Anti-settling Apparatus and Method and Apparatus for Checking the Same, and Apparatus for Preventing Settlement of Well

Abstract

The present invention relates to the field of drilling, and provides an anti-settling apparatus and a method and apparatus for checking the same, and an apparatus for preventing settlement of a well. The anti-settling apparatus of the present invention is installed in the wellhead region of the well during drilling to prevent the well from settlement. The anti-settling apparatus generally includes: an anti-settling base having an opening corresponding to the wellhead formed at the center thereof, the anti-settling base being disposed in the wellhead region during drilling; and an interlocking member 5 disposed at the opening to connect and fix a casing provided in the well with the anti-settling base. The apparatus for preventing settlement of a well comprises the anti-settling apparatus and checking method for the anti-settling apparatus.

1 . An anti-settling apparatus for well drilling in tundra, disposed at wellhead region during drilling to prevent settlement of the well, the anti-settling apparatus comprising:
 an anti-settling base, having an opening corresponding to wellhead of the well and formed at a center of the anti-settling base, the anti-settling base being disposed in the wellhead region during drilling; and   an interlocking member, disposed at the opening to connect and to fix a casing provided in the well with the anti-settling base.   
     
     
         2 . The anti-settling apparatus according to  claim 1 , wherein the anti-settling base is a hollow multi-layer structure, and the anti-settling apparatus further comprises:
 a support structure, disposed between multiple layers of the hollow multi-layer structure for support.   
     
     
         3 . The anti-settling apparatus according to  claim 1 , further comprising:
 a truss, provided along a circumference of the anti-settling base, one end of the truss being fixed on the anti-settling base at edge of the anti-settling base, and the other end being fixed on the anti-settling base at the center of the anti-settling base.   
     
     
         4 . A method for checking the anti-settling apparatus according to  claim 1 , wherein the method comprises:
 simulating a temperature field of an annular gap based on a flow rate of a drilling fluid and a temperature of a drilling fluid in a drill string;   based on the temperature field of the annular gap and a temperature field of a permafrost where the anti-settling apparatus is on, determining permafrost parameters of a thawing region of the permafrost;   determining a size of the anti-settling apparatus based on the permafrost parameters of the thawing region;   determining amount of settlement of the well based on the size; and   adjusting the size of the anti-settling apparatus based on the amount of settlement and a settlement amount threshold.   
     
     
         5 . The checking method according to  claim 4 , wherein the step of determining the permafrost parameters of the thawing region of the permafrost based on the temperature field of the annular gap and the temperature field of the permafrost comprises:
 determining a thawing boundary and a thawed amount of the thawing region based on the temperature field of the annular gap and the temperature field of the permafrost; and   determining permafrost parameters of the thawing region based on the thawing boundary and the thawed amount.   
     
     
         6 . The checking method according to  claim 5 , wherein the permafrost parameters comprise a lateral resistance coefficient and a compressive strength of the permafrost, and the step of determining the size of the anti-settling apparatus based on the permafrost parameters of the thawing region comprises:
 determining the size according to the following formula:   
       
         
           
             
               
                 
                   
                     
                       ( 
                       
                         1 
                         - 
                         f 
                       
                       ) 
                     
                      
                     G 
                   
                   + 
                   
                     
                       ρ 
                       e 
                     
                      
                     gSh 
                   
                 
                 S 
               
               ≤ 
               
                 σ 
                 p 
               
             
           
         
         wherein S indicates contact area of the anti-settling apparatus with the permafrost, G indicates gravity of a wellhead apparatus and a casing installed in the well during drilling, f indicates the lateral resistance coefficient, h indicates thickness of the permafrost, σ p  indicates the compressive strength, and ρ e  indicates density of the permafrost. 
       
     
     
         7 . The checking method according to  claim 5 , wherein the permafrost parameters further comprise porosity of the permafrost in the thawing region, wherein the step of determining the amount of settlement of the well based on the size of the anti-settling apparatus comprises:
 determining a volume compression coefficient of the permafrost in the thawing region based on the porosity; and   determining the actual amount of settlement corresponding to the size according to the following formula:
     s=a   0   h+m   v   hΔp    
   
       wherein s indicates the amount of settlement, h indicates thickness of the permafrost, a 0  indicates thaw-settlement coefficient of thawed permafrost, m v  indicates the volume compression coefficient of the permafrost, and Δp indicates pressure of the anti-settling apparatus on the permafrost at the wellhead,
 and the step of adjusting the size of the anti-settling apparatus based on the amount of settlement and the settlement amount threshold comprises: 
 increasing the size by a predetermined value to re-determine the size of the anti-settling apparatus if actual amount of settlement exceeds the settlement amount threshold. 
 
     
     
         8 . An apparatus for checking the anti-settling apparatus according to  claim 1 , wherein the checking apparatus comprises:
 a temperature field simulation module, configured to simulate a temperature field of an annular gap based on flow rate of a drilling fluid and temperature of a drilling fluid in a drill string;   a parameter determination module, configured to determine permafrost parameters of a thawing region of a permafrost where the anti-settling apparatus is on, based on the temperature field of the annular gap and a temperature field of the permafrost;   an anti-settling apparatus determination module, configured to determine size of the anti-settling apparatus based on the permafrost parameters;   a settlement amount determination module, configured to determine amount of settlement of the well based on the size of the anti-settling apparatus; and   an adjustment module, configured to adjust the size of the anti-settling apparatus based on the amount of settlement and a settlement amount threshold.   
     
     
         9 . The checking apparatus according to  claim 8 , wherein the parameter determination module is further configured to:
 determine a thawing boundary and a thawed amount of the thawing region based on the temperature field of the annular gap and the temperature field of the permafrost; and   determine permafrost parameters of the thawing region based on the thawing boundary and the thawed amount.   
     
     
         10 . The checking apparatus according to  claim 9 , wherein the permafrost parameters comprise a lateral resistance coefficient and a compressive strength of the permafrost, and the anti-settling apparatus determination module is further configured to:
 determine the size according to the following formula:   
       
         
           
             
               
                 
                   
                     
                       ( 
                       
                         1 
                         - 
                         f 
                       
                       ) 
                     
                      
                     G 
                   
                   + 
                   
                     
                       ρ 
                       e 
                     
                      
                     gSh 
                   
                 
                 S 
               
               ≤ 
               
                 σ 
                 p 
               
             
           
         
         wherein S indicates contact area of the anti-settling apparatus with the permafrost, G indicates gravity of a wellhead apparatus and a casing installed in the well, f indicates the lateral resistance coefficient, h indicates thickness of the permafrost, σ p  indicates the compressive strength, and ρ e  indicates density of the permafrost. 
       
     
     
         11 . The checking apparatus according to  claim 10 , wherein the permafrost parameters further comprise porosity of the permafrost in the thawing region, wherein the settlement amount determination module is further configured to:
 determine a volume compression coefficient of the permafrost in the thawing region based on the porosity; and   determine the actual amount of settlement corresponding to the size according to the following formula:
     s=a   0   h+m   v   hΔp    
   wherein s indicates the amount of settlement, h indicates the thickness of the permafrost, a 0  indicates thaw-settlement coefficient of thawed permafrost, m v  indicates the volume compression coefficient of the permafrost,   and the adjustment module is further configured to:   increase the size by a predetermined value to re-determine the size of the anti-settling apparatus if actual amount of settlement exceeds the settlement amount threshold.   
     
     
         12 . An apparatus for preventing settlement of a well for drilling in permafrost, wherein the apparatus comprises:
 the anti-settling apparatus according to  claim 1 ; and   the checking apparatus according to  claim 8 .   
     
     
         13 . The apparatus according to  claim 12 , further comprising:
 a thermal insulation casing disposed on wall of the well for preventing heat transfer from the well to the permafrost; and   an interlocking member for connecting and fixing the thermal insulation casing with the anti-settling apparatus.   
     
     
         14 . The apparatus according to  claim 13 , wherein the thermal insulation casing comprises:
 an outer thermal insulation casing, an inner thermal insulation casing, and a hollow portion formed between the outer and inner thermal insulation casings and filled with a gas.   
     
     
         15 . The apparatus according to  claim 14 , wherein the thermal insulation casing further comprises:
 foam pellets disposed in the hollow portion and adhered to an inner wall of the hollow portion.