A tool insertable into a wellbore for sampling formation fluids includes a body, and sample probe assemblies that project radially outward from the body and into sampling contact with the wellbore wall. Packers are provided on the outer terminal ends of the sample probe assemblies and which are urged against the wellbore wall. Actuator driven linkage assemblies selectively deploy and retract the packers from and back into the body. The sample probe assemblies are disposed at substantially the same axial location on the body, and are angularly spaced about an axis of the body. Each sample probe assembly is independently actuated, so that a discrete azimuthal portion can be sampled, and each has a dedicated sample container for storing sampled formation fluid.

BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present disclosure relates to a device and method for sample a reservoir with multiple sampling probes that are independently operated from one another. 
     2. Description of Prior Art 
     The sampling of fluids contained in subsurface earth formations provides a method of testing formation zones of possible interest. The sampled formation fluids are usually later analyzed in a laboratory environment, and sometimes provide a point test of the possible productivity of subsurface earth formations. Analyzing the fluid sometimes yields pressure and permeability information of the formation, as well as fluid compressibility, density and relative viscosity of the formation fluid. 
     Sampling connate fluid generally involves disposing a sonde into a wellbore, and communicating a sample port on the sonde with the formation surrounding the wellbore. When the sample port is proximate to an area of interest in the formation, an urging means on the sonde extends against the inner surface of the wellbore thereby engaging the sample port into the formation. The engagement of the sample port usually pierces the outer diameter of the wellbore and enables fluid communication between the connate fluid in the formation and the sample port. After urging the sample port into the formation, the connate fluid is typically siphoned into the sonde with a pumping means disposed therein. The sampled fluid is sometimes analyzed in the sonde, or on surface after being transported out of the wellbore. 
     SUMMARY OF THE INVENTION 
     Described herein is an example of a downhole tool for sampling formation fluid in a wellbore that includes a body and sample probe assemblies. In this example the sample probe assemblies are made up of linkage assemblies, pad assemblies that selectively project radially outward from the body on the ends of the linkage assemblies and into sampling engagement with a wall of the wellbore at substantially the same measured depth in the wellbore, and actuators in the body coupled with each one of the linkage assemblies and that are each selectively operated independently from the other actuators. Valves can be provided that are selectively opened and closed and that provide selective fluid sampling. The tool can optionally include sample tanks, wherein each one of the sample tanks are in fluid communication with a one of the sampling pads, so that formation fluid obtained by each of the sampling pads is stored in a one of the sample tanks. A conduit between each one of the pad assemblies and each one of the sample tanks can be included with this example. The pad assemblies can be made of a packer having an outer radial surface that contacts the wellbore wall, and a port in a mid-portion of the outer radial surface that is in fluid communication with the formation fluid in a formation intersected by the wellbore. Pressure sensors may be included that are in communication with each of the sample probe assemblies, so that pressure of a formation intersected by the wellbore can be sensed along discrete locations along the circumference of the wellbore and at the same depth in the wellbore. In an example the linkage assemblies each have an arm with an end hingedly coupled with the body, a hydraulically actuated piston coupled with the arm, and wherein the actuator is a hydraulic source in selective pressure communication with an end of the piston, so that when the hydraulic source provides pressurized fluid to an end of the piston, the arm is selectively moved radially with respect to the body to move the pad assembly with respect to the wellbore wall. In another alternative, the linkage assemblies each have an arm, and wherein the actuator is a screw having an end coupled to a motor, and having a portion that threadingly engages the arm, so that when the screw is rotated by the motor, the arm is moved radially with respect to the body. In another example, the linkage assemblies each have a series of arms pivotingly linked in series together, and wherein a one of the pad assemblies is mounted on a middle one of the arms, so that when a force is applied to an end of the series of arms, the one of the pad assemblies is urged radially with respect to the body. A controller may be included with the tool that is in communication with the actuators, so that each of the actuators is operated independently with respect to the other actuators. In an example, the linkage assemblies travel along an arcuate path between a stowed position adjacent the body and an engaged position in contact with the wellbore wall. 
     Also disclosed herein is an example of a downhole tool for sampling formation fluid in a wellbore and that includes a body, articulated linkage assemblies, each of which having an end coupled with the body, and each of which selectively and independent from one another move between a stowed position to a deployed position. The tool also includes pad assemblies on ends of the linkage assemblies that are distal from the ends that are coupled to the body and that are at substantially the same depth in the wellbore when the linkage assemblies are in the deployed position, and ports on the pad assemblies that are in selective communication with formation fluid in a formation that is intersected by the wellbore when the linkage assemblies are in the deployed position. The downhole tool can further have actuators coupled to the linkage assemblies for selectively and independently moving the linkage assemblies between the stowed and deployed positions. Conduits and sample tanks are optionally included that are in fluid communication with each of the ports through the conduits. 
     A method of sampling formation fluid from a formation is also disclosed herein and that includes providing a downhole tool having a body and sample probe assemblies coupled with the body, disposing the downhole tool into a wellbore that intersects the formation and defines a wellbore wall, extending the sample probe assemblies to locations on the wellbore wall that are at the same measured vertical depth in the wellbore, and providing communication between the body and the formation with the sample probe assemblies. The sample probe assemblies can be operated independently of one another. Fluid can be injected into the formation from one of the sample assemblies, and wherein fluid is drawn from the formation into another one of the sample assemblies. In one alternative, fluid is simultaneously communicated through the sample assemblies. Optionally, each of the sample probes has a pad assembly disposed on an end of an articulated linkage arm. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which: 
         FIG. 1A  is partial side section view of a downhole tool in a wellbore with sensor arms in a running configuration. 
         FIG. 1B  is partial side section view of a downhole tool of  FIG. 1A  and with the sensor arms in a deployed configuration. 
         FIGS. 2A-2C  are side partial sectional views of example embodiments of the sensor arms of  FIG. 1B . 
         FIG. 3  is an axial view of the downhole tool of  FIG. 1B  and taken along lines  3 - 3 . 
     
    
    
     While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF INVENTION 
     The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout. In an embodiment, usage of the term “about” includes +/−5% of the cited magnitude. In an embodiment, usage of the term “substantially” includes +/−5% of the cited magnitude. 
     It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. 
       FIG. 1A  shows one example of a downhole tool  10  disposed in a wellbore. In this example, wellbore  12  intersects a formation  14 , and downhole tool  10  is deployed in wellbore  12  on a lower end of wireline  16 . Wireline  16  is shown having an upper end spooled onto a surface truck  18  provided at surface  20 , and which is proximate an opening at the upper end of wellbore  12 . A wellhead assembly  22  is mounted over the opening of wellbore  12 , and wireline  16  is shown threaded through wellhead assembly  22 . Downhole tool  10  has a body  24 , which in one example is a generally cylindrical and elongate member. Provided on body  24  are a series of sample probe assemblies  26   1-3 . In the example of  FIG. 1A , sample probe assemblies  26   1-3  are illustrated in a stowed configuration, which may be adjacent body  24  or set within recesses (not shown) formed on the outer surface of body  24 . While in the example stowed configuration, sample probe assemblies  26   1-3  are generally parallel with an axis A X  of tool  10 . Each of sample probe assemblies  26   1-3  includes a series of pad assemblies  28   1-3  provided on their respective lower ends. It should be pointed out however, that embodiments exist wherein pad assemblies  28   1-3  are on an upper end of the sample probe assemblies  26   1-3 . Further optional embodiments exist wherein some of the sample probe assemblies  26   1-3  have pad assemblies  28   1-3  on their lower ends, wherein some of the other sample probe assemblies  26   1-3  have the pad assemblies  28   1-3  on their upper ends. Each of the sample probe assemblies  26   1-3  further include elongated linkage arms  30   1-3  which couple between the pad assemblies  28   1-3  and corresponding actuators  32   1-3  shown provided on body  24 . As will be described in more detail below, operating actuators  32   1-3  in turn moves linkage arms  30   1-3  into a designated position to urge the pad assemblies  28   1-3  radially away from body  24 . Further shown provided with body  24  are sample tanks  34   1-3  that are associated with each one of the sample probe assemblies  26   1-3 . Conduits  36   1-3  provide fluid communication respectively between ports  38   1-3  provided on pad assemblies  28   1-3  and sample tanks  34   1-3 . 
       FIG. 1B  shows an example of when the sample probe assemblies  26   1-3  are in a deployed configuration and with their respective pad assemblies  28   1-3  extended radially outward and into contact with wall  40  that is defined along the inner surface of wellbore  12 . Thus in the deployed configuration of  FIG. 1B , sample probe assemblies  26   1-3  are oblique to axis A X  of tool  10 . Also while in the deployed configuration, formation fluid within formation  14  may be drawn into the sample probe assemblies  26   1-3  and directed to sample tanks  34   1-3  for storage and/or for further analysis. As shown in the example of  FIG. 1B , the pad assemblies  28   1-3  are at substantially the same “measured depth” in the wellbore  12 , that is, the same distance along a path defined by the wellbore  12 , from the opening of the wellbore  12  to where on the wall the pad assemblies  28   1-3  are disposed. 
     Referring now to  FIG. 2A , shown in a partial side sectional view is one embodiment of a sample probe assembly  26 A. In the illustrated example a single sample probe assembly  26 A is shown as a representative example of the multiplicity of sample probe assemblies  26 A that could be included with the tool  10 . The sample probe assembly  26 A is depicted in the deployed position, with its pad assembly  28 A in contact with the wall  40  of wellbore  12 . In this example embodiment, actuator  32 A is hydraulically powered and includes a housing  42  having an inner cavity that defines a cylinder  44 . A piston  46  is reciprocatingly disposed within cylinder  44 . A hydraulic source  48  provides pressure communication to and from cylinder  44  via lines  50 ,  52  shown extending between source and housing  42 . Lines  50 ,  52  are shown on opposite sides of piston  46 , so that alternatively changing a direction fluid flow (or pressure) within lines  50 ,  52  may reciprocate piston  46  within cylinder  44 . Valves  54 ,  56  are optionally provided in lines  50 ,  52  that may be selectively opened and closed to control flow through lines  50 ,  52 . A rod  58  connects to a side of piston  46 , wherein an opposite side of rod  58  couples with linkage arm  30 A. Thus by reciprocating piston  46  and rod  58  in the path illustrated by arrow A, pad assembly  28  is urged along an arcuate path, as illustrated by arrow A R . With the pad assembly  28  in contact with wall  40 , formation fluid can make its way through port  38 , into conduit  36  and onto sample tank  34 , whereas indicated above, fluid can be analyzed real time, or stored for later analysis when the tool  10  is brought to surface. 
     Further in the example of  FIG. 2A , pad assembly  28  is shown made up of a pad  59  which connects to a terminal end of arm  30 A. A packer  60  is provided on the outer surface of pad  59  and has a surface which is in contact with wall  40 . In one example, an outer radial surface of packer  60  contacting wall  40  has a generally rectangular shape and extends along a portion of the circumference of wall  40 . Example materials for packer  60  include elastomers that are sufficiently resilient for use, however pliable enough to create a seal around port  38 . An optional pressure sensor  62  is shown in fluid communication with conduit  36 , thereby putting pressure sensor  62  in pressure communication with formation  12  through conduits  36  provided in the linkage arm  30 A. Data sensed by pressure sensor  62  may be communicated to a controller  64  via signal line  66 . Signal line  66  can be hard wired, pneumatic, or wireless. Referring back to  FIG. 1 , controller  64  may be included with tool  10  and wherein communication means  67  is shown passing along body  24 . Alternatively, controller  64  can be on surface  20 , such as in surface truck  18 . Referring back to  FIG. 2A , an optional valve  68  is shown provided within conduit  36 . An advantage of implementing valve  68  is that when multiple sample assemblies are provided on tool  10 , fluid communication through each of the sample probe assemblies can be regulated with the implementation of valve  68 . Thus in one example, one or more of the sample probe assemblies may be isolated by closing valve  68 , whereas other selective sample probe assemblies may be operated with valve  68  in an open configuration. As such, operational embodiments exist wherein the sample probe assemblies are operated independently from one another. 
     Shown in partial side sectional view in  FIG. 2B  is an alternative example of actuator  32 B for putting sample probe assembly  26 B into a deployed configuration and with the pad assembly  28  and sampling contact with wall  40  of wellbore  12 . In this example, the actuator  32 B includes a screw member  70  with threads mounted on a shaft, where shaft is rotated by a motor  72 . Screw  70  engages a nut  74  mounted on linkage arm  30 B, so that selective rotational direction of screw  70  with motor may translate linkage arm  30 B in the arcuate path represented by arrow A R . Further, operation of actuator  32 B may be accomplished via controller  64 . 
       FIG. 2C  shows in a partial side sectional view another alternate example of a linkage arm  30 C which is shown having a linkage assembly  76 . In this example, linkage assembly  76  is made up of a series of linkage arms  78 ,  80 ,  82  connected in series to one another via pins  84 . Here, pad assembly  28  is in the deployed configuration and against wall  40 . In the deployed position, arm  30 C and arm  80  are generally oblique to an axis A X  of tool  10 C whereas arms  78 ,  82  are generally parallel with axis A X . A force F applied at an end of arm  78  distal from arm  80  articulates arms  80 ,  82 ,  30 C about their pinned connected for pad assembly  28  radially outward and into contact. Conversely, applying force F in a direction away from arm  80  and aligned arm  78 ,  80 ,  82  to be substantially parallel with axis A X . 
     Referring now to  FIG. 3 , shown is an axial view of an example of tool  10  disposed within wellbore  12 , and taken along lines  3 - 3  of  FIG. 1B . In this example a series of four sample probe assemblies  26   1-4  are illustrated and in the deployed mode with their respective pad assemblies  28   1-4  in sampling contact with wall  40  of wellbore. In this example, zones Z 1-4  are represented within formation  14  at angularly spaced apart azimuthal locations along the circumference of wellbore  12 . One example of operation, one or more of the sample probe assemblies  26   1-4  may in a sampling mode, wherein one or more of other sample probe assemblies  26   1-4  may be in an injection mode, so that fluid may be taken from one of these zones Z 1-4 , while fluid is simultaneously injected into another one of the zones Z 1-4 . Another alternative, each of sample probe assemblies  26   1-4  may be simultaneously drawing fluid from within formation and from zones Z 1-4 . As indicated above, the implementation of valve  68  within the conduits  36   1-4  allows for selective sampling of one or more of the zones Z 1-4  at the same time. Furthermore, another advantage is realized by positioning the sample probe assemblies  26   1-4  within the tool body  24  so that when in the deployed configuration, the pad assemblies  28   1-4  are at substantially the same measured depth within wellbore  12 . Moreover, the mechanical nature of the linkage assemblies described herein allows for the simultaneous placement of pad assemblies  28   1-4  at the same measured depth to take place in a vertical portion of the wellbore  12 , a deviated portion of the wellbore  12 , or a horizontal portion of the wellbore  12 . Other known prior art devices are unable to achieve this functionality within the aforementioned different wellbore orientations. Further illustrated in the example of  FIG. 3  are dedicated controllers  64   1 - 64   4  for use with each of the sample probe assemblies  26   1 - 26   4 . 
     The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. In an example embodiment, sample probe assemblies can be provided that are disposed axially from one another, so that sampling can take place at different depths in the wellbore with the tool  10 . This and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.