Design Of Underground Main Control System Of Multipole Acoustic Logging While Drilling Tool

With the development of science and technology,there is more and more demand for oil and gas resources.A large number of horizontal wells and highly deviated wells have been explored and developed at home and abroad.In this complex formation,logging while drilling(LWD)has more adaptability advantages than wireline logging.In recent years,LWD is playing a more and more important role in the field of oil and gas exploration,and even has the trend of replacing wireline logging.The design of underground main control system of multipole Acoustic LWD tool is a sub-project of "key technology research of multipole acoustic LWD tool" for large oil and gas fields and coalbed methane in China.It is independently developed by the COSLUESTC Electrical Logging Joint Lab.The purpose is to design a main control system of multipole acoustic LWD tool with independent intellectual property rights and world advanced level.The main control system design of multipole acoustic LWD tool can complete the basic functions of acoustic signal acquisition,processing,storage and the overall control of the instrument.At the same time,it can realize the key functions such as stable system communication,convenient upgrade and maintenance,and efficient data operation.According to the requirements of the project,this thesis mainly discuss three aspects of function design: Firstly,in order to control the synchronous and coordinated transmission and acquisition of acoustic waves,it is necessary to connect all systems on the same bus to ensure real-time performance.Although the synchronization and realtime performance of the whole system are guaranteed,data conflicts are also caused.Aiming at the problem of data conflict on the common bus of communication system,the multiprocessor communication scheme is adopted.It eliminates the possibility of data conflict from the design principle and ensures the communication stability of the system.Secondly,considering the working environment of the instrument,it is necessary to realize the remote online upgrade function of the LWD tool,so a new design is proposed for remote upgrading the logging equipment,which has a simple hardware structure,stable file transmission and upgrade and update security.Thirdly,in order to obtain accurate formation data,it is necessary to be able to calculate a large number of acoustic data in DSP at high speed according to the STC algorithm,and calculate high-precision data of STC in a very short time.Therefore,it is necessary to transplant the algorithm of STC from PC to the DSP platform of instruments,and optimize the overall code to complete the efficient operation of workflow.At last,this thesis verifies the communication stability of the multiprocessor communication design through the system joint debugging experiment,and tests the realization process of the remote online upgrade.At the same time,it compares the STC calculation results of PC and DSP,obtains the optimization results of the workflow through the timer,and analyzes the results,proving that each module meets the functional design requirements.