Since tooling is prone to wear and tear the cost of tooling should be taken into account while considering the overall cost of operation.
Downhole tooling is selected based on the production goals of a project, geology, obstacles and ground conditions. Right tooling selection is governed by selecting the right drill bits, selecting the right sonde housing, and the correct back reaming accessories. Good downhole tooling can also help manage drilling fluid better. Since downhole tooling is an attachment, there is a possibility of losing the tools downhole.
Tooling should be sturdy, well-fitting and optimized for the drilling operation. A tool that breaks downhole can end up increasing wait time and thereby cost of the operation.
The term ‘Mechanical Set Packer’ probably doesn’t mean much to those not in the concrete repair industry. But for those close to chemical grouting, this term certainly brings about thoughts of both form and function. Mechanical packers are also referred to as ports, or more simply, packers. But we would like to be very clear that a port is not a packer.
Mechanical packers were designed to withstand high pressure injection applications by inserting them into pre-drilled holes in a concrete substrate at various diameters ranging most commonly from 1/4" – 5/8”. Mechanical packers feature a rubber base with a threaded shaft. As the threaded shaft is tightened, the rubber base is compressed, creating a compression seal inside the drill hole. The ultimate pressure tolerance is dependent upon the amount the rubber is expanded and the total surface area of the rubber base that is in contact with the drill hole. That is, a smaller diameter packer will have considerably less surface area of rubber compressed against the concrete side walls, and thus holding a lower amount of pressure when connected to high pressure equipment. Most job site and substrate conditions will permit successful injection results with a diameter of 3/8” – 1/2". Of course, some contractors have personal preference of smaller or larger sizes.
Packers also come in various types. Suppliers will market benefits of steel, brass, zinc, or aluminum. All things considered, Permanent Set Packers tend to be the most versatile packers as they are compatible with all chemical grout types, while the brass, aluminum, and zinc can exhibit signs of deterioration when using oxidizing agents such as the salt component in a polyacryate gel. However, some contractors insist that the breakdown is not as quick as marketed by suppliers, therefore utilizing brass and aluminum packers in these applications as well.
Each packer features an anti-return ball valve that is opened under pressure, allowing the passage of chemical grouts. Upon depressurizing, the ball valve will close, prohibiting the return flow of the injection resin out of the drill hole. This ball valve can be located on the top of the packer, in the base of the packer, or even freely-floating in the packer shaft to allow for maximum flow. There are pros and cons to each ball valve location depending on job site condition and application and finishing techniques.