Slumping Flows of Horizontal Cement Plugs

 

 

 

In horizontal wells, there is tendency for abandonment plugs to slump along the well. Evidently, this may lead to an incomplete seal of the well. To ensure quality of the seal, one would like to guarantee a length L of intact cement, after any slumping motion takes place.

For given yield stresses and density differences, we are able to determine the limiting extent of the slump flow, i.e. a shape that the flow will adopt when it stops. From this we can compute the excess cement volumes that need to be pumped to account for the wastage in the ends of the slump.

There are various other processes in well construction where similar slumping flows occur. Many of these may be studied by similar methods.

   

 

 

Figure 1: Scaled slump length and volume as a function of dimensionless inclination angle from horizontal

 

Figure 2: Excess cement volume required, given as a function of dimensionless yield stresses: green 0-25%; orange 25-50%; red > 50%. Well is horizontal.

Relevant publications:

 

I.A. Frigaard and G. Ngwa, “Upper bounds on the slump length in plug cementing of near-horizontal wells” Journal of Non-Newtonian Fluid Mechanics, 117(2-3), pp. 147-162, (2004).

 

Contact: Ian Frigaard for more details

 

 

Contributors:

-         I. Frigaard

-         G. Ngwa