General Bore Information:
Bore Date: 2/27/18
Bore Location: Boise, ID (downtown)
Job Type: Utility lines
Contractor: Sawtooth Drilling
Machine: Vermeer D36x50 Series 2
Bit: 4” single roller
Mud GPM: 3gpm
Water Tank Size: 1000 gallon (only filled halfway to use minimal product) – covered/heated
Bore Length: ~100ft, 10-12ft depth
Current Drilling Mud Mix: Bentonite + poly additives
PAF Product Mix: 2.5gal X1413 (added more later on, see below)
The driller had already trenched and potholed the area last week. It was evident that this was a very nasty cobble bore (approximately 80/20 cobble/sand near the surface, 90/10 or greater cobble/sand at about 10 ft deep). Sawtooth had drilled some of the bore path (~50ft) using bentonite+additives yesterday. When he found out we were coming to town with cobble product to try out, he stopped drilling so as to not contaminate the hole too much. This morning, we started off with about 2.5gal of X1413 in the tank. It took the driller about 6 min to mix all 5 bags, and an additional 7 min (after the last bag was poured) for the cobble product to completely mix (no fisheyes). We started off well, low pressures and decent returns (good to note that these returns did not “foam” at all compared to Ronnie’s mix last week – maybe due to no BoreShield being in the mix? Or possibly the bentonite already in the ground?). However, once we got about 100ft out, the pressures increased and the driller noticed the hole was not very stable. It is good to note that he was drilling down to about 12ft at a steep angle to avoid piping in the ground. So we added more X1413 to the tank and waited at least 15 minutes. There was no real difference to myself or the driller in the mud mix/returns/pressures. There were also fisheyes in the returns, and, after talking to Paxton, I believe we simply went over the threshold for X1413. We were only able to complete about 200ft pilot shot before the driller wanted to pull back completely and try to shoot it from the other side – noting that it was not our mud mix, but the simply terrible cobble conditions at the depth he was reaching. I would have loved to see the X1413 in action on a ream shot as I believe this would really show how it works in pulling cobble out of the hole.
I also weighed the returns and only got about 9.2lb/gal. I was thinking because there was so little sand in this hole and it was mostly cobble, there wasn’t going to be many cuttings returns. In this situation, it was more important to hold the hole open/keep a filter cake, which I believe this mix really struggled to do in this ground. I believe adding BoreShield to this mix may have helped in that stabilization. Unfortunately, we ran out of time and product to test this theory.
All in all, not a bad day. We did get some good in-the-field data in terms of hydration times and threshold, and now we know the next step to take in testing. The driller was excited to help us test it out and at the end of the day he said to let him know when I get more cobble product in stock so I can come back out and test with him again. Even the Vermeer sales rep and drill specialist were commenting on how the cobble was so bad that it didn’t matter what mud you mixed, it’s was going to be a tough bore. Still more testing to be done for sure, but everyone is excited to see it in action and help us get some data on it! A few photos attached, more +videos in Dropbox.