Design Of Pad Testing Device For Oil-based Mud Electric Microresistivity Scanner Logging Tool

Oil-based mud micro resistivity scanning imaging logging tool is mainly depend on acquisition data by the pad whose performance is very critical for instrument acquisition module. Its performance and parameters, such as noise level and gain value, affect the image quality of oil-based mud micro resistivity scanning imaging logging tool. In order to ensure the imaging quality of the instrument, reduce the logging cost and improve the efficiency of logging, the pads must be strictly tested before installed on the logging tool to verify its performance index. The aim of this dissertation is to design a kind of device with compatible different number of channels, which could test the performance and parameters of pad quickly, accurately and conveniently. In the meantime, to present a more intuitive test results which make acquisition data graphical presentation.According to realization principles of logging tool and requirements of pad’s function testing, the dissertation designed a kind of controlling and processing module based on DSP and FPGA. As hardware subject the module is responsible for the data and instruction transmission. An interface system, including display interface and user control interface, is designed through the integrated development platform Lab Windows/CVI of NI, which communicates with controlling and processing module through RS-232 C. DSP receives a variety of test orders issued by the user interface and parse the command to be identified by the pad waiting for test. The controlling and processing module control the pad completing data acquisition and uploading, receive testing data through the FPGA and calculate the signal amplitude using DPSD algorithm by utilizing the FPGA and DSP cooperatively. Finally, the results are uploaded to the user interface system. In the user interface system, data can be graphical displayed and recorded in excel, further analysis of the data by inserting data processing function in excel gives the pellucid parameters to judge pad performance and parameters directly.Pad test device must be compatible with the dual channel and three channel test and achieve at least 1 up to 6 pads performance and parameters testing, complete the demand of continuous processing of up to 6 pads of 150 array button data stream. For the current signal acquisition pad, the device can have a strong pertinence and reduce the collection of the voltage which is not related to the performance and parameter test of pad. Through the channel test, no-load test and gain test, the test device can complete the performance test of up to 6 plates effectively was proved.The pad’s testing device has been applied in micro resistivity scanning imaging logging tool pad debugging, maintenance and other aspects. Its rich functionality, simple operation and ideal data analysis meet the actual needs. The instrument presenting information directly and carrying conveniently has greatly improved the logging efficiency and shorten the production cycle of the pad.