Multistage downhole separator and method

Abstract

A downhole separator has first and second separation sections each with a housing defining an interior cavity divided into a first chamber and a second chamber by a flow restricting bearing housing. Each separation section has at least two pumping stages that pump production fluid into the first chamber and to the bearing housing. The bearing housing limits flow into the second chamber and generates a pressure drop in production fluid entering the second chamber, separating gas from liquid. A vortex generator in the second chamber segregates the liquid to the outside and the gas to the inside of the second chamber. The upstream separation section has a greater capacity than the downstream separation section.

1 . A downhole gas and liquid separator for a well comprising:
 an upstream, first separation section and a downstream, second separation section in flow communication with said first separation section, said first and second separation sections each including:   first and second chambers,
 at least two pumping stages, for pumping production fluid through said first chamber, and into said second chamber, and 
 means, positioned a between said first and second chambers, for restricting fluid flow to generate a pressure drop in said production fluid and to separate gas and liquid as said production fluid enters said second chamber, and 
 a vortex generator in said second chamber to centrifugally separate said fluid into gas and liquid, 
   wherein said first separation section has a selected capacity and said second separation section has a selected capacity that is smaller than said capacity of said first separation section,   whereby said first separation section separates a first portion of gas from said production fluid and said second separation section separates a remaining portion of gas from said production fluid.   
     
     
         2 . The separator as set forth in  claim 1  wherein said first and second separation sections each include a driven rotary shaft extending through said first and second chambers. 
     
     
         3 . The separator as set forth in  claim 2  wherein said vortex generator is a paddle on said shaft. 
     
     
         4 . The separator as set forth in  claim 2  wherein each said pumping stage includes an impeller on said shaft. 
     
     
         5 . The separator as set forth in  claim 4  wherein each said pumping stage includes a diffuser downstream of said impeller, that directs said production fluid toward said means for restricting fluid flow. 
     
     
         6 . The separator as set forth in  claim 2  wherein said means for restricting fluid flow is a bearing housing that has a bearing that stabilizes said shaft. 
     
     
         7 . The separator as set forth in  claim 6  wherein said bearing housing has a plurality diagonally extending passages between said first and second chambers that restrict fluid flow and propel said production fluid into said second chamber in a diagonal direction, and thereby initiate vortex generation. 
     
     
         8 . The separator as set forth in  claim 6  wherein said bearing housing in said first separation section has a selected capacity and said bearing housing in said second separation section has a selected capacity that is less than said capacity of said bearing housing in said first separation section,
 whereby said capacity of said second separation section is less than said capacity of said first separation section. 
 
     
     
         9 . The separator as set forth in  claim 6  wherein said second chamber is elongated and said vortex generator is positioned near said bearing housing,
 whereby said production fluid has increased time to separate before exiting said second chamber. 
 
     
     
         10 . The separator as set forth in  claim 1  wherein:
 said first and second separation sections each include an elongated housing having a first and second end, a base and a head, said base attaching to said first end and including inlet ports, and said head attaching to said second end and including gas and liquid outlet ports, and 
 said inlet ports in said base of said second separation section connect to said liquid outlet ports in said head of said first separation section. 
 
     
     
         11 . A downhole gas and liquid separator for a well comprising:
 a first separation section having a housing with a first end and a spaced second end, a base at said first end with inlet ports and a head at said second end with gas and liquid outlet ports, said first separation section having a first chamber and a downstream second chamber, at least two pumping stages, for pumping production fluid through said first chamber, and into said second chamber, a bearing housing positioned between said first and second chambers that restricts fluid flow to generate a pressure drop in said production fluid and to separate gas and liquid as said production fluid enters said second chamber and a vortex generator in said second chamber to centrifugally separate said fluid into gas and liquid, each said pumping stage including an impeller and a diffuser downstream of said impeller, said first separation section having a driven rotary shaft connecting to and rotating said impellers and said vortex generator, said bearing housing having a selected capacity, and   a second separation section having a housing with a first end and a spaced second end, a base at said first end connected to liquid outlet ports of said first separation section and a head at said second end with gas and liquid outlet ports, said second separation section having a first chamber and a downstream second chamber, at least two pumping stages, for pumping production fluid through said first chamber, and into said second chamber, a bearing housing positioned between said first and second chambers that restricts fluid flow to generate a pressure drop in said production fluid and to separate gas and liquid as said production fluid enters said second chamber and a vortex generator in said second chamber to centrifugally separate said fluid into gas and liquid, each said pumping stage including an impeller and a diffuser downstream of said impeller, said second separation section having a driven rotary shaft connecting to and rotating said impellers and said vortex generator, said bearing housing having a selected capacity that is less than said capacity of said bearing housing in said first separation section, whereby said first separation section separates a first portion of gas from said production fluid and said second separation section separates a remaining portion of gas from said production fluid.   
     
     
         12 . A method of separating gas and liquid from production fluid in a well comprising the steps of:
 providing a first separation section with at least two pumping stages, and connected first and second chambers,   pumping said production fluid into said first chamber of said first separation section,   generating pressure in said production fluid in said first chamber of said first separation section with said pumping stages,   limiting flow of said production fluid into said second chamber of said first separation section,   generating a pressure drop in said production fluid as said production fluid flows from said first chamber to said second chamber of said first separation section, to separate said gas and said liquid,   generating a vortex in said second chamber of said first separation section, to further separate said gas and said liquid,   providing a second separation section connected to said first separation section and having at least two pumping stages, and connected first and second chambers,   pumping said production fluid from said second chamber of said first separation section into said first chamber of said second separation section,   generating pressure in said production fluid in said first chamber of said second separation section with said pumping stages,   limiting flow of said production fluid into said second chamber of said second separation section   generating a pressure drop in said production fluid as said production fluid flows from said first chamber to said second chamber of said second separation section, to separate said gas and said liquid, and   generating a vortex in said second chamber of said second separation section, to further separate said gas and said liquid.   
     
     
         13 . The method as set forth in  claim 12  wherein:
 said step of limiting flow of said production fluid into said second chamber of said first separation section includes: 
 providing a bearing housing between said first and second chambers with said bearing housing having a plurality of restrictive passages extending between said first and second chambers, and 
 passing said production fluid through said passages, and 
 said step of limiting flow of said production fluid into said second chamber of said second separation section includes: 
 providing a bearing housing between said first and second chambers with said bearing housing having a plurality of restrictive passages extending between said first and second chambers, and 
 passing said production fluid through said passages. 
 
     
     
         14 . The method as set forth in  claim 13  wherein said bearing housing in said first separation section has a selected capacity and said bearing housing in said second separation section has a selected capacity that is less than said capacity of said bearing housing in said first separation section. 
     
     
         15 . The method as set forth in  claim 12  wherein:
 said step of generating a vortex in said second chamber of said first separation section includes: 
 providing a rotary paddle and 
 rotating said paddle, and 
 said step of generating a vortex in said second chamber of said second separation section includes: 
 providing a rotary paddle and 
 rotating said paddle. 
 
     
     
         16 . The method as set forth in  claim 15  wherein said second chamber of each of said first and second separation sections is elongated and said paddle assembly is positioned near an upstream end of said second chamber.