Evaluacion Del Shale Oil de VM_analisis de Declinacion_IAPG2013

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

April, 2013

[email protected] [email protected] [email protected]

http://www.energianeuquen.gov.ar/�

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• Introduction to Neuquén Basin Source Rocks of Neuquén Basin Vaca Muerta Formation: Ro, TOC, Thickness, 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

Outline


Neuquen Basin

BuenosAiresBahía

Blanca

Neuquén

CuencaNeuquina

Giusiano, 2010


Source Rocks of Neuquen Basin

Agrio superior

Agrio inferior

Los Molles


Vaca Muerta Formation



Vaca Muerta Formation Oil Window

• Area: 5,807,000 acres

(23,500 km2)

• Thickness: to 984 ft (300 m)

• Ro: 0.55 to 1.3 % (oil)

• TOC: 2 to 8 %



Area with potential for oil and gas exploration

OIL WET GAS DRY GAS

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 110.4 Mbbl/d

(17.561m3/d) in December, 2012.


Oil Production – Prov. Neuquén

22.09%

14.40% 15.16%

10.36%

4.19% 4.03%

2.44%

2.80%

24.53%

Oil and Condensate Production Prov. Neuquén – December, 2012

El Trapial-Curamched Loma La Lata - Sierra Barrosa

Chihuido de la Sierra Negra Puesto Hernández

Centenario Bajada del palo

Entre Lomas VM shale oil

Resto Source: Cap IV. SEN


Evolution of the Vaca Muerta oil production

5,103

118,085 284,210

14,778

0 10 20 30 40 50 60 70 80 90 100

1

10

100

1000

10000

100000

1000000

Nº

de p

ozos

pro

duct

ores

Prod

. y p

rod.

acu

mul

ada

(m3)

Acumulada (m3) Prod. mensual (m3) Nº pozos

18 23

14 12 7

0

10

20

30

0-2 2-6 6-12 12-18 18-24 Num

ber o

f wel

ls

Monthly range

Effective production months per well

Source: Cap IV. SEN

Sour

ce: C

ap IV

. SEN

Shale Thickness (Passey et.al 1990) Perforations

Vaca Muerta Top

Tordillo Top

• Target: Evaluation of

Vaca Muerta • Depth: 9,160 ft (2.792 mbbp)

• Ro=0,6 (oil window)

• TOC=4%.

• Thickness: 410ft (125m)


Bajada del Palo a-7 (1983)

Fracture

Acid stimulation

Plus Oil: 10.000m3

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


Bajada del Palo a-7

Production forecasting – Decline analysis

• 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?


Declination models

• ARPS – Hyperbolic • Stretched Exponential Model • Duong Model


Declination models

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


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

VERY LOW PERMEABILITY RESERVOIRS:

• Best-fit ‘b’ values almost always > 1

• In many cases EUR are over-estimated.

• Flow transient for large time periods.

MODIFIED HYPERBOLIC MODEL

Combination with exponential curve (minimum terminal decline rate, Dmin) makes the model applicable, giving a reasonable reserves to finite time.


Modified Hyperbolic Model

0.5

5

50

0 24

48

72

96

120

144

168

192

216

240

264

288

bblp

d

month

b= 0.5

b= 1.8

b= 1

b= 1.5

“Di” y “qi” constantes

• 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.


Hyperbolic curve – b parameter


Hyperbolic curve – b parameter

Adjustment of "b" in function of production history

1

10

100

0 2 4 6 8 10 12 14 16 18 20 22

m3/

día

Pozo 1

6 meses

b=0.9

1

10

100

0 2 4 6 8 10 12 14 16 18 20 22

m3/

día

Pozo 1

6 meses 12 meses

b=0.9

b=1.8

1

10

100

0 2 4 6 8 10 12 14 16 18 20 22

m3/

día

Pozo 1

6 meses 12 meses 21 meses

b=0.9

b=1.8

1

10

100

0 5 10 15 20 25

m3/

día

Pozo 2

6 meses

b=0.61

1

10

100

0 5 10 15 20 25

m3/

día

Pozo 2

6 meses 12 meses

b=0.61

b=1.5

1

10

100

0 5 10 15 20 25

m3/

día

Pozo 2

6 meses 12 meses 15 meses

b=0.61

b=1.5

b=1.8

Source: Cap IV. SEN

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%


Hyperbolic curve – b parameter and cumulative production

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)


Bakken Shale – Horizontal Well

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)


Production decline-curve analysis

Oil

Dry Gas

Wet Gas

Zone of production wells.


Production decline-curve analysis – Study zone

Vertical wells • Fracture stages: 3-5 • 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)


Production decline-curve analysis

Analysed wells results

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

Source: CAP IV SEN


Vertical Wells - Fm Vaca Muerta

EUR @ 25 years:

276- 389 Mbbl (44 – 61.8 Mm3)

Arps parameters: qi= 336.5 bbl/d (53.5 m3/d) Di=0.25 b= 1.6-1.8 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.


Horizontal Well - Fm Vaca Muerta

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

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

389Mbbl

176.1Mbbl

447.8Mbbl

x 1.6 - 2.2


Vertical wells Vs. Horizontal well - Fm Vaca Muerta

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, 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. Furthermore, results are comparable with BP.a-7.

• It is indicative that there would be better performance in the horizontal wells in the

Vaca Muerta formation, increasing it by a factor of 1.6 to 2.2 from vertical wells.


Discussions

• The Arps parameters have values in the order of other shale-plays estimations

with a value of ‘b’, for Vaca Muerta’s wells, from 1.6 to1.8. 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).


Discussions

Any questions? Thanks for your

attention

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Evaluacion Del Shale Oil de VM_analisis de Declinacion_IAPG2013

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