World Oilfield Forum
Does anyone know the maximum ton miles you can actually run drill line before a slip/cut?
I know the calculations, we have spread sheets, and we have a goal set on our rig.... I just need to know how the goal is determined.
Thanks for any input
It will depend on the type and size of the drill line cable, and your question is answered by API RP 9B.
However, the simplified answer for generic drill line can be found in the table at the page F24 in the "Green Book" - Drilling Data Handbook, Section F.
If anyone can give you a direct #### answer to this question then I can assure you
they are wrong. On most rigs using 1-1/2" or 1-5/8" drill line the
standard is going to be between 2700 and 3000 Ton miles. This is when all
calculations are done by hand as when the driller or T/P are calculating the
trips (weights and distance lifted) and work done using a T/M spread sheet etc.
There are as stated many variables in this process. All rigs are not the same.
Draw-works drum circumference and also block//crown sheave circumference will
have a great effect on line wear. Condition of the drum grooving on the
draw-works and fleet angle of the drill line from the crown to the kick-off
rollers of the draw-works have an effect, the wear plate condition at the edge of
the drum (are they worn which causes line damage) and does your second and
third layer wrap back perfectly as the drill line starts the next layer? Are
you drilling in the south or up north in hard rock country?
Most of these questions all have purpose and on the other hand have none at all. If
you actually had a computerized T/M counter you might find that in reality you
were really cutting at 3700 or 4100 Ton miles. Blocks are moved all the time
without being recorded. Drilling with stands and picking up singles from the
mousehole, working off of a stabbing board, so many variables are not
What does work is this. Rig history and being consistent as possible between crews
when it comes to keeping important data and information such as T/Miles. If one
crew fails to keep proper records the next crew may pay the price and it can be
a high price to pay.
Two rigs running the exact same drill line from the same manufacturer may not
achieve the same T/mile record because of the variables mentioned above.
Periodic drill line inspections should be carried out looking for broken
strands, flattened strands, distorted (out of round) drill line or
under-calipered drill line. Most drill line failures will occur naturally
closer to the fast line side of the reeve. First or second layer of the
draw-works drum, this is the oldest line and has the most actual ton miles on
it. Let’s just say your total string up is 1200 feet of cable. Each cut you
make is 100 feet. You have to achieve 12 slip and cuts to have the new line
from the first cut reach the draw-works. Always inspect the wire which is on
the first layer of the drum plus the kick off point starting the second layer.
Periodically check this drill line with a caliper (micrometer) to see if it is
still the proper diameter. If inner core is failing then the over-all diameter
will be less than normal.
Sometimes rigs do get into an accepted slip and cut program from trial and error which
really is wise and cost-effective and in this case people are not asking the
question (how many T/M can you run before slipping and cutting?) If you are
slipping and cutting constantly and consistently at 2800 T/M and never have to
make a long cut then for sure you are either running at or below the possible
achievable T/Miles. On the other hand if that line you are cutting is not
flattened or contain any broken strands then it is possible that you could
actually extend your T/Ms to 2900 or 3000. But be cautious because there is a
point which can be passed which will show up a few cuts 3 or 4 down the line
where you will see damage to the drill line and you might have to cut 200 to
400 ft of drill line to get rid of the bad line and then drop back on your
T/Miles once again to prevent a repeat. Each rig is different, time, study and
good history will only really answer your question properly.
We slip and cut around 1300 to 1600, depends on where we are at, we just got a new dw. Our old dw we were slipping at a max of 1300 which was prob a little long because everything was wore out on it, it ate line like you would not believe. This is on 10 lines of 1 1/8, but our new dw with everything new, the line still looks new when we slip and cut at 1600, so we might be gonna try and bump up our goal. Like Tracy said, visual inspection over rides it all though. I never even knew how to keep ton miles until I got my pushing job, my pushers always had me slip and cut by visually inspecting it. I don't know if they didn't know how to keep tons miles or just didn't want to but I was never told how much to slip and cut as a driller.