Dissolvable downhole frac tool having a single slip

Abstract

A downhole plug for use in completion operations within the casing of an oil well is disclosed. The settable downhole tool has a mandrel, a wedge, a seal, load ring, ratchet ring, a bottom shoe, and a ball seat. In addition, the downhole tool contains only a single slip engaging the mandrel, the slip comprised of numerous panels with multiple buttons thereon. During setting of the downhole tool, the single slip engages the wedge and is forced outward to engage the casing so as to hold the downhole tool in place during subsequent operations, including, for example, fracing.

1 . A downhole plug for use in completion operations within a casing in a hydrocarbon well, the plug being settable by a setting tool within the casing to isolate an upper zone above the plug from a lower zone below the plug, comprising:
 a mandrel having a at overall length less than about 26 inches;   a single slip engaging the mandrel, the slip comprised of panels, at least some panels having upward buttons for holding the frac plug within the casing against downward pressure, the upward buttons having an upward face inclined upwards and a lower face generally perpendicular to the slip, and at least some panels having downward buttons for holding the frac plug within the casing against upward pressure, the downward buttons having a downward face inclined downward and an upper face generally perpendicular to the slip;   a wedge engaging the mandrel and the slip for expanding the slip against the casing;   a seal engaging the mandrel for sealing the plug against the casing;   a load ring engaging the mandrel and the seal for axially moving on the mandrel to axially compress the seal to expand the seal radially against the casing;   a ratchet ring engaging the mandrel and the load ring for axially moving downward on the mandrel and holding the load ring from upward movement on the mandrel;   a bottom shoe engaging the lower end of the mandrel for holding the wedge against downward movement on the mandrel; and   a ball seat engaging the mandrel or the bottom shoe for holding a frac ball;
 wherein the plug has an overall length of less than about 28 inches and is useful in completion operations within the casing in the hydrocarbon well, the plug being settable by a setting tool within the casing to isolate an upper zone above the plug from a lower zone below the plug. 
   
     
     
         2 . The plug of  claim 1 , wherein the mandrel's overall length is less than about 16 inches and the overall length of the plug is less than about 18 inches. 
     
     
         3 . The plug of  claim 1 , wherein the mandrel's overall length is less than about 11 inches and the overall length of the plug is less than about 12 inches. 
     
     
         4 . The plug of  claim 1 , wherein at least some of the upward buttons and some of the downward buttons are on the same panel or panels, and such panels with both upward buttons and downward buttons provide resistance to both upward movement and downward movement of the plug in the casing. 
     
     
         5 . The plug of  claim 1 , wherein the ball seat is on a mandrel shoulder located on an inner wall of the mandrel and above the bottom shoe, and at least some of an upper mandrel wall above the ball seat is thinner than a lower mandrel wall below the ball seat. 
     
     
         6 . The plug of  claim 5 , wherein the upper mandrel's wall thickness above the ball seat is less than about 1.5 inches. 
     
     
         7 . The plug of  claim 5 , wherein the upper mandrel's wall thickness above the ball seat is less than about 1 inch. 
     
     
         8 . The plug of  claim 1 , wherein some of the mandrel, slip, wedge, seal, load ring, ratchet ring, and bottom shoe are polymer acid elements comprised of one or more degradable polymer acids and some of the mandrel, slip, wedge, seal, load ring, ratchet ring and bottom shoe are metallic elements comprised of metals or metal alloys, the polymer acid elements being degradable in the well's downhole fluid to produce degradation products which will sufficiently reduce the pH of the downhole fluid adjacent the metallic elements to appreciably accelerate the degradation rate of the metallic elements relative to the degradation rate of the metallic elements without the adjacent polymer acid elements degradation products so the plug releases from the casing in 80% of the time needed for a similar plug without such degradable polymer elements producing such degradation products to release from the casing. 
     
     
         9 . The plug of  claim 1 , wherein some of the mandrel, slip, wedge, seal, load ring, ratchet ring, and bottom shoe are polymer acid elements comprised of one or more degradable polymer acids and some of the mandrel, slip, wedge, seal, load ring, ratchet ring and bottom shoe are metallic elements comprised of metals or metal alloys, the polymer acid elements being degradable in the well's downhole fluid to produce degradation products which will sufficiently reduce the pH of the downhole fluid adjacent the metallic elements to appreciably accelerate the degradation rate of the metallic elements relative to the degradation rate of the metallic elements without the adjacent polymer acid elements degradation products so the plug releases from the casing in 50% of the time needed for a similar plug without such degradable polymer elements producing such degradation products to release from the casing. 
     
     
         10 . The plug of  claim 1 , further including an extra degradable element which is run into the well with the plug and is degradable in the downhole fluid to produce degradation products which will sufficiently reduce the pH of the downhole fluid adjacent the metallic elements to appreciably accelerate the degradation rate of the metallic elements relative to the rate of degradation of the metallic elements without the degradation products, so the plug releases from the casing in 50% of the time needed for a similar plug without such extra degradable element producing such degradation products. 
     
     
         11 . The plug of  claim 1 , further including an extra degradable element which is run into the well with the plug and is degradable in the downhole fluid to produce degradation products which will sufficiently increase the salinity of the downhole fluid adjacent the metallic elements to appreciably accelerate the degradation rate of the metallic elements relative to the rate of degradation of the metallic elements without the degradation products, so the plug releases from the casing in 50% of the time needed for a similar plug without such extra degradable element producing such degradation products. 
     
     
         12 . The plug of  claim 5 , wherein the extra degradable element is a tablet or capsule within the cavity of the mandrel. 
     
     
         13 . A downhole plug for use in completion operations within a casing in a hydrocarbon well, the plug being settable by a setting tool within the casing to isolate an upper zone above the plug from a lower zone below the plug, comprising:
 a mandrel having a mandrel overall length of less than about 12 inches;   a single slip engaging the mandrel, the slip comprised of panels, at least some panels having upward buttons for holding the frac plug within the casing against downward pressure, the upward buttons having an upward face inclined upwards and a lower face generally perpendicular to the slip, and at least some panels having downward buttons for holding the frac plug within the casing against upward pressure, the downward buttons having a downward face inclined downward and an upper face generally perpendicular to the slip, and wherein at least some of the upward buttons and some of the downward buttons are on the same panel or panels, panels with both upward buttons and downward buttons providing resistance to both upward movement and downward movement of the plug in the casing;   a wedge engaging the mandrel and the slip for expanding the slip against the casing;   a seal engaging the mandrel for sealing the plug against the casing;   a load ring engaging the mandrel and the seal for axially moving on the mandrel to axially compress the seal to expand the seal radially against the casing;   a ratchet ring engaging the mandrel and the load ring for axially moving downward on the mandrel and holding the load ring from upward movement on the mandrel;   a bottom shoe engaging the lower end of the mandrel for holding the wedge against downward movement on the mandrel;   a ball seat for holding a frac ball, the ball seat being on a mandrel shoulder located on an inner wall of the mandrel and above the bottom shoe, and at least some of the mandrel wall above the mandrel shoulder is thinner than the mandrel wall below the mandrel shoulder; and   some of the mandrel, slip, wedge, seal, load ring, ratchet ring, and bottom shoe are polymer acid elements comprised of one or more degradable polymer acids and some of the mandrel, slip, wedge, seal, load ring, ratchet ring and bottom shoe are metallic elements comprised of metals or metal alloys, the polymer acid elements being degradable in the well's downhole fluid to produce degradation products which will sufficiently reduce the pH of the downhole fluid adjacent the metallic elements to appreciably accelerate the degradation rate of the metallic elements relative to the degradation rate of the metallic elements without the adjacent polymer acid elements degradation products so the plug releases from the casing in 80% of the time needed for a similar plug without such degradable polymer elements producing such degradation products to release from the casing;
 wherein the plug has an overall length of less than about 13 inches and is useful in completion operations within the casing in the hydrocarbon well, the plug being settable by a setting tool within the casing to isolate an upper zone above the plug from a lower zone below the plug. 
   
     
     
         14 . The plug of  claim 10 , wherein the upper mandrel's wall thickness above the ball seat is less than about 1 inch.