Design And Research Of Digital Hydraulic Decoder And Its Control System For Downhole Layered Injection And Production

Intelligent well completion is the modern is an important area in the development of oil industry,foreign start earlier,long development cycle,to improve recovery efficiency,reduce the mining cost,etc,has made remarkable achievements,China is currently at the start-up stage,does not have a mature digital decoder equipment in intelligent well completion,in terms of domestic oil well with broad prospects for development.Downhole digital hydraulic decoder is an important part of intelligent well completion.It transmits the pressure signal of the surface hydraulic system to the downhole flow control valve,which directly controls the oil flow in and out of the producing zone.Pipeline connection sequence and internal structure of the downhole digital hydraulic decoder determine the number of valve layers that can control downhole flow.The domestic and foreign literatures on intelligent completion technology and downhole layered control technology are investigated,the research status at home and abroad is compared,a variety of intelligent completion control technology is compared,the advantages and disadvantages of a variety of decoders are analyzed,and the decoder scheme to be designed is determined.This topic has completed the research on the structure design of the decoder and calculated the necessary parameters.Aiming at the problem that only installing the decoder may bring chaos to the pressure signal,the pressure relief valve structure has been designed to timely relieve pressure on the oil return circuit of the downhole flow control valve.The strength analysis of the decoder and pressure relief valve is carried out by ANSYS software,and it is verified that they meet the design requirements.The downhole digital hydraulic decoder is connected with the surface hydraulic system through the hydraulic control long pipeline,so the friction and pressure wave transmission of the hydraulic control long pipeline are analyzed.The influence of formation temperature is needed to be considered in the friction analysis of the hydraulic control long pipeline.The friction and influence parameters of the hydraulic control long pipeline are analyzed from three aspects of calculation,simulation and experiment.The pressure wave transmission is mainly analyzed through simulation and experiment,and the response time of different pressures under the same length of pipeline and the influence of different pipeline lengths on the pressure transmission under the same pressure are compared.Aiming at the decoder designed in this paper is controlled by pure hydraulic pressure,a set of ground hydraulic system is designed,which belongs to the two-stage controlled pressure system.The pressure signal can not only meet the opening and closing pressure of the decoder,but also meet the operating pressure of the downhole flow control valve.The hydraulic components in the surface hydraulic system were selected and calculated.The simulation results of the surface hydraulic system were carried out by AMESim software.The simulation results can verify the functional requirements of the designed surface hydraulic system,and the hydraulic system can control the pressure required by the downhole equipment in real time.Finally,the experimental prototype of the decoder pressure relief valve is verified,and the leakage test,functional test,non-interference test,pressure test at the valve controlled lock sleeve,high temperature and high pressure test are completed,all of which meet the design requirements.