Abstract: A hollow body is provided with a seal by which it may be sealed within a nipple profile included in a tubing string. The body allows a wireline to be passed through it while maintaining a substantial seal. During running-in lower collet fingers engage a stop ring mounted on the body. When the plug becomes seated in the nipple profile by the weight of a logging tool also suspended on the wireline, fingers are disengaged by inward movement of external collet fingers and rollers. Consequent downward movement of the fingers allows the rope socket to push them outwardly and allows the logging tool to be lowered. An equalizing sleeve can be pulled up by the socket head from the sealing position to a raised position which allows pressure equalization above and below the plug to facilitate withdrawal thereof. Profiles on the fingers act to trap the socket head should the wireline pull out or break.

Abstract: A pressure-actuated head for detonating a gun for perforating a well bore is suspended on a tubing string for lowering down the well. The head includes a detonator pin biased towards a detonator but restrained until detonation is required. Detonation is effected by causing or allowing a pressure differential to develop across a piston. Fluid communication between chambers on respective sides of the piston is via a pressure control system which allows the pressure differential to develop over a period of time.

Abstract: A logging plug for suspension on a wireline comprises a hollow body provided with packers for sealing it to a nipple included in a tubing string, and a flow tube through which the line may slide with minimal leakage. A sliding equalizing tube in the lower position shown blocks communication across the packers. When moved upwards by striking it with a hammer or logging tool, communication is allowed via ports in the equalizing tube and in the hollow body, the annular passage around the wireline and an axial bore in the lower part of the hollow body. Any pressure differential across the packers is thus equalized, allowing the logging plug to be easily withdrawn.

Abstract: A downhole pump and perforating gun are run simultaneously down a well on a tubing string and the gun is fired under underbalanced conditions. A slip joint reduces vertical mechanical shock transmitted through the tubing string to the pump on firing; centralizers minimize whiplash vibration and a lateral shock absorber absorbs radial shock.