Patent ID: 11946350
Assignee: CHINA NATIONAL PETROLEUM CORPORATION
Field: Civil engineering (Other fields)
Classification: CPC E | IPC E

Claim 0:
1. A method for remotely shutting down a downhole unit of a rotary steering system from ground, comprising steps of:
a: setting a diversion ratio of a downlink device as k, an equivalent area of a drill water hole as s, a total displacement of a mud pump as Q, and a pressure of a riser before the downlink device is turned on as P; calculating a pressure difference P1 between a front end and a rear end of the drill water hole by a formula 1;

P1=Q2ρ/2μ2s2  formula 1;

wherein Q is the total displacement of the mud pump, m2/s; μ is a flow coefficient and μ=0.63; s is the equivalent area of the drill water hole, m2; P1 is the pressure difference between the front end and the rear end of the drill water hole, Pa; and ρ is fluid density, Kg/m3;
b: calculating an extension loss ΔP by a formula 2;

ΔP=P−P1  formula 2;

c: calculating a pressure P2 at the riser after turning on the downlink device by a formula 3;

P2=ΔP+ρ(1−k)2Q2/2μ2s2  formula 3;

d: since a pressure drop of a throttle valve of the downlink device is also P2 according to a pressure balance relationship, calculating an opening area S1 of the throttle valve of the downlink device by a formula 4;, S
       1
      
      =
      
       kQ
       /
       
        
         2
         ⁢
         
          
           P
           2
          
          /
          ρ
         
        
        μ
       
      
     
     ;
    
   
   
    
       
     
      formula
      ⁢
         
      4, and
e: adjusting the throttle valve to a calculated opening degree according to a relationship between the opening degree and the opening area S1 of the throttle valve, so that a diverting flow automatically reaches the set diversion ratio; providing a cut-off circuit to each function block of the rotary steering system; numbering each function block, and forming a preset corresponding relationship between the function block and the diverting flow of the downlink device, which is solidified in a rotary steering tool control software; if any function block is abnormal, adjusting the diverting flow of the downlink device according to the preset corresponding relationship between the function block and the diverting flow; automatically targeting a function block that needs to be cut off according to a flow change detected downhole, and shutting down the downhole unit.