American Oil and Gas Reporter - January 2017 - 66

Shale Resource Science
tions of the play are dry to lean condensate,
while shallower areas are rich-gas condensate.

ranges of information into smaller subsets
for more detailed analysis. The goal of a
data bin is to have a group of wells where
only one variable is changing.
The data binning steps performed for
this analysis included average lateral
TVD, number of frac stages, pounds of

TVD Data Binning
The next step was creating data bins
from the entire dataset by grouping similar
FIGURE 4B

Middle TVD Data Bin
Color by:
Toe-Down
Toe-Up

PRD_GAS IP (90 Day AVG)

3.2k
2.8k
2.4k
2.0k
1.6k
1.2k

800

-200 -150 -100 -50

0

50

100

TVD Change (+ve down)

750k

Toe-Down
Toe-Up

650k
550k
450k
350k
250k
150k

200

150

Color by:

850k

PRD_GAS IP (365 Day AVG)

3.6k

-200 -150 -100 -50

0

50

100 150

TVD Change (+ve down)

200

RES_GAS EUR (MMcf)

6k
5k
4k
3k
2k

Color by:
Toe-Down
Toe-Up

-200 -150 -100 -50
0
50 100
TVD Change (+ve down)

150

200

FIGURE 4C
Deep TVD Data Bin
Toe-Down
Toe-Up

4.0k
3.5k
3.0k
2.5k
2.0k
1.5k
1.0k

8k

-200 -150 -100 -50 0
50 100
TVD Change (+ve down)

150 200

Toe-Down
Toe-Up

6k

5k
4k
-200 -150 -100 -50
0
50 100
TVD Change (+ve down)

150

1.2M
1.1M

Color by:
Toe-Down
Toe-Up

1.0M

900k
800k
700k
600k
500k

-200 -150 -100 -50
0
50 100
TVD Change (+ve down)

50k

Color by:

7k

3k

PRD_GAS CUM (365 Days)

4.5k

9k
RES_GAS EUR (MMcf)

Color by:

RES_A square root of k

PRD_GAS IP (90 Day AVG)

5.0k

200

66 THE AMERICAN OIL & GAS REPORTER

150 200
Color by:
Toe-Down
Toe-Up

40k
30k
20k
10k

-200 -150 -100 -50
0
50 100
TVD Change (+ve down)

150

200

proppant, other variables that influence
well performance, and lateral TVD gain.
The primary variable in this case was
TVD, which coincides with reservoir
fluid type and pressure within the Cana
Woodford play.
TVDs of the wells then were divided
into three data bins for shallow, middle
and deep TVDs. All the wells in a bin
had very similar completion designs. The
only variable changing appreciably within
these data bins was lateral TVD gain.
There were 12 wells with shallow
TVDs ranging between 11,600 and 12,250
feet. The condensate-to-gas ratio (CGR)
of these wells was less than 75 barrels
per million cubic feet and the pressure
gradient was ≈0.6 psi/foot. The middle
TVD bin had 24 wells with TVDs ranging
between 12,250 and 12,500 feet. The
CGR was 25-50 bbl/MMcf, and the pressure gradient was ≈0.68 psi/foot. The
deep bin consisted of 44 wells with TVDs
between 12,500 and 12,850 feet. The
CGR for these wells was less than 25
bbl/MMcf, and the pressure gradient was
≈0.7 psi/foot.
Secondary variables such as number
of fracture stages/clusters, completion
design and amount of proppant were
identified from the three primary data
bins. A large number of wells in the
dataset had the same design, thereby
providing the largest data bin possible
for analysis: ≈4,800-foot laterals,10 stages,
40 clusters, and 3.5 million pounds of
proppant. Once the data bins had been
created, it was necessary to compare
production metrics with lateral TVD
change to display either a negative lateral
TVD gain (toe-up) or a positive TVD
gain (toe-down).
Toe-Up Is Better
The three primary data bins were compared with average cumulative production
over various production intervals (30-,
60-, 90-, 180- and 365-day ranges) to
identify toe-up/toe-down trends that could
impact a well's overall production. Figure
American Oil and Gas Reporter - January 2017

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