In a waterflooding process for oil recovery from oil-bearing earth formations, a high-permeability zone is isolated from a low-permeability zone at the injection well. A water solution of sodium silicate is injected into one zone, a water solution of an activator -- a chemical such as ammonium sulfate which causes sodium silicate solution to gel -- being injected into the other zone. Preferably, the two solutions are injected simultaneously, the rates of injection being proportional to the pore ...

A fluidtight joint between a pair of aligned pipes is effected by the securing together of a pair of flanges mounted one on each of the pipes. Each flange is of composite form comprising a rigid outer part and a resiliently deformable inner part which fits around the surface of the end portion of the associated tubular member. In jointing of aligned pipes the flanges are juxtaposed with the resilient inner parts registering with each other. When the outer parts of the juxtaposed flanges are urge...

A calculator having constant memory utilizing a classical CMOS metal gate process, a low power microcomputer with on-chip and external constant memory capability, and multiple partition power control of circuit groups. Incorporation of a first and second switched negative voltage and a non-switched negative voltage to the appropriate P (-) wells enables the power hungry clocked logic and the display interface and keystroke detect circuitry, to be turned off while power is maintained on the inter...

A device for conversion between flow and rotation includes a fixed revolution center shaft integrally provided with a center sprocket, at least one vane having a self-rotation shaft and turnable about the revolution center shaft and on the self-rotation shaft, a vane sprocket fixed to the self-rotation shaft and having twice as many teeth as the center sprocket, and a chain connecting the two sprockets, whereby the vane rotates through 180.degree. on the self-rotation shaft while it revolves aro...

An apparatus is disclosed for selecting between multiple radio frequency circuits such as low pass filters. Each of the circuits is mounted on a printed circuit board, with first and second terminals printed on the board. Each of the terminals has a raised electrical contact on it. Associated with the first terminals of the circuits is a first printed strip transmission line with raised contacts spaced along it, each contact near a corresponding contact on one of the first terminals of the circu...

An asynchronous interface adapter for interfacing two bidirectional data buses. Data transfer between buses may occur simultaneously with provision made for storing bus data from a first bus until a receiver on the second bus is available. The adapter provides bus requests and grant logic, parity checking, time of day clocking, and is adapted to handle variable-length bus messages with the message bytes being carried in a bit-parallel byte-serial form, asynchronously and generally in a bidirecti...

The coupling comprises a plate rigid with each shaft and a floating intermediate device connected to each of the two plates. The floating device comprises at least three levers which are assembled by a center articulation. Each of the levers is connected by a radially slidable ball joint at one end to one of the plates, and at the other end to the other plate. At least one of the ball joints of each lever is axially fixed.

A joint assembly between structural members having plate portions includes an eliptical opening through the plate portion of a first member and a notched locking plate portion on a second member. The latter plate portion is introduced through the eliptical opening parallel to the major dimension thereof and is then rotated 90.degree. to a locking position parallel to the minor dimension of the opening, whereby the notches interengage with the first plate portion to restrain separation of the two...

The concentration of deuterium relative to hydrogen in a hydrofluorocarbon is increased by contacting the hydrofluorocarbon, in the presence of an alkali metal amide, with an amine having a concentration of deuterium that is greater than that which provides equilibrium with the hydrofluorocarbon. In a preferred embodiment, a compound enriched in deuterium is produced by first exposing trifluoromethane to infrared laser radiation to selectively cause a chemical reaction involving deuterium-contai...

A fastening arrangement for removably securing a gear or hub to a shaft by means of a spring wire clip which clip includes a curved portion formed by radially and circumferentially bending an intermediate portion of the clip for resilient engagement with an axial groove formed in a central bore of the gear, a pair of loop portions extending from opposite ends of the curved intermediate portion and arranged to be fitted around the shaft for engagement with either side surface of the gear, and a p...