U. S. DEPARTMENT OF THE INTERIOR
U.S. GEOLOGICAL SURVEY
| APPENDIX
A - contniued |
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| Date:
28 May 1998
Assessment Geologist: Michele L. Tuttle, Michael Brownfield, Ronald Charpentier Region (name, no.): Sub-Saharan Africa/Antartica, Region 7 Province Name: Niger Delta Province Number: 7192 Priority or Boutique? Priority Total Petroleum System (name, no.): Cenozoic Niger Delta, 719201 Assessment Unit (name, no.): Akata Turbidite Reservoirs, 71920102 * Notes from Assessor |
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| CHARACTERISTICS OF ASSESSMENT UNIT | |||||||
| Oil or Gas (<20,000 cfg/bbl oil overall): . | oil | ||||||
| What is the minimum field size? . | 1 mmboe grown (>1mmboe) | ||||||
| (the smallest field that has potential to be added to reserves in the next 30 years) | |||||||
| Number of discovered fields exceeding minimum size: ..... | .Oil: | X | Gas: | ||||
| Established (>13 fields) | Frontier (1-13 fields) | Hypothetical (no fields) | X | ||||
| Median size (grown) of discovered oil fields (mmboe): | |||||||
| 1st 3rd |
2nd 3rd
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3rd 3rd
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| Median size (grown) of discovered gas fields (bcfg): | |||||||
| 1st 3rd |
2nd 3rd
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3rd 3rd
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| Assessment-Unit Probabilities: | |||||||
| Attribute | Probability of occurrence (0-1.0) | ||||||
| 1. CHARGE: Adequate petroleum charge for an undiscovered field >minimum size | 1.0 | ||||||
| 2. ROCKS: Adequate reservoirs, traps, and seals for an undiscovered field > minimum size | 1.0 | ||||||
| 3. TIMING OF GEOLOGIC EVENTS: Favorable timing for an undiscovered field > minimum size | 1.0 | ||||||
| Assessment-Unit GEOLOGIC Probability (Product of 1, 2, and 3): ... ..... . | 1.0 | ||||||
| 4. ACCESSIBILITY: Adequate location to allow exploration for an undiscovered field | |||||||
| > minimum size .. .. .. | 1.0 | ||||||
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| UNDISCOVERED FIELDS | |||||||
| Number of Undiscovered Fields: How many undiscovered fields exist that are > minimum size?: | |||||||
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| Oil fields: .. . ... | ..min. no. (>0) | 10 | median no. | 250 | max no. | 500 | |
| Gas fields: .. .. | ..min. no. (>0) | 4 | median no. | 100 | max no. | 200 | |
| Size of Undiscovered Fields: What are the anticipated sizes (grown) of the above fields?: | |||||||
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| Oil in oil fields (mmbo) .. | ...min. size | 1 | median size | 23 | max. size | 3000 | |
| Gas in gas fields (bcfg): ... | ...min. size | 6 | median size | 60 | max. size | 3500 | |
| AVERAGE RATIOS FOR UNDISCOVERED FIELDS, TO ASSESS COPRODUCTS | |||||||
| (uncertainty of fixed but unknown values) | |||||||
| Oil Fields: | minimum | mean | maximum | ||||
| Gas/oil ratio (cfg/bbl oil) ... | 1000 | 2000 | 3000 | ||||
| NGL/gas ratio (bbl ngl/mmcfg) .... . | 20 | 40 | 45 | ||||
| Gas fields: | minimum | mean | maximum | ||||
| Total liquids/gas ratio (bngl/mmcfg) .. | 50 | 61 | 70 | ||||
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| SELECTED ANCILLARY DATA FOR UNDISCOVERED FIELDS | |||||||
| (variations in the properties of undiscovered fields) | |||||||
| Oil Fields: | minimum | median | maximum | ||||
| API gravity (degrees) . . | 20 | 45 | 60 | ||||
| Sulfur content of oil (%) ... .. | 0.07 | 0.15 | 0.60 | ||||
| Drilling Depth (m) .. . | 800 | 3000 | 6500 | ||||
| Depth (m) of water (if applicable) ... .. | 0 | 1000 | 4000 | ||||
| Gas Fields: | minimum | median | maximum | ||||
| Inert gas content (%) ..... | low | ||||||
| CO2 content (%) ..... | low | ||||||
| Hydrogen-sulfide content(%) ... | low-nil | ||||||
| Drilling Depth (m) .. .. | 800 | 3500 | 6500 | ||||
| Depth (m) of water (if applicable) ... | 0 | 1000 | 4000 | ||||
| ALLOCATION OF UNDISCOVERED RESOURCES IN THE ASSESSMENT UNIT | |||||||
| TO COUNTRIES OR OTHER LAND PARCELS | |||||||
| (uncertainty of fixed but unknown values) | |||||||
| 1. Nigeria represents 94 areal % of the total assessment unit | |||||||
| Oil in Oil Fields: | minimum | median | maximum | ||||
| Richness factor (unitless multiplier): . .. .. | 1 | ||||||
| Volume % in parcel (areal % x richness factor): . | 94 | ||||||
| Portion of volume % that is offshore (0-100%) . | 80 | ||||||
| Gas in Gas Fields: | minimum | median | maximum | ||||
| Richness factor (unitless multiplier): .. .. | 1 | ||||||
| Volume % in parcel (areal % x richness factor): . | 94 | ||||||
| Portion of volume % that is offshore (0-100%) . | 80 | ||||||
| 2. Cameroon represents 2 areal % of the total assessment unit | |||||||
| Oil in Oil Fields: | minimum | median | maximum | ||||
| Richness factor (unitless multiplier): . .. .. | 0.5 | ||||||
| Volume % in parcel (areal % x richness factor): . | 1 | ||||||
| Portion of volume % that is offshore (0-100%) . | 70 | ||||||
| Gas in Gas Fields: | minimum | median | maximum | ||||
| Richness factor (unitless multiplier): .. .. | 0.5 | ||||||
| Volume % in parcel (areal % x richness factor): . | 1 | ||||||
| Portion of volume % that is offshore (0-100%) . | 70 | ||||||
| *Uncertainty about this mean will be calculated using statistical methods | |||||||
| 3. Equitorial Guinea represents 4 areal % of the total assessment unit | |||||||
| Oil in Oil Fields: | minimum | median | maximum | ||||
| Richness factor (unitless multiplier): . .. .. | 0.8 | ||||||
| Volume % in parcel (areal % x richness factor): . | 3.2 | ||||||
| Portion of volume % that is offshore (0-100%) . | 100 | ||||||
| Gas in Gas Fields: | minimum | median | maximum | ||||
| Richness factor (unitless multiplier): .. .. | 0.8 | ||||||
| Volume % in parcel (areal % x richness factor): . | 3.2 | ||||||
| Portion of volume % that is offshore (0-100%) . | 100 | ||||||
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