Abstract: A method of perforating a well includes selecting a desired transient underbalanced condition, configuring a perforating gun string to achieve the transient underbalanced condition, deploying the perforating gun is a wellbore, and firing the perforating to achieve the transient underbalanced condition.

Abstract: A method of perforating a well includes selecting a desired transient underbalanced condition, configuring a perforating gun string to achieve the transient underbalanced condition, deploying the perforating gun is a wellbore, and firing the perforating to achieve the transient underbalanced condition.

Abstract: An apparatus and method includes positioning a string in a wellbore, the string having a surge chamber. A closure member is provided below the well surface, with the surge chamber defined at least in part by the closure member. At least one port to the chamber is opened to create a fluid surge into the surge chamber and a local low pressure condition in a wellbore region.

Abstract: An apparatus and method of perforating and surging a section of the wellbore includes running a perforating gun into the well on a string having an isolation valve above the perforating gun, closing the valve, and perforating the well with the isolation valve closed so that the formation is isolated from the well surface. An underbalance pressure is provided above the isolation valve, and then, the isolation valve is opened to surge the formation.

Abstract: An apparatus and method includes positioning a string in a wellbore, the string having a surge chamber. A closure member is provided below the well surface, with the surge chamber defined at least in part by the closure member. At least one port to the chamber is opened to create a fluid surge into the surge chamber and a local low pressure condition in a wellbore region.

Abstract: An apparatus and method of perforating and surging a section of the wellbore includes running a perforating gun into the well on a string having an isolation valve above the perforating gun, closing the valve, and perforating the well with the isolation valve closed so that the formation is isolated from the well surface. An underbalance pressure is provided above the isolation valve, and then, the isolation valve is opened to surge the formation.

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.