Mandrel for Re-pressurization and Downhole Plugging Apparatus

Abstract

A mandrel for re-pressurization is disclosed. Said mandrel comprising a pipe body, connecting threads at both ends of the pipe body of said mandrel; a containing section and a secondary pressurizing section on the body pipe, wherein the secondary pressurizing section has a larger diameter than that of the containing section; a position of the containing section allows a compressed seal assembly to be contained in the containing section when in a setting state; a position of the secondary pressurizing section allows a internal surface of the seal assembly that is already compressed to be pressurized again in a compressing state. A downhole plugging apparatus is disclosed as well.

What is claimed is: 
     
         1 . A mandrel for re-pressurization, comprising:
 a pipe body  1  with connecting threads  101  at its both ends;   a containing section  103  and a secondary pressurizing section  104  on the pipe body  1 ;   a first position of the containing section  103  on the pipe body  1  allowing the compressed seal assembly to be contained in the containing section  103 ;   a second position of the secondary pressurizing section  104  on the pipe body  1  allowing the secondary pressurizing section  104  to pressurize an internal surface of the already compressed seal assembly again when in a compressing state.   
     
     
         2 . According to  claim 1 , the secondary pressurizing section  104  is a bulging outer surface of the pipe body  1 ; and, the containing section  103  is a circular groove on the pipe body  1 . 
     
     
         3 . The containing section  103  and the secondary pressurizing section  104  from  claim 1 , wherein the two are connected and the secondary pressurizing section  104  is a conical pipe whose diameter reduces towards the containing section  103 . 
     
     
         4 . The pipe body  1  from  claim 1 , further comprising a large diameter section and a small diameter section; wherein the large diameter section is the secondary pressurizing section, and the small diameter section is the containing section. 
     
     
         5 . The mandrel for re-pressurization from  claim 1 , further comprising a anti-rotation slot  11 , which is set on the end of the secondary pressurizing section  104  and is close to the containing section  103 . 
     
     
         6 . The mandrel for re-pressurization from  claim 2 , further comprising a anti-rotation slot  11 , which is set on the end of the secondary pressurizing section  104  and is close to the containing section  103 . 
     
     
         7 . The mandrel for re-pressurization from  claim 3 , further comprising a anti-rotation slot  11 , which is set on an end of the secondary pressurizing section  104  and is close to the containing section  103 . 
     
     
         8 . The mandrel for re-pressurization from  claim 4 , further comprising a anti-rotation slot  11 , which is set on an end of the secondary pressurizing section  104  and is close to the containing section  103 . 
     
     
         9 . A downhole plugging apparatus, comprising:
 (a) a mandrel for re-pressurization, (b) a seal assembly arranged on the mandrel for re-pressurization, (c) a upper anchor assembly and (d) a lower anchor assembly located respectively at a upper end and a lower end of the mandrel for re-pressurization;   wherein the mandrel for re-pressurization comprising a pipe body  1 , at least one connecting threads  101  set at both ends of the pipe body  1 ,   a containing section  103  and a secondary pressurizing section  104  set on the pipe body  1 , wherein a diameter of the containing section  103  is smaller than that of the secondary pressurizing section  104 ;   A containing section  103  on the pipe body  1  allowing the the seal assembly to be compressed and contained in the containing section  103 , a second position of the secondary pressurizing section  104  on the pipe body  1  allowing the secondary pressurizing section  104  to pressurize an internal surface of the already compressed seal assembly again when in a compressing state.   
     
     
         10 . Claim  9  further comprising the secondary pressurizing section  104  having a bulging external surface of the pipe body  1 ; and, the containing section  103  having a circular groove on the pipe body  1 . 
     
     
         11 . The containing section  103  and the secondary pressurizing section  104  from  claim 9 , wherein the two are connected sections, and the secondary pressurizing section  104  is a conical pipe whose diameter reduces towards the containing section  103 ; 
     
     
         12 . The downhole plugging apparatus from  claim 9 , further comprising an anti-rotation slot  11  set on an end of the secondary pressurizing section  104  and is close to the containing section  103 . 
     
     
         13 . The downhole plugging apparatus from  claim 10 , further comprising an anti-rotation slot  11  set on an end of the secondary pressurizing section  104  and is close to the containing section  103 . 
     
     
         14 . The downhole plugging apparatus from  claim 11 , further comprising an anti-rotation slot  11  set on an end of the secondary pressurizing section  104  and is close to the containing section  103 . 
     
     
         15 . The downhole plugging apparatus from  claim 9 , wherein:
 the upper anchor assembly includes (a) an upper locking nut  2  screwed on the connecting thread  101  on an upper part of the mandrel for re-pressurization, (b) a striper ring  3  contacted with the upper locking nut  2 , (c) multiple slips  4  contacted with the striper ring  3 , and (d) a conical slip holder  5  contacted with the slips  4  and with the seal assembly;   the lower anchor assembly includes (a) an lower locking nut  8  screwed on the thread  101  on a lower end of the mandrel for re-pressurization mentioned above, (b) multiple slips  4  contacted with the lower locking nut  8 , and (c) the conical slip holder  5  contacted with the slips  4  and with the seal assembly;   wherein teeth widths of thread  101  on the upper locking nut  2  and teeth widths of a upper end of the mandrel for re-pressurization are regulated to ensure a maximum failure shearing stresses of the thread on the upper locking nut  2  and the thread on the upper end of the mandrel for re-pressurization are equal;   wherein teeth widths of thread  101  on the lower locking nut  8  and teeth widths of a lower end of the mandrel for re-pressurization are regulated to ensure a maximum failure shearing stress of the thread  101  on the lower locking nut  8  is the same with that of threads  101  on the lower end of the mandrel for re-pressurization.   
     
     
         16 . The downhole plugging apparatus from  claim 10 , wherein:
 the upper anchor assembly includes (a) an upper locking nut  2  screwed on the connecting thread  101  on an upper part of the mandrel for re-pressurization, (b) a striper ring  3  contacted with the upper locking nut  2 , (c) multiple slips  4  contacted with the striper ring  3 , and (d) a conical slip holder  5  contacted with the slips  4  and with the seal assembly;   the lower anchor assembly includes (a) an lower locking nut  8  screwed on the thread  101  on a lower end of the mandrel for re-pressurization mentioned above, (b) multiple slips  4  contacted with the lower locking nut  8 , and (c) the conical slip holder  5  contacted with the slips  4  and with the seal assembly;   wherein teeth widths of thread  101  on the upper locking nut  2  and teeth widths of a upper end of the mandrel for re-pressurization are regulated to ensure a maximum failure shearing stresses of the thread on the upper locking nut  2  and the thread on the upper end of the mandrel for re-pressurization are equal;   wherein teeth widths of thread  101  on the lower locking nut  8  and teeth widths of a lower end of the mandrel for re-pressurization are regulated to ensure a maximum failure shearing stress of the thread  101  on the lower locking nut  8  is the same with that of threads  101  on the lower end of the mandrel for re-pressurization.   
     
     
         17 . The downhole plugging apparatus from  claim 11 , wherein:
 the upper anchor assembly includes (a) an upper locking nut  2  screwed on the connecting thread  101  on an upper part of the mandrel for re-pressurization, (b) a striper ring  3  contacted with the upper locking nut  2 , (c) multiple slips  4  contacted with the striper ring  3 , and (d) a conical slip holder  5  contacted with the slips  4  and with the seal assembly;   the lower anchor assembly includes (a) an lower locking nut  8  screwed on the thread  101  on a lower end of the mandrel for re-pressurization mentioned above, (b) multiple slips  4  contacted with the lower locking nut  8 , and (c) the conical slip holder  5  contacted with the slips  4  and with the seal assembly;   wherein teeth widths of thread  101  on the upper locking nut  2  and teeth widths of a upper end of the mandrel for re-pressurization are regulated to ensure a maximum failure shearing stresses of the thread on the upper locking nut  2  and the thread on the upper end of the mandrel for re-pressurization are equal;   wherein teeth widths of thread  101  on the lower locking nut  8  and teeth widths of a lower end of the mandrel for re-pressurization are regulated to ensure a maximum failure shearing stress of the thread  101  on the lower locking nut  8  is the same with that of threads  101  on the lower end of the mandrel for re-pressurization.