Abstract: Method for reducing air pollution in connection with a cryogenic facility to produce nitrogen which facility uses natural gas as fuel for the engines that drive the compressors. Oxygen is a by-product of the cryogenic facility and is usually vented. The by-product oxygen is captured and mixed with the fuel for the engines in order to reduce the amount of pollution from the engines exhaust.

Abstract: A wireline fishing tool for retrieving a fish or object from an inaccesible loction as a broken drill bit deep in a well comprises an elongated rod with two toothed jaws pivotally connected to the lower end thereof and being extendible from a bell shaped housing toward the inaccessible object and being retractable into the housing for closing the jaws around the fish, or object and a shear pin for maintaining the jaws open as the tool is lowered into the well until the jaws contact the object. Additional movement towards the object starts retraction of the jaws into the bell shaped housing, which first shears a shear pin holding the rod extended from the housing while further movement shears the second shear pin holding the jaws open whereby the jaws are then closed tight on the object by contact with the bell shpaed housing and held tight with a ratchet and pawl for locking the jaws and rod in the housing for retrieval at the surface.

Abstract: A method for plugging a well comprises (1) extending two sets of dogs on a bridge plug for engaging the sides of the well by releasing an expandable means, and (2) releasing a high pressure fluid for triggering and releasing the expandable means for extending the two sets of dogs for securing the bridge plug at the desired depth in the well. A bridge plug for carrying out the method is also disclosed.

Abstract: A simplified downhole pressure reading instrument. It has a cylindrical body which holds a charge of gas at one end. There is a concentric cylindrical element which slides longitudinally inside the body with a low friction seal between them. The body has an opening at the other end from the gas charge, to admit the downhole fluid pressure. And, there is an arrangement for taking a reading of the maximum compression of the gas charge by the longitudinal movement of the inner cylindrical element.