| The electric intelligent well system can monitor the dynamics of the formation oil and gas reservoirs in real time,and can control and adjust the formation fluids in real time and dynamically,so as to realize the selective and controlled exploitation of the oil and gas reservoirs,and improve the exploitation efficiency,recovery rate,and guarantee of the oil and gas reservoirs.National energy security is of great significance.Domestic oil and gas wells are mostly in diameter.Only a single-core cable can transmit electric power to the downhole electronic monitoring and control device,and can also realize the electric intelligent well system of underground-surface two-way data communication,which can simplify the system structure and reduce the number of wells.It occupies less space and reduces system costs,and is very suitable for the engineering requirements of such small-bore oil and gas wells.Therefore,the development of a single-core cable electric intelligent well system has excellent engineering application value.In this paper,aiming at the downhole-surface communication requirements and complex downhole working conditions of the single-core cable electric intelligent well system,the DC carrier communication technology of oil and gas wells-surface is studied.A set of undergroundsurface communication prototype of electric intelligent well system is developed.The main research contents and preliminary results are as follows:1.Aiming at the influence of formation temperature and high-frequency electromagnetic wave interference on downhole single-core cables,an equivalent circuit model for signal transmission of single-core cables is established,and numerical simulation research methods are used to study the signal of oil and gas underground single-core cables protected by steel pipes.Frequency characteristics and amplitude attenuation characteristics of transmission.According to the requirements of signal transmission distance and the environmental parameters of oil and gas wells,the working parameters of underground communication are determined.According to the engineering practice,it is determined to use Manchester code for communication.2.In view of the engineering practice of high working temperature and narrow space in oil and gas wells,a batch of integrated chips with small package size and high working temperature were screened,and the design of circuit modules such as main control module,power module,coupling module,etc.and their underground environment were completed.Adaptive testing;two rounds of design refinement were conducted to address the issues exposed during testing.3.Based on the communication requirements of the electric intelligent well system,the design of the corresponding software modules such as coding,signal acquisition,transceiver communication,etc.has been completed,the software and hardware joint debugging has been carried out,and the engineering prototype of the DC carrier communication system for bidirectional data transmission has been made.The assembly of the underground communication node,the underground measurement node,the underground formation control valve and its displacement sensor has been completed,and the prototype of the single-core cable electric intelligent well system has been made.The industrial field test experiment was carried out on the engineering prototype.The results show that the underground communication node can be packaged in an electronic sealed cabin with a length of 200 mm,a width of 25 mm and a height of 15mm;in the temperature range of 25℃～105℃,its data transmission function is normal;The function and performance of the engineering prototype meet the design requirements.These research work basically solved the downhole-surface DC carrier communication problem of single-core cable electric intelligent well system,which has engineering application value for the development of electric intelligent well system. |
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