The Key Technology Research Of A Logging While Drilling Quadrupole Tool

The logging while drilling quadrupole wave technology effectively solves the problem of real time shear wave velocity measurement in the formation.It is widely used in offshore and land oil exploration and development,and has potential to replace wireline acoustic logging.However,LWD quadrupole wave technology is monopolized by foreign oilfield service companies.As the design and production of key sensors,laboratory calibration of LWD quadrupole wave issues,this study focuses on the key technology of theory,experiment and sensor production methods.The measurement advantages of LWD quadrupole wave of low frequency are clarified,and the optimization design and manufacturing method of transmitting and multipole receiving sensors are solved.In particular,a simple calibration method and technology for LWD quadrupole wave logging tool in the laboratory is proposed.Finally,we design the LWD quadrupole acoustic logging tool,and develop new method for dispersion correction methods for quadrupole data.The major work of this paper consists of four parts as follows.In the first part,we study the LWD quadrupole wave theory,and discuss that quadrupole source of low frequency can eliminate the interference of drill collar mode waves.Based on this theory,vibration efficiency of the low-frequency bending mode of arcuate shaped piezoelectric vibrator with or without metal substrate structure is investigated,and it is proposed that the LWD quadrupole transmitter transducer with metal substrate structure can effectively improve low frequency vibration response.The effects of the physical properties of arcuate shaped piezoelectric vibrator and metal substrate on its acoustic response were investigated and analyzed,and a LWD quadrupole composite transmitter transducer with resonance frequency of about 4 kHz is optimized.In the following,a kind of encapsulation material with epoxy resin which is suitable for downhole high temperature and pressure is studied,and a device and method of vacuum encapsulation for quadrupole transmitter transducer is developed.High temperature experiments,pressure experiments and acoustic experiments is carried out for the LWD quadrupole composite transmitter transducer.It is verified that this transducer meets the low frequency and high power radiation requirements,and has typical quadrupole acoustic field radiation characteristics.In the second part,three laminated plate receiver transducer is designed,and the multipole receiver sonde is also optimized.Firstly,three laminated plate receiver transducer is analyzed by applying finite element method,and influence of boundary conditions on receiving sensitivity is investigated.The simulation results show that clamped boundary condition at both sides is suitable for LWD environment and it has good receiving sensitivity.And then we design receiving transducer packaging structure which is rectangular thin-walled aluminum shell.The experiments shows that the thin-walled structure helped to improve the quality of the received signal.Receiver sensitivity is also measured in the anechoic tank,which is consistent with theoretical simulation result.Further we design near probe acquisition circuit system,which can improve quality of the multipole signals.The azimuth quadrupole signals in the air show the advantages of the near probe acquisition system.In addition,azimuth quadrupole results which is also measured in real drilling conditions show the near probe can collect high quality formation wave signals.In the third part,we mainly study the wave field of LWD quadrupole logging tool where is put in laboratory tank.Firstly,3D finite difference method is used to simulate the quadrupole wave field in closed liquid-filled pipe.By comparing with the theoretical dispersion curve,it is proposed to use 0-order mode pipe wave to realize calibration of LWD quadrupole logging tool in the laboratory.Next,numerical simulation is further carried out in asymmetric model of arcshaped trough.It is believed that LWD quadrupole can also excite the 0-order mode pipe wave in open trough,and its velocity does not change with opening angle,but affects its amplitude.Further,we study azimuth quadrupole wave field in the arc-shaped trough,and it shows that composite signal is more helpful to improve quality of the measurement signal.Finally,influence of physical properties of arc-shaped trough on the 0-order mode pipe wave is studied,and we optimize calibration device which is suitable for LWD quadrupole logging tool of 6.75in outside diameter in laboratory.So it verifies that calibration method of LWD quadrupole logging tool is feasible by using 0-order mode pipe wave int the laboratory.In the fourth part,we develop a kind of dispersion correction method for quadrupole data.This method is obtaining theoretical dispersion curves of leaked longitudinal wave and quadrupole wave through equivalent instrument theory,and then constructs joint inversion objective function of the two modes of waves to simultaneously inverse slowness of compressional wave and shear wave.It can quickly and accurately extract real shear wave slowness.