Abstract:
A connector for a cable having a core stress member surrounded by a secondary stress member may include a connector body, a wedge, a retainer, a molded body, and a collar. The connector body may have at least one flow channel formed on an inner surface of the distal end and at least one radial hole providing fluid communication to the at least one flow channel. The wedge is disposed in a pocket of the connector body and is attachable to the core stress member. The molded body surrounds the distal end, fills the at least one flow channel, and attaches to the secondary stress member. The collar may at least partially enclose the connector body.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    This disclosure generally relates to locking arrangements and methods for connectors used to make electrical connections. 
       BACKGROUND OF THE DISCLOSURE 
       [0002]    Seismic surveys are conducted to map subsurface structures to identify and develop oil and gas reservoirs. Seismic surveys are typically performed to estimate the location and quantities of oil and gas fields prior to developing (drilling wells) the fields and also to determine the changes in the reservoir over time subsequent to the drilling of wells. Seismic surveys are conducted by deploying an array of seismic sensors (also referred to as seismic receivers) over selected geographical regions. These arrays typically cover 75-125 square kilometers or more of a geographic area and include 2000 to 5000 seismic sensors. Some of the regions may be underwater and at depths of up to seventy five meters. The seismic sensors (geophones or accelerometers) are coupled to the ground in the form of a grid. An energy source, such as an explosive charge, air gun, or a mobile vibratory source, may be used to generate or induce acoustic waves or signals (also referred to as acoustic energy) into the subsurface. The acoustic waves generated into the subsurface reflect back to the surface from discontinuities in a subsurface formation, such as those formed by oil and gas reservoirs. The reflections are sensed or detected at the surface by the seismic sensors (hydrophones, geophones, etc.). Data acquisition units deployed in the field proximate the seismic sensors may be configured to receive signals from their associated seismic sensors, at least partially processes the received signals, and transmits the processed signals to a remote unit (typically a central control or computer unit placed on a mobile unit). The central unit typically controls at least some of the operations of the data acquisition units and may process the seismic data received from all of the data acquisition units and/or record the processed data on data storage devices for further processing. The sensing, processing, and recording of the seismic waves is referred to as seismic data acquisition. 
         [0003]    The mechanical devices used to lay out and retrieve these cables put strain on the cable connections and associated equipment. This disclosure addresses the need for robust connectors that can withstand the loadings imposed by such mechanical deployment devices as well as the loadings incurred during operation. 
       SUMMARY OF THE DISCLOSURE 
       [0004]    In aspects, the present disclosure provides a connector for a cable having a core stress member surrounded by a secondary stress member. The connector may include a connector body, a wedge, a retainer, a molded body, and a collar. The connector body may have a distal end having an inner surface defining a bore for receiving an exposed section of the secondary stress member, at least one flow channel formed on the inner surface, at least one radial hole providing fluid communication to the at least one flow channel, a pocket adjacent to the bore, and a plug end opposite to the distal end. The plug end may receive an electrical connector associated with a seismic device. The wedge may be received into the pocket of the connector body and is attachable to the core stress member. The retainer may secure the wedge in the pocket of the connector body. The molded body surrounds the distal end and filling the at least one flow channel, the molded body attaching to the secondary stress member. The collar may at least partially enclose the connector body. The collar may have a first end matable with a seismic device and a second end. The collar may include a retainer ring positioned at the second end such that the connector body is captured between the retainer ring and the seismic device. 
         [0005]    In aspects, the present disclosure provides a method for connecting a cable having a core stress member surrounded by a secondary stress member to a seismic device. The method may include forming a connector body as described above, positioning a wedge in the pocket of the connector body, attaching the wedge to the core stress member, securing the wedge in the pocket of the connector body with a retainer, surrounding the distal end and filling the at least one flow channel with a molded body, the molded body attaching to the secondary stress member, and at least partially enclosing the connector body with a collar, the collar having a first end matable with a seismic device and a second end, the collar including a retainer ring positioned at the second end, wherein the connector body is captured between the retainer ring and the seismic device. 
         [0006]    Examples of certain features of the disclosure have been summarized rather broadly in order that the detailed description thereof that follows may be better understood and in order that the contributions they represent to the art may be appreciated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    For a detailed understanding of the present disclosure, reference should be made to the following detailed description of the embodiments, taken in conjunction with the accompanying drawings, in which like elements have been given like numerals, wherein: 
           [0008]      FIG. 1  shows a schematic of a seismic survey system according to one embodiment of the present disclosure; 
           [0009]      FIG. 2  shows a sectional view of a connector according to one embodiment of the present disclosure; 
           [0010]      FIG. 3  shows a sectional view of a connector body according to one embodiment of the present disclosure; and 
           [0011]      FIG. 4  shows a sectional view of a molded body according to one embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    The present disclosure relates to devices and methods for anchoring cables to seismic devices used during seismic data acquisition. As used herein, the term “anchoring” refers to a mechanical connection wherein a tensile loading is transferred between two structural features. The present disclosure may be implemented in embodiments of different forms. The drawings shown and the descriptions provided herein correspond to certain specific embodiments of the present disclosure for the purposes of explanation of the concepts contained in the disclosure with the understanding that the present disclosure is to be considered an exemplification of the principles of the disclosure. 
         [0013]      FIG. 1  depicts an embodiment of a cable seismic data acquisition system  100 . Such a system includes an array (string) of spaced-apart seismic sensor units  102 . Seismic sensors units  102  may include, but are not limited to, multi-component sensors such as a three-component accelerometer sensor incorporating micro electro-mechanical systems (MEMS) technology, velocity sensors such as a conventional geophone or a pressure sensor such as a conventional hydrophone. Any sensor unit capable of sensing seismic energy may be used. Each sensor unit  102  is typically coupled via cabling to a data acquisition device (such as remote acquisition module (RAM)  103 ), and several of the data acquisition devices and associated sensor units  102  are coupled via cabling  110  to form a line or group  108 . The group  108  is then coupled via cabling  112  to a line tap (such as fiber TAP unit (FTU)  104 ). Several FTUs  104  and associated lines  112  are usually coupled together by cabling, such as shown by the baseline cable  118 . 
         [0014]    A RAM  103  may be configured to record analog seismic signals that are generated by the sensors units  102 . The RAM  103  may be configured to convert analog signals from the sensor units  102  into digital signals. The digitized information may then be transmitted to an FTU  104 . One or more FTU&#39;s  104 , such as FTU  104   a , may be configured to transmit the digitized information to a central recording system (CRS)  106 . The devices involved in seismic data acquisition may be collectively referred to as “seismic devices,” which may include, but is not limited to: sensor units  102 , RAMs  103 , and FTUs  104 , CRS  106 , and other associated auxiliary devices  116 . 
         [0015]    As mentioned previously, the system  100  may be used on land or in water at depths to seventy five meters. The cables of the system  100  may be payed out and coiled on large drums and spools. The laying of the cables and their subsequent retrieval generates tensile forces that stress the connections between the cable and the seismic equipment positioned along the cables. Embodiments of the present disclosure allow these forces to be effectively transferred between the cables and seismic equipment without damaging the connections. 
         [0016]    Referring now to  FIG. 2 , there is shown one embodiment of a connector  200  that incorporates an anchoring arrangement for ensuring a robust load transferring connection between a cable  202  and a seismic device  204 . The seismic device  204 , which is shown in hidden lines, may be any component of a seismic data acquisition system. 
         [0017]    In one embodiment, the cable  202  may be configured for use in a marine environment. The cable may include a core stress member  206  that is surrounded by a secondary member  208 . An inner cable jacket  210  may separate the primary stress member  206  from the secondary stress member  208 . In other embodiments, the primary stress member  206  may include a bundle of woven fibers and the secondary stress members  208  may be a braided jacket or sheathing. An outer cable jacket  212  may be extruded over the inner cable jacket  210 . Thus, the outer jacket  212  encapsulates the secondary stress member  208 . The core stress member  206  may be a solid cylinderal member or a bundled fiber. The secondary stress members  208  may be a woven, braided, or sheathing. The stress members  206 ,  208  may be formed of aramid fibers or any other suitable material. It should be understood that the described construction and specified material for the cable  202  are merely illustrative and the present teachings may be used with cables of other configurations. 
         [0018]    As discussed in greater detail below, the present disclosure provides a connector assembly  220  that incorporates multiple load transmitting paths upon making up the connection between the cable  202  and the seismic device  204 . Specifically, the connector  220  uses the core stress member  206  and the secondary stress member  208  to separately transfer a tensile load along the cable  202  into the seismic device  204 . In the illustrated embodiment, the connector  220  transfers the loading to a threaded connection  205  of the seismic device. In one embodiment, the connector  220  includes a collar  222 , a connector body  224 , a stress wedge  226 , a stress wedge retaining ring  228 , a potting compound  230 , and a molded body  232 . The separate load paths discussed below each transmit the tensile loadings along the cable  202  to the collar  222 . 
         [0019]    The collar  222  is a tubular member that acts as the primary load bearing structure that transmits loading from the cable  202  to the threaded connection  205 . The collar  222  has a first end  290  and a second end  292 . The first end  290  may include threads  294  that mate with the threaded connection  205  of the seismic device  204 . The second end  292  may include a groove  298  or other recess for receiving a retaining ring  300 . The retaining ring  300  secures the connector body  224  within an interior space of the collar  222 . For instance, a shoulder  301  ( FIG. 3 ) formed on the connector body  224  may seat against the retaining ring  300 . It should be noted, that, to some degree, the connector body  224  and attached electrical plug  207  can “float” inside the collar  222 ; e.g., move axially relative to the threaded connection  205  of the seismic device  204 . This feature of the connector body  224  will be referred to as being “resiliently” disposed in the collar  222 . These features may be formed of aluminum, stainless steel, or any other suitable metal or non-metal. 
         [0020]    The connector body  224  is configured to have two separate load transmission paths. In the illustrated embodiment, the connector body  224  is a tubular member having bore  225  for receiving the cable  202  and a pocket  234  for receiving the stress wedge  226 . The connector body  224  may also include a distal end  240  and a plug end  241 . The distal end  240  acts as a load transmitting structure as further described below. The plug end  241  may be configured to receive an electrical plug  207  or other electrical interface associated with the seismic device  204 . In some embodiments, the plug end  241  may includes threads or other feature to fixedly connect with the electrical plug  207 . 
         [0021]    A first load transmission path to the collar  222  is formed by the core stress member  206  and the stress wedge  226 . The stress wedge  226  seats tightly within the pocket  234  formed in the connector body  224 . The stress wedge  226  may be a conical ring-shaped member that is fixed to the core stress member  206  using any suitable method (e.g., chemical bonding, a physical coupling, a knot formed on the core stress member  206 , etc.). In one non-limiting arrangement, the stress wedge  226  is fixed to the core stress member  206  using a knot formed on the core stress member  206  after the core stress member  206  is inserted through a central bore  227  of the stress wedge  226 . Also, the potting compound  230  may be used to bond with the material making up the core stress member  206  and thereby strengthens the load transferring connection at the stress wedge  226 . A conical shape allows the wedge  226  to compressively load the interior surfaces defining the pocket  234 . Cylindrical or disc shapes may also be used. In some embodiments, the stress wedge retaining ring  228  (e.g., a snap ring) may be used to secure the stress wedge  226  within the pocket  234  of the connector body  224 . 
         [0022]    A second load transmission path to the collar  222  is formed by the secondary stress member  208  and the molded body  232 . As used herein, the term “molded” refers to a body that is homogeneous and integral in structure as opposed to a structure that is an assembly of parts. The molded body  232  surrounds and penetrates into the distal end  240  of the connector body  224 . Referring to  FIG. 3 , the distal end  240  includes one or more flow channels  242  that are formed on an inner surface  244  and/or an outer surface  246  of the distal end  240 . In one non-limiting embodiment, the flow channels  242  may be shaped as circumferential grooves or concave conduits. The distal end  240  also includes one or more radial through holes  248  that permits fluid communication between the flow channels  242  on the inner and outer surfaces  244 ,  246 . The radial holes  248  may be staggered such that they intersect alternating flow channels  242 . However, any pattern for the flow channels  242  and the through holes  248  may be used. 
         [0023]    Referring to  FIGS. 3 and 4 , during fabrication, the through holes  248  and the flow channels  242  allow the material making up the molded body  232  to flow through and around the distal end  240 . The molded body  232  attaches to the secondary stress member  208  and also encapsulates the distal end  240 . In some embodiments, the surfaces of the secondary stress member  208  may be abraded to present a rough, textured surface. Also, a chemical treatment may be applied to chemically bond the secondary stress member  208  to the molded body  232 . In some embodiments, the molded body  232  may be formed of a suitable plastic. However, any injectable material that can flow into the flow channels  242  and affix to the secondary stress member  208  may be used. 
         [0024]    As best seen in  FIG. 4 , a section  213  of the outer jacket  212  has been stripped away to expose the secondary stress member  208 . Thus, the molded body  232  surrounds and bonds with the exposed secondary stress member  208 . The molded body  232  also has a mechanical connection with the connector body  224  because the molded body  232  has flowed into the flow channels  242 . It should be appreciated that the molded body  232  now can transfer loadings from the secondary stress member  208  to the connector body  224  due to the physical interconnection with the flow channels  242  formed on the inner and outer surface  244 ,  246 . Additional loadings may be transmitted by the contact between the molded body  232  and a covered portion  310  of the outer jacket  212 . 
         [0025]    Referring to  FIGS. 1-4 , in one exemplary mode of use, the cable  202  may be deployed into or retrieved from a body of water. As mentioned previously, the cable  202  may be used at operational depths of seventy five meters. Thus, significant loadings are applied to the cable  202  during handling. Beneficially, this loading is transferred to the seismic body  204  along two separate paths, which can increase the overall load capacity of the connector  200 . 
         [0026]    During a tensile loading, the cable  202  moves away from the seismic device  204 . The connector body  224  and electrical plug  207  also move away from the threaded connection  205  of the seismic device  204  until the connector shoulder  301  contacts the retainer ring  300 . The first load path from the cable  202  to the retainer ring  300  is formed when the core stress member  206  pulls the stress wedge  226  into compressive contact with the connector body  224 . Separately, the second load path is formed as the secondary stress member  208  pull on the molded body  232 . In response, the molded body  232  axially loads the connector body  224 . The retainer ring  300  transfers both of these loadings to the collar  222 , which transfers this loading to the seismic device  204  via the threaded connection  205 . 
         [0027]    While the foregoing disclosure is directed to the one mode embodiments of the disclosure, various modifications will be apparent to those skilled in the art. It is intended that all variations be embraced by the foregoing disclosure.