Abstract:
A spool module for a subsea well production tree and system is presented. The spool module is similar to traditional process modules, except that the spool module includes all its components and their conduits inside one body (or block). This module includes retrievable components used for production and annulus flow lines into one package. The spool module includes the production choke, annulus choke, and conduit bores integral in the block. The spool module includes all of these elements machined into one body having no additional conduits or piping outside of the body. The spool module may also be used in connection with a subsea tree during production of a well, or with several wells on a template or as part of a manifold.

Description:
BACKGROUND 
     Development and exploitation of undersea petroleum and natural gas deposits includes using offshore facilities to drill and produce oil and gas wells. The development of subsea oil and gas fields requires specialized equipment, including subsea production systems. The equipment must be reliable enough to safe guard the environment, and make the exploitation of the subsea hydrocarbons economically feasible. 
     A typical subsea system for drilling and producing offshore oil and gas can include the use of process modules that can be used to assist in production. Process modules can include individual components such as production chokes, annulus chokes, sensors, single phase or multi-phase flow meters, etc. A multi-phase flow meter is a device for measuring the velocity and phase composition (water, oil, gas) of fluid flow in a well, usually one completed for production or injection. A single-phase flow meter is a device for measuring the velocity of a single fluid in a well A choke is used to control fluid flow rate or downstream system pressure. The choke is available in several configurations for both fixed and adjustable modes of operation. Adjustable chokes enable the fluid flow and pressure parameters to be changed to suit process or production requirements. Fixed chokes do not provide this flexibility, although they are more resistant to erosion under prolonged operation or production of abrasive fluids. Additionally, the choke may be non-retrievable or retrievable separate from the process module. 
     Although these components are retrievable, most of these components can include extensive routed piping in between them. This packaging can create multiple connections that create potential leak paths and a large footprint, both of which can be undesirable. In addition, because all of these components are separately retrievable, they can be individually large. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A better understanding of the various disclosed system and method embodiments can be obtained when the following detailed description is considered in conjunction with the drawings, in which: 
         FIG. 1  is an illustrative view of a spool module connected to the production bore of a tree; 
         FIG. 2  shows multiple illustrative views ( FIGS. 2A-2H ) of a spool module; 
         FIG. 3  is an illustrative view of a spool module connected to the annulus bore of a tree; 
         FIG. 4  is an illustrative view of a spool module connected to both the production flow path and annulus flow path of a tree; and 
         FIG. 5  shows multiple illustrative views ( FIGS. 5A-5H ) of a spool module that includes facility for the production and annulus flow paths as well as flow path access. 
     
    
    
     DETAILED DESCRIPTION 
     The following discussion is directed to various embodiments of the invention. The drawing figures are not necessarily to scale. Certain features of the embodiments may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce desired results. In addition, one skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment. 
     Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness. 
     In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices, components, and connections. In addition, as used herein, the terms “axial” and “axially” generally mean along or parallel to a central axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally mean perpendicular to the central axis. For instance, an axial distance refers to a distance measured along or parallel to the central axis, and a radial distance means a distance measured perpendicular to the central axis. 
       FIG. 1  shows an embodiment of a subsea production system including a spool module  103  connected to a subsea flow control assembly, in this case a production tree  110  for the production of a subsea well. In this embodiment, the subsea production tree  110  is a subsea vertical production tree  110  attached above a tubing head spool  202 , which is connected with a wellhead  216 . A tubing hanger  204  with a vertical production bore is landed in the tubing head spool  202  below the tree  110  and supports a production tubing  208  extending into the well. The subsea tree  110  can be used to monitor and control the production of well fluids from a subsea well. Subsea trees can also manage fluids or gas injected into the well. 
     The production tree  110  also includes a vertical bore  106 . Located along the vertical bore  106  is a production swab valve (PSV)  109  and a production master valve (PMV)  108 . The tree  110  also includes a lateral production flow path  113  and an annulus flow path  213 . Included along the lateral production flow path  113  is a production outlet valve (POV)  120  that operates as and in similar manner to the PSV  109  for controlling fluid flow through the lateral production bore. 
     As shown as an example in  FIG. 1 , the production tree  110  may be installed on a tubing head spool  202 . A tree isolation sleeve  112  isolates the annulus flow path  213  from the production flow path  113  and allows for pressure testing of the tree connector gasket while isolating the tubing hanger from the test pressure. Alternatively, the production tree  110  may be installed directly to a wellhead assembly  216 . The top of the tree isolation sleeve  112  seals against the production tree  110  and the bottom of the isolation sleeve  112  seals against the tubing head spool  202 . 
     Primary and secondary sealing mechanisms, isolating the production flow path  113  from the annulus flow path  213  are provided by a production stab  114  constrained to the bottom of the tree body by the tree isolation sleeve  112 . The top of the production stab  114  may seal against the tree body by means of, for example, a primary metal-to-metal seal and a secondary elastomeric seal. The bottom of the production stab  114  seals against the tubing hanger body by means of, for example, a primary metal-to-metal seal and secondary elastomeric seal. 
     The production bore communicates with the production tubing, and the annulus bore provides fluid communication with the annulus. Typical designs of trees have a side outlet (a production wing branch) to the production bore closed by a production wing valve for removal of production fluids from the production bore. The annulus bore also typically has an annulus wing branch with a respective annulus wing valve (not shown). 
     As shown in  FIGS. 1-2 , the spool module  103  includes a body  105 . All of the elements of the spool module  103  (as will be described) are machined into one body  105  having no additional conduits or piping outside of the body  105  for those elements. The spool module  103  also includes a choke insert (or insert profile)  130  and a choke actuator  107 . The choke insert with the choke actuator  107  would be installed on the spool module  103  to complete the assembly. The choke insert profile  130  houses the choke which limits the flow of fluid through a flow path internal to the body  105  and controls the fluid flow rate from the subsea well to a fluid production line (not shown) in fluid communication with flow path. The choke insert profile  130  is located inside the body  105  of the spool module  103 . 
     The choke actuator  107  is connected with and used to actuate the choke. As an example, the actuator  107  can be a hydraulic stepping actuator of the type commonly used in choke actuation to convert the linear motion from hydraulic actuation into rotational motion to open or close the choke. Other types of chokes and choke actuators, such as linear actuating chokes, fast close/open modules, ROV override, etc. could be controlled similarly and can also be used. 
     The spool module  103  also includes one or more fluid sensors  125  that are pre-installed on the assembly using simple flange connections. The fluid sensors  125  are in fluid communication with the fluid in the entering flow path. The fluid sensors  125  typically measure at least one of the pressure and temperature of the incoming fluid. The fluid sensors  125  can also be of the type to measure composition, viscosity, density, etc. of the incoming fluid. The spool module  103  may also be used in other environments, such as on a horizontal tree, manifold, PLET (pipeline end termination), etc. The spool module can be beneficial when used in connection with a subsea tree during production of a well, or with several wells on a template or as part of a manifold. Manifolds are usually mounted on a template and often have a protective structure covering them that would be useful when combined with the structure of the spool module. 
       FIG. 2  shows multiple views of the spool module  103  including top views  FIGS. 2A-2B , side views  FIGS. 2C-2D , front views  FIGS. 2E-2F , and bottom views  FIGS. 2G-2H . The side views  FIGS. 2C-2D  show the most detail, and give a look inside the spool module  103 . The fluid sensors  125  are shown to be in fluid communication with an entering flow path  126 , taking measurements of the fluid in the entering flow path  126 . After passing the fluid sensors  125 , the fluid enters the choke  130  and then exits the spool module  103  via the exit flow path  128 . While passing through the exit flow path  128 , the flow rate of the fluid is measured by flow sensors  132 . The flow sensors  132  can include a flow meter (or multiphase flow meter) to aid in measurement of the respective flow rates or flow volumes of gas and liquid, including gas and liquid mixtures. The multiphase flow meter is used to measure the individual phase flow rates of petroleum, water and gas mixtures produced during oil production processes. Additionally, the flow meter may also be able to detect any flow resistance change. The design of the process module  103  allows the flow paths, sensors, and choke to be included in the body  105  without the need for external connections and piping. 
     A clamp connector  140  is also illustrated in this embodiment. The clamp connector  140  is used to make a connection between two fluid carrying elements and may be any suitable type of clamp connector. Most of the fluid is carried under high pressure, and/or high temperature so preferably, the clamp connector  140  is suitable for use in environments with high pressure, both internal and external as a result of the deep water depth. 
     As an addition, an optional flow path access inlet  205  is shown in both the front view ( FIG. 2E ) and the bottom view ( FIGS. 2G-2H ) of  FIG. 2 . The flow path access inlet  205  is in fluid communication with the well and allows the introduction of fluids into the well. For example, the flow path access inlet  205  allows the injection of special chemical solutions into the well to improve oil recovery, remove formation damage, and the like. Formation damage can be caused by an alteration of characteristics of a producing formation from the exposure of drilling fluids. As an example, the water or solid particles in the drilling fluids, or both, tend to decrease the pore volume and effective permeability of the producible formation in the near-wellbore region. The flow path access inlet  205  can also be used to clean blocked perforations, reduce corrosion, upgrade crude oil, or address crude oil flow-assurance issues. The chemical injection can be administered continuously or in batches. 
       FIG. 3  shows another embodiment of the present invention. This embodiment illustrates a spool module  303  connected to the annulus flow path  213  of the subsea tree  110 . The spool module  303  is similar to the spool module  103  shown in  FIGS. 1 and 2  with the exception that it is connected for annulus fluid flow. As shown an inlet pipe  302  in fluid communication with the annulus flow path  213  connects to the spool module body  105 . The spool module  303  also includes a body  105  and also includes a choke  130  (not shown) and a choke actuator  107 . The choke  130  limits the flow of fluid through a flow path internal to the body  105  and controls the fluid flow rate from the subsea well to a fluid production line (not shown) in fluid communication with the annulus flow path in the spool body  105 . The choke  130  may be located, for example, at least partially inside the body  105  of the spool module  103 . 
     The fluid sensors  125  are in fluid communication with the annulus fluid coming from the inlet pipe  302 . The fluid sensors  125  measure a characteristic of the incoming annulus fluid, such as pressure and temperature. The fluid sensors  125  of this embodiment can also be of the type to measure composition, viscosity, density, etc. of the fluid mixture. The choke actuator  107  is used to actuate the choke, and can be any type suitable for use with the annulus flow path  213 . The design of the process module  303  allows the flow paths, sensors, and chokes to be included in the body  105  without the need for external connections and piping. 
     The spool module  303  operates in much the same manner as the spool module  103  shown in  FIGS. 1-2  except that the fluid flowing through the spool module  303  is fluid from the annulus bore of the tree  110 , which, for example, may be the fluid from the annulus between the production tubing  208  and the surrounding production casing. 
       FIG. 4  shows an embodiment of the spool module  410  used for both the production flow path  113  and the annulus flow path  213  of the production assembly simultaneously. This system for producing fluid from a subsea well includes a production assembly (in this embodiment a subsea tree  110 ) including an annulus flow path  213  and a production flow path  113 , and a spool module  410 . The spool module  410  is similar to the spool modules  103 ,  303  described above and in addition to a first entering and exit flow path in fluid communication with the production flow path  113 , the spool module  410  further includes a second entering flow path inside the spool module body in fluid communication with the annulus bore. This system also includes a second exit flow path inside the body and a second choke in fluid communication with and that can control flow between the second entering flow path and the second exit flow path. 
     As shown in  FIGS. 4 and 5  (top views  FIGS. 5A-5B , side views  FIGS. 5C-5D , front views  FIGS. 5E-5F , and bottom views  FIGS. 5G-5H ), the inlet pipe  401  of the production flow path  113  connects to the spool module body  105 , and allows production fluid to flow into the spool module  410  into a production entering flow path  508 . As the fluid flows in the production entering flow path, the fluid flows past fluid sensors  125 , which are able to measure characteristics of the fluid, such as pressure, temperature, composition, viscosity, density, etc. The fluid then passes through the choke  130 , and exits through a production exit flow path  509  and into the outlet pipe  403 . The spool module  410  includes flow meter sensors  132  to measure flow characteristics of the production fluid in the production exit flow path  509 . A production choke actuator  407  connects with the production choke  130  and is used to actuate the production choke  130 . 
     The spool module  410  also includes annulus flow paths  510  and  514  in the body  105 . As shown, an annulus inlet pipe  402  in fluid communication with the annulus flow path  213  connects to the spool module body  105  and allows annulus fluid to flow into the spool module  410  into the annulus entering flow path  510 . As the fluid flows in the annulus entering flow path, the fluid flows past fluid sensors  135 , which are able to measure characteristics of the fluid, such as pressure, temperature, composition, viscosity, density, etc. The fluid then passes through the annulus choke  512 , and exits through an annulus exit flow path  514  and into the outlet pipe  409 . The spool module  410  includes flow meter sensors  132  to measure flow characteristics of the annulus fluid in the annulus exit flow path  514 . An annulus choke actuator  406  connects with the annulus choke  512  and is used to actuate the annulus choke  512 , as shown from the top views in  FIGS. 5A-5B . The embodiments shown in  FIGS. 4 and 5  include the production flow path  113  in fluid communication with the production entering flow path  508  and the annulus flow path  213  in fluid communication with the annulus entering flow path  510 . However, it should be appreciated that the entering flow paths may be placed in communication with either the production flow path  113  or the annulus flow path  213  and the labeling of the flow paths as production or annulus or as entering or exiting is for explanation purposes only. The design of the process module  410  allows the flow paths, sensors, and chokes to be included in the body  105  without the need for external connections and piping. 
     As an addition, an optional flow path access inlet  505  in the body  105  is shown in both the front view ( FIG. 5E ) and the bottom view ( FIGS. 5G-5H ) of  FIG. 5 . The flow path access inlet  505  is in fluid communication with the well and allows the introduction of fluids into the well. For example, the flow path access inlet  505  allows the injection of special chemical solutions into the well to improve oil recovery, remove formation damage, and the like. The flow path access inlet  505  can also be used to clean blocked perforations, reduce corrosion, upgrade crude oil, or address crude oil flow-assurance issues. The chemical injection can be administered continuously or in batches. 
     Other embodiments of the present invention can include alternative variations. These and other variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.