The field of the invention is actuators and actuation methods for operating a subterranean tool and more particularly actuation of a tool disposed about a tubular without a wall opening in the tubular using potential energy in the actuator when running in.
Many operations in a subterranean borehole involve the setting of tools that are mounted outside of a tubular string. A common example is a packer or slips that can be used to seal an annular space or/and support a tubular string from another. Mechanical actuation techniques for such devices, which used applied or hydrostatic pressure to actuate a piston to drive slips up cones and compress sealing elements into a sealing position, involved openings in the tubular wall. These openings are considered potential leak paths that reduce reliability and are not desirable.
Alternative techniques were developed that accomplished the task of tool actuation without wall openings. These devices used annular fluid that was selectively admitted into the actuator tool housing and as a result of such fluid entry a reaction ensued that created pressure in the actuator housing to operate the tool. In one version the admission of water into a portion of the actuator allowed a material to be reacted to create hydrogen gas which was then used to drive a piston to set a tool such as a packer. Some examples of such tools that operate with the gas generation principle are U.S. Pat. No. 7,591,319 and US Publications 2007/0089911 and 2009/0038802.
These devices that had to generate pressure downhole were complicated and expensive. In some instances the available space was restricted for such devices limiting their feasibility. What is needed and provided by the present invention is an actuator that goes in the hole with stored potential energy that employs a variety of signaling techniques from the surface to actuate the tool and release the setting pressure/force. The preferred potential energy source is compressed gas. Those skilled in the art will further understand the invention from a review of the description of the preferred embodiment and the associated drawings while further appreciating that the full scope of the invention is to be determined by the appended claims.
An actuator and method for setting a subterranean tool uses an externally mounted actuator on a tubular string that is operably engaged to the tool to be actuated. At the desired location for actuation a signal is given to a valve assembly. The opening of the valve releases the pressurized compressible fluid against a floating piston. The piston drives viscous fluid ahead of itself through the now open valve that in turn drives an actuating piston whose movement sets the tool. The triggering mechanism to open the valve can be a variety of methods including an acoustic signal, a vibration signal, a change in magnetic field, or elastic deformation of the tubular wall adjacent the valve assembly.
Opening valve 34 can be performed by an acoustic signal 46 that is illustrated schematically. Alternatively the valve 34 can be actuated with a dart 48 that passes close to valve 34 and has a field such as an electromagnetic or permanent magnet field that communicates with sensor 50 on the valve housing 32. Another method to operate valve 34 is to elastically deform the wall of the tubular in string 10 adjacent a sensor in the housing 32. A straddle tool having a pair of spaced seals to create an enclosed volume into which pressure is delivered to flex the wall of the tubular 10 is envisioned. Alternatively, a wireline tool can be lowered to communicate with the valve housing 32 using magnetic, radio, ultrasonic, acoustic or mechanical signals.
The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below.