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Assessment of Vaca Vaca Muerta Formation Shale Oil Production Decline-Curve Analysis
Anticlinal Picún Leufú
Nicolás Gutierrez Schmidt, Julio C. Alonso y Adolfo Giusiano Dirección de Estudios www.energianeuquen.gov.ar
December, 2012
[email protected] [email protected]
Assessment of o f Vaca 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 decline-curve analysis Analysis of Decline models Forecast of Vaca Muerta Shale Oil production
• Discussions
Assessment of o f Vaca 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 decline-curve analysis Analysis of Decline models Forecast of Vaca Muerta Shale Oil production
• Discussions
Assessment of o f Vaca Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis Neuquén Basin
Cuenca Neuquina
Neuquén
Bahía Blanca
Buenos Aires
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis Source Rocks of Neuquén Basin Vaca Muerta Upper Agrio Lower Agrio
Los Molles
Lower Quintuco
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
Vaca Muerta Formation Area with potential for oil and gas exploration
• Area: 3,508,900 acres (14,200 km2)
DRY GAS
WET GAS
OIL
• 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 Oil and Condensate production in the Neuquén province was 115.5 Mbbl/d (18,386m3/d) in J uly, 2012.
• Main fields: – El Trapial-Curamched (Chevron Argentina S.R.L)
– Puesto Hernández (Petrobras Energía S.A)
– Chihuido de la Sierra Negra (YPF S.A.)
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis Bajada del Palo a-7 well
•Target: Evaluation of Vaca Muerta (1983) •Depth: 9,160 ft (2.792 mbbp) • Ro=0,6 (oil window) Vaca Muerta Top
• TOC=4%. •Thickness: 410ft (125m) Perforations Tordillos Top
Shale Thickness (Passey et.al 1990 )
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis Bajada del Palo a-7 well August 2012 Fracture Fracture ?
• 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.
Plus Oil: 63Mbbl 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
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis ARPS – Hyperbolic Curve THEORETICAL BASIS FOR ARPS’ DECLINE EQUATION:
50
To “Di” and “qi” constants
• Well or reservoir in boundarydominated flow (BDF) • Production at constant BHP
d p l b b
• Constant radius drainage 5
• No transient flow data • Solution for 0
b= 1.8 b= 1.5 b= 1
b= 0.5
• In 24 months’ time there are no significant differences between in the curves with b from 1.5 to 1.8.
0.5 0
4 2
8 4
2 7
6 9
0 2 1
4 4 1
month
8 6 1
2 9 1
6 1 2
0 4 2
4 6 2
8 8 2
• Special attention on b estimation on short production periods.
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis ARPS – Hyperbolic Curve 35000
30000
32%
25000 ) 3 m ( 20000 e v i t a l u15000 m u C
47%
10000
5000
0 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 1 2 3 4 6 7 8 9 0 2 3 4 5 6 8 9 0 1 2 4 5 6 7 8 0 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 3
Month
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.
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis Modified Hyperbolic Model VERY LOW PERMEABILITY RESERVOIRS: MODIFIED HYPERBOLIC MODEL
• Best-fit ‘b’ values almost always > 1 • In many cases EUR are over-estimated. • Flow transient for large time periods. 100
10 d / 3 m
Dmin 1
0.1 0
8 4
6 9
4 4 1
2 9 1
Meses
0 4 2
8 8 2
6 3 3
4 8 3
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 Example: North Dakota Bakken
EUR @ 30 years 546Mbbl (86.000m3) Fracture stages: 28 to 32. Lateral length: 9,186 ft (2,800 mts)
ARPS parameters: qi = 459 bbl/d (73 m3/d) b= 1.4 Di= 0.197 Source: J. Mason – Oil Production Potential of the North of
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
Dry Gas
Lower Quintuco Wet Gas
Oil
Vaca Muerta
Zone of production wells.
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 Vertical-type well Vaca Muerta
16,000
100
14,000 ) d / 3 m 10 ( e t a r n o i t c u 1 d o r P
12,000
) 3 m 10,000 ( e v 8,000 i t a l u 6,000 m u C
4,000
2 1
Min well Nq.VMUT-2 Nq.VMUT-3 Nq.VMUT-4 Nq.VMUT-1
Cum. Med Cum. Min
0 0
Med. well
Cum. Max
2,000 0.1
Max. well
4 2
Months
Max. Well Med. Well
qi (m3/d) 54 32
b 1.69 1.81
Di n.yr 0.45 0.46
Dmin (%/yr) 6 6
t @ Dmin (yrs) 9.75 9.11
q @25 yrs (m3/d) 1.51 1.03
EUR @ 25 years: 176,120 bbl (28,000 m 3 ) Range: 98 Mbbl – 620 Mbbl
Arps parameters: qi= 200 bbl/d (32 m3/d) Di=0.45 b= 1.8 Dmin= 6%/yr EUR @ 25 yrs (m3) 42,500 27,900
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis Horizontal well - Fm Vaca Muerta 100
70,000 60,000
Only a well with considerable production period.
) d / 3 m ( e t a r 10 n o i t c u d o r P
50,000 ) 3 m ( 40,000 e v i t a l 30,000 u m u 20,000 C 10,000
1
0 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 1 2 3 4 6 7 8 9 0 2 3 4 5 6 8 9 0 1 2 4 5 6 7 8 0 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 3
Months
Nq.VMUT-5(h) Source: CAP IV SEN
Horizontal well
Cum. Hor. Well
Horizontal-typed well Vaca Muerta
EUR @ 25 years: 389,000 bbl (61,800 m 3 )
Arps parameters: qi= 336.5 bbl/d (53.5 m3/d) Di=0.25 b= 1.8 Dmin= 6%/yr
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis Vertical wells Vs. Horizontal well - Fm Vaca Muerta 70,000
100
Horizontal Well vs. Vertical Wells
389Mbbl
60,000
) d / 10 3 m ( e t a r n o i t c u d 1 o r P
50,000
x 2.2
) 3 m 40,000 ( e v i t a l 30,000 u 176.1Mbbl m u C
20,000
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
10,000 0
0.1 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 1 2 3 4 6 7 8 9 0 2 3 4 5 6 8 9 0 1 2 4 5 6 7 8 0 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 3
Months
Cum. Hor. Well
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis Horizontal well – Lower Quintuco + Vaca Muerta 100
Only a well with considerable production period.
) d / 3 m ( e t a r 10 n o i t c u d o r P
140,000 120,000 100,000 ) 3 m ( 80,000 e v i t a l 60,000 u m u 40,000 C
Horizontal well Lower Quintuco + Vaca Muerta EUR @ 300 meses: 812,416 bbl (129,160 m 3 )
20,000 1
0 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 1 2 3 4 6 7 8 9 0 2 3 4 5 6 8 9 0 1 2 4 5 6 7 8 0 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 3
Months Hor. Well QTUC+VMUT Sourse: CAP IV SEN
Nq.QTUC-VMUT-1
Cum. QTUC+VM Hor. Well
Arps parameters: qi= 500 bbl/d (80 m3/d) Di=0.125 b= 1.8 Dmin= 6%/yr
Assessment of Vaca Muerta Formation Shale Oil: Production Decline-Curve Analysis Lower Quintuco + Vaca Muerta Vs. Vaca Muerta 100
140,000 812Mbbl 120,000
x 2.1
) d / 10 3 m ( e t a r n o i t c u d 1 o r P
100,000 ) 3 m 80,000 ( 447.8Mbbl e v i t a l 389Mbbl u 60,000 m u C
40,000
x 2.2
176.1Mbbl 20,000
0.1
0 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 1 2 3 4 6 7 8 9 0 2 3 4 5 6 8 9 0 1 2 4 5 6 7 8 0 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 3
Months
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).
