Patent Publication Number: US-7901247-B2

Title: Electrical connectors and sensors for use in high temperature, high pressure oil and gas wells

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to electrical connectors and sensors useful in many applications, but particularly intended for use in hostile environments. More specifically, the present invention relates to single and multi-pin electrical connectors and sensors for use in high-pressure, high-temperature applications which commonly occur in the oilfield, but which are also encountered in geothermal and research applications. 
     Oil wells are being drilled to deeper depths and encountering harsher conditions than in the past. Many of the electrical connectors in the oilfield are exposed to the environment of the open well bore, where at maximum depth, pressures rise to over 30,000 psig, temperatures exceed 500 degrees, F, and the natural or chemically-enhanced well bore environment is extremely corrosive. 
     There have been many attempts made in the prior art to design, manufacture and market electrical connectors for use in such hostile environments, some of which have met with more success than others. For example, U.S. Pat. No. 6,582,251 to Burke et al, describes an “all plastic” body connector, i.e., all plastic other than for the metal conductor pin and the threaded metal body, in which the metal conductor pin is embedded in a molded body formed from polyetherketone (PEK), or other polymeric materials such as ULTEM, PAEK, PEEK or PEKK. When used with a threaded metal body, the plastic body will oftentimes extrude away from the metal conductor pin, causing the conductor pin to contact the metal body, causing immediate failure. At temperatures and pressures approaching 500° F. and 30,000 psi, respectively, the extrusion can be so severe that fluids leak between the conductor and the threaded metal body and flood the very instrument the connector was intended to protect. 
     The all plastic connector, even when not used with a metal body, will oftentimes fail, based upon the extrusion of the plastic in the instrument gland may cause the conductor pin to move so much that the connection to the boot is lost. In extreme cases the extrusions give rise to a hydraulic failure due to deformation of the o-ring gland of the connector to the point that the seal is no longer effective. 
     In addition to the all plastic connector, the prior art also includes U.S. Pat. Nos. 3,793,608 and 3,898,731, each to Sandiford Ring and Russell K. Ring, which disclose electrical connectors which operate quite well in harsh environmental such as very hot, very deep, high pressure wells, in which such connectors use glass seals in combination with ceramic seals. 
     In addition, U.S. Pat. No. 7,364,451 to John H. Ring and Russell K. Ring discloses an electrical connector for use in very hot, high pressure wells using, in combination, glass seals, ceramic seals, a plastic body molded, for example, from aromatic polyetherketones or other thermoplastic materials and in some embodiments, includes a thermoplastic jacket made from PAEK, PEEK, PEK and PEKK, or the like. 
     However, even with all the success experienced by the electrical connectors using glass seals in combination with ceramic seals, it should be appreciated that glass seals are relatively expensive. There thus exists a need for electrical conductors in high pressure, high temperature wells without the use of glass seals. The electrical connectors of the present invention provides some of the high pressure, high temperature capabilities of the hybrid type of connectors, but having manufacturing costs quite similar to the all plastic versions of electrical connectors of the prior art. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an elevated view, in cross-section, illustrating an electrical connector, known in the prior art, commonly known as an all plastic connector, having a body molded from insulative thermoplastic, illustrating a first mode of failure; 
         FIG. 2  is an elevated view, in cross-section, illustrating the prior art electrical connector of  FIG. 1 , showing a second mode of failure when used with a rubber boot; 
         FIG. 3  is an elevated view, partly in cross-section, of an electrical connector having a single conductor pin according to the present invention; 
         FIGS. 4A-4F , together provide an exploded view, with some parts in cross section, of the electrical connector illustrated in  FIG. 3 , showing a process for manufacturing and assembling such electrical connector, according to the invention; 
         FIG. 4G  graphically illustrates a partial view of the interface of a raised section on the electrical conductor pin sealing against the insulated bushing illustrated in  FIG. 3 ; 
         FIG. 5  an elevated view, partly in cross-section, of an electrical connector having multiple conductor pins according to the invention; 
         FIG. 6  is an elevated view, partly in cross section, of an electrical connector/sensor according to the invention, having multiple conductor pins used with a first type of downhole sensor; 
         FIG. 7  is an elevated view, partly in cross section, of an electrical connector/sensor according to the invention, having multiple conductor pins used with a second type of downhole sensor; and 
         FIG. 8  is an elevated view, partly in cross section, of an electrical stab connector according to the invention; 
         FIG. 9  is a multi-pin connector according to the invention having the ability to withstand high pressure from either or both directions; and 
         FIG. 10  is an alternative embodiment of the invention illustrated in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF INVENTION 
     Referring now to  FIG. 1 , a prior art, all plastic electrical connector  10  having an electrical conductor located within the interior of an all plastic body  14 , with the plastic body  14  typically molded around the metal electrical conductor  12 . A rubber O-ring  16  is also located on the exterior surface of the plastic body  14 . A threaded metal body  18  encircles a portion of the plastic body  14 . All too often, the plastic body  14  extrudes away from the electrical conductor  12 , allowing the conductor  12  to touch the metal body  18 , causing immediate failure of the intended function of the connector  10 . 
       FIG. 2  illustrates a second failure mode of the all plastic, prior art connector  10  illustrated in  FIG. 1 . When used with a rubber boot  20 , the pin  12  depends upon electrical contact with electric conductor  22  in normal operation. The boot normally excludes conductive fluids from reaching the conductor while making a reliable electrical connection. Under extremes of temperature and pressure, the plastic body deforms and extrudes through the threaded metal body  18 , carrying with it the conductor pin  12  that disconnects with contact  22  and causing in this case both an electrical and hydraulic failure. 
     Thus, the all plastic connectors illustrated in  FIGS. 1 and 2  are prone to failure in the field, for a plurality of reasons. 
     FIGS.  3  and  4 A- 4 F illustrate an electrical connector  30  according to the invention having a body  34  molded around the metallic electrical connector pin  32 . The electrical conductor pin  32  may be comprised of Inconel, Monel, copper, Alloy 52, beryllium copper, molybdenum, stainless steel, brass, nickel-iron bearing alloys, and other known conductive materials. 
     The molded plastic body  34  is preferably comprised of insulative thermoplastic, and even more preferably from aromatic polyetherketones (PEK, PEEK) but can also be comprised of other polymeric materials such as PAEK and PEKK, and blends of PEK, PEEK, PAEK and PEKK with other plastics, thermosets, modifiers, extenders and polymers. 
     The insulating bushing  36  is comprised of a strong insulator, preferably from ceramic, zirconia, or other known strong insulators, for example, aluminium oxide (Alumina), mullite, silicon nitride, or forsterite. Non-conductive silicon carbide can also be used as a strong insulator, but it should be appreciated that some versions of silicon carbide are conductive and should not be used as a strong insulator for this application. The insulating bushing  36  is comprised of an electrical insulator with high compressive strength, preferably ceramic, zirconia, or similar material that will not melt, weaken or significantly degrade at well bore temperatures. The present invention does not use a glass seal. 
     The threaded support washer/sleeve  38  can be comprised from a variety of metals, but preferably is comprised of beryllium copper, Inconel or stainless steel. The O-ring is comprised of rubber. The threads on the washer/sleeve  38  are typically provided for installation of the connector, but are considered to be optional. 
     In  FIGS. 4A-4F , there is illustrated a preferred process for manufacturing and assembling the electrical connector according to  FIG. 3 . The insulating bushing  36  of  FIG. 4A , the support washer/sleeve  38  of  FIG. 4B  and the conductor pin  32  of  FIG. 4C  are preferably fabricated as single components, and then assembled, but could be fabricated, if desired, as a single component comprising the conductor pin  32 , the insulating bushing  36  and the washer/sleeve  38 , or as a single component combining any one of the three components with one of the remaining two components. 
       FIG. 4D  illustrates, before the molding step, the assembly of components  32 ,  36  and  38 , with the insulating bushing  36  being slidably engaged over the conductor pin  32  until preferably contacting a shoulder on the conductor pin  32 . As illustrated and described hereinafter, the connectors according to the invention preferably has the shoulder on the conductor pin  32 , but the connector according to the invention will also function in an acceptable manner without the shoulder, as illustrated and described with respect to  FIG. 10 . The washer/sleeve  38  is slidably engaged over the exterior surface of the insulating bushing  36  until a shoulder of the insulating bushing  36  preferably engages a shoulder of the washer/sleeve  38 . All three components are preferably assembled together, wherein such components are fixedly connected together by well known processes involving bonding, cement, glue, epoxy or other materials, in the final assembly, having melting temperatures well in excess of 500° F. to remain secure during molding at very high temperatures and very high pressures. 
       FIG. 4E  illustrates the assembly illustrated in  FIG. 4D , after the molding step, but prior to the machining step used to achieve the end product illustrated in  FIG. 4F . With the O-ring  40  in place, also shown in  FIG. 3  and in  FIG. 4E , the molded body  35  becomes body  34  as a consequence of the final machining step. 
     Referring now to  FIG. 4G , there is illustrated a partial, enlarged view of an important, but optional, feature of the present invention. In the one or more embodiments illustrated in  FIGS. 3 ,  4 A- 4 G,  5 ,  6 ,  7 ,  8 ,  9  and  10 , the electrical conductor pin or pins each have a plurality of enlarged diameter areas, for example, areas  33  in  FIG. 4G . The diameter of the area  33  is preferably greater than the diameter of the conductor pin  32  mounted within the interior channel of the ceramic insulating bushing  36 . This difference in diameter creates a seal between the thermoplastic body  34  ( FIG. 3 ) and the raised area  33 , on the one hand, and the ceramic insulating bushing, wherein such seal prevents the thermoplastic from extruding along the conductor pin  32  and through the inside diameter of the ceramic insulating bushing  36 , thus effectively eliminating the failure modes discussed herein with respect to all plastic electrical connectors. A second seal between the ceramic insulating bushing  36  and threaded sleeve  38  prevents the extrusion of thermoplastic along the outside diameter of the ceramic insulating bushing  36  at location  60  of  FIG. 3 , thus helping to eliminate the failure modes discussed herein with respect to all plastic electrical connectors. 
     Referring now to  FIG. 5 , there is illustrated a multi-pin electrical connector  100 , according to the invention, having a plastic body  134  molded around the plurality of electrical connector pins  132 . The electrical conductor pins  132  may be comprised of Inconel, Monel, Alloy 52, beryllium copper, molybdenum, stainless steel, brass, nickel-iron bearing alloys, and other known conductive materials. 
     The molded plastic body  134  is preferably comprised of insulative thermoplastic, and even more preferably from aromatic polyetherketones (PEK, PEEK) but can also be comprised of other polymeric materials such as PAEK and PEKK, and blends of PEK, PEEK, PAEK and PEKK with other plastics, thermosets, modifiers, extenders and polymers. 
     The plurality of insulating bushings  136  are each comprised of a strong insulator, preferably from refractory materials, non-conducting silicon carbides, ceramic, zirconia or other high strength insulating materials that do not melt, weaken, or significantly degrade at well bore temperatures. 
     The threaded support washer/sleeve  138  can be comprised of a variety of metals, but preferably is comprised of beryllium copper, Inconel or stainless steel. The O-ring  140  is comprised of rubber. The threads on the support washer/sleeve  138  are provided for installation of the connector into the gland and are optional. 
     The manufacture and assembly process for the electrical conductor  100  of  FIG. 5  is essentially identical to the process illustrated in  FIGS. 4A-4F , and may or may not have threads on the support washer/sleeve  138 . 
     Referring now to  FIG. 6 , there is illustrated a multi-pin electrical connector  200  according to the invention, having a plurality of electrical conductor pins  232  connected to a sensor element  242  embedded in the molded thermoplastic body  234 . The sensor element  242  is typically protected from the downhole environment by a cover  244 , as desired, and may be fabricated from metal, rubber, plastic or other known materials as needed, depending upon the type of sensor element  242  being used. 
     The electrical connector portion  234  of  FIG. 6  is manufactured and assembled essentially identically to the process used for the electrical connector  100  of  FIG. 5 , other than for the use of the two connector pins  232  connected by the conductors  233  and  235 , respectively, to the sensor element  242 . 
     Referring now to  FIG. 7 , there is illustrated a multi pin electrical connector  300 , according to the invention, having a plurality of electrical conductor pins  332  connected, respectively, to a sensor element  341 . The sensor element  341  comprises a plurality of electrode rings  342 , two of which are rings  333  and  335  which are tied electrically to the conductor pins  332 , respectively. The process for manufacturing and assembling the components included in the conductors illustrated in  FIGS. 3 ,  4 A- 4 F,  5 ,  6  and  7 ,  8 ,  9  and  10  including the materials used to manufacture the component parts of each of such electrical conductors, are essentially identical. 
     Referring now to  FIG. 8 , there is illustrated a single pin electrical connector  400 , according to the invention, having a single electrical conductor pin  432  connected to a metallic stabbing element  431 . The stabbing element  431  may preferably comprise beryllium copper, Inconel, copper or stainless steel. The component parts  436 ,  438  and  440  correspond essentially with the corresponding component parts  34 ,  36 ,  38  and  40  of the connector  30  in  FIG. 3 , both as to the materials used, the assembly and the manufacturing process. However, the electrical conductor pin  432  is preferably fabricated as a single part to include the stabbing element  431  having a larger diameter than the diameter of the pin end  432 . The body part  435  and the body part  434  are both molded from thermoplastic, and are separated from the stabbing element  431  so that electrical contact with the female receptacle (not illustrated) occurs when connector  400  is fully engaged in the intended apparatus. 
     It should be appreciated that the corresponding parts of the various embodiment illustrated in  FIGS. 3 ,  4 A- 4 F,  5 ,  6 ,  7 ,  8 ,  9  and  10  are essentially identical as to the materials used and the manufacturing and assembly process steps, other than for the first identifying digit. For example, the part  436  in  FIG. 8  is essentially identical to part  36  in  FIG. 3 . 
       FIG. 9  is a multi-pin connector  500  according to the invention which can withstand high pressure from either or both directions, i.e., from the conductor pin end  532  and/or from the conductor pin end  632 . The corresponding component parts  532  (conductor pin),  536  (insulating bushing),  538  (threaded washer sleeve), and  560  (outside diameter at first end of insulating busing  536 ) are identical to parts  632 ,  636 ,  638  and  660 , respectively. The thermoplastic body  534  and the O-ring  540  are common to both ends. The treaded washer sleeves  538  and  630  can be threaded, or unthreaded, as desired. 
     It should be appreciated that a very important feature of the present invention, is the seal formed between the thermoplastic body  34  in  FIG. 3 , the support washer/sleeve  38  in  FIG. 3  and the insulating bushing  36  in  FIG. 3 . This seal is generally noted as the external surface  560  along the outside diameter of the insulating bushing  536  in  FIG. 9 , but is preferably present in all the embodiments of the invention illustrated in  FIGS. 3 ,  4 F,  5 ,  6 ,  7 ,  8 ,  9  and  10 . Although being preferable, such seal is optional in all such embodiments. 
       FIG. 10  is an alternative embodiment according to the invention as illustrated in  FIG. 3 , but which can be used to modify  FIGS. 3 ,  4 A- 4 F,  4 G,  5 ,  6 ,  7 ,  8  and  9  if desirable.  FIG. 3 , for example, has a raised section on its conductor pin  32  having an outside diameter greater than the internal diameter of the insulating bushing  36  creating a seal as herein discussed. In  FIG. 10 , the conductor pin  32  may or may not have the raised section, but if present, the raised section of conductor pin  32  does not seal against the insulating bushing  36 . The embodiment of  FIG. 3  is preferred over the embodiment of  FIG. 10 , but the embodiment of  FIG. 10  will still provide a viable connector. 
     Thus, there has been illustrated and described herein the preferred embodiments of high temperature, high pressure electrical conductors having the ability to withstand pressures in excess of 30,000 psiq, and temperature in excess of 500° F., all without the use of glass seals in such conductors.