American Oil and Gas Reporter - February 2019 - 48

FIGURE 4A

FIGURE 4B
Three-Stage, 15-Cluster Interval
With Diversion Drops Between Stages

Proppant Signature for
Perf-then-Divert Stages

achieved excellent cluster efficiency in
the Marcellus 1H, even with approximately
15 clusters (three stage lengths) or more
open at the same time (Figure 3A). High
counts of proppant tracer surround each
of the parent stage perforation clusters.
Another benefit of the plugless and diversionless method was added by gradually
screening out each cluster from low toeside rates. This helped ensure that proppant
remained in the near-wellbore area and
minimized overflush volumes. The high
returns of gas tracer further indicated that
the plugless and diversionless technique
was successful in the Marcellus 1H.
A dramatic difference was observed in
the perf-then-divert stages (stages 21-28).
Perf cluster efficiency was much lower
and proppant was extremely well contained,
and this technique had the lowest gas tracer
returns (Figure 3B). It is likely that the diversion material was working too well; it
not only sealed the prior stage's perforations,
but also some of the new clusters.
Stage 21 was the plug-and-perf stage
using the composite plug to separate the
diversionless and plugless interval from

the subsequent perf-then-divert and divert-then-perf intervals. The stage is
shown on the far right of Figure 4A. It
was traced with scandium (yellow) proppant tracers. All five clusters are surrounded by high counts of the parent
stage proppant tracer. The results of stage
21 provide a good basis of comparison
to plugless stages. Fewer stages were
traced with the perf-then-divert technique
because of higher pumping pressures at
lower pumping rates, likely as a result of
the limited number of open clusters.
Proppant containment on the divertthen-perf stages (stages 29-50) was better
than the plugless and diversionless stages,
but not as good as the perf-then-divert
stages. Proppant typically traveled into the
prior stage before tapering off. Cluster efficiency was good and high counts of proppant
tracer were observed in each parent stage's
perforations. Gas tracer returns were about
average from this technique.
Three-Stage Interval
Figure 4B 16 is the log of a 15-cluster,
three-stage interval that was fractured in

FIGURE 5
Marcellus 1H Completion Data
Stage #

12k

Perf then Divert

11k

10k
9k

Avg. Treating
Pressure (psi)

5k
4k

Pressure

Avg Slurry Rate

Avg. Slurry
Rate (bpm)

Breakdown
Pressure (psi)
ISIP (psi)

1k
0k

0
2

48 THE AMERICAN OIL & GAS REPORTER

Diversion
Response
Pressure (psi)

the Marcellus 1H. The clusters for stages
45, 46 and 47 were shot at the same
time. Then they were fractured consecutively with diversion drops between stages.
Stage 45 was treated with scandium (yellow) proppant tracer and shows the broadest coverage, even into stage 44. Once
stage 45 was completed, diversion material
was pumped and then stage 46 was treated
with iridium (red) proppant tracer. The
coverage of iridium proppant tracers was
more limited and begins to concentrate
toward the heel-side clusters.
Finally, after stage 46 and the second
diversion drop, antimony (blue) was used
to trace stage 47. Proppant coverage concentrated even more toward heel-side
clusters in stage 47. The concentration
of proppant toward the heel-side of large
perforated intervals with every subsequent
diversion drop and stage is very common
and is evident in this three-stage test.
The cluster efficiency of this 15-cluster
interval along with the divert-then-perf
method was not as high as the smaller
five-cluster, single-stage intervals. This
test was included to see if longer intervals
can be stimulated as effectively as single-stage intervals.
Figure 5 displays frac data from the
Marcellus 1H. The blue bars are the average slurry rate (bbl/min). The average
treating pressure (orange line) reveals
that there was constant pressure and that
the treatment was pressure-limited in
every stage. The maximum frac pressure
was set to 9,000 psi. The higher pressures
suggest that each stage was treating new
rock and avoiding thief zones. Thief zones
would cause a downward-trending average
treating pressure with little change in
breakdown pressures between stages.
The red box in the middle (stages 2028) of the figure highlights the stages
that utilized the perf-then-divert method.
The average slurry rates were much lower
and more erratic in these stages, even
though the pressures were high. This indicated the increased difficulty in pumping
the stages to their designed fluid and

American Oil and Gas Reporter - February 2019

Table of Contents for the Digital Edition of American Oil and Gas Reporter - February 2019