Discussing how the proper drilling fluid can enhance project outcome.
“The Holy Grail is a sacred
object … said to possess miraculous powers” (Wikipedia.org). While preparing to
write this month’s article, I must confess to some serious writer’s block. I
was sitting at the computer with a few ideas, but no real firm direction, when
all of the sudden, it popped into my head (well, really, on my screen). I got
an email from a customer, asking, “In your opinion, other than a high-yielding
bentonite, what would be the most versatile drilling fluid for us to carry that
would fit all situations?” I bet you can answer this one real fast. The answer
is easy; it would be a product called “Driller’s Dream.” It comes in a bag, and
you pour and mix it in; it will self-adjust to the soil conditions. I feel safe
putting the trade name in this article because neither my company nor any of
the competitors have a product like this.
There is no sacred product with miraculous powers; however, the proper mix can
be a powerful fluid.
The good news was that this email broke the writer’s block, and we are off and
running. When I read a question like that, I think drilling mud is being
confused with drilling fluid. Drilling mud refers to just that. It is the
sodium bentonite used as a standalone drilling fluid or as the base for a
bentonite-based drilling fluid.
A drilling fluid, on the other hand, is the total or complete mix. This fluid
can be bentonite, bentonite and polymer, bentonite, polymer and additives,
polymers only, foam, foam and polymer – I think you get the point. It is the
correct mix for the soil you are drilling in now. The next borehole may be very
different, and your setup will be, too. Some contractors and distributors are
looking for a single product, or a few products that will work each and every
time. Unfortunately, unless you drill in the same area all the time, you will
need to adjust with several different products. In many places, a matter of
feet can change the drilling fluid needed.
In May 2011, I was called out to a jobsite where the drilling contractor was
having terrible results on a horizontal directional drilling job. The driller
was unable to get the product back more than 100 feet before the crew would
have to dig, free and fuse. The last 280-foot shot to complete the project was
under a state highway that could not be completely closed, and for sure, could
not be dug up if they got stuck. The engineers shut down the job until they
could prove they had a plan to complete a successful bore.
When I arrived, the driller had been let go, and I had an experienced driller
sitting on a different color rig than he was used to. The drill manufacturer’s
specialist was on-site to assist the driller with the new rig controls, and the
project manager gave me two guys to mix the drilling fluid. Before arriving, I
had completed the mud plan based on the sand I had seen the week before at the
site. I was going to start with a good base of bentonite drilling fluid, and
add some PAC (polyanionic cellulose) for the sand and a touch of xanthan gum as
insurance to suspend the cuttings as they traveled out of the hole. The xanthan
gum was more to relax the two engineers watching from the sidelines. This was a
typical sand shot with some bigger gravel going into and out of the road
The morning of the shot, the new driller told me how on the other shots, the
rig was chained to the support truck, as the rig was exerting so much pressure.
On the other shots, they were using drilling mud and a synthetic polymer
designed to inhibit clay and not shore up the filter cake like the PAC is
designed to do. I was not onsite for the
other shots, but my gut tells me that the old driller was outrunning his mud or
not giving it time to do the job downhole. The engineers on-site kept asking
me, “Will they make this shot?” I would assure them, and then go on to explain
why they could and would make the shot. I gave my speech about no one being
able to guarantee success 100 percent, but with the right fluid, tooling and
patience, they had a 100-percent better chance than before. The job was like so
many other sand jobs, but so many people were questioning it – I thought I
might be missing something. Fortunately, I was not. By changing their
drilling-fluid mix, slowing down the driller so the fluid could do its job
downhole, and monitoring the returns, the job went off without a
The mix they were using prior to my arrival was right for their last job, as
they had been in some clay; it was not right for this job. Each soil requires
you to tweak the fluid a bit. Different companies will have different mixes,
and it is important for you to follow the respective manufacturers’ mix recipes
for best results. A proper mix also can help protect your tooling and
equipment, and keep repair costs low.
It really does not matter if it is a horizontal or vertical job, construction
or geothermal borehole, or for that matter, the size of the job. It all starts
with soil identification. Sand, gravel or other unconsolidated soils need to
have a different mix than clay, shale or consolidated earth. The drilling fluid
is the “total mix” and not just the bagged bentonite. So, to answer the question
that came across my screen, you will need several products in your arsenal to
be prepared for success.