Abstract:
A system and method of gathering sample cores from a subterranean formation with coring bit assemblies, where each of the coring bit assemblies retain a sample core within. Included is a container equipped with compartments for individual storage of each coring bit assembly and coring sample, so that each sample can be stored at the pressure at which it was obtained. The coring bit assemblies can be sequentially inserted into the container after being used to collect its sample core. In this instance, scaling devices, such as o-ring seals or a coining surface, are provided in the container. Bach coring bit assembly can also be disposed in a chamber, that is selectively scaled after the coring bit assembly gathers its coring sample.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of Invention 
         [0002]    The present disclosure relates to a system and method for obtaining core samples from a sidewall of a wellbore where each core sample is stored at the pressure at which it was obtained. 
         [0003]    2. Description of Prior Art 
         [0004]    Production of hydrocarbons typically involves excavating a borehole from the Earth&#39;s surface, through the underlying subterranean formation, and that, intersects a hydrocarbon bearing reservoir downhole. To aid in identifying hydrocarbon bearing locations, sample cores are sometimes obtained from a sidewall of the borehole, which is generally referred to as coring. The step of coring often employs a coring tool having a side coring bit that is rotatable and can be urged radially outward from the coring tool. The coring bit is usually made up of a sleeve having a cutting surface on of its end that is projected outward from the tool Thus sample cores can be gathered by rotating the coring bit while urging it against the sidewall, thereby cutting a sample away from the formation that is collected within the sleeve. The end of the sample adjacent the cutting surface breaks away from the rest of the formation so that the coring sleeve with sample inside can be drawn back into the coring tool. Often multiple com samples are obtained with a single trip downhole of the coring tool. Typical practice is to eject the multiple core samples together into a single storage area. 
       SUMMARY OF THE INVENTION 
       [0005]    Disclosed herein is an example of a system for obtaining core samples from a sidewall of a wellbore, that in one embodiment includes a housing, spaces in the housing, pressure barriers selectively disposed between the spaces so that a pressure in each of the spaces is maintained at a particular value, and a coring bit assembly disposed in each one of the spaces. Each of the coring bit assemblies include a sleeve that selectively receives a one of the core samples and a cutting head on an end of the sleeve that selectively is projected from the housing and into cutting engagement with the sidewall. A coring driver can be included in the housing that selectively engages an end of the sleeve distal from the cutting head. In this example, the coring driver is selectively movable axially within the housing. In one alternative, the coring bit assemblies are arranged in a row that extends axially within the housing, and wherein the coring bit assemblies are moveable axially with respect to the coring driver. The system may further include a cylindrically shaped riser member in the housing, wherein the spaces are formed in the riser member, and wherein the coring bit assemblies with core samples are selectively disposed in the spaces. In this example, the riser member is made of a tubular with an axis that is substantially parallel with an axis of the housing and has planar barriers provided between each adjacent coring bit assembly and that span across an inner circumference of the tubular to define pressure barriers. Further included with the riser member are rear openings through which a coring driver is selectively inserted and forward openings through which coring bit assemblies project through when the cutting head is in cutting engagement with the sidewall. This embodiment can further have a container in which the riser member is selectively coaxially inserted, the container comprising an inner circumference with o-ring seals strategically located thereon, so that when the riser member is inserted into the container, at least one of the o-ring seals is between adjacent rear openings and adjacent forward openings. In an example, the riser member is made up of a substantially solid cylindrical member having chambers transversely formed therein that are selectively pressure isolated from one another and wherein a one of the coring bit assemblies is disposed in each of the chambers. This example can further have a piston coaxially mounted in each of the chambers, and seals between the pistons and inner surfaces of the chambers that define a pressure barrier, wherein each of the pistons is coupled with an end of a coring bit assembly, so that when a coring bit assembly drive rotatingly and longitudinally motivates a one of the pistons, an attached coring bit assembly is urged out of the respective chamber and into coring engagement with the sidewall. Apertures may be included that are in a sidewall of the housing and through which the coring bit assemblies are inserted through, and a capping system having covers that are scalingly mounted over the apertures so that the space is pressure sealed. Further optionally included is a container with a metal inlay disposed axially along a sidewall of the container, wherein the coring bit assemblies are disposed into the container so that the cutting heads are in sealing contact with the metal inlay, wherein the metal inlay is formed from a material having a yield strength that is less than a yield strength of a material making up the cutting heads, and wherein the spaces are formed as the cutting heads are urged into sealing contact with the metal inlay. In one embodiment a cap is inserted into an open end of the sleeve to define a pressure seal for an inside of the sleeve, the cap having a circular base and walls circumscribing the base that project axially away from the base and abut an inward facing surface of the cutting head. The system can optionally further include a cap inserted into an open end of the sleeve to define a pressure seal for an inside of the sleeve, where the cap is made up of a circular base and waits circumscribing the base that project axially away from the base and are threadingly coupled with an inner circumference of the cutting head. In an example, the particular value is substantially the same as a value of pressure in a subterranean formation from which the core sample was obtained. 
         [0006]    Another example of a system for obtaining core samples from a sidewall of a wellbore includes a housing, spaces formed in the housing that are selectively maintained at different pressures, and a coring bit assembly in each one of the spaces, each of the coring bit assemblies having an annular cutting head and a sleeve having an open end coaxially affixed with the cutting head, so that when the cutting head is rotatingly and longitudinally urged into cutting contact with subterranean formation at the sidewall, a core sample is formed and deposited into the sleeve and maintained in the sleeve at a pressure that is substantially the same as a pressure of the subterranean formation from which the core sample was taken. The spaces can be formed in an annular riser member that is disposed in the housing, wherein the riser member includes a tubular with planar pressure barriers, wherein the spaces are defined between adjacent barriers. Optionally, the spaces are formed in an annular riser member that is disposed in the housing, and wherein the riser member is a substantially solid cylinder with chambers transversely formed through the riser member. Pistons may be included with this embodiment, where the pistons are coaxially disposed in the chamber that couple with an end of each coring bit assembly, and seals between the circumference of each piston and an inner wall of each chambers, so that by rotatingly and longitudinally motivating a one of the pistons, a corresponding coring bit assembly is put into coring engagement with the sidewall for retrieval of a coring sample. In an example, the spaces are formed by sealing an open end of each of the sleeves with a cap. 
         [0007]    Also disclosed herein is an example of a method of obtaining core samples from a sidewall of a wellbore and which includes providing a coring system that is made up of a housing and coring bit assemblies, each coring bit assembly having a cutting head and a sleeve. The method can further include using a one of the coring bit assemblies to gather a core sample, storing the one of the coring bit assemblies and the core sample in the housing at a particular pressure, using another one of the coring bit assemblies to gather another core sample, and storing the another one of the coring bit assemblies and the another core sample in the housing at another particular pressure. The one of the coring bit assemblies and the another one of the coring bit assemblies can be stored in an elongated riser member. This example can further include inserting the elongated riser member into a container, and strategically providing seals at axial locations between the riser member and container, so that spaces formed transversely through the riser member are pressure Isolated from one another. Alternatively, the one of the coring bit assemblies and the another one of the coring bit assemblies can be disposed in chambers transversely formed through the riser member, the method may further involve providing pistons in ends of the chambers, coupling the pistons respectively to one of the coring bit assemblies and the another one of the coring bit assemblies, selectively rotating and longitudinally urging a one of the pistons to obtain a core sample. In an embodiment, the step of storing includes sealing open ends of the coring bit assemblies with caps. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0008]    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: 
           [0009]      FIG. 1  is a side sectional view of an example of a coring system disposed in a wellbore. 
           [0010]      FIGS. 2A and 2B  are side perspective and partial sectional views of an example of obtaining a core sample with the coring system of  FIG. 1 . 
           [0011]      FIG. 3  is a perspective view of an example of core sleeves with core samples being stored in a sealed container. 
           [0012]      FIGS. 4A and 4B  are side sectional views of an example of sealing an open end of a coring sleeve with a cap, and where a core sample is in the coring sleeve. 
           [0013]      FIG. 5  is a side sectional view of an example of sealing an open end of a coring sleeve with a threaded cap, and where a core sample is in the coring sleeve. 
           [0014]      FIG. 6  is a perspective view of an embodiment of a coring system having a device for capping apertures formed in a housing of the coring system. 
           [0015]      FIG. 7  is a perspective view of an alternate example of core sleeves with core samples being stored in a sealed container. 
           [0016]      FIG. 8  is a side sectional view of an example of core sleeves with core samples being stored in a sealed container that has a coined surface. 
           [0017]      FIG. 9  is an axial sectional view of the container of  FIG. 4  and taken along lines  9 - 9 . 
           [0018]      FIG. 10  is a perspective view of an alternate embodiment of a coring system having coring bit assemblies provided in a scalable chamber. 
       
    
    
       [0019]    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 
       [0020]    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. 
         [0021]    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. 
         [0022]      FIG. 1  shows in a side partial sectional view one example of a coring system  10  disposed in a wellbore  12 , where wellbore  12  intersects a subterranean formation  14 . Coring system  10  includes a main body with an outer housing  16 . Included within housing  16  is a power unit  18  and a coring section  20  adjacent power unit  18 . A lower section  22  is shown on an end of coring section  20  distal from power unit  18 . In the example of  FIG. 1 , the coring system  10  includes a coring bit assembly  24 , which is shown being driven by a coring bit assembly driver  26  to obtain sample cores  28  from a sidewall of wellbore  12  and from formation  14 . Embodiments exist where the power unit  18  includes power sources, such as batteries, hydraulic sources, or other forms of energizing the coring bit assembly driver  26 . In one alternative, a storage container  30  is shown within housing  16  and where sample cores  281   1−n  are optionally stored. One example, each of the sample cores  281   1−n  is stored at a pressure that is different from a pressure at which another one of the sample cores  281   1−n  is stored. Examples exist wherein the pressure at which the sample cores  281   1−n  are stored at substantially the same pressure within formation  14  from where they were obtained. 
         [0023]    A wireline  32  is shown being used for deploying the coring system  10  within wellbore  12 , however, any other deployment means to be used with coring system  10 , such as coiled tubing, slick line, drill pipe, cable, and the like. Further, a surface truck  34  is shown provided at surface  36  for selectively raising and lowering wireline  32  and for deploying coring system  10 . Wireline  32  is shown being inserted through a wellhead assembly  38  that mounts on an upper open end of wellbore  12  at surface  36 . Further optionally, the storage container  30  may be selectively moved from within coring section  20  and into lower section  22 . 
         [0024]      FIG. 2A  shows in perspective side partial sectional view one example of a portion of coring section  20  of the coring system  10 . In this example, coring section  20  includes an outer housing  39  which provides a covering and protection for components of the coring section  20 . Here, coring bit assemblies  241   1−n  are shown provided within a riser member  40 ; in this example an axis A R  of riser member  40  is shown substantially parallel and radially offset with an axis A H  of housing  39 . Alternate examples exist wherein riser member  40  is canted within housing  39  such that axis A R  is oblique with respect to axis A H . Riser member  40  of  FIG. 2A  includes a tubular  41  member having a diameter less than the diameter of housing  39  and is asymmetrically offset within housing  39 . Between adjacent ones of the coring bit assemblies  241   1−n  are planar barriers  42   1 - 42   n   +1 . Barriers  42   1 - 42   n   +1  span across the entire inside of the tubular  41  to define spaces  43   1   1−n  therebetween. It is within the spaces  43   1   1−n  where the coring bit assemblies  24   1−n  are provided. Each of the coring bit assemblies  24   1−n  include an annular sleeve  44   1−n , each of which have a closed end and an open end; where a cutting head  45   1−n , is provided at the open end. In the example of the  FIG. 2A , coring bit assemblies  24   1-2  are shown each having a core sample  28   1 ,  28   2  disposed within their respective sleeves  44   1 ,  44   2 . Forward openings  46   1−n  are provided within the sidewall of the tubular  41  to allow the respective coring bit assemblies  24   1−n  to be urged radially outward from within the tubular  41 . Similarly, rearward openings  47   1−n  are provided through a sidewall of the tubular  41 , opposite from associated forward openings  46   1−n ; wherein die rear openings  47   1−n  provide a pathway for the coring bit assembly driver  26  to selectively engage one of the coring bit assemblies  24   1−n . 
         [0025]    Coring bit assembly driver  26  includes a body  48  and a drive attachment  50 . Body  48  is depicted as a generally cylindrical member, and drive attachment  50  is shown provided on an end distal from the riser member  40 . A drive surface  52  is provided on an outermost portion of drive attachment  50  that can be profiled for selective coupling with one of the coring bit assemblies  24   1−n . Although not shown, the profiles can resemble teeth, gears, or any other type of elements or projections wherein rotational force from one body can be transferred to another. Coring bit assembly driver  26  is shown further including a drive member  54  that couples with drive attachment  50  via an elongated drive shaft  56 . Examples exist where drive member  54  is a motor driven by an electrical power source (not shown) or can be hydraulically driven to provide rotational and longitudinal motivation to the body  48  and drive attachment  50 . For example, the drive member  54  can be energized from a power source disposed in power unit  18  ( FIG. 1 ). Moreover, elongated tracks  58  are shown disposed within housing  39  that extend axially and proximate an inner surface of housing  39 . Coring bit assembly driver  26  is axially moveable within housing  39  and along tracks  58 . Alternate embodiments exist, wherein coring bit assembly driver  26  remains within its axial location within housing  39 , and selective ones of the coring bit assemblies  24     1 −n  are moved axially into a position adjacent the coring bit assembly driver  26 . In one example, the riser member  40  is moved axially to selectively position the coring bit assemblies  24   1−n . Further provided in  FIG. 2A  are apertures  60   1−n  that are formed radially through a sidewall of housing  39 . As will be described in more detail below, when apertures  60   1−n  register with forward openings  46   1−n , selected one or more of the coring bit assemblies  24   1−n  may be inserted through their respective forward openings  46   1−n  and aperture  60   1−n  and into coring engagement with the formation  14 . 
         [0026]    Shown in  FIG. 2B  is one example of obtaining a sample core  28   3  from formation  14 . Here, coring bit assembly driver  26  is disposed on tracks  58  at a selected axial location within housing adjacent coring bit assembly  24   3  and oriented for coring engagement with coring bit assembly  24   3 . Here, drive shaft  56  is extended radially away from drive member  54  so that the cutting head  453  is being rotated and pushed against formation  14  to cut away rock in the formation. Continued radial pushing of coring bit assembly  24   3 , combined with its rotation, cuts away a cylindrically shaped sample core  28   3  that is drawn within can gathered within sleeve  44   3 . Further, as indicated above, sleeve  44   3  and cutting head  45   3  have been inserted through the forward end  46   3  and the registered aperture  60   3 . After obtaining the core  28   3 , the coring bit assembly driver  26  can return to its configuration of  FIG. 2A , moved axially along tracks  58 , and another one of the coring bit assemblies  24   4−n  can be engaged to obtain additional sample cores. As will be described in further detail below, alternatives exist wherein the particular sample core  28   1−n  is selectively stored at a particular pressure. Either by sealing the coring bit assembly  28   1−n  within the riser member  40 , or inserting the riser member  40  within a containment-type vessel that then provides sealing of the coring bit assemblies  24   1−n  with their respective cores  28   1−n  at live designated pressures. 
         [0027]    In the example of  FIG. 3 , riser member  40  is inserted within an annular container  62 . In this example, O-ring seals  63  are shown provided at strategic locations along an axis A C  of container  62  and between adjacent ones of openings  46   1−n , and  47   1−n . As such, containment spaces  64   1−n  are formed so that the respective sample cores  28   1−n  can be stored at a pressure at which they were obtained. In one example of operation, coring bit assembly  24   1  is the first one of the coring bit assemblies  24   1−n  to be used for obtaining its respective sample core  28   1 . Prior to obtaining additional sample cores, tubular  41  is inserted into container  62  far enough so that an uppermost one of the O-ring seals  64  is between openings  46   1 ,  47   1  and openings  46   2 ,  47   2 . As such, a sealed space  64   1  is formed within the tubular  41  between barrier  42   1  and barrier  42   2 . And in the volume of space that surrounds coring bit assembly  24   1  and its sample core  28   1 . Accordingly, as uppermost of the coring bit assemblies  24   2−n  are engaged to obtain a corresponding core sample  28   2−n , the tubular  41  may be sequentially urged farther within container  62  and thereby forming additional sealed spaces  64   2−n  as illustrated in  FIG. 3 . In this manner, the individual sealed spaces  64   1−n  may be at a pressure that is substantially the same as a pressure in the formation  14  ( FIG. 1 ) at which the sample cores  28   1−n  were obtained, in one example pressure in sealed space  64   3  is substantially the same as the pressure in formation  14  from where sample core  28   3  was gathered. Further shown in the example of  FIG. 3  is that the tubular  41  is substantially coaxial with container  62 , so that axes A R , A C  substantially occupy the same space. 
         [0028]    Referring now to  FIGS. 4A and 4B , shown in a side sectional view is one example of securing a cap  65  to an open end of a sleeve of a coring bit assembly  24  after a core sample  28  has been collected and disposed in the sleeve  44 . In this example, cap  65  includes a disk-like base  66  with a curved outer periphery, and walls  67  that project axially away from the outer periphery of base  66 . In the example of  FIG. 4A , the walls  67  are directed away from the open end of sleeve  44 . A rod  68  is shown applied to base  66  and used for urging cap  65  in the direction of arrow A and towards the open end of sleeve  44 . As the cap  65  is urged past the cutting head  45 , the force applied by rod  68  on base  66  causes flexing of cap  65  so that it may be inserted past the inner circumference of cutting head  45 . Ultimately, the walls  67  extend past the inside of cutting head  45  and so that the walls  67  abut the inward lacing surface of cutting head  45 . The configuration of  FIG. 4B  illustrates a cap  65  that provides a seal on the open end of sleeve  44  thereby defining a sealed space  69  within sleeve  44 , which is one optional way of individually pressure sealing the sample core  28 . It is well within the capability of those skilled in the art to create a means for urging rod  68  against cap  65  to provide the sealing capabilities of the cap  65 . It is to be understood that this method of sealing illustrated in  FIGS. 4A and 4B  may be applied to one or more of the coring bit assemblies  24   1−n  ( FIG. 2A ). In an alternate embodiment shown in  FIG. 5 , cap  65 A may have threads on an outer circumference that mate with threads on an inner surface of the cutting head  45 . In this configuration, threadingly attaching cap  65 A to cutting head  45 A defines a threaded connection  70  between cap  65 A and cutting head  45 A and creates a sealed space  69 A within sleeve  44 A. In these examples, sealed spaces  69 .  69 A can be at substantially the same pressure at which the corresponding core sample  28  was obtained. 
         [0029]    Shown in  FIG. 6  is an alternate embodiment of a portion of coring system  10 A and with coring bit assemblies  24   1−n  disposed within housing  39 . Missing from the embodiment of coring system  10 A is a pressure containment system for the coring bit assemblies  24   1−n . Instead, a cover deployment system  81  is shown and that is used for providing covers  82   1−n  over the respective apertures  60   1−n  formed though the sidewall of the housing  39 . Cover deployment system  81  includes a rail assembly  83  on which covers  82   1−n  are mounted and arranged along a path that circumscribes the outer surface of housing  39 . An urging means (not shown) selectively moves the covers  82   1−n  into position and registration with their respective aperture  60 . Coupling of the covers  82   1−n  with apertures  60  can involve a threaded fitting, so that by rotating the covers  82   1−n , they can be inserted into apertures  60 . In an alternative embodiment caps  65  ( FIGS. 4A, 4B ) may be provided with the cover deployment system  81 , so that instead of covers the caps  65  can be attached to the coring bit assemblies  24   1−n  as described above. 
         [0030]      FIG. 7  illustrates in side perspective view an example of a series of the coring bit assembles  24   1−n  each holding a sample core  28   1−n . In this example, the coring bit assemblies  24   1−n  are disposed in a container  62 A that is pressure sealed so that the sample cores  28   1−n  can be drawn to surface and analyzed. Here, a planar bracket  72  holds the coring bit assemblies  24   1−n  in a row within the container  62 A to define a cartridge  73 . In one example of operation, the coring bit assemblies  24   1−n  are slideable with respect to bracket  72  along a direction that is parallel to an axis A X  of each of the coring bit assemblies  24   1−n . This allows the individual coring bit assemblies  24   1−n  to be moved radially outward from within the housing  39  ( FIG. 2B ) for gathering core samples  28   1−n  as described above. After the sample cores  28   1−n  are obtained with the coring bit assemblies  24   1−n , the cartridge  73  can be then moved axially within the coring system  10 B from the housing  39 , and into container  62 A where they arc stored under pressure. 
         [0031]      FIG. 8  shows an example of an example of a cartridge  73  that is made up of series of coring bit assemblies  24   1−n  wherein their respective sample cores  28   1−n  arc stored at substantially the same pressure in the formation  14  ( FIG. 1 ) from where the sample cores  28   1−n  were obtained. The cohesive structure of the cartridge  73  facilitates inserting coring bit assemblies  24   1−n  and sample cores  28   1−n  within container  62 B and as a single unit. In this example, an inlay  74  is shown provided along an inner surface of container  62 B and extending substantially along the length of container  62 B and along a portion of its circumference. Optionally, however, the entire inner surface of container  62 B may include inlay  74 . In an example of operation of the embodiment of  FIG. 8 , the coring bit assembly  24   1  is the first to be used for obtaining sample core  28   1  and then the cartridge  73  is moved from within housing  39  and axially into container  62 B a distance just far enough so that the open end of sleeve  44   1  and the cutting head  45   1  coring bit assembly  24   1  are in sealing contact, with inlay  74 . Example materials for inlay  74  include materials that are pliable, and have a yield strength less than a yield strength of a material used for forming cutting head  45   1 . In the illustrated example, the material of inlay  74  deforms and can provide a sealing surface to create a sealed space  69   1 B- 69   n B within sleeve  44   1 . As sample cores  28   1−n  at different depths or locations within wellbore  12  ( FIG. 1 ) can be initially at different pressures, pressures in the different sealed spaces  69   1 B- 69   n B can be different as well. In the example of  FIG. 8 , each of the coring bit assemblies  24   1−n  have been deployed to obtain their respective sample cores  28   1−n  and the cartridge  73  has been inserted fully into container  62 B. As such, axially sliding cartridge  73  into container  62 B, combined with a radial force to individually urge the coring bit assemblies  24   1−n  against inlay  74 , creates a coined surface  76  along the outer surface of inlay  74 . So that the coring bit assemblies  24   2−n  may maintain sealing contact with relay  74 , the respective lengths of the sleeves  44   1−n  can increase in length with ascending order in which they are provided in the cartridge  73 . For example, the axial length of sleeve  44   n  would be greater than any of the axial lengths of sleeves  44   1-4 . Alternatively, the coring bit assemblies  24   1−n  may be staggered with respect to their position on bracket  72  to ensure their respective cutting heads  45   1−n  maintain a sealing contact with coined surface  76 . Shown in an axial view in  FIG. 9 , which is taken along lines  9 - 9  of  FIG. 8 , depicts how cutting head  45   3  is urged into sealing contact with inlay  74 . Alternatively, the lower portion  78  can be thinner and the upper portion  80  thicker.