Digital Computation And Implementation Of Non-orthogonal Attitude Parameters

The rotary steering drilling system is a novel drilling system based on rotary drilling technology,which can provide a set of whole drilling solutions.At present,many types of rotary steering drilling system have been used in foreign countries,but rotary steerable drilling system still can't reach the standard for commercial application in our country.Real time control of well trajectory and accurate measurement of downhole attitude parameters of drilling tool are core technologies for rotary steering drilling system in commercialization.Traditional rotary steering drilling system is based on the orthogonal attitude measurement model of the resolving on borehole attitude parameters.Due to the low amplitude and poor anti-interference ability of weak voltage signals in practical applications,they are often submerged and the attitude signal can't be accurately resolved.Therefore,the numerical solution of the non-orthogonal attitude parameters is proposed.According to the characteristics of the well site environment and the accuracy requirement of digital computation technology for attitude parameters,the digital decoding circuit is designed based on TMS320F2812.Control circuit,voltage sampling circuit,amplifying circuit,display circuit etc are included in the digital decoding circuit to realize collecting,calculating and displaying voltage signal of the posture parameters.By using CCS integrated development environment and combining with the theory model of non-orthogonal attitude measurement,decoding program for non-orthogonal attitude parameters is developed.Combined with decoding circuits,decoding on well-inclination angle and tool-face angle are realized.The built-in A/D module is unable to reach the 12 bit sampling precision.Correction circuit for A/D converter and corresponding software are proposed in the thesis.The precision of digital decoding is improved.Experimental results show that the proposed digital solution circuit for the attitude parameters can realize the precise calculation on well-inclination angle and the tool-face angle.Especially for weak voltage signals,the precision of decoding method based on non-orthogonal attitude parameters is higher than that of orthogonal attitude method.It embodies that non-orthogonal attitude measurement method has a good application prospect.