Bp Corporation North America Inc.

Other

Aw Creative Technologies Limited

Mark Francis Lucien Harper

Joseph Anthony Dellinger

Graham Openshaw

Martin Thompson

Michael Ray Gorman

A compact seismic source for seismic acquisition generating a humming signal includes a casing and a low-frequency reciprocating drive. The casing defines a fluid tight chamber and comprises a first casing section and a second casing section of roughly equal mass. The drive is disposed within the fluid tight chamber and, in operation, reinforces the natural reciprocating oscillation of the first and second casing sections relative to one another at a low seismic frequency. In one aspect, this action omni-directionally radiates the low frequency, humming seismic signal. On another aspect, the compact seismic source is substantially smaller than the wavelength of the low seismic frequency. Such a compact source may be deployed to omni-directionally radiate a low frequency, humming seismic signal during a seismic survey.

Compact seismic source for low frequency, humming seismic acquisition

A method for controlling trajectory in a resonant marine seismic source comprises: controlling the source frequency and controlling the motion trajectory. Controlling the source frequency includes: estimating the source frequency from its internal state and the state of its environment; deriving a frequency error as the difference between the estimated frequency and the frequency of the desired trajectory; and driving the frequency error to zero. Controlling the motion trajectory includes: detecting a motion trajectory of the source; deriving a motion trajectory error as the difference between the desired motion trajectory and detected motion trajectory; and driving the motion trajectory error to zero.

Operational control in a seismic source

There is taught herein a system and method for creating an improved seismic source signal by applying a feedback mechanism, active adaptive control, to perturb a resonator device configuration on the fly so as to ensure that the overall trajectory of the sweep is correctly produced, even though the precise details of each oscillation of the source are still not constrained. An embodiment teaches a method for adjusting the squeeze piston or tow depth of a resonant piston seismic source to bring the resonant frequency to a desired value. As a consequence, the resulting seismic signal is improved as compared with seismic signals acquired via resonators that do not utilize the instant teachings.

System and method for resonator frequency control by active feedback

The output spectrum of a controllable swept-frequency acoustic source at a given frequency can be controlled by making the rate of change of frequency equal to the desired output power spectrum divided by the squared envelope amplitude of the source output signal, both measured at the time after the start of its frequency sweep at which the sweep frequency passes through the given frequency. The system and method can also be used to correct for propagation effects outside the source by dividing the desired spectrum by the propagation effect. The method can further be used either to obtain an output spectrum of a desired shape from a source operating at maximum output or to design a sweep of a minimum feasible duration that will result in an output spectrum of a specified shape and with a specified amplitude.

System and method for performing seismic surveys with a controlled source using maximum-power sweeps

An apparatus as disclosed for mounting a liquid-filled pipe by the use of ultrasound techniques. The apparatus comprises a vehicle capable of fitting inside the pipe, and of being transported along the pipe by the liquid flowing into it, together with rings of several ultrasonic transducers spaced circumferentially round the vehicle. The rings are so arranged that one ring operates in the reflection mode purely radially while two further rings operate as a pair in a longitudinal refraction mode. A fourth ring is used in a circumferential refraction/reflection mode. The vehicle has an associated power supply, data gathering and storage capability and a vehicle for measuring the distance traveled along the pipe.

Monitoring pipes

When an underground pipe carrying a fluid, such as a buried water-pipe, develops a leak the leak must first be located before it can be repaired. One common location method makes use of the fact that the leaking fluid often creates a noise, typically a hissing sound, which is transmitted through the ground, and although rapidly attenuated can be heard with suitable highly sensitive ground microphones and is therefore useful to field crews as a means of locating leaks. Unfortunately, the sound levels can be grossly distorted by underground heterogenities, and can easily be confused or even swamped by other sound sources above ground, and in general ground microphones used like this do not seem to be effective. The invention deals with the problems entailed in this technique by a method&mdash;and apparatus &mdash;which involves using semi-automated equipment to listen (either simultaneously or sequentially) to the leak sound source (,) from a multiplicity of different positions (as,) spaced all around the sound source, and by then suitably combining and processing the received signals to provide the desired indication of the source's location.

Growing community of inventors

Cambridge, United Kingdom

Mark Francis Lucien Harper