American Oil and Gas Reporter - January 2015 - 120

FIGURE 2
Production Analysis Workflow
Data Processing and Analysis

*
*
*

*

*

142 Wells on production (March 2012)
60 had more than 120 days of
production.
Data used in the analysis:
* Rates (gas, oil, water)
* Wellhead pressure
* Choke size normalized
* Perforated lateral length
* Initial reservoir pressure
* Reservoir temperature
* PVT data (API, gas, gravity, etc.)
Data preprocessing includes:
* Data filtering
* Data normalization (elapsed day)
Calculated flow parameters:
* Pwf
* Drawdown (Initial Press - Pwf)
* Productivity Index
* Normalized Rates (Mcf/1,000 ft)
* Rate ratios (GOR, GWR, etc.)

Ranking Plots

Consolidation of Data
Diagnostic Plots

FIGURE 3
Brittle Mineral and Kerogen Thickness versus Well Performance
Three tiers of separation of well performance
1-20
21-40

Ranking

41-XX

Bubble Size = Net/Gross
Bubble Color = Ranking

175
155
135

Brittleness/Thickness

115
95
75
VBRIT: > 70%
TOC: > 8%
VCL: < 28%
PIGE: > 8%

55
35
15
-5

0

10

20

30

40

TOC/Thickness

120 THE AMERICAN OIL & GAS REPORTER

50

60

70

80

90

Wells with pilot data

produced at a higher choke, it could
have a higher rate than an offset well
produced at a lower choke.
The analysis ranked wells in order of
overall performance and plotted them
against key geologic and petrophysical
parameters and properties. An example
is shown in Figure 3, which plots brittleness/thickness and total organic
content/thickness with respect to well
rankings. Some of the key performance
drivers identified were thickness of clay
content, seal thickness and integrity, TOC
thickness, and porosity.
Key performance drivers had different
impacts across the trend and were unique
to each area. There were several other
parameters (faulting, seal thinning, etc.)
that influenced well performance in areas
with identified performance drivers.
The design of an Eagle Ford wellbore
depends primarily on its location within
the trend and true vertical depth. Typically,
operators have implemented two- or
three-string casing designs at shallower
depths. Bottom-hole static temperatures
and reservoir pressures range from 280
to 350 degrees Fahrenheit and 8,00011,000 psi, respectively. Production casing
is typically cemented 51⁄2-inch, 23-pound
P-110. A tapered (51⁄2- x 41⁄2-inch) casing
design also has been used. Most Eagle
Ford wells are drilled now on multiwell
pads and stimulated/completed using the
plug-and-perforation method.
A typical fracture stage is 350-420
feet in length with four to six perforation
clusters per stage using 200,000-400,000
pounds of proppant per stage pumped at
a rate of 70-80 barrels a minute. To develop sufficient fracture width and place
higher proppant concentration in the created fractures, Eagle Ford wells typically
use a "hybrid" fluid design consisting of
a slickwater prepad and cross-linked
treatment fluid.
Completion Optimization Plan
Since an individual completion variable
can have significant influence on well
performance, it is critical to have a completion optimization plan that tests one
completion variable at a time. An optimization plan for cutting costs and/or
improving well performance should be
implemented in an expeditious manner
so that optimum design solutions are
available early in the development program. The plan may have a net incre-
American Oil and Gas Reporter - January 2015

Table of Contents for the Digital Edition of American Oil and Gas Reporter - January 2015
