Abstract: A method and apparatus for recording acoustical and seismic signals at the ocean bottom with minimal noise. A seafloor seismic recorder couples geophones to the water bottom, stores the seismic data, and is retrievable. The device is comprised of a chassis, a ballast ring, an electronics control package, a geophone package, a buoy means, and a leg extension means. The geophone package is disconnectably connected to the portion of the control package housing, so that the geophone package can remain coupled to the seafloor, when the control package and chassis rise toward the surface for a short distance. The buoy means permits the ballast ring and geophone package to become embedded in the sediment upon impact, and allows the chassis, geophone package, and control package to rise to the surface upon release of the ballast ring.

Abstract: An apparatus for testing water quality for subsurface injection that provides for samples of infinite volume to be passed over a membrane filter at a constant pressure. The apparatus uses a positive displacement pump drawing suction on the water source and discharging to a membrane filter. Between the pump discharge and the filter is an oil/water separation vessel to allow for sampling of well production fluids before oil removal if necessary. Fitted to the oil separation vessel is an adjustable pressure regulator, also known as a back pressure regulator, for maintaining constant pressure over the filter. The filter discharge water is collected in a volume calibrated vessel. The vessel is connected to load cells, and a data collection device records weight as a function of time. By measuring the water density, a time/volume curve can be automatically plotted by the data collection device.

Abstract: An oil and gas well casing inspection tool is disclosed. The casing inspection tool comprises a body; inner and outer contact rollers extending from the body; means for generating a current between the outer contacts; and means for measuring a potential difference between the inner contacts. To enhance the accuracy of the device, capacitance is used downhole to increase the amount of current that can be supplied to the casing. Leaf springs engage the contact rollers to maintain a clean connection between the body and the casing. Signal coders and decoders are also disclosed.

Abstract: A method and apparatus for generating a nonlinear sweep signal to be supplied to a seismic vibrator. A seismic sweep time is determined and is divided into a plurality of preselected time intervals. The rate of change of the frequency is determined for each of these time intervals to generate an output signal of a desired shape. The rate of change of the frequency for each time interval is calculated in response to the starting frequency of the sweep, the range of the sweep, the sweep time, and the desired shape of the output signal. The rate of change is supplied to a frequency generator which generates a signal to be supplied to the vibrator.

Abstract: Method and apparatus for determining the true cathode polarization potential for automatically regulating the impressed current in a cathodic protection system.