Device for temporarily closing duct-formers in well completion apparatus

A duct-forming device for use in well completion apparatus of the kind wherein a bore hole casing is positioned in a bore hole and duct-forming devices of acid-and abrasion-resistant metal are secured at spaced levels to the casing in alignment with holes machined in the casing wall, and wherein, upon pressurizing the casing space, each duct-forming device is laterally projected from the casing for making contact with a producing formation, each said duct-forming device comprising:

• (a) a terminal sleeve adapted to make contact with the producing formation when the duct-forming device has been laterally projected;
• (b) a plug of acid-and/or alkaline soluble material positioned at the free end of said terminal sleeve and having at least one passage for establishing communication between said formation and the interior space of said duct-forming device;
• (c) a removable piston assembly within said interior space of the duct-forming device and including a piston having passages therethrough and blocking means thereon, said piston being movable between an initial position in which the piston passages permit fluid flow through the passage of said plug, a blocking position in which the piston blocking means blocks fluid flow through the passage of said plug and an ultimate position in which the piston and the entire piston assembly are forced from the interior of said duct-forming device into the casing space, said piston assembly further including a spring, first and second abutment means removably mounted in said terminal sleeve, said spring bearing against said first and second abutment means for holding said piston in said initial position, said piston assembly further including a chamber adjacent said casing, ball means located within said chamber and seat means, within such chamber for said ball means;
• (d) an acid- and/or alkali soluble closure cap screwed on to said duct-forming device at its end which is secured to said casing and having at least one hole;
• (e) an acid- and/or alkali soluble flow-impeding plate screwed into said duct-forming device between piston assembly and said closure cap, and
• (f) sealing means permitting said movements of said piston within the interior of the duct-forming device in a fluid-tight manner.

A duct-forming device for use in well completion apparatus of the kind wherein a bore hole casing is positioned in a bore hole and duct-forming devices of acid-resistant metal are secured at spaced levels of the casing in alignment with holes machined in the casing wall, and wherein upon pressurization of the casing space each duct-forming device is laterally extended from the casing for making contact with a producing formation, each of said duct-forming device comprising:

• (a) a terminal sleeve adapted to make contact with the producing formation when the duct-forming device has been laterally extended, said terminal sleeve having an internal wall defining passageway means for establishing communication between said formation and the interior space of said duct-forming device;
• (b) a check member made of acid and/or alkali soluble material mounted within said passageway means forming a restriction therein limiting fluid flow therethrough to a predetermined initial amount, with dissolution of said check member as a result of exposure thereof to acid and/or alkali liquid operating to remove said restriction;
• (c) an acid and/or alkali-soluble closure cap having hole means, said closure cap being mounted in said duct forming device adjacent the end at which the duct-forming device is secured to said casing;
• (d) an acid and/or alkali soluble flow-impeding means located within the interior of said duct-forming device and being interpositioned between said closure cap (c) and said check member (b);
• (e) a non-soluble ball check member interpositioned between said flow-impeding means (d) and said check member;
• and
• (f) seat means within said terminal sleeve passageway means adapted to have said ball check member seated thereupon to block fluid flow through said passageway means in a direction from said casing toward said formation;
• with acidic or alkaline liquid forced down said casing operating to impinge upon and dissolve said closure cap while simultaneously passing through said hole means of said closure cap to make contact with and dissolve said flow-impeding means, said liquid, after having eaten through said flow-impeding means flowing through said restricted passageway means into said formation while, depending upon its flow rate and its pressure, said liquid gradually dissolves said check member, with complete dissolution of said check member operating to effect movement of said ball check member into seated engagement with said seat means to block communication between the formation and the interior of said duct-forming device, and after said liquid has substantially totally dissolved said flow-impeding means, said check member and said closure cap and the formation pressure exceeds the pressure within the interior of said duct-forming device, fluid from said formation forces said ball check member off said seat means and towards and into said casing space.