Drilling fluid properties when it comes to rock formations are typically straight forward. Lubrication and carrying capacity are important in this activity.
The fluids have to carry the cuttings from a borehole and serve as lubrication so that the tool won’t get damaged. Maintaining the viscosity level is enough to carry the cuttings from a bore. This is very important in keeping the penetration rate. Let us help you as being Rock Drilling Expert.
If the viscosity is too low, the cuttings will fall from the area of the slurry to the area behind the drill head. But if the viscosity is too high, it will increase the pumping pressure which limits the flow properties. This will decrease penetration rates.
Typically, the marsh-funnel that has a viscosity between 50 to 60 seconds and even slightly higher works well. Rock drilling fluids when it comes to HDD (horizontal directional drilling) applications are typically bentonite, fresh water based. The extended sodium-betonites that are high-yielding are the more common products in the HDD applications. The extended bentonites have been formulated to give high yields and fast hydration at lower concentrations typically at around 3%.
Typically expressed as the “barrel yield” the products would be categorized in the 200bbl/ton.
The term “barrel field” is the oilfield term that measures viscosifying capabilities of the bentonite clay. This is defined as a number of oil-field barrels which is 42 gal of 35-second mud which can be created from one ton of the bentonite. This means that one ton of 200bbl bentonite produces 8,400 gals off a 35-second slurry. Contractors have to know this so they can pinpoint other material types that can double these application rates easily.
The addition of a few polymer additives can aid lubrication along with the flow properties. These polymers are known as shear thinning and allow the pumping out of the higher viscosity fluids without the need to increase pumping pressure. What this means is that contractors can maximize flow patterns inside annular spaces and still maintain the higher viscosities and a reasonable pumping pressure.
However, note that “polymer” is just a generic term which is used to describe categories of products. Polymers exhibit entirely different properties, particularly when introduced with the bentonite drilling fluid. To achieve desired results you have to understand the properties of the elements, as well as the right polymer.
What is Rock Drilling?
Besides drilling into rocks, the rock drill can be used for a number of activities — preparing foundations, exploring minerals and digging wells.
There are various manufacturers of rock drills that offer a variety of models to meet specific needs. These rock drills are usually costly and the users need special training to operate one properly.
Drilling into rocks is usually challenging as the substrate is extremely hard. This tough task damages standard drills quickly.
Rock drills usually have very hard bits that are usually made from a hard material such as industrial diamonds. These bits have cooling and lubrication systems in order to limit the stress caused by excessive friction.
These drills also act as an air blower that clears out drilling holes. The air present lessens the chances of the drill getting damaged because of particular materials and rock dust. A rock drill can also be attached to a drilling rig, in case there’s a need to drill at great depth.