Abstract:
A subsea production station (SPS) including at least a production manifold and a multi phase pump unit (MPP) for subsea operation is shown. Each of them has respective modules for control/operation operatively connected to at least a floating production storage and offloading unit (FPSO), subsea umbilicals, risers, flow lines, subsea wells, installations such as X-mas tree and other units in the system. The manifold ( 4 ) is adapted for its application for producing hydrocarbons from a plurality of wells. The pump unit ( 7 ) is adapted to add kinetic energy along the flow lines. The manifold ( 4 ) and the pump unit ( 7 ) are integrally disposed adjacent to one another on a common foundation ( 2 ) and are adapted to have a common support structure and common suction anchor ( 1 ).

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates in general to a subsea production system having a simplified design which is technically reliable and is cost effective. The subsea production system includes floating production storage and offloading units (hereinafter referred to as FPSO at places), subsea umbilicals, risers, flow lines (hereinafter collectively referred to as SURF at places), subsea wells, installations such as a X-mas tree and other units all operatively connected to an integrated production manifold and multiphase pump unit (hereinafter referred to as MPP at places). More particularly, the present invention relates to an integrated production manifold and multiphase pump unit which has a technically reliable simplified design and is cost effective, in as much as significant savings in respect of application of connectivity/features between the production manifold, MPP and other components in the subsea production system (hereinafter referred to as SPS at places) are achieved. Specifically, the present invention provides a subsea production system according to claim  1  and an integrated production manifold and multi phase pump unit for its application in a SPS, according to claim  13 . 
       TECHNICAL BACKGROUND 
       [0002]    In the field of off shore oil exploration, it is known that a subsea production system (SPS) includes production manifolds, multi phase pump units, FPSO, subsea umbilicals, risers, flow lines (SURF), subsea wells, installations such as a X-mas tree and other features, as are known to persons skilled in the art. A floating production storage and offloading unit (FPSO) is usually known to be a floating vessel used by the off-shore industry for the processing and storage of oil and gas. A FPSO vessel is designed to receive oil or gas produced from nearby platforms or subsea template, process it and store it until oil or gas can be offloaded onto a tanker or transported through a pipe line. Subsea production manifolds are known to be applied for producing hydrocarbons from a plurality of wells. It may comprise an accessory system of piping to a main piping system (or another conductor) that serves to divide a flow into several parts, to combine several flows into one, or to reroute a flow to any one of several possible destinations. Alternatively, it may be a pipe fitting with several side outlets to connect it with other pipes. It is also known that a subsea multi phase pump increases the pressure in the well field. In other words, it adds kinetic energy directly to the flow. The effect is as if the flowing pressure is increased. The flow from the wells increases until a new balance between fluid pressure and system resistance is achieved. The effect is net increase in oil production. The importance of subsea umbilicals, risers, flow lines and other features in subsea production systems are known to persons skilled in the art. 
         [0003]    Now, for exploration of oil and gas in a subsea environment, production manifolds and multiphase pump units are known to be separately installed along different installations and this involves application of several complicated connectivity/features for ensuring operative association between the production manifolds, multiphase pump units, umbilicals, risers, flow lines, subsea wells and other units including installations, such as a X-mas tree, in a subsea production system. Obviously, these involve very high maintenance and installation costs and issues often relating to technical reliability crop up due to the complexities. 
         [0004]    Over the years, attempts have been made to simplify and/or reduce the components required for operative association between the various units in a subsea production system. However, in prior art technology there has been no attempt to integrate the production manifolds and multiphase pump units with a view to simplify and/or reduce the components, to ensure operative association between the various units in a subsea production system. WO 2008/070648 A2 discloses an improved manifold system comprising two or more subsea trees each connected to a subsea well, a manifold connected to each subsea tree and a first common riser connected to the manifold. Production, maintenance and/or workover of each subsea well take place through the common riser. This document does teach in an indirect manner simplification and reduction in the components required for operative association between the various units including installations, such as a X-mas tree, in a subsea production system. However, it does not directly teach integrating a production manifold and a multiphase pump unit with a view to achieve such motive. Rather, it focuses on proving a low cost manifold that can be used with an Early Production System (EPS) to produce, maintain and/or workover multiple subsea wet-tree wells through a common riser system. 
         [0005]    Framo engineering has developed a multi port selector manifold (MSM) which includes production and test facilities, a lift gas system, a multi phase flow meter and a multi phase booster pump and controls. (Offshore Magazine, Published 1 st  Aug. 2006). Very much like the disclosure in WO 2008/070648 A2, Framo engineering concentrates on reducing the size and weight of the compact manifold. It also advocates a single control system that can control not only a large number of valves and sensors for each pod, but also the pump, multiphase meter and the tree controls. However, Framo engineering does not advocate directly integrating a production manifold and a multiphase pump unit with a view to simplify and/or reduce the components required to ensure operative association between the various units in a subsea production system. 
         [0006]    Accordingly, there was a long felt need for a design in a subsea production environment for simplification and/or reducing the components required to ensure operative association between the various units in a subsea production system, so that effective cost saving is achieved and simultaneously, technical reliability of the entire system is substantially enhanced. The present invention meets this long felt need and other needs associated therewith. 
       OBJECTS OF THE INVENTION 
       [0007]    The present invention aims to meet the above need hitherto not taught by prior art, by providing a subsea production system which by virtue of its specially configured construction, plays a significant role to simplify and/or to reduce the components required for operative association between the various units, in a subsea production system. 
         [0008]    Another object of the present invention is to provide an integrated production manifold and multiphase pump unit for its application in a subsea production system for simplifying and/or for reducing the components required for operative association between the various units, in a subsea production system. 
         [0009]    It is another object of the present invention to provide an integrated production manifold and multiphase pump unit for its application in a subsea production system such that significant cost effectiveness is achieved without compromising with the technical effectiveness. 
         [0010]    It is another object of the present invention to achieve SURF scope savings in a subsea production station. 
         [0011]    It is a further object of the present invention to achieve SPS and MPP scope savings in a subsea production station. 
         [0012]    It is another object of the present invention to achieve advantageous configurations in the control system and umbilicals of a subsea production station. 
         [0013]    It is a further object of the present invention to substantially enhance technical reliability and to achieve significant cost savings in the operation of a subsea production station/system, by reducing the number of subsea connections and equipments in a subsea production system. 
         [0014]    It is another important object of the present invention to provide a subsea production station incorporating subsea production systems, each such system by virtue of its specially configured construction, plays a significant role to simplify and/or to reduce the components required for operative association between the various units including production manifolds, multiphase pump units, umbilicals, risers, flow lines, subsea wells, installations such as a X-mas tree, in a subsea production station. 
         [0015]    In addition, the present invention discloses some advantageous features still not disclosed in prior art. 
         [0016]    Throughout the entire specification, including the claims, the words oil, gas, hydrocarbons, SPS, production manifold, multiphase pump unit, ROV are to be interpreted in the broadest sense of the respective terms and includes all similar items in the field known by other terms, as may be clear to persons skilled in the art. Furthermore, the term production wherever applied, should be understood as relating to production of oil, gas and other hydrocarbons involved in subsea drilling operations. 
       SUMMARY OF THE INVENTION 
       [0017]    According to a first aspect of the present invention there is provided a subsea production system (SPS) including at least a production manifold and a multi phase pump unit (MPP) for subsea operation. The production manifold and the pumping unit have respective modules for control/operation. The manifold and the pumping unit are operatively connected to at least a floating production storage and offloading unit (FPSO), subsea umbilicals, risers, flow lines, subsea wells, installations such as X-mas tree and other units in said system. The manifold is adapted for its application for producing hydrocarbons from a plurality of wells. The pump unit is adapted to add kinetic energy along flow lines. According to the invention the manifold and said pump unit are integrally disposed adjacent to one another, on a common foundation and are adapted to have a common support structure and common suction anchor system, along a single installation. 
         [0018]    According to a preferred embodiment of the first aspect of the present invention, the MPP modules and equipments associated therewith are incorporated within said manifold module. 
         [0019]    Preferably, the pump high voltage power supply cables are incorporated within the production umbilicals. 
         [0020]    According to another preferred embodiment of the first aspect of the present invention, said manifold and said pump unit are adapted to have commonality of spares and are adapted to be operated by the same ROV tools. 
         [0021]    According to a second aspect of the present invention, there is provided an installation operatively connected to the subsea production system according to a first aspect of the present invention. 
         [0022]    Preferably, the installation is a X-Mas tree. 
         [0023]    According to a third aspect of the present invention there is provided a subsea production station comprising at least a subsea production system (SPS) according to the first aspect of the present invention. 
         [0024]    According to a fourth aspect of the present invention, there is provided an integrated production manifold and multi phase pump unit (MPP) for application in a subsea production system, each having respective modules for control/operation. The manifold and the pumping unit are operatively connected to at least one floating production storage and offloading unit (FPSO), subsea umbilicals, risers, flow lines, subsea wells, installations, such as a X-mas tree, and other units of said production system. According to the fourth aspect of the present invention, the manifold and pump unit are integrally disposed adjacent to one another on a common foundation and are adapted to have a common support structure and common suction anchor system along a single installation. The MPP modules and equipments associated therewith are incorporated within manifold modules and high voltage pump power supply cables are incorporated within the production umbilicals. 
         [0025]    The present invention also embraces a plurality of such integrated manifold and multiphase pump units, operatively connected to each other and to other units in a subsea production station. 
     
    
     
       SHORT DESCRIPTION OF THE FIGURES 
         [0026]    Having described the main features of the invention above, a more detailed and non-limiting description of some exemplary preferred embodiments will be given in the following with reference to the drawings, in which: 
           [0027]      FIG. 1(   a ) is a perspective view of the integrated unit according to the present invention. 
           [0028]      FIG. 1(   b ) is a perspective view of a preferred embodiment of the integrated unit according to the present invention, showing the connectivity between the various components. 
           [0029]      FIG. 1(   c ) is a front exploded view of the integrated unit illustrated in  FIG. 1(   b ). 
           [0030]      FIG. 1(   d ) is a top elevation view of the integrated unit illustrated in  FIG. 1(   a ). 
           [0031]      FIG. 2  is a block diagram of the various interfaces of the integrated unit, according to the present invention. 
           [0032]      FIG. 3  is a flow diagram, illustrating the connectivity between the various components of the MPP system according to a preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]    The present invention aims to simplify and/or to reduce the components required for ensuring operative association between the various units, in a subsea production system. The present invention ensures significant reduction in costs and simultaneously ensuring substantial enhancement in technical reliability in the operation of a subsea production system. This is primarily achieved by a brilliant engineering manoeuvring which involves integrating the production manifold and the multiphase unit in a subsea production station, such that components required for connection between the production manifold and the multiphase pump unit and between the other units such as FPSO, SURF, subsea wells, installations such as X-mas trees in a subsea production station are simplified and/or reduced. 
         [0034]    The accompanying  FIG. 1(   a ) elaborately illustrates the integrated production manifold  4  and the multiphase pump unit  7  according to the present invention. As will be readily understood from this figure, the manifold  4  includes the ROV panel  6 , a housing having preferably eight production inlets into which individual wells are connected. Advantageously, it has a main production outlet and a testing outlet. It also has the guide post  5 . It can be of larger size as compared to other CLOY manifolds, as will be known to persons skilled in the art, but this is not consequential to the present invention. Similar comments apply in respect of the multiphase pump unit  7  as well, which is field proven over several years. The novelty and inventive step lies in the integration of these two units into a comprehensive unit, whereby distinctive technical advantages and economic significance, hitherto not achieved in the industry are arrived at. As it will be evident from the accompanying  FIG. 1 , this integrated unit is installed along a single installation, thereby doing away with old requirement of separate installations for both such units. The integrated unit rests on a common foundation  2  and is anchored along a common suction anchor  1 . The levelling frame  3  advantageously facilitates integrated adjacent disposition of the production manifold  4  and the multiphase pump unit  7  along a single installation. Advantageously, the flow lines connected to the manifold  4  forms a pigging loop (not shown) about the guide post  5  in the manifold. 
         [0035]    In the above context it is hereby clarified that for the sake of understanding only one integrated unit is shown in the accompanying  FIG. 1(   a ), but the present invention embraces a plurality of such integrated units being applied in a subsea exploration operation. 
         [0036]    The accompanying  FIG. 1(   b ) illustrates another preferred embodiment of the integrated unit according to the present invention. In this embodiment the connections between the various components are shown. The same reference numerals as in  FIG. 1(   a ) indicate the same features as in  FIG. 1(   a ). In this preferred embodiment, the manifold  4  is shown disposed on the left of the multiphase pump unit  7 . It also shows the manifold valves  4 ′. The accompanying  FIG. 1(   c ) is an exploded view of the unit shown in  FIG. 1(   b ), the like reference numerals are indicating the same features. The accompanying  FIG. 1(   d ) illustrates a top view of the unit shown in  FIG. 1(   a ). 
         [0037]    Combining the production manifold and the multiphase pump to one combined subsea manifold/pump station according to the present invention, reduces cost and increases reliability by reducing the number of subsea connections and equipments in a subsea production system. 
         [0038]    Advantageously, according to the present invention, the high voltage pump power supply cables are incorporated within the production umbilicals, thus avoiding the need for a dedicated pump umbilical. 
         [0039]    An outline of the subsea umbilicals, risers, flow lines (SURF) scope savings are as follows:
       2 off flow line spools saved between manifold and pump.   Installation of 1 off manifold saved (installation of one combined manifold instead of separate pump and manifold installation).   Installation of 1 off manifold foundation saved.   Installation of 2 off flow line spools between manifold and pump saved.   1 off production umbilical saved functionality for production umbilical included in the pump umbilicals based on combined design (i.e. reducing double functions).       
 
         [0045]    An outline of the subsea production system (SPS) and multiphase pump unit (MPP) scope savings are as follows:
       Tie-in hubs saved (piping on manifold directly connect to piping on pump, and hence no jumpers needed),   1 off manifold module saved (one combined manifold module only needed for combined pump/manifold),   1 off manifold support structure saved (one combined manifold support structure only needed for combined pump/manifold),   1 off suction anchor saved (one combined MPP/production suction anchor instead of separate MPP and SPS manifold suction anchors).       
 
         [0050]    An outline of the FPSO scope savings are as follows: 
         [0051]    Save guide tube on FPSO 
         [0052]    The accompanying  FIG. 2  illustrates a block diagram of the various interfaces of the integrated unit according to the present invention. It shows the production umbilicals  14 ′ connecting to the power control module (PCM)  8  and to the MPP system control unit (SCU)  9  and to the subsea production system (SPS)  10 . These production umbilicals therefore have high power supply cables for both the pump unit as well as for the production manifolds. The power cores generate a quite high temperature when the umbilicals are exposed to warm air in the I-tube. The temperature in the combined cross-sections (two smaller umbilicals) is 15° C. less than that stand alone (one large umbilical). That apart commonality of spares is ensured. Furthermore, either of the production umbilicals  14 ′ is adapted to function in a sacrosanct manner, in the event of break down of the other. 
         [0053]    The other interfaces shown in the accompanying  FIG. 2  are the high voltage jumper  13 , the barrier fluid jumper  12 , the umbilical terminal heads  14 , the ten inches spools  20  and the welding interface  23 . The pump station comprises ten inches ball valves  21  which are hydraulically/ROV operated (2 off for each pump module), eight inches gate valves or ball valves  22 ,  22 ′ which are hydraulically/ROV operated (2 off for each pump module), sensors on pump module  16 , sensors on retrievable pump  17 , hydraulic functions  18 , MPP subsea control module  15  and sensor jumpers  11 . This figure also shows ten inches header pipes  19  on the production manifold  4 . 
         [0054]    As it will be understood from the description of the invention with reference to the drawings as provided hereinafter, the main benefits of the combined MPP/SPS subsea station according to the present invention are: 
         [0055]    a) The MPP modules and associated equipment are incorporated within the production manifold, thus removing the need for a dedicated MPP manifold. 
         [0056]    b) The MPP support structure is incorporated into the SPS support structure, thus removing the need for a dedicated MPP support structure. 
         [0057]    c) The MPP suction anchor is incorporated into the SPS suction anchor, thus removing the need for a dedicated MPP suction anchor. 
         [0058]    The main benefits of the control system applied in the present invention are: 
         [0059]    a) Utilisation of existing subsea production system (SPS) power and communications distribution equipment to support the MPP system. 
         [0060]    b) MPP subsea control module (SCM)/subsea control module mounting base (SCMMB) design and associated controls equipments are subject to the same specification requirements and share the same common envelope and ROV interface features as the main SPS equipment ensuring commonality of tooling and test equipment. 
         [0061]    c) MPP system control modules (SCM) are controlled and monitored via the main subsea production system (SPS) subsea control unit (SCU)/subsea production control unit (SPCU). 
         [0062]    d) Commonality of spares. 
         [0063]    The main benefits of the umbilicals applied in the present invention are: 
         [0064]    a) The power cores generate a quite high temperature when the umbilicals are exposed to warm air in the I-tube. The temperature in the combined cross-sections (two smaller umbilicals) as illustrated in the accompanying  FIG. 2  and explained hereinbefore, is 15° C. less than the stand alone (one large umbilical). 
         [0065]    b) Commonality of spares. 
         [0066]    c) Increased reliability/availability of the pump system. With one power umbilical damaged/down, there is still another one to supply power to one pump system and communication to both pump system control modules. 
         [0067]    The main benefits of the tie-in system applied in the present invention are: 
         [0068]    a) Removal of tie-in connections between the MPP and SPS manifold 
         [0069]    b) Commonality of spares. 
         [0070]    The main benefits of the Intervention System and ROV Tooling applied in the present invention are: 
         [0071]    a) Usage of same ROV tools as for both Pump system and manifold system. 
         [0072]    b) Commonality of spares. 
         [0073]    In a nut shell, the present invention primarily achieves substantial enhancement in technical reliability and significant cost savings in the operation of a subsea production station/system, by reducing the number of subsea connections and equipments in a subsea production system. 
         [0074]    The accompanying  FIG. 3  is a flow diagram, illustrating by way of understanding and not by way of limitation, the connectivity between the various components of the MPP system according to a preferred embodiment of the present invention. It shows the pump  7 , the chemical injection valve  24 , choke  25 , outlet branch valves  26 , flow splitter  27 , the recirculation line  28 , the flow mixer  29 , the inlet branch valves  30 , by pass header  31 , and the by pass valve  32 . Further, the six inches, eight inches and ten inches dimensions provided are exemplary and non-limiting. The working of the various components will be clear to persons skilled in the art. 
         [0075]    The present invention has been described with reference to some exemplary embodiments and some drawings for the sake of understanding only and it should be clear to persons skilled in the art, that the present invention includes all legitimate modifications within the ambit of what has been described hereinbefore and claimed in the appended claims.