Applications for gel quality attapulgite in “drilling” include oil & gas well drilling, foundation and footing construction drilling, and trenching for environmental containment. When drilling deep wells for oil and gas, the hole is kept continually filled with a fluid mud slurry. The mud suspends the cuttings, pushes them to the surface and there they are removed when the mud is recirculated through a de-sander or screen. The mud cools and lubricates the drill bit and also forms a filter cake which helps reduce fluid loss.
Unlike bentonite and other swelling mineral thickeners, the rheological properties of AMI’s Florigel® HY gel-quality attapulgite product is unaffected by high ionic concentration in the drilling environment. This has led many customers to simply call it “salt gel”. A clear advantage over other mineral thickeners is that attapulgite’s special properties allow the makeup water to be not just fresh water but the driller can also use the local environment’s brackish or brine water, water saturated with salt, or even contaminated with gypsum or cement…at any pH level. Another unique feature of attapulgite is that it is unaffected by over-shearing. Other rheology modifiers fade with prolonged or repeated shear, but Florigel HY performance will remain unchanged.
Some fracking fluids also have suspension and thixotropic thickening requirements. Fracking fluids containing boron mineral pose a difficult challenge with dispersion and suspension. Our Acti-Gel® 208 rheology modifier and stabilizer is very effective at keeping the boron dispersed and suspended throughout its application. In addition, Acti-Gel® 208 additive’s low dosage and very low grit content makes it far less abrasive on mixing and pumping equipment than other mineral products.
Florigel® HY attapulgite product meets API specification 13A/ISO 13500.
Acti-Gel® 208 additive is well proven in a myriad of cement-based applications for improving pumpability and workability while increasing density, chloride impermeability and strength of the cured cement composite. In drilling cement, these improvements are likewise valuable where pumping long distances without segregation and a stronger, more resistant barrier in the bore hole are needed.
Foundation Drilling and Trenching Using the Clay Slurry Method
Drilling or trenching is often necessary in construction of reinforced concrete foundations for bridges, various tower applications, and cut-off walls. The slurry method is frequently used in sandy soils with high water tables. As the hole or trench is opened, it is kept filled with clay slurry. Its function is to keep the hole or trench from collapsing by providing a more stable, uniform and higher density fluid in the cavity, than the surrounding groundwater; form a cake or seal the cavity walls, reducing fluid loss into the surrounding formation, and to suspend materials so they do not settle to the bottom of the hole or trench. For structural foundations, after the reinforcement is placed, the slurry is either pumped or forced out by the concrete as it is tremied into the hole or trench. For in-ground environmental cut-off walls the slurry may be left in the ground indefinitely so the slurry must have sufficient density to prevent the walls from sloughing or collapsing, sufficient viscosity to keep the clay in suspension and a viscosity low enough to enable pumping of the slurry over some distances. Yield stress of the slurry must be high enough to suspend sand particles and all of these characteristics must not change on aging of the slurry. AMI produces and markets high quality attapulgite clays used to formulate these slurries. They offer several benefits compared to other materials, including formation of slurries in fresh water with a lower clay concentration, formation of stable slurries in salt water and formation of slurries with higher gel strength and better suspending ability.