flowbase via an MTU.

Water catchment line - This is a flexible line that has, at one end, a submerged buoy that elevates it and maintains it to a certain extent in relation to the seabed. At this end the capture is made through an inlet nozzle with sieve and support for fixing on the float. The line then descends and before touching the seabed makes a slight catenary. Part of the line is bottom and goes towards the pump suction connection module.

• Hydraulic Power Units - For seabed pumping systems currently used for water injection, two hydraulic power units are required. One control fluid and one barrier fluid UPH, both installed in the Floating Unit. The former is responsible for the supply of hydraulic fluid for actuation and control of subsea valves, while the latter is responsible for the supply of barrier fluid to the electric motor of the motorcycle pump assembly.

• Variable Speed Driver (VSD) - This surface mounted equipment is responsible for controlling the speed of the pump required for flow adjustment.

• Electrical panels - Surface equipment assemblies include the electrical panels required for pump control and operation.

BRIEF DESCRIPTION OF THE FIGURES

The structure and operation of the invention, together with further advantages thereof, may be better understood by reference to the accompanying drawings and the following description:

Figure 1 represents, in perspective, one of the preferred constructivities for the equipment used in the innovative underwater seawater injection system, which employs a sustaining buoy;

Figures 2, 3 and 4 represent perspectives on alternative constructions of the equipment that employs a buoy;

Figures 5 and 6 illustrate models of the innovative underwater seawater injection system equipment utilizing, instead of the float, a filter applied to the upper end of the intake tube; Figure 7 illustrates, through perspective, the first option for installing innovative equipment on top of the ANM;

Figure 8 represents a second configuration option, where the equipment is installed in the injection chuck; and

Figures 9 and 9A illustrate a third installation configuration where the apparatus is located on a torpedo sub-base with an injection line interconnecting it with the ANM; Figures 9 and 9A illustrate two positioning versions of equipment in the form of a pump set pickup tube used in the present system.

DETAILED DESCRIPTION OF THE INVENTION

While the present invention may be susceptible to different embodiments, a preferred embodiment is shown in the drawings and the following detailed discussion with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention and is not intended to be limited to what is illustrated and described. on here.

This technology is intended for the oil exploration and production area and the like, specifically in the production of new fields, as a method of injecting water into oil or gas reservoir aquifers that require a secondary recovery method by injection of Water. Its full use is mainly intended for injection wells where the injection of untreated seawater does not cause undesired formation damage. Its application is directly linked to the reduction of water injection plants installed in floating units.

According to the present invention, the innovative submersible centrifugal pump pumping water injection system - BCS is formed by an equipment (E1) consisting of a pickup tube (2), consisting of a steel tube of up to 50m and with sufficient diameter to accommodate the main components of the pumping system inserted inside it, which also has a structural function.

The pickup tube (2) is fully open at the upper end (2a) and is partially closed at the lower end (2b) and further receives a guide funnel (2c) surrounding the connector (2d) designed for various assemblies, such as on ANM (22) (figure 7) or base (24) arranged on the sea floor (figures 8 and 9); at the upper end (2a) of the pickup tube and outside it a first filter device is installed which, in one option may be configured by sieve (3) associated with a float (4) (figures 1 to 4) or may be a module (5) provided with a sieve (6) and filter (8) or (9) installed therein (figures 5 and 6), each of which is responsible for trapping larger particles and preventing marine life from entering the interior. pickup tube (2). The float (4) is responsible for the tensioning of the structure or suspension of all equipment (E1) in certain assembly configurations, dealt with below, which tensioning is allowed by means of mooring cables (7). The float (4) is optional as it depends on the arrangement or installation chosen.

Inside the pickup tube (2) is housed a backwash filter (8) or cyclonic filter (9), each of which is responsible for filtering particles with smaller particle size that can damage the formation of the reservoir, consequently reducing injectivity. These particles, due to their size, are not retained in the sieve (3) or filter (6).

Inside the pickup tube (2) is also installed the

Submerged Centrifuge or BCS (1), depending on the configuration required, may be only one BCS or several mounted in series with the first discharge directed to the second suction, and so on. Mentioned BCS pump (1) is responsible for increasing the pressure and flow required for injection. BCS or the various Mounted in series are aligned, centered or arranged within the pickup tube via pump bracket (W) which has the function of centering, sustaining and absorbing BCS vibration as well as aligning and arranging for multiple pumps.

At one end of the BCS pump (1) is coupled a shroud or shroud (10), required in some equipment mounting configurations (E1), which is responsible for conducting water entering the pickup (2) until the suction of the BCS (1) causing captured water flow (F1) to pass outside the engine (1 1) to help cool it. In the case of two or more pumps in series, the discharge of one pump is connected with the suction of the other.

Coupled, in turn, to the other end of the BCS pump (1), discharge piping (12) is provided which directs the discharge flow (F2) from pump (1) directly to the flow meter (13). This tubing is not present in some configurations. Said flow meter (13) is responsible for measuring the pump discharge discharge value (1) required for injection control and pump operation. The equipment (E1) still employs a choke valve (14) responsible for injection flow control.

At least one backwash line (15) is equipped with at least one check valve (16) that prevents reverse flows. The backwash tubing (15) is required to backwash the filter (8) or (9) and also acts as a recirculation line. Backwash valve (17) is provided which controls the backwash flow. Electrical cables (18) required to supply power to the BCS pump motor (1) are also employed, as well as electric valve actuators, all interconnected with a ROV panel (19). In the mentioned panel (19), besides the power cables (18) are installed product injection hoses when necessary, and have valve operation interfaces.

The equipment (E1) is connected to a VSD (Variable Speed Driver) panel (20), which comprises the speed variator used to control the motor speed (11) and consequently its flow and discharge pressure.

All equipment that makes up the injection system is installed inside the pickup tube (2) in series, except for the VSD (20), which is installed on the surface of a floating production unit.

As can be seen from the attached figures, there are several possible mounting configurations of the BCS (1) inside the pickup tube (2). In all assemblies, 'fresh' seawater enters the upper part of the pickup tube (2) and is pumped through a BCS (1) located inside it, exiting from the bottom of the same pickup tube (2). with flow and discharge pressure adjusted by engine speed (11), which in turn is controlled by a VSD (20).

In the assembly of figure 1, the pump (1) is mounted and coupled to the jacket (10) surrounding the pump suction and the motor (11), forcing the water flow (F1), which goes towards the suction of the pump. outside the motor (1 1), aiding its cooling. The jacket 10 in the assembly of figure 1 is opened at the lower end.

Depending on the mounting of figure 2, it is possible not to use the sleeve (10), with the pump (1) mounted upside down, with the motor (1 1) mounted above the suction and the discharge flow. directly to the flowmeter (13). Figure 2 further shows the pump holder (W) which centralizes and absorbs pump vibrations. This device will vary according to the type of mounting, but its function remains the same. In the assembly of figure 3 the flow (F1), after exiting the sieve (3), passes through the filter (8) or (9) and enters directly into the jacket (10) and, after exiting through the discharge pipe (12) of the pump. (1), goes into the space between the jacket (10) and the inside of the pickup tube (2).

There is also the possibility of the pickup tube (2) playing only the structural role (figure 4), where the flow from the filter (8) or (9) enters the jacket (10) and goes straight to the BCS suction (1). , mounted in the inverted position, exiting through the discharge pipe (12) directing the flow at the pump discharge directly to the flow meter (13). In this assembly there is no flow inside the pickup tube (2).

Despite the various configurations, the flow always passes first through the sieve (3), then through the filter (8) or (9) and goes towards the suction of the BCS pump (1), which will always be isolated from the discharge, or through from a discharge pipe (12) or by means of a jacket (10) which isolates the suction from the discharge.

There are only three possible situations, which are: open suction to the pickup tube (2) and insulated discharge with a pipe (12) that goes to the flowmeter block (13) or insulated pickup tube suction (2) ) by means of a jacket (10) which receives the flow from the sea, with the discharge of the pump (1) directed into the pickup tube (2) or the suction and discharge of the pump (1) isolated from the pickup tube. (2) by means of jacket (10) and discharge tube (12) respectively, in which case the pickup tube (2) serves only as a structural component.

After the BCS discharge (1) comes the flowmeter block where the single-phase flowmeter (13) itself is located and a small pipe (21) that discharges to the sea. In this pipe there is a choke valve (14) responsible for the flow control. Part of this tubing (21) from the recirculation line or backwash (15) is responsible for the flow used to clean the filter (8) or (9).

Figures 5 and 6 show a mounting alternative in which the filter (8) or (9) is placed in a retrievable module coupled to the end of the pickup tube (2) and can be retracted and replaced without the need for decoupling or retrieval of the filter. rest of the system. To make the backwash line connection (21), it can be made directly through an interface between the module and the pickup tube (X), or through a hose (Y) installed by ROV (Remote Operated Vehicle). Finally, figures 7, 8, 9 and 9A represent that the pickup tube (2) can be installed according to three different configurations: (i) The first configuration, figure 7, is the top installation of the ANM (22) in place. from Treecap. In this case, the injection is made with ANM valves that allow open injection for access to the injection column; (ii) the second configuration, figure 8, is the installation of the system with equipment (E1) in the injection chuck (23). In this case, the injection is made with ANM valves that allow open injection; and iii) the third configuration is the installation of this system and equipment (E1) in a foundation equipment or system, which may be, inter alia, a torpedo mini pile (24), connected to equipment (E1) floating to the preset depth; secured via tendon (Z) with an injection line (25) interconnecting it with the ANM (22), or mounted to the seabed directly on a torpedo subfloor (24) or other foundation system.

Claims

1) "SUBMARINE SEA WATER INJECTION SYSTEM THROUGH SUBMERSE CENTRIFUGAL PUMP", more particularly it deals with subsea water injection system in oil or gas reservoir aquifers that require a secondary recovery method by injection of Water; characterized in that the system consists of:

- a pickup tube (2) which holds and longitudinally aligns the pumping assembly formed of BCS pump (1), pump holder (W), motor (11), sieve (3) or filters (6) and (8 ) or (9) and flow meter (13);

- the water flow is filtered through the sieve (3) or filter (6), then through the filter (8) or (9) and towards the suction of the BCS pump (1);

- the suction of the BCS pump (1) is isolated from the discharge by means of discharge pipe (12) or by means of a jacket (10);

- the pickup tube (2) is floating by means of a float (4) and tethers (7) or be connected / mounted directly on the ANM (22) or on foundation system (24);

- provide ROV panel (19) for connection of power cables and chemical injection hoses, when necessary, and have interfaces for valve operation;

- the motor speed (11), hence its flow and discharge pressure be controlled by a speed variator (20) disposed externally to the pickup tube (2).

"SYSTEM" according to Claim 1, characterized in that the suction is opened (2a) towards the pickup tube (2) and the discharge is isolated with a pipe (12) that goes into the flowmeter block. (13).

3. "SYSTEM" according to Claim 1 and in a constructive variation, characterized in that the suction is isolated from the pickup tube. (2) by means of a jacket (10) which receives the flow from the sea after passing through a sieve (3) or filter (6) and filters (8 or 9), the pump discharge (1) being directed to the inside the pickup tube (2).

"SYSTEM" according to Claim 1, characterized in that the pickup tube (2) is open at the upper end (2a) and is closed at the lower end (2b) and further receives a guide funnel (2c); at the upper end (2a) of the collection tube and outside it is fitted with a filter device (3) or (6) larger particle retainer and preventing the entry of marine life inside the collection tube (2); below the filters (3) or (6) and disposed within the pickup tube (2) is housed a backwash filter (8) or a cyclonic filter (9) for particles with smaller particle size.

5. "SYSTEM" according to Claims 1 and 4, characterized in that the intake tube (2) receives a BCS (1) aligned with the motor.

(11) -

"SYSTEM" according to claims 1 and 4 and in a constructive option with respect to claim 3, characterized in that the inlet pipe (2) receives several BCSs (1) mounted in series with the discharge of the first directed towards the suction of the second, and so on.

"SYSTEM" according to Claims 1 and 4 and in a constructional option, characterized in that the flow (F1) of water entering the pickup tube (2) until the suction of the pump (1) surrounds and cools the engine ( 11) housed in the tube (2) itself or in a jacket (10) coupled to one end of the BCS pump (1).

"SYSTEM" according to Claim 1, characterized in that the pickup tube (2) consists of a steel tube of up to 50 m in length and of sufficient diameter to accommodate the main components of the pumping system inserted in a your inside.

"SYSTEM" according to Claim 1, characterized in that the pump assembly includes a choke valve (14) responsible for injection flow control.

"SYSTEM" according to claim 1, characterized in that the pump assembly includes backwash tubing (15) with backwash flow control valve (17) and reverse flow check valves (16).

"System" according to Claims 1 and 10, characterized in that the backwash line (15) acts as a recirculation line.

12) "SYSTEM" according to claim 1, characterized by a ROV panel (15) where power cables and chemical injection hoses are connected when required, and has interfaces for valve operation.

13. "SYSTEM" according to the preceding claims, characterized in that the system equipment (E1) eliminates the need for a seabed flow base.

14. "SYSTEM" according to one of Claims 1 to 12, characterized in that the motor assembly (11) and BCS pump (1) housed within the pickup tube (2) eliminate the use of barrier fluid, the use of umbilical and termination module, plus the barrier fluid hydraulic power unit.

"SYSTEM" according to Claim 1 and in a first mounting configuration, characterized in that the equipment (E1) is installed on top of the ANM (22).

"SYSTEM" according to Claim 1 and in a second mounting configuration, characterized in that the equipment (E1) is installed on the injection spindle (23) of the ANM (22).

17) "SYSTEM" according to claim 1 and a third Mounting configuration, characterized in that the equipment (E1) is installed on a torpedo sub-base (24) with an injection line (25) interconnecting it with the ANM (22).