Research On The Establishment And Method Of Risk Assessment Matrix For Controlled Pressure Drilling

Due to the continuous development of petroleum exploration and development technology and the complexity of geological conditions,the problem of narrow density safe drilling has become a difficult problem restricting petroleum exploration and development.Controlled pressure drilling(MPD)technology can realize accurate control of bottomhole pressure,improve drilling timeliness and safety,and become an effective means of safe and efficient drilling of narrow density window oil and gas Wells.In order to identify and analyze the factors that may lead to drilling accidents and safety problems,take appropriate measures to control and reduce the level of these risks,and ensure the safety and efficiency of subsequent drilling operations,it is necessary to carry out risk assessment in the drilling process.Drilling risk assessment is a systematic and scientific assessment method in the drilling process,which is of great significance to ensure the safety and efficiency of operation and to predict the changes of risks in real time and take corresponding measures.At present,a large number of researches have been carried out on the risk assessment of managed pressure drilling at home and abroad,but the research on the risk matrix is still in the initial stage.This paper mainly does the following research work:(1)The situation of managed pressure drilling accidents at home and abroad is investigated.Based on the investigation results of typical managed pressure drilling accidents,the causes,consequences,severity and countermeasures of four types of typical accidents that may occur in the process of managed pressure drilling(blowout,loss,overflow and stuck)are analyzed,and risk symptoms are obtained according to the changes of logging parameters when risks occur.(2)According to the analysis of the risk characteristics of managed pressure drilling,the bow-knot topology diagram of typical accident risk assessment of managed pressure drilling is established.As another way to express the graphic representation of risk matrix,the topology diagram has guiding significance for how to react when the risk is monitored.(3)Carry out the calculation research on the risk matrix parameters of managed pressure drilling.By analyzing the control steps of managed pressure drilling,the control principle of bottom hole pressure and the production principle of wellhead back pressure,the calculation model of wellhead back pressure,the calculation model of wellhead return flow and the calculation model of wellbore annulus pressure are established.(4)A four-stage controlled pressure overflow,collapse and loss risk assessment matrix is established,and the control method and corresponding back pressure increment of each stage risk are proposed.The matrix quantifies the risks into 12 levels of 4×4,which has the advantages of programming and strong operability,and has great guiding significance for real-time monitoring and prevention of drilling risk accidents...