Tool and process for stimulating a subterranean formation
First Claim
1. A tool for stimulating a subterranean formation comprising, an elongate propellant stack constructed from propellant material modules that are formed from a combination of propellant materials such that the propellant module combination will have a desired burn rate, propellant modules of a center portion to have identical convex and concave surfaces as the respective top and bottom faces thereof with end propellant modules to form the propellant stack ends each having an end face to fit within or over one of said center portion propellant modules convex or concave faces;
- adhesive means containing grains of a propellant or explosive mixed therein to provide a burn rate that is approximately that of the propellant stack for bonding said selected propellant modules together, said adhesive means to burn with the propellant stack;
means for supporting and lowering said propellant stack into a well bore to a subterranean formation to be stimulated; and
means for igniting said propellant stack.
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Accused Products
Abstract
A high energy gas fracturing tool for radially fracturing a rock formation in a well bore consisting of a cylindrical canister that is holed to pass gas and is for housing a stack of propellant modules that are selected to provide a desired burn rate when ignited. Each propellant module mating face is angled from the horizontal between forty-five (45) to seventy-five (75) degrees, and the modules are bonded together with an epoxy resin wherein propellant or explosive particles are mixed, the resin to exhibit burn characteristics similar to those of the propellant stack. The tool, additional to the propellant containing canister, an ignitor rod and explosive device for igniting the propellant stack, mounts a bull head end over a lower end and a reverse thruster assembly that is connected to the canister upper end. The reverse thruster assembly includes a housing with nozzles formed therein that are angled from the vertical to pass gas on propellant deflagration, creating thereby a force against the tool lifting during propellant burning. Above the reverse thruster assembly is arranged a pressure pulse monitor that is battery powered to operate a pressure transducer for sensing pressure pulses at the tool. The monitor to turn on when a sufficient strength of pressure pulse is received, to store pressure pulses sensed over time, with the stored pressure data retrieved when the tool is removed from the well bore. The recorded pressure pulse data is used for determining the dynamic window of the formation, whereat, at a certain pressure over time the formation will be optimally radially fractured. The tool is suspended from the surface on a wire line and includes a collar locator for locating it at a certain level within the well bore.
95 Citations
35 Claims
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1. A tool for stimulating a subterranean formation comprising, an elongate propellant stack constructed from propellant material modules that are formed from a combination of propellant materials such that the propellant module combination will have a desired burn rate, propellant modules of a center portion to have identical convex and concave surfaces as the respective top and bottom faces thereof with end propellant modules to form the propellant stack ends each having an end face to fit within or over one of said center portion propellant modules convex or concave faces;
- adhesive means containing grains of a propellant or explosive mixed therein to provide a burn rate that is approximately that of the propellant stack for bonding said selected propellant modules together, said adhesive means to burn with the propellant stack;
means for supporting and lowering said propellant stack into a well bore to a subterranean formation to be stimulated; and
means for igniting said propellant stack. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- adhesive means containing grains of a propellant or explosive mixed therein to provide a burn rate that is approximately that of the propellant stack for bonding said selected propellant modules together, said adhesive means to burn with the propellant stack;
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11. A propellant stack constructed from individual propellant modules each formed to have a specific burn rate, the combining of which propellant modules in a single stack to provide a propellent having a certain burn rate comprising, propellant modules each formed from a combination of propellant materials to have a certain burn rate, which propellant modules for a center portion of said stack are identically cylindrically shaped and each has, respectively, a regular convex top surface to fit exactly within an opposite identical regular concave undersurface, the angle of which regular convex and concave surfaces is between forty-five degrees (45) and seventy-five degrees (75) to the horizontal;
- top and bottom end propellant modules formed from the same combinaton of propellant material as said center portion propellant modules each having an end surface to exactly fit within an opposite regular concave or convex surface of a propellant module of said center portion; and
binding means for joining together the modules contacting regular convex and concave surfaces, which binding means is a resin containing propellant or explosive particles to have a burn rate that is like that of the propellant stack. - View Dependent Claims (12, 13, 14, 15)
- top and bottom end propellant modules formed from the same combinaton of propellant material as said center portion propellant modules each having an end surface to exactly fit within an opposite regular concave or convex surface of a propellant module of said center portion; and
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16. A tool for stimulating a subterranean formation comprising, a cylindrical canister that is radially holed therearound over its length and is to contain a propellant stack fitted therein that is formed from propellant modules selected to provide a certain burning rate when ignited, which propellant modules are bonded together with an adhesive material to have a burn rate that is approximately that of the propellant stack;
- means for igniting said propellant stack at its longitudinal center to burn radially therefrom;
a pulse monitor assembly for arrangement with said cylindrical canister that includes a pressure pulse sensor means for sensing pressure pulses as occur during propellant deflagration that includes means for recording in memory those pulses over time;
wire line means for suspending said tool from the ground surface that includes means for passing an electrical current from the surface to ignite said propellant stack; and
means for interrogating said pulse monitor assembly memory to retrieve and store the pressure date generated and recorded during propellant deflagration. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
- means for igniting said propellant stack at its longitudinal center to burn radially therefrom;
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29. A process for stimulating a subterranean formation utilizing a high energy gas fracturing tool to optimally radially fracture the formation where the tool propellant charge is formed from individual propellant modules each having a known burn rate comprising the steps of, from an analysis of the known characteristics of the subterranean formation, selecting and combining individual propellant modules, each having a known burn rate, into a propellant stack, the propellant stack to have a certain burn rate such that propellant deflagration will produce gas and water at a pressure and velocity to be within a dynamic window of the formation to optimally radially fracture that formation;
- positioning the propellant stack to a pre-determined location within the subterranean formation; and
igniting the propellant stack, the deflagrating propellant to appropriately fracture the subterranean formation alongside the propellant stack. - View Dependent Claims (30, 31, 32, 33, 34, 35)
- positioning the propellant stack to a pre-determined location within the subterranean formation; and
Specification