posted by Rod McCoremick, Blog author, Fordia Powered by Epiroc
January 28, 2021
The equipment needed for underground drilling is different than what you need for surface drilling. The main and obvious difference is that with surface drilling, you’re drilling downwards while when you are underground your boreholes can go up or horizontal. That means that you are often drilling with gravity working against you. To counteract the effects of gravity, you need equipment that can help you install in-hole equipment into an up-hole. A stuffing box is an example of that type of equipment and it’s great when you can find a stuffing box that gives you extra features.
A stuffing box is also known as a packing box, and or a loading chamber, and is a tool that provides a seal around the wireline cable. When the angle of the hole is shallower than -25 degrees, it will be necessary to pump in your overshot, because gravity will be working against you. In order to pump the overshot up to the waiting inner tube, you have to make sure there is a good seal around the wireline cable as it is being pulled into the rod string by the pump-in overshot. Without a seal, water will be able to escape from around the annulus of the wireline cable and thus, prevent movement of the overshot. The stuffing box uses adjustable rubber seals on the wireline to prevent water loss.
If you are drilling in difficult ground conditions such as clay or other swelling ground, it can be a huge advantage to keep a slow rotation of the drill string. The Rotating Pump Through (RTP) stuffing box allows for this slow rotation and offers a few other advantages as well. Let’s take a look at them.
Keep the rods moving
The RPT has a two-part construction so that when the overshot is being pumped and you are retrieving the inner tube assembly, the rod string can still be turned slowly. This can be really important if you are drilling in difficult ground conditions like clay or other grounds that can swell. Having your drill rods sit still while you retrieve the inner tube assembly can result in your rods getting stuck in the hole which can delay operations. The RPT will not rotate the rods quickly, but even a slow rotation will allow you to avoid stuck drill rods.
During drilling operations in clay and other sticky formations, maintaining a slow steady rotation, while pumping your overshot, can help keep a water trail all the way back to the collar. When the clay starts to squeeze the equipment, the water pressure will go up as well, so this is a way to keep in-hole water pressure down. In addition, you will be able to keep your torque down, meaning that your equipment won’t have to work as hard. When drilling, you always want the drill to penetrate with the least amount of force necessary.
Broken wire line cable no longer a total disaster!
A great advantage to the RPT stuffing box is that it doesn’t require clean cable. You can pump a wireline splice, cable crimp, Nico press, Micro sleeve, copper sleeve… whatever you choose to call it, right through the stuffing box. No stopping. No adjustment. The special cable packing allows for the splice to pass through without losing water pressure. This saves you time, money and headache.
It changes to other drilling sizes easily
The RPT has adaptor subs to fit most drilling rod sizes, from B to P, but more importantly, it is designed to allow you to quickly switch over to a different size rod diameter. All the other parts in the assembly are the same. This means you have less inventory to keep on site and less likelihood that you will be missing an important part in order to continue drilling.
The RPT stuffing box is available now. If you have any questions about using it or need any guidance, you can contact our technical team who will be more than happy to help you. Our goal is to make drilling easier, one drill site at a time.