American Oil and Gas Reporter - March 2020 - 36

pages 34-39_Layout 1 3/6/2020 11:30 AM Page 36

SpecialReport: Unconventional Resource Science
middle of the micropropped stage appears
to be a change in pump rate rather than a
reservoir response. While Figure 2 shows
only one stage, most of the 44 stages in
this well exhibited the same behavior.
Pressure Behavior
Figure 3 is a treating plot from a micropropped well in the SCOOP play in
Oklahoma. The treating pressure drop
between flags 1 and 2 was caused by hydrochloric acid reacting with near-wellbore
rock during prefracturing perforation
cleanup operations. The treating pressure
drop between flags 2 and 3 denotes when
the microproppant was being pumped
across the formation. As seen in the wells
treated in the Delaware Basin, there also
appeared to be some cluster or fracture
diversion, as evidenced by the pressure
spikes and break backs. Again, this behavior was observed consistently on the
stages pumping microproppant.
Discussions with the operator indicated
that the main reason the microproppant
was used was to reduce pressure screenouts and allow increased pump rates to
improve fluid efficiency, and therefore,
expose more rock area. Only after the
wells had produced for about six months
did a production improvement become
apparent.

This treating pressure behavior appears
to be formation-specific. Wells treated
with microproppant in the Marcellus also
exhibited this behavior, but treatments in
the Utica did not. This may be explained
by differences in the horizontal stresses
where the Marcellus and Utica exhibit
less near-wellbore tortuosity.
The third proposed mechanism for
improving production with microproppant
is to reduce the near-wellbore pressure
drop related to convergent flow. Microproppant erodes the rock near the wellbore,
which can provide channels of improved
conductivity around the borehole, theoretically reducing the near-wellbore
"choke" caused by the fracture adjusting
to far-field stresses as it moves away
from the hoop stresses.
Manufactured as a dry solid, microproppant has been pumped in slurry form
in slickwater frac treatments in hundreds
of U.S. wells. Microproppant does not
contain silica, so there is no silicosis dust
hazard. The slurry composition varies,
but is generally an aqueous solution of a
viscosifying agent and microproppant.
The microproppant concentration target
is 65% by weight of solution. This translates into roughly 8.2 pounds of microproppant per gallon of slurry.
A microproppant slurry is viscous and

FIGURE 4
Cumulative Production per 1,000 feet of Lateral
(Woodford SCOOP Nine-Well Test)
Offset D

Offset F

Offset A

Microproppant Well 3

Microproppant Well 2

Microproppant Well 1

Offset C

Offset B

Offset E

25,000
Microproppant Well 1
24,000
23,000
+16% Uplift
192 days

22,000
21,000
+12% Uplift
160 days

20,000
19,000
18,000
17,000

Cumulative Oil Production

16,000
15,000

Microproppant Well 3

14,000
13,000

Microproppant Well 2

12,000
11,000
10,000
9,000
8,000
7,000
6,000
5,000
4,000
3,000
2,000
1,000

1
6
11
16
21
26
31
36
41
46
51
56
61
66
71
76
81
86
91
96
10
101
6
11
1
11
126
1
12
6
13
1
13
6
14
1
14
156
151
6
16
1
16
6
17
1
17
6
18
1
18
6
19
1
19
6
20
1
20
6
21
1
21
6
22
1
22
6
23
1
23
6
24
1
24
6
25
1
25
6
26
1
26
6
27
1
27
6
28
1

0
Total Days on Production

36 THE AMERICAN OIL & GAS REPORTER

develops a static gel strength. The density
of the slurry is 13.5-13.6 pounds per
gallon. Totes or ISO tanks are used to
transport the slurry to a well location. In
the field, the microproppant slurry flows
easily out of ISO tanks through a 3.0inch valve and hose attached to a centrifugal pump to provide boost pressure.
The slurry is pumped into a missile manifold, where it is proportioned in the frac
fluid by varying the microproppant concentration added by slurry to the total
fluid rate. Initially, the material was added
into the pad at a concentration of 0.1
pound/gallon, but to minimize water
usage, concentrations as high as 0.7
pound/gallon are being used now.
In addition to pumping the microproppant slurry from an ISO tank or tote
container with a centrifugal pump, microproppant can be introduced into a well
by pulling the slurry from the tank/container with the blender's suction pump
and adding the microproppant at design
concentration on the fly with the rest of
the incoming water from the frac tanks.
The slurry can be pumped by all pumps
or a bank of pumps designated for pumping proppant during any given stage or
frac. Another alternative that may reduce
transportation and product cost is to add
microproppant as a dry material to the
sand hopper through a silo or box system.
Field Applications
Field applications in multiple shale
basins demonstrate the potential to improve
productivity by pumping microproppants
as part of the well completion design.
One of the earliest applications was an
11-well trial in the Barnett Shale in Wise
County, Tx. Four of the wells were micropropped. They had lateral lengths between 3,792 and 5,252 feet. The remaining
seven offset wells were used as control.
They had lateral lengths between 3,952
and 6,124 feet.
In these treatments, 4,200 pounds of
microproppant were mixed in a liquid
slurry and added to the pad at a concentration of 0.1 pound/gallon. Comparing
the average cumulative production in barrels of oil equivalent normalized to a
per-lateral foot basis, all 11 wells started
at about the same point, but the four
wells with microproppant soon began to
separate themselves from the seven offsets
and the production uplift continued to
improve with time. These results are consistent with the concept of microproppants

American Oil and Gas Reporter - March 2020

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