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Why is this important?
Because permeable formations are not all one size. But
what about reservoir impairment? Is it acid soluble?
Tests conducted in accordance with a major oil company’s
recommendation show zero reservoir impairment. No, it is
not acid soluble and does not need to be, because the
particle size is larger than 5 micron and it is
polymeric materials smaller than 5 micron that cause
reservoir damage. We all know CaCO3 is not the solution
whether acid soluble or not. Massive amounts of CaCO3
will cause reservoir sealing and acidizing on the Gulf
Coast is not always practical. XP-911 seals without
damaging the reservoir and it works with down hole
motors too. Talk to a Setac representative and get the
whole story.
Additive
Benefits
XP-911 is not acid soluble, but will not harm any
producing reservoir because the smallest micron size is
larger than the pore throat of a producing reservoir.
Reservoir impairment tests show zero impairment.
XP-911 has been tested in a down hole motors, found to
be compatible and not cause any damage, and may actually
act as a lubricant.
XP-911 will not change the fluid viscosity even with 50
lbs per barrel added to any mud. The product is
compatible with any water base and any oil base mud with
equal performance.
XP-911 should be added in 15 lb/bbl sweeps until product
is seen coming over the shaker. Decrease the amount in
the sweeps until the thief zone stops taking mud and
product quits coming over the shaker screen.
The product is slippery and spills should be cleaned as
soon as possible. Wet product should be removed with an
absorbent material and disposed in accordance with
appropriate regulations.XP-911 Versus Cellulose Fiber
A generic #7 mud was prepared using 22 pounds per barrel
(PPB) bentonite,
4 ppb CLS, one PPB Caustic Soda, 7 PPB Sea Salt, One PPB
PAC L/V, 0.25 PPB xanthan Gum to ensure no settling and
100 PPB barite.
Two samples were prepared with 6 PPB LCM added to each.
Sample one had 6 PPB commercial grade Cellulose Fiber
Sample two had 6 PPB XP-911.
All samples were hot rolled @ 150º F for 16 hours. Each
sample was tested in a permeability plugging test
apparatus with a 90-micron disk at 2000 PSI.
|
Results |
|
|
|
|
|
|
Sample One |
Fine Cellulose Fiber |
|
Sample Two XP-911 |
|
|
|
Spurt |
2 |
|
0 |
|
|
|
30 Minute |
4.6 X 2 |
|
1.6 X 2 |
|
|
|
Total Loss |
11.2 |
|
3.2 |
|
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XP-911 Versus Coarse Cellulose Fiber
Test was conducted with a coarse cellulose fiber in a
190-micron disk.
Sample one had 15 PPB Coarse Fiber
Sample two had 15 PPB XP-911
Coarse Fiber
XP-911
Total PPT
32 cc 3.2 cc
Note: The viscosity of the mud may
have been a factor for the high PPT for the coarse
fiber. You need 15 PPB to obtain sealing, but the
viscosity of the mud was almost three times higher with
the fiber. Similar tests with this particular fiber show
total PPT values from 15 to 30, while XP-911 remains
fairly constant and very little change in viscosity even
with 50 PPB of material included.
XP-911 Vs. Old School LCM Cure All
Many mud engineers feel they can accomplish sealing by
using old state of the art materials in combination
while on the job site. This test shows that theory to be
false. A base mud was prepared with 25 pounds per barrel
(PPB) Natural Gel, 20 PPB Rev Dust, 6 PPB
Lignosulfonate, 2 PPB lime, 1 ppb caustic soda, 2 PPB
1-100 cornstarch and 200 PPB barite.
Two samples were drawn from the base mud. Sample one was
treated with
15 PPB of the following mixture:
12.5 % Nut Plug Medium
12.5% Nut Plug Fine
25% Calcium carbonate
25% Mica Coarse
25% Commercial Available FiberSample two was treated with 15 PPB XP-911
Both samples were hot rolled at 175º F for 12 hours. The
rheology was taken after stirring 5 minutes in a
Hamilton Beech mixer and heated to 110º F. The
PPT was obtained at 110º F, since temperature stability
was not a factor, 2000 PSI with a 190-micron disk.
Results
| |
Mica/CaCo3/Nut Plug/Fiber Mix |
|
XP-911 |
|
|
|
600 |
80 |
|
42 |
|
|
|
300 |
50 |
|
24 |
|
|
|
P/V |
30 |
|
18 |
|
|
|
Y/P |
20 |
|
6 |
|
|
|
G/S 10 Sec |
4 |
|
0 |
|
|
|
G/S 10 Min |
80 |
|
4 |
|
|
|
Spurt Loss |
42 |
|
3 |
|
|
|
30 Min Loss |
6 |
|
5.6 |
|
|
|
Total Loss |
48 |
|
8.6 |
|
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Notes
Sample one had a high shear value and had to be scooped
out of the aging cell. This condition was not apparent
before aging and apparently due to a result of a
physical change in the material during the aging
process. It was difficult to get pressure and a lot of
mud was lost before the disk sealed enough to attain
2000 PSI. It did seal once pressure was obtained.
Sample two poured out of the cell with no assistance
needed. Pressure came up immediately and remained at
2000 PSI with very little pumping required during the
test.
XP911 does not change shapes, swell or in any way alter
the viscosity of the mud. It works immediately and will
continue to perform. Loss circulation is easier to
control if the mud viscosity remains low. Obviously,
XP911 is superior to the old methods of treating loss
circulation.
Independent Laboratory Test Separating Myth From Reality
Synthetic graphite is promoted because under pressure
the particle tends to spring back to each original shape
and this “spring back” phenomenon supposedly improves
the sealing capability in a porous formation due to its
resiliency, whereas sized petroleum coke would not be as
resilient and tend to break down under pressure and
break the seal. Some reports tout synthetic graphite has
a “Corking” effect and compresses small enough to seal a
permeable zone. Realistically this is impossible and the
truth is sealing is accomplished by appropriately sizing
the particle size forming a seawall effect across a
permeable zone. This is difficult to accomplish with
synthetic graphite only. Accordingly, all commercial
loss circulation materials using synthetic graphite
include sized petroleum coke because it is the coke that
does the work. However, the secret is the particle
sizing, whereas particles with equal sizes, or
improperly sized will not seal effectively.
Resiliency can be a problem if the particles tend to
break down under pressure because the ideal particle
size will be altered and the seal broken, but as
mentioned, products using a combination of petroleum
coke and synthetic graphite would have the same problem.
Tests conducted for high-pressure resiliency are done
unilaterally in a dry medium, but this is not a
realistic test. Loss circulation materials are always
added to a drilling fluid, whether oil or water base,
and in a well bore the pressures are multilateral.
In a fluid the pressures on a particle would not be the
same as when tested dry unilaterally. The force of the
drill string against the formation could break down
fragile materials, such as calcium carbonate or mica,
but petroleum coke does have some spring back effect and
is highly resilient.
The fact synthetic graphite is more resilient in a dry
unilateral test is inconsequential in a drilling fluid
as long as the petroleum coke included is not affected
in a multilateral pressured fluid.
The true test is how the product performs under pressure
in the Permeability
Plugging Tester in a properly prepared drilling mud. The
results below were conducted by an independent
laboratory and indicate XP-911 has better sealing than
does synthetic graphite.
PPT Results
CaCO3 Graphite
Synthetic Graphite
XP-911
18.8
13.6
18.2
10.8
XP-911 competes favorable with all graphite materials
and in all particle size disks. The secret is the
particle size distribution that remains constant
throughout the drilling process. XP-911 does not
infringe on any known patent.
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