Research On Real-time Monitoring And Analysis System For Wellbore Cleaning

With the increasing demand for petroleum energy in China,the oil and gas exploitation is gradually moving toward the direction of complex structure well like horizontal well and large displacement well.However,large displacement wells often lead to debris retention or formation of cuttings bed due to uncleanness of borehole,so the monitoring and identification of well cleaning conditions can effectively prevent a series of drilling accidents,such as pump suffocation and sticking of tool.Well hole cleaning monitoring is usually achieved through the PWD in foreign countries,they identify the hole cleaning status by monitoring bottom hole pressure.However,the PWD instrument is expensive and the measurement technology of PWD is not yet mature at home,so the well cleaning monitoring is realized by using the mud logging unit in China,but this method of indirect measurement is difficult to achieve accurate monitoring of hole cleaning status.And although a large number of theoretical and empirical models have been put forward to the problem of wellbore cleaning evaluation and analysis in China,but there is no comprehensive and reliable analysis method of well hole cleaning evaluation has been formed so far because of the complexity of cuttings migration.In view of this,based on the existing technology of well cleaning monitoring and evaluation analysis,this paper presents a set of real-time monitoring and analysis techniques for borehole cleaning by using the ground and downhole measurement parameters,and achieved the following results:1.Through the research on the monitoring and analysis technology of well cleaning,a set of real-time monitoring and analysis system of well cleaning which is suitable for different site conditions has been designed and developed,it can realize the real-time monitoring and dynamic analysis of the wellbore cleaning state,and ensure the safety and efficiency of the drilling operation;2.Based on the research of the three layers of debris migration model,a safety monitoring model for borehole cleaning has been established.It can realize the stable and efficient monitoring of the wellbore cleaning condition under the conditions of the PWD instrument;3.Based on the research of traditional hydraulic calculation and analysis method,combined with bottom hole pressure correction technology,a set of methods for static and dynamic correction of bottom hole pressure has been formed.It can realize the true and false discrimination of the measurement data of the PWD instrument and the real-time monitoring of the well cleaning in the state of the instrument failure or the loss of the packet.4.According to the research of well cleaning evaluation standards,a set of full hole analysis method of well cleaning has been established,and it can achieve the single point and multipoint analysis of different types of target wells,provide guidance for wellbore cleaning evaluation in different construction periods;5.Based on the research and analysis of well cleaning monitoring and correction method and debris migration model,the overall scheme design of the real-time monitoring and analysis system for borehole cleaning has been completed.According to the demand analysis of real-time data acquisition,combined with the hardware equipment,the data acquisition software system and supporting database for well cleaning has been designed and developed,it provides data support for real-time monitoring and analysis of borehole cleaning;6.According to the overall design scheme of the system,combined with the supporting ground and underground instruments,the structure design of the real-time monitoring and analysis system for well cleaning has been carried out,and the development and integration of the system has been completed,then a set of monitoring and analysis system for well cleaning has been formed;The well cleaning real-time monitoring and analysis system has been applied to 6 wells in Liaohe Oilfield.The application results show that the system can meet the needs of real-time monitoring and analysis for borehole cleaning,and has important guiding significance for drilling operation.