Pulse detonation tool, method and system for formation fracturing

Abstract

According to one aspect of the invention, a pulse detonation tool is provided for fracturing subterranean formations. The pulse detonation tool includes a pulse detonation combustor and creates an isolated zone within a wellbore. The tool generate a series of repeating supersonic shock waves that are directed into the subterranean formation to cause propagation of multiple fractures into the formation. According to another aspect of the invention, a method and system for fracturing a subterranean formation using pulse detonation is provided.

Description

BACKGROUND[0001]Formation fracturing is becoming an important tool for hydrocarbon production. There is an increasing need to produce hydrocarbons from wells in subterranean formations that contain a sufficient volume of hydrocarbon fluids, but have low permeability or restricted flow near the wellbore so that production is slow or difficult and, thus, not economical. In addition to oil and / or gas producing wells, formation fracturing is also an important tool for injection wells, storage wells, brine or water production wells, and disposal wells.[0002]Flow of a fluid, such as oil or gas, through a porous medium, i.e. a subterranean formation, is directly related to the permeability of the formation. A formation with low permeability can occur naturally due to the geological conditions of the formation. Low permeability can also be caused by damage to the formation from drilling, cementing and perforating operations. Further, mature wells can incur damage from the buildup of fine pa...

AI Technical Summary

Benefits of technology

[0009]In one aspect of the invention, a pulse detonation tool for fracturing subterranean formations is adapted to be lowered into a production tubing disposed within a wellbore and comprises a first and second sealing mechanism configured to create an isolated zone having an axis parallel to and extending through the production tubing, wherein the first sealing mechanism has at least one inlet port configured to allow a fuel and an oxidizer to flow into a pulse detonation combustor disposed within the isolated zone and wherein the first sealing mechanism is further configured to connect to an oxidizer and a fuel source by way of a fluid injection line extending from the surface through the tubing; at least one valve assembly to achieve controlled delivery of the fuel and oxidizer to the pulse detonation tool; the pulse detonation combustor comprising: a combustion region defining a fluid flow path; a mixing region for producing a flammable mixture comprising a controlled volume of fuel and oxidizer, wherein the mixing region is in fluid communication with the at least one inlet port and the combustion region; an ignition device configured to periodically ignite the flammable mixture; and means for initiating a series of repeating detonations that generate a series of repeating supersonic shock waves, wherein the shock waves are directed into the subterranean formation to cause propagation of multiple fractures into the formation.

Problems solved by technology

There is an increasing need to produce hydrocarbons from wells in subterranean formations that contain a sufficient volume of hydrocarbon fluids, but have low permeability or restricted flow near the wellbore so that production is slow or difficult and, thus, not economical.

Low permeability can also be caused by damage to the formation from drilling, cementing and perforating operations.

Further, mature wells can incur damage from the buildup of fine particulates and contaminants.

The success of this method has been limited, however, due to safety hazards and because frequently the explosive compaction of the formation opposite to the explosion fracture causes formation and wellbore damage, which results in a decrease rather than increase of permeability.

Although this method is successful, the equipment and labor involved in hydraulic fracturing is extensive and expensive.

The resulting radial fractures, however, do not penetrate deep enough into the formation (i.e only 50-75 feet) and thus it is often necessary to combine them with, for example, hydraulic fracturing or chemical treatments.

Each of the current methods of formation fracturing thus have drawbacks.

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