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US 2014/0190685 A1Published application
Downhole tools having non-toxic degradable elements and methods of using the same
AssigneeFrazier Technologies, L.L.C.
InventorsW. Lynn Frazier, Garrett Frazier, Derrick Frazier
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Abstract
Downhole tools for use in oil and gas production which degrade into non-toxic materials, a method of making them and methods of using them. A frac ball and a bridge plug comprised of polyglycolic acid which can be used in fracking a well and then left in the well bore to predictably, quickly, and safely disintegrate into environmentally friendly products without needing to be milled out or retrieved.
Claims44
A method of producing hydrocarbons from multiple zones from a well, the well having a wellbore with a wellbore casing, the method comprising the steps of:
- providing a first set of frac plugs, each with an inner conduit, adapted to fit within the wellbore casing, and a first set of frac balls, each frac ball adapted to fit within one of the provided frac plugs and to block the frac plug's inner conduit;
- wherein at least one of either the frac ball or the frac plug in each frac plug and frac ball combination is comprised of a homogenous, non-metallic, degradable material that will begin to degrade in a fluid at a temperature of at least above about 150° F. within about one month of being exposed to downhole fluid in the casing, resulting in a sufficient loss in mass that the frac plug and frac ball combination ceases to isolate zones;
- perforating the casing and fracking a first lower zone;
- running a bottom hole assembly comprising at least a first frac plug and a setting tool into the casing to a first setting depth;
- setting the first plug at a first setting depth in the lower zone;
- inserting a first ball down the casing until it seats within the first plug and seals its inner conduit, isolating the first lower zone;
- perforating the casing at a second lower zone above the first set frac plug and fracking the second lower zone;
- and
- repeating the running, setting, inserting, seating, sealing, and isolating steps above the second lower zone with and additional frac plug and frac ball from the first set of degradable frac plug and frac ball combinations;
- wherein the wellbore within the lower zone has fluid at a temperature of at least about 150° F. and the first set of frac plugs in the lower zone are not drilled out, but rather degrade within one month of being exposed to the downhole fluid in the wellbore casing resulting in a sufficient loss in mass that each frac plug and frac ball combination therein ceases to isolate zones.
7 more elements
A downhole tool for engaging a wellbore casing of a hydrocarbon well, the downhole tool comprising:
- structural elements including a cylindrical mandrel having an outer surface and an inner surface, the inner surface defining an inner conduit, and also structural elements disposed on the outer surface of the mandrel, at least some configured to engage the inner walls of the wellbore casing in a set position and some others to drive those configured to set into the set position from a run in position;
- wherein at least some of the structural elements comprise a non-composite degradable material that will begin degradation at fluid temperatures above about 150° F. and will degrade into environmentally harmless products.
A device for use in a well comprising a borehole extending from a surface location and penetrating a hydrocarbon bearing interval and with a casing string in the borehole having a minimum internal diameter, the device comprising:
- a flapper valve assembly and a tubular housing with an inner diameter, providing part of the casing string and being at a location between the hydrocarbon bearing interval and the surface location;
- a flapper valve engaging the tubular housing and moveable between a first operative position allowing upward and downward flow through a casing string and tubular housing and a second operative position allowing upward flow and preventing downward flow through the casing and tubular housing, the flapper valve member being substantially homogenous, nonmetallic and comprised of a degradable material, degradable in acidic or non-acidic fluids at temperatures above about 150° F.
A method of temporarily plugging a section of casing at a well at a well site with degradable frac balls, comprising:
- providing a set of polyglycolic acid (“PGA”) frac balls to the well site, the balls in the set of balls having preselected diameters, at least some of the balls having preselected constant incremental diameter differences, the ball diameters of the balls in the set of balls being selected through use of ball degradation rate factors, and estimated formation conditions in the well, so at least some of the balls within the set of balls are appropriate for temporarily plugging a first frac plug and a second frac plug within the section of casing at the well;
- determining a location in the well for positioning the first frac plug;
- determining a location in the well for the second frac plug, the second frac plug being located above the first frac plug;
- estimating formation conditions at the location for positioning the first frac plug in the well;
- including at least formation temperature, and determining a desired duration for the first frac plug to be plugged;
- estimating formation conditions at the location for positioning the second frac plug in the well;
- including at least formation temperature, and determining a desired duration for the second frac plug to be plugged;
- determining appropriate ball size for a first frac plug seat size and appropriate frac ball size for a second frac plug seat size using PGA ball degradation rate factors, and well conditions at the first and second frac plugs, and the desired duration for the first and second frac plugs to be plugged;
- estimating the maximum frac pressure that the first frac plug will be subject to;
- selecting, from the set of frac plug balls, considering the pressure integrity for a ball diameter, a first frac ball for the first frac plug that provides sufficient overlap to withstand the estimated maximum pressure, and inserting the first frac ball into the well casing, pumping the first frac ball down the well until its seats with the first frac plug;
- using the first frac ball within the first frac plug to frac the well, pumping the second frac ball down into the well until its seats with the second frac plug, using the second frac ball within the second frac plug to frac the well, the first and second frac balls thereafter opening the first and second frac plugs by deteriorating into non-toxic materials.
8 more elements
An assembly for use in at least two downhole isolation valves in production operations in a well, comprising:
- a set of homogenous, non-metallic, degradable frac balls, the balls in the set of balls having preselected diameters, at least some of the balls having preselected constant incremental diameter differences, the ball diameters of the balls in the set of balls being selected through use of ball degradation rate factors and estimated formation conditions at the downhole isolation valves, so at least some of the balls within the set of balls are appropriate for temporarily plugging a first isolation valve and a second isolation valve within the well.
A subassembly for use downhole in a hydrocarbon well, the subassembly comprising:
- at least one disk having a body and a perimeter;
- and
- a support structure having an inner conduit, the support structure for engaging the at least one disk at the perimeter of the disk;
- wherein the disk is dimensioned in an initial condition to block the inner conduit within the support structure, the disk comprised of a homogenous, non-metallic, degradable material, which is capable of degrading in downhole fluid.
1 more element
A device for setting a downhole tool against the inner diameter of a downhole casing of a well the device comprising:
- a cylindrical slip having an outer section comprised of teeth and an inner section comprised of an inner wall,
- wherein the teeth are comprised of a metallic material;
- and
- wherein at least part of the inner walls are comprised of a non-metallic,
- homogenous, degradable material that will begin to degrade when exposed to a downhole fluid at a temperature of at least at about 150° F. so that when used in well with downhole fluid at a temperature of at least 150° F., the inner walls detach from the teeth and degrade into smaller fragments within a predetermined time which do not substantially interfere with completing the well.
2 more elements
An isolation sub for use in subterranean hydrocarbon recovery comprising:
- a rigid casing configured to interface with a casing string or tubing string;
- and
- a plurality of ports disposed along the circumference of the rigid casing, each port having seated therein a retaining plug, each retaining plug having seated therein a plug consisting essentially of polyglycolic acid.
A downhole assembly comprising:
- a downhole tool having setting elements engaging a mandrel, the mandrel defining an inner conduit and supporting a seat;
- a non-composite body configured to engage the seat in an initial configuration, wherein the non-composite body is substantially stable in a dry condition at ambient temperature, and, when exposed to a downhole fluid having a temperature of at least about 136° F., the non-composite body will change to a subsequent configuration that does not engage the seat and, in its changed configuration, is then capable of passing through the seat and inner conduit;
- wherein:
- the non-composite body is prepared from polyglycolic acid (PGA);
- the non-composite body is spherical, and is in the range of between about 0.750 inches to about 4.625 inches in diameter;
- the non-composite body is homogenous;
- and
- the non-composite body will degrade into environmentally non-toxic substances within up to about one month of being exposed to the downhole fluid.
5 more elements
Dependencies are inferred from the claim text.