Risk Analysis And Evaluation Of Pinnate Horizontal Well Drilling In Coalbed

With the rapid development of global economy,the world's demand for energy is growing,conventional oil and gas is in short supply,and people face the enormous negative impact of energy shortages on society.But the people of all countries are working hard to find new energy,thus stimulating the enthusiasm of the exploration and development of the unconventional oil and gas resources.As an important part of the unconventional energy,coalbed methane(CBM)has been paid more attention by domestic society in recent years.The pinnate horizontal well mining technology has been widely used in coalbed methane development as an important technical means to increase coalbed methane production.The Pinnate horizontal well mining technology is a complex process with more drilling branches,which is difficult to mine.In the event of accidents,it may cause serious consequences,so it is necessary to analyze and evaluate the risk.This paper systematically analyzes and classifies the risk factors existing in the process of pinnate horizontal well drilling by reviewing the literature and data on the practical application of plume horizontal horizontal well drilling technology at home and abroad.Using the fishbone diagram to establish the safety evaluation index system of plume-like horizontal well drilling in coalbed methane production in five aspects:man,machine,environment,technology and management.Through the consultation with the relevant professional drilling teachers to determine the importance of hidden factors and use of yaahp software to calculate the index weight.Because of the particularity of plume-like horizontal well exploitation,this paper emphasize analyzes the downhole accidents in mining process.Establish a fault tree with downhole accident as top event,with four typical underground accidents: well leaks,stuck drilling,drilling tools fall off and shaft collapse as the starting point,by using the fuzzy fault tree method,the control measures are formulated by sorting the fuzzy probability importance of the basic events and combining with the actual situation of the plume operation of the horizontal plume of coalbed methane,and laying a foundation for the safety management in the mining process.Finally,based on the theory of security barrier,Bow-tie model is established for the downhole accidents using bow-tie analysis,and refine the butterfly map model,and establish an effective Security barrier.