optimizing well spacing and completions in the bakken/three forks plays

An Analytic Approach to Optimizing Well Spacing and Completions in the Bakken/Three Forks Plays M. Roth, M. Roth, C. Rodriguez 2014

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How can Analytics help optimize field development?

Analytics Impact: - Vertical sweetspots - Lateral sweetspots - Well spacing optimization


Major Bakken/Three Forks Producing Wells

Mean IP 666 b/d Maximum IP > 7000 b/d Daily > 800,000 b/d - >1% World 7.3 Billion barrels technically recoverable (USGS-04/13)

• ~6,000 producing Middle Bakken and Three Forks wells • Most development consists of infill wells in the Middle Bakken and Three Forks formations • Operators are expanding drilling programs to multiple benches (levels) of the Three Forks • Optimizing oil recovery depends on optimizing well spacing for reservoir quality


Williston/Bakken-Three Forks Stratigraphy


Paleo-Williston/Bakken-Three Forks


Bakken/Three Forks

9800

9900

10000

Lodgepole

U Bakken Shale

Middle Bakken

L Bakken Shale

Three Forks

50’


Braaflat 11-11H Lithofacies – Cluster Analysis


Braaflat 11-11H Lithofacies – Cluster Analysis

Primary Target

4 - fine ss, siltstone, mudstone

3 - medium-grained ss

CBF - very fine-grained ss, siltstone

2 - limy/dolomitic siltsonte

1 - lime mudstone


Bakken/3-Forks Hierarchical Facies Classification


Three Forks Benchs


West-East Traverse through Verticals


Traverse Flattened Top Upper Bakken

Middle Bakken

Three Forks


Base Bakken Surface – Across Borders

MONTANA

CANADA

NORTH DAKOTA

Nesson Anticline


Regional Mapping (Bakken/Three Forks)

Depth Thickness Thermal Maturity

Total Organic Carbon Upper Bakken

Oxygen Index Total Organic Carbon Lower Bakken


Hierarchical Map-Based Classification



But how much can Sweetspots be Drilled?



Is there Bakken/Three Forks Interaction?



45 bbl/d increase

100 bbl/d increase

90 bbl/d increase



45 bbl/d increase

100 bbl/d increase

90 bbl/d increase

TTT Ranch 11-6H TTT Ranch 12-6H

TTT Ranch 11-6H TTT Ranch 12-6H


There IS Bakken/Three Forks Interaction!

45 bbl/d increase

100 bbl/d increase

90 bbl/d increase

TTT Ranch 11-6H TTT Ranch 12-6H TTT Ranch 4-6TFH

TTT Ranch 11-6H TTT Ranch 12-6H TTT Ranch 4-6TFH


What is the optimal well spacing to use? Production Profile Comparison Production Analytics Microseismic Analysis


Oil Production Profile Comparison

#1 Rick Clair 25-36H Spacing = 10,000ft Open Hole #2 Myhra 28-33H Spacing = 4,432ft 9 Stages #2 Chad Alan 25-36H Spacing = 1,830ft Open Hole #2 Craft 27-34H Spacing = 4,067ft 9 Stages #2 William Richard 35-26H Spacing = 2,438ft Open Hole #6 Joy 26-35H Spacing = 2,812ft Open Hole #7 TTT Ranch 33-28H Spacing = 1,760ft 30 Stages #8 TTT Ranch 34-27XH Spacing = 1,629ft 23 Stages #9 Lucas 36-25H Spacing = 1,187ft 37 Stages #10 Katherine Mariah 26-35H Spacing = 1,273ft 37 Stages


Daily Oil Production Rates

#1 Rick Clair 25-36H Spacing = 10,000ft Open Hole #2 Myhra 28-33H Spacing = 4,432ft 9 Stages #2 Chad Alan 25-36H Spacing = 1,830ft Open Hole #2 Craft 27-34H Spacing = 4,067ft 9 Stages #2 William Richard 35-26H Spacing = 2,438ft Open Hole #6 Joy 26-35H Spacing = 2,812ft Open Hole #7 TTT Ranch 33-28H Spacing = 1,760ft 30 Stages #8 TTT Ranch 34-27XH Spacing = 1,629ft 23 Stages #9 Lucas 36-25H Spacing = 1,187ft 37 Stages #10 Katherine Mariah 26-35H Spacing = 1,273ft 37 Stages


Daily Oil Production Rates (Relative Time) #1 Rick Clair 25-36H Spacing = 10,000ft Open Hole #2 Myhra 28-33H Spacing = 4,432ft 9 Stages #2 Chad Alan 25-36H Spacing = 1,830ft Open Hole #2 Craft 27-34H Spacing = 4,067ft 9 Stages #2 William Richard 35-26H Spacing = 2,438ft Open Hole #6 Joy 26-35H Spacing = 2,812ft Open Hole #7 TTT Ranch 33-28H Spacing = 1,760ft 30 Stages #8 TTT Ranch 34-27XH Spacing = 1,629ft 23 Stages #9 Lucas 36-25H Spacing = 1,187ft 37 Stages #10 Katherine Mariah 26-35H Spacing = 1,273ft 37 Stages

The first well, with older completion technique, still one of the best producers which could be due to not having to compete for production

With the high variability of engineering and completions, direct comparison of decline curves is misleading. Differences in engineering and completions must be normalized out to isolate the impact of well spacing on production


Production Normalization Long wells bad?

-0.011 Correlation

0.237 Correlation

In order to understand the relationship between well spacing and production, the production must first be normalized None of the engineering or completion attributes have higher than a 0.26 correlation with 6 month oil production Because of the low correlations of individual engineering/completion parameters with production, the production cannot be normalized using a single attribute Production must be normalized by the combination of key engineering and completions parameters


Middle Bakken Geology: Water Cut

Regional water cut shows geologic “sweetspots” that are driving improved performance To understand the impact of well spacing, the influence of the geology, the production must be normalized for the regional geology in addition to the engineering and completions variability

-.450 Correlation

6 M

onth

Cum

ulat

ive

Oil

Prod

uctio

n (b

bl)

Regional Water Cut Map

Water Cut


Multi-Variate 6 Month Cum Oil Model

0.709 Correlation

Pred

icte

d 6

Mon

th C

umul

ativ

e Pr

oduc

tion

Using a non-linear, multi-variate technique, the 6 Month Cumulative Oil production was modeled using a combination of key engineering, completions, and geologic attributes: • Horizontal Length • Stage Spacing (Length/#Stages) • Proppant per Length • Water Cut • Average Well Spacing at the time of well first production The resulting model has a 0.709 correlation coefficient between actual and prediction production

Actual 6 Month Cumulative Oil Production (bbl)


Multi-Variate Parameter Transformations

Multi-variate model determines relationships between each input variable and production The relationships for well length, stage spacing, proppant per foot, and water cut are used to normalize the production and isolate the impact of well spacing on production Well spacing relationship indicates: • Wells begin seeing the effects of well spacing at 1,200ft • For an average engineered well in average geology, the impact of decreasing spacing from 1,200ft to 800ft is a 15% decrease in 6 Month Oil


What is the optimal well spacing to use?

The well spacing relationship was simulated for differing completion designs to estimate how the effects of well spacing relate to completions The effects are well spacing are predicted to be lessened by increasing the number of stages and the amount of proppant


Microseismic Event Analysis

Surface microseismic data acquired by the DOE for a Middle Bakken well with 6 hydraulic fracture stages


Microseismic Energy Density

Based on microseismic magnitude and event density, a geocellular model of microseismic energy can be created Higher microseismic energy should correlate to greater fracture conductivity


Stimulated Reservoir Volume Estimate

Stimulated reservoir volume can be estimated based on the extents of the microseismic energy Based on the extents of high energy density, the stimulated reservoir volume appears to have an average half-width of 600ft


Stimulated Reservoir Volume Overlap

Assuming Stimulated Reservoir Volume Half- Width = 600ft Neighboring Middle Bakken well spacing: 1,500ft Stimulated Reservoir Volume Overlap = 0%



Assuming Stimulated Reservoir Volume Half- Width = 600ft Neighboring Middle Bakken well spacing: 800ft Stimulated Reservoir Volume Overlap = 33%


Summary (part 1)

The Bakken/Three Forks petroleum system currently produces over 1% of World oil, with an estimated 7.3 Billion barrels recoverable • The Middle Bakken and multiple benches of the Three Forks are viable but not isolated producing zones • Optimizing oil recovery in the Middle Bakken and Three Forks petroleum system depends upon optimizing well spacing • Direct comparisons of decline curves and crossplots of data can be misleading and should be augmented by more advanced analytical techniques


Summary (part 2)

• Multi-variate analytics can normalize the impact of variable completions and geology to isolate well spacing relationships

•Based on regional analysis of Middle Bakken wells, decreasing spacing from 1,200ft to 800ft appears to reduce well performance by 15 to 25% •Outside of 1,200ft spacing, Middle Bakken wells do not display negative effects on production •Effect of decreasing well spacing is less for more modern completions (more stages and proppant) than for older completions

• Microseismic stimulated reservoir volume half-widths of 600 ft supports 1,200 ft spacing to avoid negative effects on production • Well spacing decisions must be made based on economics, but can be better guided using advanced statistical techniques


Thanks!

•DrillingInfo for access to production and well data and Transform Software •Peter Emanuel for specialized programming •North Dakota Industrial Commission

optimizing well spacing and completions in the bakken/three forks plays

Technology

middle bakken

middle bakken

forks interaction

ttt ranch

respective

rights reserved

east traverse

multiple benches