Abstract:
A high power opto-electrical cable with multiple power and telemetry paths and a method for manufacturing the same includes at least one cable core element and at least one high-power conductor core element incased in a polymer material jacket layer. The cable core element has at least one longitudinally extending optical fiber surrounded by a pair of longitudinally extending arcuate metallic wall sections forming a tube and a polymer material jacket layer surrounding and incasing the wall sections, wherein the optical fiber transmits data and the wall sections transmit at least one of electrical power and data.

Description:
BACKGROUND 
       [0001]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
         [0002]    The present disclosure is related in general to wellsite equipment such as oilfield surface equipment, oilfield cables and the like. 
         [0003]    As easily accessible oil reserves become increasingly less common, oil exploration may require drilling to greater depths. Concurrently, more complex, versatile downhole tools have greater requirements for electrical power and/or telemetry. Wireline cables containing only copper conductors are unable to adequately meet today&#39;s requirements for both power and telemetry. 
         [0004]    Optical fibers, while occupying much smaller space, can provide much lower telemetry attenuation compared to copper conductors. Utilization of optical fibers frees up the cable core real estate and thereby makes it possible to integrate larger conductors for power transmission. Therefore, replacing a copper conductor with an optical fiber in order to increase telemetry capability will provide viable solutions to both telemetry and power problems. 
         [0005]    It remains desirable to provide improvements in wireline cables. 
       SUMMARY 
       [0006]    In the embodiments described below, a cable core element has optical fibers for transmitting data and a surrounding metallic tube for transmitting electrical power and/or data. The tube is covered in a layer of polymer material insulation. 
         [0007]    The optical fibers are packaged in copper tube shields, which shields can be comprised of two or more arcuate copper wall sections. Micro-bundled fibers can be used to increase the number of fibers in the copper shields. Bundled fibers can include single mode and multi-mode fibers. These fibers can be used for telemetry and/or as sensors to measure distributed temperature, pressure, and longitudinal stain, etc. These fibers are cabled in a helix, increasing the longitudinal strain they can sustain. The copper shields can have one or more layers. Copper shield layers or tubes are separated with insulating polymers. A package with two copper shield layers can operate as a coaxial cable core. 
         [0008]    Optical fiber packages with copper conductors are possible in “TRIAD” or “QUAD” designs which are mechanically stable and can transmit high power. The designs contain a high voltage electrical path and a low voltage electrical path. The low voltage path has the option to connect ground to either the copper shield tube or the armor wires. The “QUAD” design can also supply AC power to downhole tools. Embodiments in these designs offer at least two power paths as well as copper and fiber optic telemetry paths. 
         [0009]    A first embodiment cable core element comprises at least one longitudinally extending optical fiber, a pair of longitudinally extending arcuate metallic wall sections forming a tube surrounding the at least one optical fiber, and a polymer material(s) jacket(s) layer surrounding and incasing the wall sections, wherein the optical fiber is adapted to transmit data and the wall sections are adapted to transmit at least one of electrical power and data. The metallic wall sections can be formed of copper and the optical fibers may comprise uncoated optical fibers. 
         [0010]    A second embodiment cable core element includes the first embodiment cable core element described above with another pair of arcuate metallic wall sections surrounding the jacket layer and forming another tube adapted to transmit at least one of electrical power and data. The another metallic wall sections can be formed of copper and be surrounded by another polymer material jacket layer. 
         [0011]    A cable core embodiment for transmitting data and electrical power includes at least one of the optical fiber cable core elements, at least one longitudinally extending high-power electrical conductor core element, and a polymer material layer surrounding and incasing the at least one optical fiber cable core element and the at least one electrical conductor core element to form the cable core. The cable can include at least one layer of armor wires surrounding the polymer material layer and may or may not have one outer layer of polymer material surrounding and incasing the at least one layer of armor wires. 
         [0012]    A method for manufacturing a cable for transmitting electrical power and data, comprises the steps of: providing at least one longitudinally extending optical fiber; surrounding the at least one optical fiber with a metallic tube; surrounding and incasing the tube with a polymer material jacket layer to form a cable core element wherein the at least one optical fiber is adapted to transmit data and the tube is adapted to transmit at least one of electrical power and data; providing at least one longitudinally extending high-power electrical conductor core element; and forming a cable core by surrounding and encasing the at least one optical fiber cable core element and the at least one electrical conductor core element with an extruded polymer material layer. 
         [0013]    The method can include prior to performing the step of forming the cable core, providing a central element in the form of a deformable filler rod or an insulated conductor, helically cabling the at least one optical fiber cable core element and the at least one electrical conductor core element around the central element, extruding a polymer material outer jacket layer over the cable core. The method further can include applying at least one layer of armor wires at a predetermined lay angle over and partially embedded into the outer jacket layer and extruding an outer layer of polymer material over the at least one layer of armor wires. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    These and other features and advantages of the present disclosure will be better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
           [0015]      FIG. 1  is a radial cross-sectional view of a typical prior art wireline hepta cable; 
           [0016]      FIG. 2  is a radial cross-sectional view of a first embodiment wireline cable core element according to the present disclosure; 
           [0017]      FIG. 3  is a radial cross-sectional view of a second embodiment wireline cable core element according to the present disclosure; 
           [0018]      FIG. 4  is a radial cross-sectional view of a first embodiment wireline cable core according to the present disclosure; 
           [0019]      FIG. 5  is a radial cross-sectional view of a second embodiment wireline cable core according to the present disclosure; 
           [0020]      FIGS. 6A and 6B  are radial cross-sectional views of a third embodiment wireline cable core with and without a center conductor respectively according to the present disclosure; 
           [0021]      FIGS. 7A and 7B  are radial cross-sectional views of a fourth embodiment wireline cable core with and without a center conductor respectively according to the present disclosure; 
           [0022]      FIG. 8  is a radial cross-sectional view of the wireline cable core shown in  FIG. 5  with an armor wire package according to the present disclosure; and 
           [0023]      FIG. 9  is a radial cross-sectional view of the wireline cable core shown in  FIG. 8  with the armor wires bonded in a polymer material jacket according to the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    The methods described herein are for making and using oilfield cable components with optical fibers packaged in copper shields. However, it should be understood that the methods may equally be applied to other fiber optic components having metallic shields formed of metallic material other than copper, for example, and that methods for making and using such components are also within the scope of the present disclosure. 
         [0025]    The most commonly used prior art hepta cables  10  have seven conductors, with six conductors  11  cabled around a central conductor  12 , as shown in  FIG. 1 . Each of the conductors  11  and  12  is formed with a plurality of metallic wires incased in a polymer material. The conductors  11  are positioned about the central conductor  12  and all of the conductors are incased in a polymer material inner jacket  13 . The jacket  13  is surrounded by an inner layer of smaller-diameter armor wires  14  and an outer layer of larger-diameter armor wires  15 . The wires  14  and  15  can be incased in a polymer material outer jacket (not shown). Generally, the cable size is restricted due to requirements of surface equipment. The conductor size in hepta cables cannot be increased freely due to the limited real estate available. This situation limits the potential of the prior art hepta cable  10  to provide high-power transmission. Considering the above, typical wireline cables are unable to adequately meet today&#39;s ever demanding requirements for power and telemetry. 
         [0026]    A first embodiment cable core element  20  according to the present disclosure is a one layer copper halves configuration shown in  FIG. 2 . Longitudinally extending optical fibers  21  are arranged inside two arcuate metallic wall sections  22  that form a longitudinally extending tube shielding the fibers. A polymer material jacket layer  23  is extruded over the wall sections  22  to serve as insulation and protection. Although the wall sections  22  are shown as being abutting semicircular halves, each section could have a different arc and more than two sections could be used to form the tube. In an embodiment, the wall sections  22  are formed of copper. 
         [0027]    One feature of this first embodiment is that the optical fibers  21  are packaged loosely into the two copper wall sections  22 . Because the optical fibers  21  are protected inside the “tube” formed by the sections  22 , the additional expense of carbon coating on the fibers may be avoided and, therefore, the optical fiber or fibers  21  may be uncoated optical fibers  21 . The two copper wall sections  22  are protected with the polymeric material jacket  23  which is extruded over the copper walls. The polymeric material jacket  23  also serves as an insulation material which enables the wall sections  22  to transmit electrical power and/or data. 
         [0028]    A second embodiment cable core element  30  according to the present disclosure is a two layer copper halves configuration shown in  FIG. 3 . At the center of the core element  30 , there are positioned the optical fibers  21 , the wall sections  22 , and the jacket layer  23  shown in  FIG. 2 . The wall sections  22  are first wall sections forming an inner tube and the jacket layer  23  is an inner jacket layer. Another layer of two arcuate metallic second wall sections  31 , such as, but not limited to, copper, can be placed over the inner jacket layer  23  surrounding the first wall sections  22  to form an outer tube in a coaxial configuration. An outer jacket layer  32  of polymer material is placed over the outer copper layer or tube of the wall sections  31 . The two layers of copper wall sections  22 ,  31  can be used as a coaxial cable to transfer data and/or they can be used as positive and ground to transfer electrical power. 
         [0029]    A first embodiment cable core  40  comprises a “TRIAD” configuration as shown in  FIG. 4 . The cable core  40  has three equal-diameter cable core elements cabled around a central element in the form of a deformable polymeric or any other suitable material filler rod  41 . One of the cable core elements is the cable core element  20  shown in  FIG. 2  wherein the two wall sections  22  are used for electrical high-power transmission. The optical fibers  21  are used for data transmission. The wall sections  22  and armor wires (not shown) could be used for low-power transmission. 
         [0030]    As shown in  FIG. 4 , the cable core  40  is assembled according to the following steps: 
         [0000]    1. A deformable polymer material is extruded over a twisted synthetic yarn or a metallic wire to create the deformable central filler rod  41 .
 
2. Two high-power conductor core elements  42 , similar in construction to the hepta cable  10  of  FIG. 1 , and the one copper tube cable core element  20  are cabled helically around the central filler rod  41 . The three core elements  20 ,  42 ,  42  have the same diameter. As an option, the filler rod  41  could be softened by heating it to facilitate its deformation.
 
3. As the copper tube core element  20  and the two high-power conductor core elements  42  come together over the filler rod  41 , the polymer material of the filler rod deforms to fill the interstitial spaces among the three core elements.
 
4. Additional soft polymer material is extruded in a layer  43  over the cabled core elements  20 ,  42 ,  42  to create a circular profile and allow the core elements to move within this matrix.
 
5. An additional outer jacket layer  44  of polymer material that has high resistance to deformation is extruded over the layer  43  to take the compression forces exerted by outer armor wires (not shown).
 
         [0031]    A second embodiment cable core  50  also is a “TRIAD” configuration as shown in  FIG. 5 . The cable core  50  is similar to the cable core  40  shown in  FIG. 4 , but the cable core element  20  of  FIG. 2  is replaced by the dual layer copper tube cable core element  30  of  FIG. 3 . As in the cable core  40 , the two layer tubes cable core element  30  and the high-power conductor core elements  42  are cabled over the deformable central filler rod  41 . The two stranded copper conductor core elements  42  are used for high-power electrical transmission. The optical fibers  21  are used for data transmission. The dual layered copper tubes could be used as a coaxial cable for data transmission and/or could be used for low-power electrical transmission. Therefore, there is no need for returning power through outer armor wires (not shown). 
         [0032]    A third embodiment cable core  60  comprises a “QUAD” configuration consisting of four equal-diameter core elements cabled around the deformable polymeric filler rod  41  as shown in  FIG. 6A . Two of the stranded copper conductor core elements  42  are used for high-power electrical transmission. Two of the optical fiber cable core elements  20  are used for data transmission. The two copper tubes could be used for data transmission and/or for low-power electrical transmission. Therefore, there is no need for returning power through outer armor wires. As an alternative to the filler rod  41 , a similar cable core  61  shown in  FIG. 6B  has a central element in the form of an insulated copper conductor  62  with a deformable polymeric jacket to provide an extra path for telemetry or power. 
         [0033]    A fourth embodiment cable core  70  comprises a “QUAD” configuration consisting of four equal-diameter core elements cabled around the deformable polymeric filler rod  41  as shown in  FIG. 7A . Three of the copper conductor core elements  42  are used for AC high-power electrical transmission. The optical fibers of the cable core element  30  are used for data transmission. The two layers of copper tubes could be used as a coaxial cable for data transmission and/or for low-power electrical transmission. Therefore, there is no need for returning power through armor wires. As an alternative to the filler rod  41 , the insulated copper conductor  62  with a deformable polymeric jacket can be placed in the center of the cable core  71  shown in  FIG. 7B  to provide an extra path for telemetry or power. 
         [0034]    There is shown in  FIG. 8  an armored cable core  80  including the cable core  40  with an armor wire package of strength members applied in two layers. An inner layer comprises a plurality of the larger-diameter armor wires  15 . The inner layer is covered by an outer layer of the smaller diameter armor wires  14 . The wires  14  and  15  may be standard armor wires cabled over the core  40  at counter-helical lay angles. 
         [0035]    There is shown in  FIG. 9  an armored cable  90  including the cable core  50  with an armor wire package of strength members applied in two layers and incased in a bonded polymer material jacket. The bonded polymer jacket system may be applied according to the following steps: 
         [0000]    1. A layer  91  of virgin or short-fiber-reinforced polymer material is applied over the cable core  50 .
 
2. A layer of the larger-diameter armor wires  15  is applied over and partially embedded into the polymer layer  91  at a suitable lay angle.
 
3. A second layer  92  of virgin or short-fiber-reinforced polymer material is applied over the armor wires  15 .
 
4. A second layer of the smaller-diameter armor wires  14  is applied over and partially embedded into the polymer layer  92  at a counter-helical lay angle to the first armor wire layer.
 
5. An optional third layer  93  of virgin or reinforced polymer material is extruded over the armor wires  14 . Optionally, a final layer (not shown) of virgin polymer material may be extruded over the cable  90  to provide a smoother sealing surface.
 
6. Each of the layers  92 ,  92  and  93  may be bonded together from the core  50  of the cable to the outermost jacket layer  93 .
 
         [0036]    The focal point of the embodiments disclosed herein provides optical fibers packaged in copper shields. Together with copper conductors, these embodiments provide the outstanding mechanical stability needed to withstand elevated cable tension and downhole pressure. These embodiments also provide multiple power paths for a downhole tool or tools (attached at an end of the cable and disposed within a wellbore penetrating a subterranean formation) through copper conductors and copper shields. Telemetry may also be run through copper conductors and copper shields to achieve reverse compatibility. 
         [0037]    Embodiments of cables disclosed herein may be used with wellbore devices to perform operations in wellbores penetrating geologic formations that may contain gas and oil reservoirs. Embodiments of cables may be used to interconnect well logging tools, such as gamma-ray emitters/receivers, caliper devices, resistivity-measuring devices, seismic devices, neutron emitters/receivers, downhole tractors, mechanical service tools, and the like, to one or more power supplies and data logging equipment outside the well. Embodiments of cables may also be used in seismic operations, including subsea and subterranean seismic operations. The cables may also be useful as permanent monitoring cables for wellbores. 
         [0038]    The preceding description has been presented with reference to present embodiments. Persons skilled in the art and technology to which this disclosure pertains will appreciate that alterations and changes in the described structures and methods of operation can be practiced without meaningfully departing from the principle, and scope of the present disclosure. Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.