Controlling transient underbalance in a wellbore
AssigneeSchlumberger Technology Corporation
InventorsAshley B. Johnson, Lawrence A. Behrmann, Wenbo Yang, Fokko Harm Cornelis Doornbosch
Life of this patent
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Abstract
A method and apparatus for controlling a transient underbalance condition is provided. Transient underbalance can be enhanced by using a porous material, such as a porous solid, around the explosive device. The porous material contains a volume to receive wellbore fluids in response to activation of the explosive device. This causes a local drop in pressure, which enhances the transient underbalance effect. In another application, it is desired to reduce the transient underbalance effect. This is accomplished by reducing the pressure drop generated as a result of explosive detonation. In one arrangement, the shot density is reduced by using solid masses.
Claims28
A method of controlling an underbalance condition in a wellbore, comprising:
- configuring a perforating gun string according to a target transient underbalance condition in a perforating interval;
- generating substantially the target transient underbalance condition in the perforating interval of the wellbore when the perforating gun string is shot;
- and
- determining the target transient underbalance condition based on one or more predetermined criteria.
A method of controlling an underbalance condition in a wellbore, comprising:
- configuring a perforating gun string according to a target transient underbalance condition in a perforating interval;
- and
- generating substantially the target transient underbalance condition in the perforating interval of the wellbore when the perforating gun string is shot,
- wherein configuring the perforating gun string comprises reducing a total explosive mass by using charges with reduced explosive mass that is less than a maximum explosive mass for which the perforating gun string is designed.
A method of controlling an underbalance condition in a wellbore, comprising:
- configuring a perforating gun string according to a target transient underbalance condition in a perforating interval;
- and
- generating substantially the target transient underbalance condition in the perforating interval of the wellbore when the perforating gun string is shot,
- wherein configuring the perforating gun string comprises reducing a shot density of the perforating gun string.
A method of controlling an underbalance condition in a wellbore, comprising:
- configuring a perforating gun string according to a target transient underbalance condition in a perforating interval;
- and
- generating substantially the target transient underbalance condition in the perforating interval of the wellbore when the perforating gun string is shot;
- and
- providing a porous solid proximate at least a portion of the perforating gun string, the porous solid having an initially sealed volume to receive wellbore fluids in response to detonation of the perforating gun string.
An apparatus comprising:
- a tool containing explosives;
- and
- an amount of porous solid provided around the tool to provide an initially sealed volume to receive wellbore fluids in response to detonation of the explosives, the amount of porous solid based on a target transient underbalance condition in a wellbore interval.
A method for use in a wellbore, comprising:
- determining a target transient underbalance condition in a wellbore interval;
- lowering a tool having explosives to the wellbore interval;
- providing a porous solid proximate the explosives, the porous solid having an initially sealed volume;
- detonating the explosives;
- and
- shattering the porous solid and exposing the sealed volume of the porous solid to increase the effective volume of the wellbore interval to achieve substantially the target transient underbalance condition in the wellbore interval.
A method for use in a wellbore, comprising:
- determining a target transient underbalance condition;
- lowering a tool containing explosives into the wellbore;
- and
- configuring a number of explosives in the tool based on the target transient underbalance condition such that, upon detonation of the explosives to the system achieves substantially the target transient underbalance condition.
A perforating apparatus for use in a wellbore, comprising:
- a carrier line;
- a perforating gun;
- and
- a sealing device to control a rate of fluid flow from a first region of the wellbore to a second region of the wellbore proximate the perforating gun,
- the sealing device adapted to reduce a rate at which pressure increases to an overbalance condition in the second region,
- wherein the sealing device comprises one of a leaky packer and leaky anchor.
A method of perforating in a wellbore, comprising:
- providing a string having a carrier line and a perforating gun;
- providing a sealing device to control a rate of fluid flow;
- and
- reducing, with the sealing device, a rate at which pressure increases to an overbalance condition in a perforating interval proximate the perforating gun,
- wherein providing the sealing device comprises providing one of a leaky packer and leaky anchor around the carrier line.
Dependencies are inferred from the claim text.