Patent ID: 11922335
Assignee: CHINA UNIVERSITY OF PETROLEUM (EAST CHINA)
Field: Measurement (Instruments)
Classification: CPC G  E | IPC E  G

Claim 1:
2. The method for evaluating the macro resilience of the offshore oil well control equipment of claim 1, wherein
when the components of the offshore oil well control equipment are subjected to a single-stress action,
S211, determining a degradation model of the offshore oil well control equipment component under the influence of the external disaster;
(1) when the well control equipment is influenced by temperature, the failure time of the component is shown in formula (1):, 1
          t
        
        =
        
          A
          ⁢
          
            e
            
              
                -
                E
              
              ⁢
              
                a
                /
                K
              
              ⁢
              T
            
          
        
      
    
    
      
        (
        1
        )
      
    
  

wherein t is a pre-failure time of the component; A is a pre-exponential factor; Ea is an activation energy; K is the Boltzmann constant; and T is an absolute temperature, which is related to the strength of the disaster;
(2) when the well control equipment is influenced by humidity, the failure time of component is shown in formula (2):

t=(RH)n·exp(Ea/KT)   (2)

wherein t is a pre-failure time; RH is a relative humidity, which is related to the strength of the external disaster; Ea is an activation energy; K is the Boltzmann constant, KJ/(mol·K); T is an absolute temperature; and n is an exponent, which value is a constant;
(3) when the well control equipment is influenced by vibration, the failure time of the component is shown in formula (3):, Δɛ
          p
        
        =
        
          C
          ×
          
            
              σ
              f
              ′
            
            E
          
          ⁢
          
            
              (
              
                N
                f
              
              )
            
            
              -
              n
            
          
        
      
    
    
      
        (
        3
        )
      
    
  

wherein Δεp is a strain range, which value is related to the strength of the external disaster; σ′f is a fatigue strength coefficient; E is an elastic modulus; and Nf is the life cycle, that is, the failure time;
(4) when the well control equipment is influenced by electrical stress, the failure time of the component is shown in formula (4):

L=L0V−n   (4)

wherein L is a failure time; L0 is a constant; n is an exponent; and V is the electrical stress, which value is related to the strength of the external disaster;
S212, mapping the degradation model of the components of the offshore oil well control equipment into a BN;
(1) the formula (1) is mapped into a BN, to obtain the failure time distribution and probability of the components of the well control equipment under the influence of temperature; the BN is divided into two layers: a first layer including four nodes of A, Ea, K, and T as an influence factor layer; and a second layer including one node of the failure time t as a result layer and the computational results indicate the failure time distribution and probability of the components of the offshore oil well control equipment under the influence of the temperature;
(2) the formula (2) is mapped into a BN, to obtain the failure time distribution and probability of the components of the well control equipment under the influence of the humidity; the BN is divided into two layers: a first layer including five nodes of Rh, Ea, k, T, and n as an influence factor layer; and a second layer including one node of the failure time t as a result layer, and the computational results indicate the failure time distribution and probability of the components of the offshore oil well control equipment under the influence of the humidity;
(3) the formula (3) is mapped into a BN, to obtain the failure time distribution and probability of the components of the well control equipment under the influence of the vibration; the BN is divided into two layers: a first layer including five nodes of C, E, εp, σf, and n as an influence factor layer; and a second layer including one node of the failure time Nf as a result layer, and the computational results indicate the failure time distribution and probability of the components of the offshore oil well control equipment under the influence of the vibration;
(4) the formula (4) is mapped into a BN, to obtain the failure time distribution and probability of the components of the well control equipment under the influence of the electrical stress; the BN is divided into two layers: a first layer including three nodes of L0, V, and n as an influence factor layer; and a second layer including one node of the failure time L as a result layer, and the computational results indicate the failure time distribution and probability of the components of the offshore oil well control equipment under the influence of the electrical stress;
S213, calculating the failure rates of the components of the offshore oil well control equipment under single-stress influence; calculating the failure rates of the components of the offshore oil well control equipment under single-stress influence through a weighting method;
when the components of the offshore oil well control equipment are subjected to a multi-stress action,
S221, determining a degradation model of the offshore oil well control equipment component under the influence of the external disaster; the degradation model formula is the same as that in step S211 except that: the number of degradation models of the components is greater than one under the multi-factor influence, and it is necessary to determine the degradation models of the components of the offshore oil well control equipment under different influence factors respectively;
S222, mapping the degradation model of the components of the offshore oil well control equipment into a BN; similar to step S212, the different degradation models are mapped into BNs, respectively, to obtain the failure time distribution and probability of the components of the offshore oil well control equipment under different influence factors;
S223, coupling the failure times of the components of the well control equipment under different influence factors; when the components of the well control equipment are influenced by multi-stress action, the single-factor failure times under single-stress influence are coupled using formula (5) after the failure times of the components under single-stress influence are determined respectively, and the formula (5) is mapped into a BN, to obtain the failure time distribution and probability of the components of the well control equipment under multi-factor influence;, D
          total
        
        =
        
          
            ∑
            
              i
              =
              1
            
            p
          
          ⁢
          
            
              n
              i
            
            
              N
              i
            
          
        
      
    
    
      
        (
        5
        )
      
    
  

wherein ni is a coupling correction factor; Ni is the failure times of the components under single-factor influence; and p is the number of influence factors.