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Lesson-12Reserve and Resource
Estimation
Edi B. Setyobud i2014
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Further Readings
Tearpock, D.J. & R.E. Bischke, 1991
“Applied Subsurface Geological Mapping” –
Chapter 14
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How to Phantom Down
Formation Top =
Seismic Marker
Reservoir Top
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Maps Needed
Structure Maps
Thickness Maps:
Isopach (Isochore) Map
Isochron Map (seismic time interval)
Other Maps:
Porosity Map
Net / Gross Ratio Map
Etc
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Gross – Net Thickness and Net Pay
Gross Thickness:
Formation / member
Zone
Reservoir (sand / carbonate / others) Net Thickness:
Portion of the thickness that porous and permeable – eg
above cut-offs
Net Pay:
Portion of Net thickness that contains producible
hydrocarbon – eg above saturation cut-offs
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Gross – SandThickness - Ratio
Formation thickness:• Well A – 605’
• Well B – 701’
Gross sand thickness:
• Well A:• Sand-1 – 99’
• Sand-2 – 101’
• Sand-3 – 103’
• Well B:
• Sand-1 – 102’ • Sand-2 – 151’
• Sand-3 – 129’
Well A Well B
Sand – Shale Ratio: Well A: 303’ / 605’ = 0.50
Well B: 382’ / 701’ = 0.54
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Any special purpose map such as Sand Shale Ratio Map,
Porosity Map – you name it – can be generated
Formation Thickness Map - Isochore
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Net Sand Isochore Map
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Pay Thickness
Pay –
portion of
reservoir
that
containsproducible
hydrocarbon
• Net oil• Net gas
Phantoming down – use gross thickness map
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Bottom and Edge Water
Bottom Water Edge Water
Pay attention to geometry differences
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Bottom Water
Key Components:
• Structure map on top
• Oil Water Contact
Net Pay Map Construction
Very simple task:
• Subtract contour values
with OWC number
• Adjust to net values
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Edge Water Reservoir
Key Components:
• Structure on top
• Structure on base
• Oil water contact
• Net sand thickness
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Key Components:
• Structure on top• Structure on base
• Oil water contact
• Net sand thickness
Edge Water
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Edge Water
Important aspects:
• OWC on top – marksouter limit of oil - blueline
• OWC on base – marks
inner limit of water –inside this line:
net sand = net pay – redline
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Edge Water - Detail Procedure-1
1. Draw depth structure
map on top reservoir –
mark OWC – blue line
2. Draw depth structure
map on base reservoir
– mark OWC – red line
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3. Take net sand isochore
map – draw OWC on
base (red line)
4. Remove contour
outside the circle
5. Draw OWC on top(blue line)
Edge Water - Detail Procedure-2
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Edge Water - Detail Procedure-3
6. Connect contour
lines – start from
thickest part
7. Complete thecontour lines as
necessary
8. Planimeter the map
to calculate net oil
sand volume
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Edge Water Reservoir – Oil and Gas
GASGAS / OIL
CONTACT
Key Components:• Structure on top
• Structure on base
• Oil water contact
• Gas oil contact
• Net sand thickness
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1. Draw depth structure map
on top reservoir – mark
OWC – blue line and GOC – red line
2. Draw depth structure map
on base reservoir – mark
OWC – green line andGOC – brown line
Edge Water Reservoir – Oil and Gas:
Detail Procedure-1
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Edge Water Reservoir – Oil and Gas:
Detail Procedure-2
3. Take net sand isochore
map – draw GOC on base
4. Remove contour outside
the circle
5. Draw GOC on top
6. Connect contour lines –
start from thickest part
7. Complete the contour linesas necessary
8. Net gas pay map done
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Edge Water Reservoir – Oil and Gas:
Detail Procedure-3
9.Draw:OWC on top (blue),
OWC on base (green),
GOC on top (red),
GOC on base (brown)
Note:
• area between OWC
on base and GOC on
top – full net sand
thickness
• Area inside GOC on
base – no oil zone
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10. A) Overlay NetSand Map
Edge Water Reservoir – Oil and Gas:
Detail Procedure-4
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10. B) Remove contourlines outside full netsand thickness
Edge Water Reservoir – Oil and Gas:
Detail Procedure-5
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Edge Water Reservoir – Oil and Gas:
Detail Procedure-6
11. Complete contour
lines as necessary
Final products:
• Net gas pay
• Net oil pay
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Rock Volume Calculated Slice by Slice
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Rock Volume Slices (Vb)
Trapezoidal
Pyramidal
Where:
• An = area of one contour
• An+1 = area of the next contour
• h = contour interval
Note: if An/An+1 > 0.5 use Trapezoidal
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Calculate Reservoir Volume
• Add all slices from
bottom up
• Never miss the
volume of crestal
point
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Initial Hydrocarbon In Place
Symbol Remarks IHCIP Initial hydrocarbon in place
Resv Volume Reservoir volume
Ф
Porosity
(1 – Sw) Hydrocarbon saturation
FormationVolume Factor
Ratio of HC in reservoir vs atsurface
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Thanks for your
kind attention
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