When drilling in highly fractured or broken ground, you run the risk of hitting a void or large fracture and having your drill water escape through that fault. You find yourself with a dry hole and dry bore holes are a pain to deal with. You end up drilling blind because you are not getting any water return and you will not get an indication that the core is blocking. No water return also increases the vibration in the hole, greatly increases your drilling cycle time and, if you are in an area with limited water resources, you will not be able to recycle your water.
When you hit a void or fracture, you will immediately notice that your water return suddenly drops off. Here are some suggested steps to try and control the water loss.
- The best way to deal with a dry bore hole is to try and prevent them by using drilling fluid additives to condition your hole. Download your guide to mixing drilling fluid additives here. Drilling additives are like an insurance policy – well worth it when trouble happens. Using them beforehand can allow you to plug up small cracks and fissures before they become a problem
- Identify where the fault is. You can do this by immediately stopping operations so you do not drill beyond the fault. If you have already drilled past the fault, you can always check your core as it will indicate where the water fault occurred. You want to identify the precise location so you can send down the additives to the right spot, which is just above the fault.
- Prepare a “pill” to control your water loss using an additive made for this, such as DD X-Pand. Make sure you allow the mixture to “cure” for half the recommended time. The additives usually take about 20 minutes to absorb water and reach maximum volume. You want to send the mixture down when it is halfway cured, i.e. 10 minutes, so the pill will absorb the water in the fault effectively.
- Pour the pill down the bore hole and continue pumping water down the hole until the pill is no longer in the drill string. You want to make sure the pill goes to the fracture or void and does not stay in the equipment. Another way to ensure this is by using a displacement plug. You put the plug in the drill string after the pill, and pump water until you notice a drop in pressure meaning that the plug has exited the rod string. This means that the pill has exited as well. If you followed step #2, your pill will have gone directly to the fault.
- Stop pumping water and wait 30-60 minutes for the pill to fully expand. DD X-Pand will enlarge to 50-100 times its original size.
- If you don’t succeed with the first pill, make a second one and follow steps 3-4 again. It could be that your void is particularly large and you will need to use the coarser version of the additive, in this case, DD X-Pand Coarse, in order to achieve success.
Note that while this process will fix most water loss problems, it will not guarantee success. You may need to call in the Fordia technical crew that has specific expertise in controlling water loss.