American Oil and Gas Reporter - January 2017 - 83

of Eagle Ford production in the area.
The plot locates decline rates as a function
of ultimate recovery by well location, relating credited production to expected
future performance. Lease well decline
rates run the gamut from good to bad,
with the majority ranging between 25
and 60 percent. Unfortunately, decline
rates for the two good wells are within
this same range. It appears that the EAU1
and E8 wells certainly require further review. Well EAU1 is a good producer, so
why no additional reserves?
Figure 4 is a composite production
plot comparing production histories for
wells in the southern lease area. The A1
and E4 wells are clearly outliers to the
surrounding wells, and seem to have recompletion potential. Well A1 probably
suffered casing problems or sanded up
around 1,200 days. Well E4 seemed to

have suffered an ineffective completion.
A final note is that the good wells appear to produce at a nearly constant rate,
which leads to a rather critical question:
Could the reserves be underestimated?
This study helps identify bypassed reserves and additional remedial potential
in this portion of the Eagle Ford producing
trend. Although there were considerable
variations in well production, areas with
both low potential and high remaining
value were identified.
The public data-based analysis reveals
two possibilities for follow-up studies:
reviewing the potential for drilling offset
wells in the EAU1 area, and for working
over the two wells located in the southern
area (possibly extending the productive
northwest limit). In either case, however,
the geological studies must be incorporated
into more in-depth evaluations.
r

FIGURE4
Composite Production Plot for Eagle Ford Study Area

Oil Rate (BOPD)

1,000

100

A1
E4

S4
0

200

400

600

DARIO H. ROMERO is president of
CPQ Energy & Analytics in Houston.
His expertise includes reserves evaluation
and appraisal, statistical data mining,
and analytics. Before founding CPQ,
Romero served in technical and leadership capacities at Schlumberger, including
as Middle East production and reservoir
engineering team leader, production
business development manager, and senior production optimization engineer.
He holds a B.S. in geodetic engineering
from the University of Zulia, and an
M.S. in computer science from Simón
Bolívar University, with associate-level
studies in petroleum engineering.

800
Time (d)

1,000

1,400

1,600

STEVEN W. POSTON is professor
emeritus of petroleum engineering at
Texas A&M University. With more than
45 years of industry experience, his
career includes reservoir engineering
and decline curve analysis, teaching,
and consulting in the United States,
Middle East, Africa, Latin America and
Russia. Poston has served on numerous
technical society committees, and is author or co-author of two petroleum engineering textbooks. He holds a B.S.
and an M.E. in geological engineering,
and a Ph.D. in petroleum engineering
from Texas A&M University.

JANUARY 2017 83

American Oil and Gas Reporter - January 2017

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