Chevron Research Company

Swan A Sie

Jorg A Angehrn

Peter Graebner

Earl J Brown

An optical binary signal geophone is described. The geophone utilizes an optical fiber for the transmission of light to the geophone. The geophone contains a light chopping means which oscillates in response to vibrations imparted into a geologic formation. As the chopping means such as a baffle or a tubular member vibrates, it chops the light signal and creates an on/off light pattern. The light passing through a slit in the baffle or tubular member is returned to the seismic vehicle for further processing. The optical geophone creates a binary signal directly without the use of clipping electronics and magnets or coils used in conventional geophones.

Sign bit optical geophone

A method and means for determining the amount of stretch in a well logging cable is disclosed. An optical fiber is run into a well with a logging cable and looped back to the surface. A second optical fiber of nominal length is maintained on the surface. A source of monochromatic light is passed through both fibers and recombined. As the well logging tool is raised and lowered in the wellbore, the number of interference fringes passing a fixed point is determined. The change in length of the optical fiber and, therefore, the cable will be equal to 1/2 the number of interference fringes passing a fixed point times the wavelength of light used. A precise determination of vertical location can then be made when this information is combined with information from a surface mounted odometer or encoder. This information further allows a precise determination of interval bulk density or other formation parameters in which it is important to know the depth of a tool.

Interferometric means and method for accurate determination of

A method and apparatus for determining the vertical location of a logging tool in a wellbore is disclosed. An electrical signal is transmitted through a conductor in a well logging cable and a second conductor in the surface. Change in length of the well logging cable is determined by monitoring phase changes in the signals from the first and second conductors.

Electrical phase measurement means and method for accurate determination

An optical-electrical geophone which generates a binary signal is described. The geophone utilizes an optical fiber for the return transmission of a light source in the geophone. The geophone contains a light chopping means which oscillates in response to vibrations imparted into a geologic formation. As the chopping means such as a baffle or a tubular member vibrates, it chops the light signal and creates an on/off light pattern, i.e., binary signal. The light passing through a slit in the baffle or tubular member is returned to the seismic vehicle through an optical fiber for further processing. The optical-electrical geophone creates a binary signal directly without the use of clipping electronics and magnets or coils used in conventional geophones.

Sign bit optical-electrical geophone

In accordance with the present invention, a marine streamer test system and method (MARSTEST) is disclosed for testing field-worthiness of hydrophone sections within the streamer under both passive and dynamic operating conditions. With regard to a passive operating state, five (5) test parameters are automatically generated and compared with upper and lower limits stored within a mini-computer housed aboard the marine exploration boat. Any out-of-specification values trip an alarm network and a printer to warn of the malfunctioning streamer section. Result: replacement or other repair can be effected. With regard to dynamic operating conditions, acceptable 'signature' characteristics of the streamer (such characteristics can be 2 or more of the above 5 parameters) are stored within the computer aboard the exploration boat and are compared with actually generated field parameter values acquired during operations, say between 'shots', i.e., between the sequential activation of the seismic source used in the generation of the seismic data. Result: any seismic data acquired by the suspect hydrophone section can be properly interpreted in view of the malfunctioning state of that section.

Growing community of inventors

Placentia, CA, United States of America

Swan A Sie