Abstract
Many wells completed in soft, poorly consolidated formations tend to underperform because of drilling and completion prac-tices in which formation-incompatible fluids are lost to the formation, resulting in significant near-well permeability loss. Advances in soft-rock stimulation technology have made frac-packing the preferred method for bypassing this formation damage. Choosing a suitable proppant for frac-packing soft formations is often paramount to overall stimulation success because many soft formations produce fines that can plug screens or packs.
Numerous studies describe the optimization of proppant size as a way to minimize fines invasion into the proppant pack and maximize conductivity. A recent study suggests that the conventional proppant-sizing criteria can be increased to pro-vide increased conductivity while maintaining sufficient fines invasion properties by the simple application of a tackifier to the surface proppant grains. This work indicated that the formation of a stable proppant-pack formation interface is key in preventing formation fines invasion into the proppant pack.
The data presented in this paper show the long-term maintenance of permeability and conductivity for packs that are invaded by fines. The proppant-pack data compare packs treated with a tackifier to untreated packs. Laboratory model study results are provided for a variety of materials and flow regimes. In addition, this paper addresses finer-sized fines infiltration that can cause deep proppant-pack damage. It is generally believed that finer particles produce through the proppant pack without causing significant permeability reduction. The impact of adsorbing finer particles onto a tackified proppant surface is addressed.
