Patent ID: 6550321
Filing Date: 2003-04-22
Classification: E21B

Abstract:
Apparatus for measuring and recording data from a borehole, wherein:the apparatus includes a surface unit and a down-hole unit; the apparatus includes a unit-connecting-means, which includes a mechanical suspension means for supporting the down-hole unit from the surface unit; the down-hole unit includes a base unit, which remains fixed to a bottom end of the suspension means; the down-hole unit includes a plurality of modules, which house respective sensors; the unit-connecting-means includes two long, relatively-insulated, metal conductors, running from the surface unit; the base unit includes two relatively-insulated metal conductors, which correspond to, and remain in metal-to-metal electrical contact with, the two conductors in the unit-connecting-means; each module includes two relatively-insulated metal conductors, corresponding to the two conductors in the base-unit; the structure of the base unit, and of each module, is such that the two conductors in the module make metal-to-metal electrical contact with the corresponding two conductors in the base unit, the apparatus includes a data transmission system, for transmitting data via the conductors between the surface unit and the modules; the modules include: each an operable data-reader, which is effective, when operated, to take a reading of the respective sensor; each a digitiser, representing that reading digitally, as a series of electrical pulses; and each an operable data-transmitter, which is effective, when operated, to apply that series of electrical pulses to the conductors in the module; the data transmission system includes a multiplexer, for allocating respective transmission periods of time to the modules, each transmission period being a period during which the module can apply its own series of pulses to the conductors; and the modules include each a line-monitor, for recognizing that module's allocated transmission period, and for operating the data-transmitter of that module, and thereby for applying that module's series of pulses between the two conductors, during that period.