Abstract: A downhole, inline well safety shutoff valve has a spring-loaded, normally closed flapper shutoff valve element that may be opened by a downwardly driven movement of an operator tube coaxially and slidably disposed within the tubing string bore. The operator tube is vertically driven by a rod structure disposed in an offset passageway in the safety valve housing and operated by fluid control pressure transmitted thereto from the surface. To substantially preclude undesirable communication in the passageway between pressurized production fluid and pressurized rod control fluid, the rod structure is slidably carried within a specially designed seal structure including a cylindrical sleeve coaxially received in the offset passageway, and a sealing ring captively retained between the top end of the sleeve and an annular ledge formed in the passageway. The sealing ring functions to create a dynamic seal around the rod side surface and a static seal between the ring and the interior passageway surface.

Abstract: A retrievable fluid control valve apparatus is provided for controlling fluid flow into a tubing string of a well. The control valve apparatus includes a housing. The housing includes a seal for sealingly engaging a landing nipple of the tubing string. A flow passage is defined through the housing and has an open end defined in the housing below the seal. A flow port is defined through the housing and communicates the flow passage with an exterior of the housing above the seal. A flow valve is disposed in the housing and is movable between a closed position wherein the flow passage is closed and an open position wherein the flow passage is open. A spring is associated with the flow valve for biasing the flow valve toward its closed position. A differential area piston is associated with the flow valve for overcoming the force of the spring and moving the flow valve to its open position when a fluid pressure in the tubing string exterior of the housing exceeds a predetermined value.

Abstract: A method of determining the orientation of a fracture or fractures created in a subterranean formation penetrated by a wellbore is provided. The method comprises creating a fracture in the formation extending from a lower end portion of the wellbore and then removing a location orientated core containing a portion of the fracture from the wellbore to thereby determine the orientation of the fracture in the formation.

Abstract: The invention relates to a clay based aqueous drilling fluid containing dissolved inorganic salts for use in drilling through either or both shale and salt formations. The fluid is prepared by dissolving designated quantities of ammonium chloride and sodium chloride in the aqueous fluid prior to admixing of the clay and other additives.

Abstract: A method of preventing permeability damage due to clay swelling, disintegration and migration in subterranean formations producing oil and gas, where such formations are to be the subject of enhanced oil recovery techniques using anionic or caustic flood chemicals. Prior to the use of such enhanced oil recovery techniques, a cationic organic polymer capable of stabilizing clays is introduced into an oil reservoir treatment area followed by introduction of a sufficient amount of a non-anionic aqueous spacer fluid to cause the cationic organic polymer to reorient itself on the reservoir clays in a substantially monomolecular layer and manner such that it will continue to stabilize the reservoir clays but will not substantially react with the anionic or caustic flood chemicals to form permeability damaging precipitates or to decompose thereby reducing its clay stabilization effectiveness.