American Oil and Gas Reporter - September 2017 - 82

the proppant in the cross-linked gel portion
of the treatment. Moreover, it was hoped
that tailing in with curable resin-coated
sand would curtail any flowback from

the fractures into the casing during the
plug and gun runs. Pressure was maintained in the casing while perforating by
pumping at a low rate to keep the pressure

FIGURE 2
Well Path (Uncemented Section Highlighted)

9,120

400
60

9,140
350
50
9,160
300
40
TVD

9,180
250

30
9,200

200

20

RSD

9,220

150

10

9,240

100

0

9,260
9,500

10,000

10,500

11,000

11,500

12,000

12,500

13,000

13,500

14,000

12,000

12,500

13,000

13,500

14,000

MD
-10

50

GR (aapi)

0150

-20
0

0100

-30
-50

100
200
GR (aapi)

0050
50

100

9,500

150

10,000

10,500

11,000

11,500

TABLE 1
Perforation Tops and Bottoms of Each Stage
(Uncemented Section Highlighted)
Stage

Top MD

Bot MD

1

14,226

14,394

2

14,006

14,156

3

13,780

13,940

4

13,436

5

13,036

6

12,630

7
8

Spacing ft. # of Shots

SPF

Plug Depth

36

6

14,467

70

36

6

14,180

66

36

6

13,980

13,616

164

36

6

13,735

no cement

13,256

180

36

6

13,310

no cement

12,810

226

36

6

12,960

no cement

12,070

12,344

286

36

6

12,520

no cement

11,720

11,900

170

36

6

12,018

9

11,456

11,630

90

36

6

11,674

10

11,204

11,374

82

36

6

11,422

11

10,912

11,104

100

36

6

11,160

12

10,544

10,834

78

36

6

10,872

13

10,282

10,466

78

36

6

10,496

14

10,006

10,196

86

36

6

10,236

FIGURE 3
ECDP Treatment Pump Rate and Pressure (Stage 7)
Surf Pressure (psi)
Prop Conc (ppg)

10,000
10.000
8,000
8.000

100.00
10,000

4,000
4.000

60.00
6,000

SIP1 =
1,905 PSI

2,000
2.000

42.00

84.00

Time (min)

82 THE AMERICAN OIL & GAS REPORTER

80.00
8,000

BHTP2 =
6,815 PSI

BHTP1 =
5,891 PSI

6,000
6.000

0.0
0.0 0.00

Slurry Rate (bpm)
Meas'd Btmh Press (psi)

40.00
4,000

SIP1 =
2,829 PSI

126.00

168.00

20.00
2,000

210.00

0.0
0.0

above the instantaneous shut-in pressure
(ISIP) from the previous stage just in
case there was some free sand in the annular above that might fall in on the gun
after perforating.
Avoiding casing failures during treatment was also a challenge. In a well with
good cement throughout the lateral, the
only burst concern is in the unsupported
casing above the cement top in the vertical
section. Having unsupported casing in
the lateral brought into play burst and
collapse risk in the lateral. This risk was
mitigated by keeping maximum BHTP
less than 80 percent of the casing collapse
plus formation pressures.
During drillout with coiled tubing, nitrogen had to be added to the fluid stream
to maintain circulation in the underpressured
environment. If circulation was lost and
sand settled out, the CT string could become
stuck. An additional short trip was added
in the unsupported section and a less aggressive mill was used that required more
fluid and nitrogen to be pumped. The less
aggressive mill also caused the milled up
pieces of the plug to be smaller, allowing
them to be flowed out of the well easier.

ECDP Treatment
The log in Figure 1 shows the pay
target in the Granite Wash "F" section.
The horizontal target was moderately
tight with a net height of 20 feet. Figure
2 shows the well path, with the uncemented 1,600-foot section highlighted.
Table 1 shows the top and bottom
perforations of each stage. Note that the
varied spacing distance is related to the
fact that stages pumped in the uncemented
section of pipe were separated by a greater
distance than stages in the cemented section. Stages four-seven were pumped in
the uncemented annulus.
To create multiple transverse fractures
in the four stages pumped in the open
annulus, the treatment design incorporated
a three-pronged diversion method consisting of:
* Multiple frac rate changes and shutins with variable pump rates with sudden
pressure changes;
* Limited-entry perforations and annular frictional diversion; and
* Surface modification agents and
cyclic changes in rate, viscosity, density,
proppant slugs and sweeps and solid diversion drops (termed "chaos frac").
With the ECDP process, these three
diversion processes are cycled through
many times during a single frac stage.
Figure 3 shows actual pump rates and
the pressure response to ECDP treatment
for stage seven, the last of the four stages
in the open annulus section. All four
stages had incremental increases of 300-
American Oil and Gas Reporter - September 2017

Table of Contents for the Digital Edition of American Oil and Gas Reporter - September 2017
