Research And Design Of A Main Control System Of The3D Induction Logging Tool

In order to resolve drawbacks of the low accuracy of the resistivity measurementsand electrical anisotropy effects in the conventional induction logging technology indeviated wells and in dipping beds, three-dimensional (3D) induction logging, a newangle for induction logging, can accurately measure and identify resistivity measurementsin dipping formations, laminated pay intervals and a new structural dip measurement.This thesis, based on the basic principles of induction logging, derives the apparentconductivity tensor for a homogeneous isotropic medium environment, combined withthe technical requirements of the main control system, carry out the research and designwork of the main control system of three-dimensional induction logging tool.The main control system of3D induction logging tool, choosing Digital signalprocessor (DSP) and field programmable gate array (FPGA) as the core system frame,describes and designs the hardware circuits and software algorithm realization of keytechnologies, such as transmitted waveform’s trigger control, high-precisionmulti-frequency multi-channel data acquisition and calibration switching, multi-channeldata acquisition channel adaptive calibration, auxiliary parameter acquisition andcommunication interface design based on controller area network (CAN).This thesis initially verifies the feasibility of the hardware and software design of themain control system under the built experimental platform. Using A3P1000for paralleldata acquisition and control of AD7760chips on2-way data channel, amplitude andphase results has a very good consistency. Using FPGA’s kernel to realize theaccumulative operation of digital phase-sensitive detection (DPSD) on multi-frequencysignal has proved a good consistency on the calculation of the amplitude results, witherror less than1%. The design of a band-pass, finite impulse response (FIR) filter with598-order Kaiser-window based on FPGA, can effectively extract the20kHz component from the multi-frequency signal mixed with white noise. Using circuit processingtechnologies, such as preamplifier, signal conditioning and cascade amplification,combined with oversampling technology and DPSD algorithm processing, it can extractmulti-frequency mixed signal with amplitude about30nV (or even10nV), effectivelydemonstrating the weak signal detection capability of the designed system.The research and design work in this thesis preliminary satisfies the demand indexfor the design of the master control system design in3D induction logging tool.