C.A.G.E.S.

Computer Aided Grouting Engineering System

CAGES is a real time, data acquisition program developed by ECO to monitor and assess the apparent permeability of the medium being grouted. CAGES performs two functions: monitoring and assessment of the grouting operation in real time, enabling an Engineer or Contractor to evaluate the effectiveness of a grouting program and the suitability of the selected grout formulation for the medium being grouted.  

CAGES monitors the evolution of the grouting operation by recording the pressure and flow data for each hole over time (as an X-Y recorder would do).  

CAGES evaluates the amenability of the formation to be grouted and assess' the apparent permeability of the formation with time. Prior to grouting, the permeability or Lugeon (Lu) value of the formation to be grouted is determined with a water test. The Newtonian fluid (water) is used as a test fluid and the total aperture size (intersecting the borehole) accessible to water (Lu_wa) is calculated. Lu_wa in turn is related to the total aperture width per metre of drill hole.  

The goal of CAGES and the grouting operation, is to reduce the permeability of the formation from a Lu_wa to zero and to track and assess the process in real time. In the meantime, CAGES displays the "average" grout spread as the operation unfolds (in real time). During the initial stages of grouting, the Lugeon value for the same formation is determined with the Binghamian fluid (grout) as a test fluid (Lu_gr). The ratio of the Lugeon values (Lu_gr/Lu_wa) is referred to as the amenability coefficient (A_c). The amenability of a formation refers to what percentage of pores that are accessible by water are also accessible by grout. This initial information is vital to the engineer in assessing whether the appropriate formulation is being used in the grouting operation.  

The A_c also gives the grouting engineer an indication of the residual permeability which can be expected in a formation using a particular grout. The difference between Lu_wa and Lu_gr is the apparent residual permeability of the formation. For example, if the A_c is 0.75, then the apparent residual permeability will be approximately 25% of the initial permeability determined in the water test.  

If the A_c is too low or if Lu_gr is decreasing sharply, then the engineer can adjust the formulation to decrease the particle size (e.g. switch from regular cement based to microfine cement based grout or microfine cement based grout to solution grout). Conversely, if the A_c is high or if the Lu_gr increases during the grouting program, then the engineer can adjust the formulation to increase the solids content and/or the thixotropic properties of the grout.  

CAGES makes it possible for the engineer to concentrate on the assessment of the displayed information rather than on the number crunching.  

Advantages of CAGES:  

• Provides information to assess the suitability of a grout formulation in a particular formation.
• Performs real time monitoring and assessment of up to 6 injection zones or holes in the grouting operation simultaneously.
• Provides a graphical display of time vs. pressure, flow, grout spread and evolution of apparent Lugeon values.
• All data are stored in files as a permanent record of the grouting operation.
• Determines the initial amenability of a formation.
• Allows for the addition of other injection zones or holes which are simultaneously injected and monitored while the grouting operation continues. These holes are brought on line when the apparent Lugeon value of the holes which are already on line, has been reduced to the one of the new hole.
• Creates a much more efficient grouting operation resulting from a better knowledge of what is going on in the formation in real time.
• Provides a significant cost savings by reducing the amount of time spent pumping unsuitable grout formulations into a formation, necessitating more grout holes to further reduce the residual permeability.
• Optimizes the grout hole spacing.
• Establishes the maximum allowable pressure before hydrofracturing occurs.

A major economic advantage of using CAGES and the amenability theory is the ability to perform multiple hole grouting. Zones with similar permeability are grouted simultaneously until the apparent Lugeon value has been reduced to a level similar to the other zones. At that time the other zones are brought on line and a grout formulation which is suitable for all zones can be used. CAGES makes this very easy for the experienced grouting engineer to assess.