Assessment of Vaca Muerta Shale Oil_aapg_2012_eng_vers

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

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

http://www.energianeuquen.gov.ar/�

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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


Neuquén Basin

BuenosAiresBahía

Blanca

Neuquén

CuencaNeuquina


Source Rocks of Neuquén Basin

Vaca Muerta

Lower Quintuco

Upper Agrio Lower Agrio

Los Molles

Vaca Muerta


Vaca Muerta Formation


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


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.


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)


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


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?


Declination models

• ARPS – Hyperbolic • Stretched Exponential Model • Duong Model


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



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.



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%


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.


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)


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)


Production decline-curve analysis – Study zone

Oil

Dry Gas

Wet Gas

Zone of production wells.

Vaca Muerta

Lower Quintuco


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


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


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


Vertical wells Vs. Horizontal well - Fm Vaca Muerta

Horizontal Well vs. Vertical Wells

x 2.2

389Mbbl

176.1Mbbl


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


Lower Quintuco + Vaca Muerta Vs. Vaca Muerta

389Mbbl

176.1Mbbl

447.8Mbbl

812Mbbl

x 2.1

x 2.2


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.


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

Assessment of Vaca Muerta Shale Oil_aapg_2012_eng_vers

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