Research On Stabilizing Platform For Strapdown Automatic Vertical Drilling System Technology

Automatic vertical drilling technology (AVDT) can effectively solve the engineeringtechnical problems of drilling fast without deflection in high steep structure and large-angledeviated strata. It is an advanced drilling technology which can realize automatic inclineprevention and correction, keep the borehole vertical, and ensure fast ROP and high quality ofwell trajectory. At present there is no domestic vertical drilling system, and we have to rely onforeign equipment rental, which is expensive and difficult to maintain. Therefore, it is crucialto develop an automatic vertical drilling system with independent intellectual property rightsof our own. Such an action can break through the technology barriers formed by some foreigncompanies, promote domestic automation drilling process and enhance the internationalcompetitiveness.Combining the strap-down inertial navigation technology usually used in spacetechnology and petroleum drilling engineering, this paper present an AVDT solution forautomatic incline prevention and correction with strap-down inertial navigation technology ascore. The measuring principle of hole deviation angle and azimuth angle under staticcondition was referred in this solution, the dynamic signal feature of the gravity sensor andmagnetic location sensor was studied, and the measurement model of well deviation in slimholes and the posture of dynamic rotation drilling tool was set up. Based on the principlesmentioned above, a dynamic measurement algorithm of well deviation and azimuth wasprovided.The design process of the measuring unit and the transfer model for the inaccuracy ofmeasurement were in their detailed forms and two calibration algorithms based on orthogonal design and trigonometric functions base value fitting were also present in this paper.To meet the requirements of AVDT, the following technologies were elaborated: a closedloop position servo control scheme, a permanent magnet synchronous motor vector controlstrategy was given and a PID optimization algorithm to avoid integral saturation based onposition loop, speed loop and current loop control.Based on the theoretical analysis, the measurement method for the key parameters ofAVDT was given in this paper. An instrumentation which takes into consideration the drillingtools posture, the rotating speed of drill collars, and the torque load was developed withcombination of engineering practice.The theory and method present in this paper has been applied to field test. A prototype ofAVDT has been applied to Tuo181Well and Xuanye1Well. Good performance of thisprototype has demonstrated the feasibility and effectiveness of AVDT which will providepowerful technical support for the measurement and control theory of AVDT system.