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Computer Simulation of Hydrocarbon Generation, Migration, and Accumulation under Hydrodynamic Conditions -- Examples from the Williston and San Juan Basins, USA*

By

Fred F. Meissner1 and Richard B. Banks2

 

Search and Discovery Article #40179

Posted November 10, 2005

 

*Oral Presentation at AAPG International Conference and Exhibition, October 15-18, 2000, Bali, Indonesia

 

1Colorado School of Mines, Golden, CO

2Scientific Computer Applications, Inc, Tulsa, OK (dbanks@scaitul.com)

 

Abstract 

We have developed a PC-based program that uses basic data to identify and map an area of source rock maturity and the volumes of oil or gas it may generate, map secondary migration routes for generated hydrocarbons under hydrodynamic conditions, and predict the areas and volumes of hydrocarbon accumulation along a migration path.

 

Input data required for mapping the area of source rock maturity and generation volume includes kerogen type, organic carbon content, source rock thickness, kerogen transformation ratio, and amount of hydrocarbons retained in the source rock. Contour maps of these data are generated and integrated on the PC.

 

Input data required for mapping secondary hydrocarbon migration paths within a carrier/ reservoir unit charged by a mature source rock include datum elevations on top of the reservoir, pressure data, and reservoir fluid densities. Structure and groundwater potentiometric surface maps may be modified by a fluid density controlled "tilt amplification factor" to create "phantom" hydrocarbon-water contact (HWC) datum elevation contour map. The intersection of contours on the structure and phantom HCW maps may be used to create contours of equal hydrocarbon potential energy that control migration paths and sites of potential entrapment.

 

 

uAbstract

uTechnique

  uData used

  uPrimary contour maps

  uBasic relations

uWilliston Basin

  uFigures 1-12

  uBakken Shale

  uHC potential

  uOil generated

  uOil expelled

uSan Juan Basin

  uFigures 13-19

  uHubbert’s relation

uSummary

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

uAbstract

uTechnique

  uData used

  uPrimary contour maps

  uBasic relations

uWilliston Basin

  uFigures 1-12

  uBakken Shale

  uHC potential

  uOil generated

  uOil expelled

uSan Juan Basin

  uFigures 13-19

  uHubbert’s relation

uSummary

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

uAbstract

uTechnique

  uData used

  uPrimary contour maps

  uBasic relations

uWilliston Basin

  uFigures 1-12

  uBakken Shale

  uHC potential

  uOil generated

  uOil expelled

uSan Juan Basin

  uFigures 13-19

  uHubbert’s relation

uSummary

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

uAbstract

uTechnique

  uData used

  uPrimary contour maps

  uBasic relations

uWilliston Basin

  uFigures 1-12

  uBakken Shale

  uHC potential

  uOil generated

  uOil expelled

uSan Juan Basin

  uFigures 13-19

  uHubbert’s relation

uSummary

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

uAbstract

uTechnique

  uData used

  uPrimary contour maps

  uBasic relations

uWilliston Basin

  uFigures 1-12

  uBakken Shale

  uHC potential

  uOil generated

  uOil expelled

uSan Juan Basin

  uFigures 13-19

  uHubbert’s relation

uSummary

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

uAbstract

uTechnique

  uData used

  uPrimary contour maps

  uBasic relations

uWilliston Basin

  uFigures 1-12

  uBakken Shale

  uHC potential

  uOil generated

  uOil expelled

uSan Juan Basin

  uFigures 13-19

  uHubbert’s relation

uSummary

 

 

 

 

 

 

 

 

Technique and Advantages 

  Technique allows use of primary contour maps to generate secondary maps.

  Primary maps may come from disparate data from different locations or sources.

  One can use published contour maps for which no primary supporting data are available.

 

Data Used to Generate Primary Maps 

      Source Rock Data:

  Total Organic Carbon (TOC), Thickness, Kerogen Type, Maturity (Ro), Transformation Ratio, Solvent Extractables 

      Structural Data 

      Hydrodynamic Data

  Pressures or Hydraulic Heads

  Fluid Densities

 

Primary Contour Maps 

      Total Organic Carbon (TOC)

      Thickness

      Maturity (Ro)

      Fraction Of Ultimate Generation (Transformation Ratio)

      Non-expelled HCs

      Structure Map

      Potentiometric Surface Map In Reservoir/carrier

 

Basic Relations 

 

Vg= A*T*TOC*Q*F

 

WHERE

  Vg  = Volume Of Generated HCs 

    A  = Area, Acres

    T  = Thickness, Feet

TOC = Total Organic Carbon, Fraction

    Q  = Ultimate Yield, Bbl/acre-foot

           -Function of Kerogen Type

    F = Ultimate Generation

          -Function of Source Rock Maturity (Ro)

 

Ve = Vg - Vne 

WHERE

Ve  = Volume of Expelled HCs

Vg  = Volume of Generated HCs

Vne = Volume of Non-Expelled HCs

 

Volumes calculated by computer contouring and integration.

 

Williston Basin (Madison- Bakken Oil System) (Figures 1-12)

Figures 1-12

Figure 1. Data source.

Figure 2. Kerogen type and ultimate generation capacity at Ro 1.4.

Figure 3. Source rock net thickness.

Figure 4. Total organic carbon.

Figure 5. TOC * net thickness.

Figure 6. Ultimate HC generation potential. Contours in Bbl/AC.

Figure 7. Maturity (Ro) and fraction of ultimate generation.

Figure 8. Present day generation, BBL/AC.

Figure 9. Ro vs extractable HCs.

Figure 10. Ro vs fraction of ultimate generation.

Figure 11. Volume of HCs retained, Bbl/AC.

Figure 12. Area of Madison/Bakken oil fields.

 

Click to view sequence of Williston Basin maps (Figures 3-8, 11).

 

Bakken Shale

 

With Bakken Shale as source rock, Type II oil-generating kerogen yields 3200 Bbl/acre-foot (Figure 2).

 

Ultimate HC Generation Potential

Gross Area (AC)                                  =            25,000,000

Gross Volume (AC/FT)                        =          603,000,000

Net Volume (AC/FT)               =                        25,000,000

 

25,000,000 * 7758 * 3200/7758=80 Billion Barrels

 

Amount of Generated Oil 

Present day volume of oil generation is 32 billion barrels.

 

Amount of Oil Expelled  

Volume of expelled oil is 28.8 billion barrels.

 

San Juan Basin (Mesaverde Gas System)

Figures 13-19

Figure 13. Data source.

Figure 14. Relation of potentiometric surface to HC-W contact

Figure 15. Structure contour map, top of Mesaverde.

Figure 16. Groundwater potentiometric surface map.

Figure 17. Gas potentiometric map.

Figure 18. SW-NE cross section.

Figure 19. NW-SE cross section.

Click to view sequence of San Juan Basin maps (Figures 15-17). 

Hubbert’s Relation: Potentiometric Surface to HC-Water Contact           

DX/DY = TAF X DX/DZ

WHERE

TAF =            water density           
            water density – HC density

 BASIC RELATION:

PEhc = TME - SE

WHERE

      PEhc = Potential energy factor for HC

      TME = Tilt Map* contour elevation

      SE = Structure map contour elevation

 

Summary and Conclusions

Computer assisted intercept solutions for contour maps of certain key parameters may be used to construct maps depicting generation, migration and accumulation patterns and amounts.

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