Integrated 3D Geological Model of the Mississippian Devonian Bakken Formation, Elm Coulee, Williston Basin: Richland County, Montana

Transcription

1 Integrated 3D Geological Model of the Mississippian Devonian Bakken Formation, Elm Coulee, Williston Basin: Richland County, Montana Adrian Almanza Colorado School of Mines

2 Outline Location Stratigraphy Petrophysics DSTs and Production Fractures Conclusions

3 Data ~400 digital logs from TGS 4 cores with porosity, permeability and XRD analysis: Jackson Rowdy, Lonetree, Foghorn, Brutus 2 cores previously examined by the CSM consortium with porosity and permeability: Vaira, Williams IHS production data for the Elm Coulee field

4 Elm Coulee Montana North Dakota Contours on top of Bakken Shale Elm Coulee located in Richland County, Montana Location of digital logs and cored wells

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6 Cross Sections F G F G

7 Structural Cross Section S N Bakken Three Forks Bird bear F F

8 Structure Map: Top Bakken

9 Stratigraphic Cross Section S N G G G

10 Thickness Map: Middle Bakken

11 3D Geological Structural Model Bakken Lodgepole Three Forks

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13 Lone Tree Edna (From Alexandre 2011) Porosity: 9.3% Permeability: md

14 Brutus Bulk Density and XRD Cross Plots Average Rhob Dolomite: 2.66 Average Rhob Calcite: Rhob vs XRD Dolomite % 2.75 Rhob vs XRD Limestone% % % 70

15 Lone Tree Edna Bulk Density and XRD Cross Average Rhob Dolomite: 2.63 Plots 2.75 Rhob vs XRD Dolomite % The cross plots indicate that reservoir facies have an average bulk density of The cross plots indicate that calcite has an average bulk density of Dolomite has a specific gravity of % 37.5% 75%

16 Average Bulk Density Well spots Production >250,000 bbls

17 Porosity Map Well spots Production >250,000 bbls Average porosity (PHIA) calculated from density porosity and neutron porosity logs.

18 SoPhiH Map SoPhiH Map Calculated from: -Average porosity (PHI) -Oil saturation (So) -Gross pay (H) Sw n Rw m Rt Rw=0.015 Rt=ResD n=1.74 m=2 ɸ=Average porosity

19 CSM_B Facies Porosity vs Permeability 1 Foghorn_CSM_B y = ln(x) R² = Lonetree_CSM_B Foghorn_CSM_B 0.1 y = ln(x) R² = Log. (Foghorn_CSM_B) 0.01 Foghorn_CSM_B Average Permeability Average Permeability Brutus_CSM_B Jackson_Rowdy_CSM_B y = ln(x) R² = Brutus_CSM_B 0.1 y = ln(x) R² = Jackson_Rowdy_CS M_B Average Permeability Average Permeability

20 Porosity % Middle Bakken Core Data Core Data y = ln(x) R² = Core Data Log. (Core Data) Permeability (md)

21 Porosity and Permeability Curves 2 n d exp( ) 1.109

22 Porosity and Permeability Middle Bakken porosity: Minimum= 0% purple Maximum= 8% yellow Middle Bakken permeability: Minimum= md purple Maximum= 0.1 md red

23 Net Pay (ft) Net Pay vs EUR 18 Net Pay vs EUR y = 2E-05x R² = High pay should relate to high recovery. This would produce a proportional tend with pay vs. EUR EUR (BBLS)

24 Production Data Production data is gathered from IHS and used to generate first year cumulative production, and expected ultimate recovery (EUR) maps. EUR vs net pay cross plot shows a poor correlation.

25 Drill Stem Tests Well Pressure Gradient (psi/ft) DST Perm (md) Core Perm (md) Parsons n/a 62 Drainage (ft) Several wells in Elm Coulee had DSTs, however only 4 showed sufficient build-up curves to extrapolate pressure data. The build-up curve geometry can indicate the permeability of the reservoir. DST permeability is an order of magnitude higher than core permeability. Sorenson Vaira Bahl

26 First Year Cumulative Production

27 Williston Basin Fracture Orientations Sonnenberg,S., LeFever, J., Hill,R. 2011

28 Elm Coulee Fracture Orientations Micro-seismic results indicated a NE-SW fracture orientation for both wells. A: Plan view results B: Area view with stream orientations D.O Brien,R. Larson et all; SEP,2011

29 First Year Cumulative Production with Trend Micro Seismic

30 Conceptual Fracture Model Orthogonal fracture fabric ~2500 ft. Spacing Elm Coulee Field Regional fracture swarm trend influenced by basement lineaments ~25,000 ft spacing Maximum Principal stress direction fracture fabric ~1250 ft Spacing

31 Petrel Fracture Model +

32 Fractures Production data was used to identify fracture trends. Used stress directions in literature to influence production data and highlight fracture swarms. EUR production data shows a correlation with matrix and fracture sweet spots.

33 Cumulative Production >6% porosity + fracture swarms Production_GT_ >500,000 Production_GT_ >400,000 Production_GT_ >300,000 Production_GT_ >200,000 Production_LT_ <100,000

34 EUR Oil (BBLS) EUR s Elm Coulee Wells P90 P50 P10 Sweet Spots >6% Porosity <6% Porosity P90-P50-P10 Fit P90-P50-P10 Fit P90-P50-P10 Fit Expon. (Sweet Spots) Log. (<6% Porosity) Expon. (<6% Porosity)

35 P90-P50-P10 EUR for Trends P90 P50 P10 Mean EUR Median EUR Cumulative EUR # of Wells >6% porosity + fracture swarms >6% Porosity fracture swarms 120, , , , ,000 32,000, , , , , ,000 58,000, <6% Porosity 35,000 95, , , ,000 40,000, All Wells 46, , , , , ,000,

36 Matrix Model + Fracture Model + + Dual porosity model =

37 Future Work Test the geologic model in a reservoir simulation. Geochemistry study to better understand dolomitization in the Bakken. 3D seismic study to identity fractures in Elm Coulee. Reservoir study to determine the contribution of fracture reservoir properties.

38 Conclusions Diagenesis via dolomitization played a critical role in creating reservoir producing porosity and permeability. First year cumulative production data was the key factor to locate production sweet spots and derive regional fracture swarms. Sweet spots are a located where fractures are present and matrix properties are favorable. Whole core porosity and permeability measurements would probably be a better approach in understanding reservoir quality and performance.

39 Colorado School of Mines Bakken Consortium Mike Johnson Consulting Geologist

40 Back ups

41 Porosity vs Permeability Lonetree Jackson Rowdy POROSITY MAX K POROSITY MAX K UBKKNS CSM C UBKKNS CSM C CSM B CSM A TRFKS CSM B CSM A LBKKNS TRFKS

42 Elm Coulee Fracture Orientations Micro-seismic results indicated a NE-SW fracture orientation for both wells.

43 Production 2 wells with production Elm Coulee production and spatial distribution Brutus: Cumulative oil 25,000 bbls Cumulative water 29,581 bbls Foghorn: Cumulative oil 92,000 bbls Cumulative water 10,856 bbls

44 Elm Coulee EUR + SoPhiH

45 Core + XRD Jackson Rowdy Lonetree Foghorn Brutus

46 IP Sweet Spots and Operators

47 First year Cumulative OIL First Year Cumulative Production Burlington Continental Enerplus EOG Newfield Petro-Hunt Slawson SM XTO First Year Prod API

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