Downward communication in a borehole through drill string rotary modulation

A method for downward communication in a borehole containing a pipe string, comprising the steps of:

• a) imparting a series of rotary motions to an upper portion of the string, said rotary motions representing at least two levels of a coded data sequence, said rotary motions imparted to said string upper portion effecting generally comparable motions at a string lower portion,
• b) said motions at the string lower portion effecting a downhole detectable condition or conditions indicative of said imparted rotary motions,
• c) detecting said condition or conditions to determine a corresponding coded data sequence,
• d) and processing said corresponding data sequence to recover the imparted coded data sequence, from which a unique transmitted message is determinable,
• e) said condition or conditions comprising one or more parameters related to inertial rotary motion,
• f) said detecting including detecting acceleration of said string lower portion, producing an output in response to said detecting, and filtering and amplifying said output.

The method for transmitting a message between upper and lower zones of a pipe string in a borehole, that include the steps

• a) effecting rotary displacement of the pipe string at said upper zone in a manner to effect a corresponding pipe rotary displacement at said lower zone,
• b) said displacement representing at least two levels of a coded data sequence containing said message,
• c) detecting said corresponding pipe displacement at said lower zone by providing a sensor in the borehole, and operating said sensor to provide said detecting of said corresponding pipe displacement, at said lower zone,
• d) and wherein said sensor includes an accelerometer detecting vibrational acceleration of pipe string due to rotation, and having an output, there being a sampler means responsive to the accelerometer output to sample at time intervals in excess of 50 times per second, there also being a filter to filter and average the output of the sampler, and including the step of determining from the output of the filter whether pipe string rotation is occurring, and if such rotation is determined as occurring then monitoring an output device from the output of the accelerometer to detect transitions above and below a threshold, for message determination.

A method for downward communication in a borehole containing a pipe string, comprising the steps of:

• a) imparting a series of rotary motions to an upper portion of the string, said rotary motions representing at least two levels of a coded data sequence, said rotary motions imparted to said string upper portion effecting generally comparable motions at a string lower portion,
• b) said motions at the string lower portions effecting a downhole detectable condition or conditions indicative of said imparted rotary motions,
• c) detecting said condition or conditions to determine a corresponding coded data sequence,
• d) and processing said corresponding data sequence to recover the imparted coded data sequence, from which a unique transmitted message is determinable,
• e) and wherein said detecting includes providing and operating an accelerometer to detect said downhole condition or conditions, the accelerometer having an output, and said processing includes filtering and amplifying said output.

A method for downward communication in a borehole containing a pipe string, comprising the steps of:

• a) imparting a series of rotary motions to an upper portion of the string, said rotary motions representing at least two levels of a coded data sequence, said rotary motions imparted to said string upper portion effecting generally comparable motions at a string lower portion,
• b) said motions at the string lower portion effecting a downhole detectable condition or conditions indicative of said imparted rotary motions,
• c) detecting said condition or conditions to determine a corresponding coded data sequence, said detecting including providing and operating means to detect said downhole condition or conditions, there being an accelerometer having an output which is filtered and amplified,
• d) and processing said corresponding data sequence to recover the imparted coded data sequence, from which a unique transmitted message is determinable,
• e) said condition or conditions comprising one or more parameters related to inertial rotary motion,
• f) and wherein said rotary motions correspond to talkdown signal coding pulse waveforms, characterized by provision of one or more of the following:
• i) each waveform has exactly three rising edges,
• ii) every waveform begins with a synch which is 1 pulsewidth ON, 1 pulsewidth OFF, followed by a rising edge for a pulse of any width,
• iii) every pulse begins a multiple of pulsewidths from the first rising edge of the message,
• iv) there is at least a pulsewidth sized OFF time after every pulse,
• v) every message ends with a falling edge,
• vi) every message is exactly 7 pulsewidths in duration.