Patent Publication Number: US-8522864-B1

Title: Stripper blow out preventer for small diameter oil field tubing or small diameter polished rods

Description:
FIELD 
     The present embodiments generally relate to a stripper blow out preventer for small diameter oil field tubing or small diameter polished rods usable with oil field equipment. 
     BACKGROUND 
     A need exists for a high pressure blow out preventer usable with a variety of small diameter oil field equipment, such as coiled tubing, polished rods, and lubricators for oil field equipment. 
     The present embodiments meet these needs. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The detailed description will be better understood in conjunction with the accompanying drawings as follows: 
         FIG. 1  is a perspective view of the stripper blow out preventer. 
         FIG. 2  is a cross sectional view of the stripper blow out preventer. 
         FIGS. 3A-3C  depict the stripper blow out preventer at various stages of operation. 
     
    
    
     The present embodiments are detailed below with reference to the listed Figures. 
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Before explaining the present apparatus in detail, it is to be understood that the apparatus is not limited to the particular embodiments and that it can be practiced or carried out in various ways. 
     The present embodiments relate to a stripper blow out preventer for small diameter oil field tubing or small diameter polished rods. 
     The stripper blow out preventer can include a housing with a longitudinal bore for engaging oil field work over equipment or oil field stimulation equipment, such as coiled tubing, polished rods, and lubricators for oil field equipment. 
     The oil field equipment can have a diameter ranging from about 1 inch to about 3.5 inches. 
     The housing can have an upper housing portion having a studded American Petroleum Institute (API) connection, and a lower housing portion having an API flanged connection. 
     The studded API connection, the API flanged connection, or combinations thereof can be configured to accommodate oil field equipment having: a 1 13/16 inch diameter connection, a 2 1/16 inch diameter connection, a 2 9/16 inch diameter connection, a 3 1/16 inch diameter connection, or a 4 1/16 inch diameter connection. 
     The stripper blow out preventer can include an open port in the housing for accepting hydraulic fluid. 
     The stripper blow out preventer can include a close port in the housing for accepting hydraulic fluid. 
     The stripper blow out preventer can include a grease port in the housing for allowing grease to lubricate housing threads in the housing. 
     The stripper blow out preventer can include a dual diameter annular recess having a first diameter and a second diameter. The first diameter can be from about 30 percent to about 50 percent larger than the second diameter. The dual diameter annular recess can be in fluid communication with the longitudinal bore. 
     The stripper blow out preventer can include a dual threaded retainer ring. The dual threaded retainer ring can include inner threads and outer threads. The outer threads can engage the housing threads of the housing. 
     The dual threaded retainer ring can include a beveled seal surface. The dual threaded retainer ring can be threadably engaged with the housing within the dual diameter annular recess. 
     The dual threaded retainer ring can also include a first inner seal surface, a second inner seal surface, and an outer sealing surface. 
     A piston with a piston beveled seal surface and a piston bottom edge can be disposed in the dual diameter annular recess. 
     The piston can have a first diameter portion for sealing against the second diameter of the dual diameter annular recess in the housing. 
     The piston can have a second diameter portion for sealing against the second inner seal surface of the dual threaded retainer ring. 
     The piston can have a third diameter portion for sealing against the first diameter portion of the dual diameter annular recess in the housing. 
     The first diameter portion of the piston can be smaller than the second diameter portion of the piston. The second diameter portion of the piston can be smaller than third diameter portion of the piston. 
     A radially expandable resilient seal element can be disposed in the dual diameter annular recess between the dual threaded retainer ring and the piston. The radially expandable resilient seal element can have a resilient seal element top beveled seal surface and a resilient seal element bottom beveled seal surface. 
     The radially expandable resilient seal element can have a resilient seal element thru bore having a diameter identical to the diameter of oil field work over equipment, oil field stimulation equipment, or other oil field equipment. 
     The radially expandable resilient seal element can have a plurality of ridges extending into the resilient seal element thru bore to seal with the oil field equipment. 
     The radially expandable resilient seal element can be made of a compressible elastomeric material, such as hydrogenated nitrile butadiene rubber. 
     The radially expandable resilient seal element can have a side planar face that seals against the second inner seal surface of the dual threaded retainer ring between the resilient seal element top beveled seal surface and the resilient seal element bottom beveled seal surface. The resilient seal element top beveled seal surface and the resilient seal element bottom beveled seal surface can be disposed at an angle of 135 degrees from the side planar face. 
     An insert, which can be a replaceable insert, can threadably engage the inner threads of the dual threaded retainer ring. The replaceable insert can have a diameter ranging from about 1 inch to about 3.5 inches, and can be configured to accommodate different size diameters of oil field equipment within the housing. As such, the same sized housing can be used for sealing different diameter pieces of oil field equipment. 
     The replaceable insert can have a first seal face that seals against the first inner seal surface of the dual threaded retainer ring. 
     The replaceable insert can have insert threads that engage the inner threads of the dual threaded retainer ring, and an insert beveled edge that seals against the resilient seal element top beveled seal surface. 
     The replaceable threaded insert can have an insert inner face that is oriented towards the longitudinal bore. 
     The replaceable threaded insert can have an installation pocket that can be used to torque the replaceable insert into the inner threads of the dual threaded retainer ring. 
     One or more embodiments of the stripper blow out preventer can include a plurality of piston type seals sealing between the first diameter of the housing and the piston. Piston seals can also be disposed between the dual threaded retainer ring and the replaceable threaded insert. A piston seal can be disposed between the dual threaded retainer ring and the housing. 
     A rod seal can be disposed between the dual threaded retainer ring and the piston, and a plurality of rod seals can be disposed between the piston and the housing. 
     In operation, when the close port is pressured, the piston can move axially in a first direction in the longitudinal bore. The piston can press against the radially expandable resilient seal element to create a high pressure seal against the oil field equipment in the longitudinal bore. 
     When the open port is pressurized, the piston can move axially in a second direction opposite the first direction to relax the radially expandable resilient seal element from the oil field equipment in the longitudinal bore. In one or more embodiments, the close port and the open port can be hydraulically operated. 
     Turning now to the Figures,  FIG. 1  depicts a perspective view of the stripper blow out preventer  5 . 
     The stripper blow out preventer  5  can have a housing  1  with an outer surface  12 . The housing  1  can be made of carbon steel. 
     In one or more embodiments, the housing  1  can be made of multiple different materials to provide the housing  1  with multiple different physical properties. For example, the housing  1  can be made of a first material configured to withstand sour service and cold climates, while also being made of a second material configured to withstand hot climates. 
     The housing  1  can have an upper housing portion  4  with a studded American Petroleum Institute (API) connection  6 . 
     The housing  1  can also have a lower housing portion  8  with an API flanged connection  10 . The lower housing portion  8  can be connected to the upper housing portion  4 . 
     The studded API connection  6 , the API flanged connection  10 , or combinations thereof can be configured to accommodate oil field equipment having: a 1 13/16 inch diameter connection, a 2 1/16 inch diameter connection, a 2 9/16 inch diameter connection, a 3 1/16 inch diameter connection, and a 4 1/16 inch diameter connection. 
     A longitudinal bore  2  can be disposed through the housing  1 , and can engage small diameter oil field equipment, such as oil field work over equipment or oil field stimulation equipment. The oil field work over equipment or oil field stimulation equipment can be coiled tubing, polished rods, lubricators, or combinations thereof. The oil field work over equipment or oil field stimulation equipment can have diameters ranging from about one inch to about four inches. 
     An open port  20  can be disposed in the housing  1  through the outer surface  12 . The open port  20  can receive a hydraulic fluid. 
     A close port  22  can be disposed in the housing  1  through the outer surface  12 . The close port  22  can receive hydraulic fluid. 
     A grease port  24  can be disposed in the housing  1  through the outer surface  12 . The grease port  24  can receive grease from a grease source. For example, grease that passes the Shrimp Test for use in the ocean can be used. 
       FIG. 2  depicts a cross sectional view of the stripper blow out preventer  5 . 
     A recess  3 , also called a dual diameter annular recess, can surround the longitudinal bore  2 . The recess  3  can have a first diameter  14  and a second diameter  16 . The first diameter  14  can be from about 30 percent to about 50 percent larger than the second diameter  16 . 
     Housing threads  18  can be formed on at least a portion of the first diameter  14 . The housing threads  18  can engage with outer threads  30  on a retainer ring  26 , also called a dual threaded retainer ring, thereby attaching the housing  1  to the retainer ring  26 . 
     The grease port  24 , the open port  20 , and the close port  22  are shown extending through the housing  1 . 
     The grease port  24  can receive grease from a source external to the housing  1 , and can flow the grease into the housing  1  at or proximate the housing threads  18  to lubricate the housing threads  18 . 
     The retainer ring  26  can have inner threads  32  for attaching the retainer ring  26  to an insert  90 , also called a replaceable insert. 
     The retainer ring  26  can have a first inner seal surface  36  to form a seal with the insert  90 . The retainer ring  26  can have a second inner seal surface  37  to form a seal with a seal element  62 , also called a radially expandable resilient seal element. 
     The retainer ring  26  can have an outer sealing surface  38  to form a seal with the housing  1 . The retainer ring  26  can have a top  40 , a bottom  42 , and a beveled seal surface  44 . 
     The insert  90  can be disposed in the longitudinal bore  2  between the retainer ring  26  and the seal element  62 . 
     The insert  90  can be made of the same material as the housing  1 , or another material. 
     The insert  90  can have a first seal face  92  to form a seal against the first inner seal surface  36 . 
     The insert  90  can have insert threads  94  engaged with the inner threads  32 . 
     The insert  90  can have an insert beveled edge  96  that can form a seal with a resilient top seal surface  64 , also called a resilient seal element top beveled seal surface, of the seal element  62 . 
     The insert  90  can have an insert inner face  98 , which can be oriented towards the longitudinal bore  2 . 
     The insert  90  can have an installation pocket  93 , which can be used to torque the insert  90  into the inner threads  32 . In one or more embodiments, the installation pocket  93  can have a depth ranging from about one inch to about two inches, and a width ranging from about ¼ of an inch to about ¾ of an inch. 
     In operation, the insert  90  can be replaced with another sized insert, allowing the diameter of the longitudinal bore  2  to be widened or narrowed to fit different sizes of oil field equipment. The diameter of the longitudinal bore  2  can be configured to range from about one inch to about four inches to accommodate different sizes of oil field equipment within the housing  1 . Therefore, a single housing  1  can be used to seal different diameter pieces of oil field equipment, lowering costs and simplifying replacement of the insert  90 . 
     The seal element  62  can be positioned in the first diameter  14  portion of the recess  3 . The seal element  62  can be made of an elastomeric material that is compressible, such as hydrogenated nitrile butadiene rubber. The seal element  62  can have a thru bore  68  centrally formed therein. 
     The seal element  62  can have the resilient top seal surface  64  and a resilient bottom seal surface  66 , also called a resilient seal element bottom beveled seal surface. The resilient bottom seal surface  66  can be disposed opposite the resilient top seal surface  64 . 
     The seal element  62  can have a side planar face  70  disposed between the resilient top seal surface  64  and the resilient bottom seal surface  66 . The side planar face  70  can form a seal against the second inner seal surface  37 . 
     The resilient top seal surface  64  and the resilient bottom seal surface  66  can both be disposed at an angle to the side planar face  70  ranging from about 100 degrees to about 160 degrees. In one or more embodiments, the resilient top seal surface  64  and the resilient bottom seal surface  66  can both be disposed at an angle of 135 degrees from the side planar face  70 . 
     In one or more embodiments, a plurality of ridges, such as ridge  72   a , can be disposed around an inner surface of the thru bore  68  and can extend into the thru bore  68 . The plurality of ridges can include from about two ridges to about eight ridges. 
     In one or more embodiments, the seal element  62  can have a length ranging from about two inches to about four inches and a width ranging from about three inches to about four inches. 
     The stripper blow out preventer  5  can have a piston  46 . The piston  46  can have a first piston beveled seal surface  47  and a second piston beveled seal surface  48 . 
     The piston  46  can have a first diameter portion  52  for sealing within the second diameter  16  of the recess  3 . 
     The piston  46  can have a second diameter portion  54  for sealing against the second inner seal surface  37  during operation. 
     The piston  46  can have a third diameter portion  56  for sealing against the first diameter  14  of the recess  3 . 
     The first diameter portion  52  can be smaller than the second diameter portion  54 , and the second diameter portion  54  can be smaller than the third diameter portion  56 . 
     The piston  46  can also have a piston bottom edge  60  and an inner planar face  50 . 
     The stripper blow out preventer  5  can have one or more seals. For example, a plurality of first seals, such as first seal  76   a  and first seal  76   b , can seal between the piston  46  and the housing  1  within the first diameter  14 . 
     A second seal  80  can seal between the insert  90  and the retainer ring  26 . A third seal  74  can seal between the retainer ring  26  and the housing  1 . A fourth seal  75  can seal between the retainer ring  26  and the piston  46 . 
     A plurality of fifth seals, such as fifth seal  78   a  and fifth seal  78   b , can seal between the piston  46  and the housing  1  within the second diameter  16 . 
     The various seals usable with the stripper blow out preventer  5  can be rod type seals and/or piston type seals, such as those available from OEM Components from Houston, Tex. or U-tex Industries, of Columbus, Tex. 
       FIGS. 3A-3C  depict the stripper blow out preventer  5  at different stages in operation. 
       FIG. 3A  depicts the stripper blow out preventer  5  in an opened or relaxed configuration. 
     The stripper blow out preventer  5  has an oil field tubing or polished rod  7  disposed within the longitudinal bore  2 . 
     The piston  46  is shown in a retracted configuration, and the seal element  62  is depicted in a relaxed configuration. 
     In operation, the open port  20  can receive hydraulic fluid, such as from a hydraulic fluid source outside the housing. The hydraulic fluid can flow through the open port  20  to the retainer ring  26  and the piston  46 . 
     In one or more embodiments, the hydraulic fluid can be an environmentally friendly hydraulic fluid that passes the National Oceanic and Atmospheric Administration (NOAA) Shrimp Test for reduced levels of toxicity. 
       FIG. 3B  shows the stripper blow out preventer  5  in a partially stoked configuration. 
     The close port  22  can receive hydraulic fluid and flow the hydraulic fluid to the piston  46 . 
     When the close port  22  is pressured by the hydraulic fluid, the piston  46  can move axially in a first direction  9   a  within the longitudinal bore  2 . 
     The piston  46  can press against the seal element  62  to create a high pressure seal against the oil field tubing or polished rod  7  in the longitudinal bore  2 . 
     The piston  46  is depicted having partially moved towards the retainer ring  26  and the seal element  62  relative to the position of the piston  46  in  FIG. 3A . 
     The seal element  62  is depicted in a partially compressed configuration, with the seal element  62  forming a seal with the oil field tubing or polished rod  7 . 
       FIG. 3C  shows the stripper blow out preventer  5  in a fully stoked configuration. 
     The piston  46  is shown fully moved in the first direction  9   a  within the longitudinal bore  2  towards the seal element  62 . 
     The seal element  62  is depicted in a fully compressed configuration, with the seal element  62  forming the high pressure seal against the oil field tubing or polished rod  7 . 
     When the open port  20  is pressurized by the hydraulic fluid, the piston  46  can move axially in a second direction  9   b  opposite the first direction  9   a , which can allow the seal element  62  to relax from the oil field tubing or polished rod  7  and return to the relaxed configuration depicted in  FIG. 3A . 
     In one or more embodiments, the housing can be adapted to support high pressure seals configured to sustain pressures ranging from about 2000 pounds per square inch (psi) to about 15,000 psi, such as when the stripper blow out preventer  5  is used to form high pressure seals around tubing that is 2⅞ inch in diameter. 
     The grease port  24  can be used to grease the housing threads before stroking the piston  46 , during stroking of the piston  46 , or after stroking the piston  46 . 
     While these embodiments have been described with emphasis on the embodiments, it should be understood that within the scope of the appended claims, the embodiments might be practiced other than as specifically described herein.