Systems and methods for communicating downhole data

Abstract

Systems and methods for communicating downhole signals using a mud pulser. The method includes encoding data collected from a downhole sensor as symbols into electrical pulses received by the mud pulser; transmitting the electrical pulses as pressure pulses through using the mud pulser; converting the pressure pulses into full wave pressure signals; processing the full wave pressure signals to recover the symbols; and decoding the symbols to provide the data.

What is claimed is: 
     
       1. A method for communicating downhole signals, the method comprising:
 a) encoding data collected from a downhole sensor and parity information as symbols into pulses for transmission by a pulser to a receiver as the downhole signals; 
 b) transmitting the pulses through use of the pulser; 
 c) receiving the downhole signals with the receiver and converting the pulses into a time series numerical representation of the downhole signals with the receiver; 
 d) correlating a segment of the numerical representation with a group of possible symbols from the symbols; 
 e) selecting the possible symbols with a maximum correlation; 
 f) assembling the selected possible symbols from the numerical representation into a packet; 
 g) comparing a parity symbol representing parity information of the packet with a computed parity symbol; 
 h) interpreting the packet as data value where the parity symbol and the computed parity symbol are equivalent; and, 
 i) where the parity symbol and the computed parity symbol are not equivalent, correcting the selection of the possible symbols by selecting another possible symbols from the group of the possible symbols, 
 wherein the data comprises information measured, determined, or reported by a directional sensor, the downhole sensor, or any downhole equipment. 
 
     
     
       2. The method of  claim 1  wherein the pulser is a bottom mount linear mud pulser. 
     
     
       3. The method of  claim 1  wherein the symbols comprise a cyclic block code having four time slots per symbol. 
     
     
       4. The method of  claim 1  wherein the downhole signals comprises a synchronization header followed by symbolic signals interspersed without a synchronization marker or at least the synchronization marker. 
     
     
       5. The method of  claim 4  wherein the synchronization header does not correlate to regular symbols used in communication. 
     
     
       6. The method of  claim 4  wherein the synchronization marker comprises a long statistically unlikely sequence different from the symbols and the synchronization header. 
     
     
       7. The method of  claim 4  wherein the downhole signals further comprises a survey header following the synchronization header. 
     
     
       8. The method of  claim 1  wherein the data comprises directional information. 
     
     
       9. The method of  claim 8  wherein the directional information comprises orientation of the directional sensor, the data from the downhole sensor in a drill string, or status flags from any component in the drill string. 
     
     
       10. The method of  claim 1 , wherein the data collected from the downhole sensor comprises background radiation level, vibration level, downhole pressure, formation resistivity, gamma spectra, rotational orientation, RPM, or directional radiation levels. 
     
     
       11. The method of  claim 1  wherein the pulses comprise pressure pulses and the pressure pulses are converted into pressure signals by at least one pressure transducer. 
     
     
       12. The method of  claim 11  wherein said converting the pressure pulses comprises combining readings from two or more pressure transducers to remove pump noise. 
     
     
       13. The method of  claim 11  wherein the received downhole signals are pre-filtered. 
     
     
       14. The method of  claim 13  wherein the pre-filtering comprises using a filter to determine an average pressure value and subtracting the average pressure value from each value of the received signals. 
     
     
       15. The method of  claim 1  wherein the parity symbol comprises two parity bits, with a first bit corresponding to first few symbols in the data and a second bit corresponding to a rest of the data. 
     
     
       16. The method of  claim 1  wherein the received downhole signals is stored in its entirety into a single file. 
     
     
       17. The method of  claim 1 , wherein the group of possible symbols comprises valid, likely invalid, and unlikely invalid symbols and only the valid symbols are selected. 
     
     
       18. The method of  claim 1 , wherein the correction of the selection of the possible symbols starts with a new selected symbol with a least correlation. 
     
     
       19. The method of  claim 1 , wherein the another possible symbols comprises a new symbol with a next least correlation in the group of possible symbols. 
     
     
       20. The method of  claim 1 , wherein said correcting selection of the possible symbols is repeated until the parity symbol and the computed parity symbol are equivalent. 
     
     
       21. The method of  claim 1 , wherein the pulses comprises acoustic pulses or electromagnetic pulses. 
     
     
       22. The method of  claim 1 , wherein the group of possible symbols comprises symbols, non-symbols wherein signal degradation transforms a symbol into a related non-symbol. 
     
     
       23. The method of  claim 22 , further comprising replacing the selected possible symbols with a first valid symbol associated with a first related non-symbol, wherein the possible symbols comprises a non-symbol. 
     
     
       24. The method of  claim 1  further comprising assigning confidence to the data value based on the level of error correction applied. 
     
     
       25. A method for communicating downhole signals, the method comprising:
 a) encoding data collected from a downhole sensor and parity information as pulses into symbols; and 
 b) transmitting the symbols as the downhole signals to a receiver uphole: 
 c) correlating a segment of the signals with a group of possible symbols; 
 d) selecting the possible symbols with a maximum correlation; 
 e) assembling the selected possible symbols from the downhole signals into a packet; 
 f) comparing a parity symbol representing parity information of the packet with a computed parity symbol; and 
 g) interpreting the packet as data value where the parity symbol and the computed parity symbol are equivalent; and, 
 h) where the parity symbol and the computed parity symbol are not equivalent, correcting selection of the possible symbols by selecting another possible symbols from the group of symbols, 
 wherein the data comprises information measured, determined, or reported by a directional sensor, the downhole sensor, or any downhole equipment.