2007 Ground Water Summit

Tuesday, May 1, 2007 : 10:20 a.m.

Determination of Effectiveness and Efficient Design of Desanding Tools for Well Development

Peter Nillert, GCI Ingenieurgesellschaft

The process of removing fines from formation material around the screen interval, both after construction or rehabilitation, is often carried out without much thought to the design of the desanding tool. A typical desanding tool usually consists of between one and three meters of perforated pipe that is bounded by rubber collars or packers at each end.  A pump chamber is situated above the upper packer to allow for removal of material during the desanding process.  Standard engineering practice, dictates that extraction rates through the perforated pipe should be approximately 5-10 times higher then the normal extraction rate for that section of the screen.  The goal of the desanding tool is to create high velocity flow in the filter pack / formation to facilitate the movement of fines or drilling fluids into the well.

 A numerical model was used to evaluate the velocity changes occurring in the gravel pack due to the operation of the desanding tool.  The modelling showed that the desanding tool caused a majority of the water to move vertically within the gravel pack above and below the packers.    Once water entered the area between the packers, the highest flow velocities occurred 0.1-0.2 m above and below the top and bottom collars.  Velocity of water between the collars is similar to what occurs during normal pumping.  The modelling also indicates that the shorter the distance between the top and bottom collars, the higher the overall flow velocities into the well and the more effective the desanding process.

Peter Nillert, GCI Ingenieurgesellschaft Managing Director GCI GmbH Ground Water Consulting Ingenieurgesellschaft


The 2007 Ground Water Summit