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SOFTWARE FOR CALCULATION VALUES OF CRITICAL VELOCITY AND FLOW, WHICH  CAUSE PACKING OF A WELL

The value of flow  which causes packing of a well  is calculated by the critical velocity which causes packing of well as: 

                                     Q(l/s)= Vcr*p*l*d

The critical velocity which causes packing of well is in function of the coefficient of permeability (K) as shown in the diagram below:

                                                  Vcr(m/s) = f(K)

Krit-brzina.gif (83848 bytes)

These observed values can be expressed with following relations:

                                    - za k 6*10-4 →   Vcr(m/s) = K1/3 / 110

                                             - za k < 6*10-4  →  Vcr(m/s) = K1/2 / 30

Approximate values of coefficient of permeability for different kinds of ground according to Russian authors  V. I. Aravin and S. N. Numerov are represented in next table

 

No SOIL CHARACTER Coefficient of permeability (m/s)
1. Coarse gravel with pebbles 1 x 10E-3
2. Coarse gravel with admixture of sand (1 - 2) x 10E-3
3. Coarse sand (1 - 5) x 10E-4
4. Fine and dust sand (1 - 2) x 10E-5
5. Sandy clay (0.1 - 2) x 10E-5
6. Firmly compacted sandy materials (1 - 5) x 10E-6
7. Sandy humus materials with large admixture of clay 1 x 10E-6  and less
8. Clear clay 1 x 10E-8  and less

For calculation values of critical velocity (Vcr) and flow (Q) enter next parameters in indicated gauge units:

     - The coefficient of permeability              K                 (m/s)
      - The well borehole diameter                  D                (mm)
      - The aquifer  thickness                            L                  (m)

Enter the value of permeability coefficient  - K (m/s)  
Enter the value of well borehole diameter - D (mm) 
Enter the value of aquifer thickness - L (m)
 

The critical velocity  - Vcr (m/s) which cause packing of well  amounts
Flow -  Qr (l/s) which cause the critical velocity  apropos packing of well  amounts

CONCLUSION: IN ORDER TO THE APPEARANCE OF WELL PACKING WOULDN'T HAPPEN, THE FLOW IN A WELL MAST BE LESS THAN CALCULATED FLOW  Qr WHICH CAUSE THE CRITICAL VELOCITY Vcr