Abstract: A system for successively uncovering a plurality of contiguous ports in a tubing liner within a wellbore, or for successively uncovering individual groups of ports arranged at different but adjacent locations along the liner, to allow successive fracking of the wellbore at such locations. Sliding sleeves in the tubing liner are provided, having a circumferential groove therein, which are successively moved from a closed position covering a respective port to an open position uncovering such port by an actuation member placed in the bore of the tubing liner. Each actuation member comprises a dissolvable plug which in one embodiment is retained by shear pins at an uphole end of a collet sleeve, the latter having radially-outwardly biased protuberances (fingers) which matingly engage sliding sleeves having cylindrical grooves therein, based on the width of the protuberance.

Abstract: Apparatus and methods for selectively actuating sliding sleeves in sub members which are placed downhole in a wellbore, to open ports in such sub members to allow fracking of the wellbore, or to detonate explosive charges thereon for perforating a wellbore, or both. A simplified dart and sleeve is used which reduces machining operations on each. The dart is preferably provided with coupling means to permit a retrieval tool to be coupled thereto, which upon the retrieval tool being so coupled allows a bypass valve to operate to assist in withdrawing the dart from within the valve subs. Upward movement of the retrieval tool allows a wedge-shaped member to disengage the dart member from a corresponding sleeve to allow the dart to be withdrawn.

Abstract: A baffle system for use in well casing having a plurality of landed subs therein, for progressive injection of a fracking or treating fluid into a hydrocarbon formation via existing or created perforations in the well casing. The baffle members provide a plug seat, and are each frangibly affixed to a conveying tool and have collet finger protuberances thereon. The collet finger protuberances of each baffle are of a different width, and respectively engage only one annular recess of a corresponding width in a respective landing sub. Each annular recess and/or collet finger protuberance on an uphole edge thereof has a chamfer which allows disengagement of the collet finger protuberances and thus removal of the baffle member from the well casing upon upward force being applied to the baffle member. A method of using the baffle system is also disclosed.

Abstract: A system for successively uncovering a plurality of contiguous ports in a tubing liner within a wellbore, or for successively uncovering individual groups of ports arranged at different but adjacent locations along the liner, to allow successive fracking of the wellbore at such locations. Sliding sleeves in the tubing liner are provided, having a circumferential groove therein, which are successively moved from a closed position covering a respective port to an open position uncovering such port by an actuation member placed in the bore of the tubing liner. Each actuation member comprises a dissolvable plug which in one embodiment is retained by shear pins at an uphole end of a collet sleeve, the latter having radially-outwardly biased protuberances (fingers) which matingly engage sliding sleeves having cylindrical grooves therein, based on the width of the protuberance.