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Assessment of Vaca Muerta Formation Shale Oil
Production Decline-Curve Analysis
Nicolás Gutierrez Schmidt, Julio C. Alonso y Adolfo Giusiano
Dirección de Estudios www.energianeuquen.gov.ar
December, 2012
Anticlinal Picún Leufú
Vaca Muerta - The Leading Shale Play in Latin America 2-4 December | Buenos Aires, Argentina InterContinental Hotel
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Outline
• Introduction to Neuquén Basin Source Rocks of Neuquén Basin Vaca Muerta Formation: Ro, TOC, Tickness, Area
• Oil production of Neuquén province Production of Conventional and unconventional Oil Bajada del Palo a-7 well
• Production decline-curve analysis Analysis of Decline models Forecast of Vaca Muerta Shale Oil production
• Discussions
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Neuquén Basin
BuenosAiresBahía
Blanca
Neuquén
CuencaNeuquina
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Source Rocks of Neuquén Basin
Vaca Muerta
Lower Quintuco
Upper Agrio Lower Agrio
Los Molles
Vaca Muerta
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Vaca Muerta Formation
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Vaca Muerta Formation
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Vaca Muerta Formation
Area with potential for oil and gas exploration
OIL WET GAS DRY GAS
Vaca Muerta Formation • Area: 3,508,900 acres
(14,200 km2)
• Tickness: to 984 ft (300 m)
• Ro: 0.6 to 1.2 % (oil)
• TOC: 2 to 8 %
Conventional and Unconventional Oil Production
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Conventional and Unconventional Oil Production
• Main fields: – El Trapial-Curamched
(Chevron Argentina S.R.L) – Puesto Hernández
(Petrobras Energía S.A) – Chihuido de la Sierra Negra
(YPF S.A.)
Oil and Condensate production in the Neuquén province was 115.5 Mbbl/d
(18,386m3/d) in July, 2012.
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Bajada del Palo a-7 well
Shale Thickness (Passey et.al 1990) Perforations
Vaca Muerta Top
Tordillos Top
• Target: Evaluation of
Vaca Muerta (1983) • Depth: 9,160 ft (2.792 mbbp)
• Ro=0,6 (oil window)
• TOC=4%.
• Thickness: 410ft (125m)
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Bajada del Palo a-7 well
Fracture Fracture ?
Plus Oil: 63Mbbl
August 2012
• State: In effective production. • Art. Lift: Beam Pump. • Oil Prod. = 54.7 bblpd
(8.7 m3/d) • Oil. Cum = 752.3 Mbbl
(119.6 Mm3) • Prod. time: 27 years.
Hyperbolic Match Di:0.024 A.n b: 1.5 Dmin: 6%/yr EUR @ 2030: 875.4 Mbbl
Production forecasting – Decline analysis
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Declination models
• To take into account: – Very-low permeability reservoirs – Wells with hydraulic fracture stimulation – Flow transient for long time – Drainage area is not necessarily circular
– What type should be used? – Minimum production time for reliable forecast?
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Declination models
• ARPS – Hyperbolic • Stretched Exponential Model • Duong Model
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
ARPS – Hyperbolic Curve
where: t: time (months) q(t): rate to time t (m3/d or bblpd) qi: initial rate (m3/d or bblpd) to t=0 b: Arps parameters Di: Initial decline
qi, Di y b
0.5
5
50
0 24
48
72
96
120
144
168
192
216
240
264
288
bblp
d
month
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
ARPS – Hyperbolic Curve
THEORETICAL BASIS FOR ARPS’ DECLINE EQUATION: • Well or reservoir in boundary-dominated flow (BDF) • Production at constant BHP
• Constant radius drainage
• No transient flow data
• Solution for 0<b<1
b= 0.5
b= 1.8
b= 1
b= 1.5
To “Di” and “qi” constants
• In 24 months’ time there are no significant differences between in the curves with b from 1.5 to 1.8.
• Special attention on b estimation on short production periods.
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
ARPS – Hyperbolic Curve
For a period of 25 years, keeping constants ‘Qi’ and ‘Di’, there is a difference of EUR of 32% between b=1.5 and b=1.8. Comparing the first ‘b’ value with b=1, the difference is 47% less.
0
5000
10000
15000
20000
25000
30000
35000
0 12
24
36
48
60
72
84
96
108
120
132
144
156
168
180
192
204
216
228
240
252
264
276
288
300
Cum
ulat
ive
(m3)
Month
32%
47%
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Modified Hyperbolic Model
VERY LOW PERMEABILITY RESERVOIRS:
• Best-fit ‘b’ values almost always > 1
• In many cases EUR are over-estimated.
• Flow transient for large time periods.
0.1
1
10
100
0 48
96
144
192
240
288
336
384
m3/
d
Meses
Dmin
MODIFIED HYPERBOLIC MODEL
Combination with exponential curve (minimum terminal decline rate, Dmin) makes the model applicable, giving a reasonable reserves to finite time.
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Bakken Shale – Horizontal Well
ARPS parameters: qi = 459 bbl/d (73 m3/d) b= 1.4 Di= 0.197
Example: North Dakota Bakken
Source: J. Mason – Oil Production Potential of the North of Dakota Bakken (February, 2012)
EUR @ 30 years 546Mbbl (86.000m3)
Fracture stages: 28 to 32. Lateral length: 9,186 ft (2,800 mts)
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Production decline-curve analysis
Methodology • Estimation of ‘b’ and ‘Di’ parameters by fitting of production data with the mathematical model and by minimizing squared error (MS Solver Excel). • The wells with more production history are used
• A maximum and minimum is considered for estimation of the type well.
(Source: SEN Cap. IV)
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Production decline-curve analysis – Study zone
Oil
Dry Gas
Wet Gas
Zone of production wells.
Vaca Muerta
Lower Quintuco
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Production decline-curve analysis – Study zone
Vertical wells • Fracture stages: 3 • h average: 330 ft (100 m) Horizontal wells • Lateral length: 3,281ft (1,000 m) • Fracture stages: 10 • xf: 130 ft (40 m) • h average: 164 ft (50 m)
Analysed wells results
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Vertical Wells - Fm Vaca Muerta
EUR @ 25 years: 176,120 bbl (28,000 m3)
Range:
98 Mbbl – 620 Mbbl
Arps parameters: qi= 200 bbl/d (32 m3/d) Di=0.45 b= 1.8 Dmin= 6%/yr
Vertical-type well Vaca Muerta
qi b Di Dmin t @ Dmin q @25 yrs EUR @ 25 yrs (m3/d) n.yr (%/yr) (yrs) (m3/d) (m3)
Max. Well 54 1.69 0.45 6 9.75 1.51 42,500 Med. Well 32 1.81 0.46 6 9.11 1.03 27,900 Min. Well 28 1.30 0.40 6 12.66 0.45 15,600
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
0.1
1
10
100
0 12
24
Cum
ulat
ive
(m3)
Prod
uctio
n ra
te (m
3/d)
Months
Max. well
Med. well
Min well
Nq.VMUT-2
Nq.VMUT-3
Nq.VMUT-4
Nq.VMUT-1
Cum. Max
Cum. Med
Cum. Min
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Horizontal well - Fm Vaca Muerta
EUR @ 25 years:
389,000 bbl (61,800 m3)
Arps parameters: qi= 336.5 bbl/d (53.5 m3/d) Di=0.25 b= 1.8 Dmin= 6%/yr
Horizontal-typed well Vaca Muerta
Source: CAP IV SEN
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
1
10
100
0 12
24
36
48
60
72
84
96
108
120
132
144
156
168
180
192
204
216
228
240
252
264
276
288
300
Cum
ulat
ive
(m3)
Prod
uctio
n ra
te (m
3/d)
Months
Nq.VMUT-5(h) Horizontal well Cum. Hor. Well
Only a well with considerable
production period.
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
0.1
1
10
100
0 12
24
36
48
60
72
84
96
108
120
132
144
156
168
180
192
204
216
228
240
252
264
276
288
300
Cum
ulat
ive
(m3)
Prod
uctio
n ra
te (m
3/d)
Months
Vertical type well
Nq.VMUT-2
Nq.VMUT-3
Nq.VMUT-4
Nq.VMUT-1
Horizontal well
Nq.VMUT-5(h)
Cum- Vert. Type well
Cum. Hor. Well
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Vertical wells Vs. Horizontal well - Fm Vaca Muerta
Horizontal Well vs. Vertical Wells
x 2.2
389Mbbl
176.1Mbbl
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Horizontal well – Lower Quintuco + Vaca Muerta
EUR @ 300 meses:
812,416 bbl (129,160 m3)
Arps parameters: qi= 500 bbl/d (80 m3/d) Di=0.125 b= 1.8 Dmin= 6%/yr
Horizontal well Lower Quintuco + Vaca
Muerta
Sourse: CAP IV SEN
0
20,000
40,000
60,000
80,000
100,000
120,000
140,000
1
10
100
0 12
24
36
48
60
72
84
96
108
120
132
144
156
168
180
192
204
216
228
240
252
264
276
288
300
Cum
ulat
ive
(m3)
Prod
uctio
n ra
te (m
3/d)
Months
Hor. Well QTUC+VMUT Nq.QTUC-VMUT-1 Cum. QTUC+VM Hor. Well
Only a well with considerable
production period.
0
20,000
40,000
60,000
80,000
100,000
120,000
140,000
0.1
1
10
100
0 12
24
36
48
60
72
84
96
108
120
132
144
156
168
180
192
204
216
228
240
252
264
276
288
300
Cum
ulat
ive
(m3)
Prod
uctio
n ra
te (m
3/d)
Months
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Lower Quintuco + Vaca Muerta Vs. Vaca Muerta
389Mbbl
176.1Mbbl
447.8Mbbl
812Mbbl
x 2.1
x 2.2
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Discussions
Based on the study is considered that:
• It can adjust with decline curves for the analyzed wells, obtaining values of EUR
that differentiate the performance between horizontal and vertical wells and different
producing intervals, besides giving results comparable to other shale plays.
• The approach taken in this study of rate production decline is comparable with that
adopted in others basins, such as Bakken Shale.
• It is indicative that there would be better performance in the horizontal wells in the
Vaca Muerta formation, increasing it by a factor of 2.2 from vertical wells, which are
also increased by a factor of 2.1 with the participation of lower Quintuco.
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis
Discussions
• The Arps parameters have values in the order of other shale plays estimations
with a average value of ‘b’, for Vaca Muerta’s wells, of 1.8. The Di value can vary
from 0.45 to 0.25.
• Might be considered that a production period of at least two years can get
production forecasts with significant reliability.
• From the analyzed wells it would be indicator that the EUR is directly proportional
to the initial production rate, being it related to well completion (fracture design and
number of fracture stages).
Any questions?
Thanks for your attention