Shallow Gas Prospect F07/F10-P1 - EBN

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Factsheets: Shallow Gas Lead F07/F10-P1
April 2012

Scale: 1:100.000

Summary
Bright Spot: F07/F10-P1
Status
License
GIIP (P50)
Lead
Open acreage
1.7 BCM (2 sand layers) 2.2 BCM (4 sand layers)
POS 100%?
Offset Wells
Seismic
Coverage
Bright Spot
Characteristics
F07-01: 1970, targeting Bunter Fm; dry plugged and
abandoned, F07-02: 1992, targeting Westphalian Fm, dry
plugged and abandoned, F10-02: 1985, targeting Limburg
Gp, dry plugged and abandoned
3D vintage Z3PET1994B acquisition 1994 (Petroland),
reprocessed and added to Terracube 2009 (Fugro)
2D lines DGM98, Dutch Graben Margin from Fugro
Bright spot type FDC (fault-dip closure), NU formation,
alternation of sand and clay, conform to structure, 4 major
bright spots of which 2 form the main target

Prospect Overview
2D seismic
3D seismic

Offset wells
F07-01 (through prospect edge):
• Drilled Dec 1970
• Dry, plugged & abandoned
• Max depth 2195 m
• Target: Tertiary, Cretaceous, Jurassic and Triassic (Bunter)
• Hydrocarbon indications: gas recorded between 325-980 m. Best
shows in lower Pleistocene between 375-685m: up to 2.1% methane
Source: Final Well Report, www.nlog.nl

Offset wells
F07-02:
• Drilled 1992
• Dry, plugged & abandoned
• Max depth 4200 m
• Primary target: Westphalian sandstone (Carboniferous)
• Secondary target: Slochteren formation (Lower Permian)
Source: End of Well Report, www.nlog.nl

Offset wells
F07-02:
335-337 m MD: clays with minor sands
377-450 m MD: clear sand bodies up to 15m thick with clay bands, gas levels 200 ppm C1
450-593 m MD: clays with minor clear sand bodies up to 8m thick, gas levels 500 ppm C1
593-677 m MD: clays with occasional thin, clear sand interbeds, gas levels 500-3200 ppm
C1
677-807 m MD: clays with traces of clear sand, gas levels 1550-2570 ppm C1
807-868 m MD: clays with traces of clear sand, gas levels 4500 ppm C1 (max 4857 ppm)
868-982 m MD: clays/claystone with sand and sandstone lenses, gas levels 775 ppm C1
982-1019 m MD (MMU) : siltstone grading to claystone, gas levels 410-710 ppm C1

* Of largest bright spot
Prospect analogy A12-FA & F02a-B-Pliocene
producing fields
Z-axis: TWT, scale 1:8
MMU
A12-FA F07/F10-P1 F02a-B-Pliocene
Field/Prospect Area* (km 2 )
A12-FA 52
F02a-B-Pliocene 15
F07/F10-P1 14

3D seismic
• 8 levels show amplitude
anomalies
• S3, S6, S7, S8 clearest
anomalies included in
volumetrics
• Prospect partly covered by
3D seismic
• Additional 3D available
~June 2012 (Fugro)
• Prospect bounded by fault in
west
• Velocity pull down in lower
horizons indicate gas in the
system

2D seismic

Time & seismic amplitude map S3

Time & seismic amplitude map S6

Time & seismic amplitude map S7
Velocity pull down/Incised by channel?

S7: Velocity pull down/Incised by channel?
Velocity pull down
Incised by channel?

Time & seismic amplitude map S8
Velocity pull down

Seismic to well tie
Case hole logging:
GR difficult to interpret
Checkshot data from www.nlog.nl (F07-01 data applied at shallow depths for F10-02)

Correlation based on GR patterns
Well correlation

GIIP method & assumptions
Area
Thickness
P10 P50 P90
Area P50 +
~10%
Based on thickness
generally seen in area
Outline amplitude
anomaly F07/F10-P1
From GR
well F07-01
Area P50 -
~10%
Based on thickness
generally seen in area
Geometric
correction factor
Minimum correction,
based on modelling
Average correction,
based on modelling
Maximum correction,
based on modelling
N/G
PHIE
In line with A12-FA and F02a-Pliocene field data
In line with A12-FA and F02a-Pliocene field data
Sg
Expansion
factor (1/Bg)
In line with A12-FA and F02a-Pliocene field data
From 1/Bg - depth relationship based on
A18-FA, B10-FA, B16-FA & B17-FA field data
at center of
P50 + 2
P50 - 2
formation

GIIP method & assumptions
‣ Gas expansion factor from 1/Bg – depth relation:
1/Bg = 0.12 * TVDss – 4.62
‣ GIIP: Probabilistic evaluation using Monte Carlo simulation
‣ GRV calculated from: area bright spot * thickness using a
geometrical correction factor range of 40-70%
‣ Sand layers assumed to be fully gas bearing at crest

GIIP method & assumptions
Gross Rock Volume:
• Area x thickness
• Thickness sand from log data only
• Geometric correction: 40-70%
Outline amplitude anomaly
thickness

GIIP input parameters
Input Area (km2) Thickness (m) Geometric correction factor
Zone P10 P50 P90 P10 P50 P90 P10 P50 P90
S3 8 7 6 20 12 4 0.70 0.55 0.40
S6 9 8 7 20 12 4 0.70 0.55 0.40
S7 15.5 14.0 12.5 20 12 4 0.70 0.55 0.40
S8 11 9 7 30 20 10 0.70 0.55 0.40
Input N/G (v/v) PHIE (v/v) Sg (v/v)
1/Bg
Zone P10 P50 P90 P10 P50 P90 P10 P50 P90 P10 P50 P90
S3 0.95 0.75 0.55 0.35 0.30 0.20 0.70 0.55 0.40 49 47 45
S6 0.95 0.75 0.55 0.35 0.30 0.20 0.70 0.55 0.40 62 60 58
S7 0.95 0.75 0.55 0.35 0.30 0.20 0.70 0.55 0.40 86 84 82
S8 0.95 0.75 0.55 0.35 0.30 0.20 0.70 0.55 0.40 94 92 90

GIIP results - Probabilistic
Main target
Monte Carlo simulation: 20000 runs
Input : P10-P50-P90
GIIP (BCM)
Zone P10 P50 P90
S7 1.68 0.77 0.23
S8 1.89 0.92 0.37
Total 3.57 1.69 0.60
Possibly additional
production from
S3-S6
S3 0.48 0.21 0.06
S6 0.69 0.31 0.09
Total 4.74 2.21 0.75

Conclusions
• F07/F10-P1 is a fairly large, shallow prospect of FDC type
• Partly 3D seismic coverage, additional 3D data available 2012
• Several bright, stacked levels
• 8 bright levels mapped (S1-S6: 350-550 m, S7-S8: 750-850 m)
• S3, S6 possibly similar to A12-FA sands
• S7, S8 possibly similar to F02a-B-Pliocene sands
• Velocity pull down of S7-S8 indicates gas at shallower depths

Conclusions
• Seismic-to-well-tie for S1-S5 difficult due to quality and availability of
log data (case hole logging)
• In Monte Carlo probabilistic GIIP calculation uncertainties included
• P50-P10 GIIP: 1.7 – 3.6 BCM
• P50-P10 upside GIIP: 2.2 – 4.7 BCM

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