The Reliability Evaluation Of The 7000 Metres Oil Rig Substructure

Along with the development of the drilling project,the number of type of drilling rig is increasing in order to adapt to different work environment,so need to design more types of rig substructure.Rig substructure is the foundation of the whole drilling rig system,carrying most of the drilling equipment,and under the artificial and natural factors.Reliable operation of the rig substructure is very important for drilling operation.For example,the reliability assessment is carried out for the 7000 metres land oil rig substructure.First,this paper studied on structure reliability theory,and adopted JC method of first order second moment by comparing several method of structural reliability calculation.JC method is convenient and simple,accuracy can meet the actual requirements of general engineering,so using the JC method to calculate structure reliability can save time cost.Secondly,this paper gives a brief introduction of analysis steps for the analytic hierarchy process,and has carried on the risk assessment using the analytic hierarchy process to rig substructure.Finally draw a conclusion that the biggest influence factors on the safety of rig substructure is the base component failure.To launch mechanics analysis should be carried out of rig substructure component to ensure the rig substructure under load in a reasonable range.At the same time,in order to make the calculation simple,using Matlab software to write the software to calculate the analytic hierarchy process.In addition,the static analysis and modal analysis has been done for the rig substructure using ANSYS.Under high load of rig substructure units and rig substructure ' s natural frequency and vibration mode have been obtained respectively through static analysis and modal analysis,then rotary speed that can cause drill rig substructure resonance has been gotten through the analysis of the vibration.Finally,according to the finite element analysis of rig substructure stress data,using the JC method to calculate component reliability of the cross section of the rig substructure.The minimum reliability index is 6.61,failure probability is 1.92 E-11,the results meet the "reliability design unified standard for the design of building structures".According to above conclusions,put forward safety measures on base to ensure safe running of rig substructure.