06b intensity pt1

8/12/2019 06b Intensity Pt1

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Determining Optimum Well

Locations & Well Paths

Predicting or delineating fracture sweet

spots with high fracture intensity and/or

good connectedness

Predicting or delineating dominant open

fracture direction to plan deviated well

paths to encounter the best fractures Plan well paths that optimize fracture &

matrix properties


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Mechanical Stratigraphy

Subtle changes in rock character

(petrologic & petrophysical) control rock

deformation. Variations in deformation type and

intensity mimic subtle changes in rock

character.

Nelson (1985)


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Mechanical Predictions

Relative rock strength can be used to

predict fracture intensity.

Stronger rocks generally contain closer

spaced fractures.

Above usually works because most

shallow reservoir rocks are brittle &show little variation in stain at failure.

(fracture toughness)Nelson (1985)


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Composition

Rocks composed of predominately strong

and brittle components are stronger and

generally contain closer spaced fractures

Nelson (1985)


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Sun (2001)

Fracture Intensity as a Function of Rock Type (Mechanical Properties)

Cooper & Wharbaton Basins,

S. Australia


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Strength vs Composition

Dev. Antrim Sh

Michigan BasinStrength increases with

% brittle minerals

Nelson (1985)


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Rock Properties vs Depth, Texaco 17#2

0

2

4

6

8

10

12

14

16

17200 17300 17400 17500 17600 17700 17800 17900 18000 18100

Depth, ft

RockProperty

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

Young's Mod. E06psiPoisson's Ratio

Youngs Modulus and Poissons Ratio

Logs for a Well in the Permian Basin


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Porosity

Lower porosity rocks are stronger and

more brittle and generally contain closer

spaced fractures

Nelson (1985)


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Nelson (1985)


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Ward (1987)

Fracture Intensity vs Porosity

Ls, Tectonic Fracures


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All Fracture Intensity vs AH Depth, MOW-4 Core

0

0.5

1

1.5

2

2300

2400

2500

AH Depth, m

A

llFractureIntensity,

#/0.5m

Fracture Intensity Curve

(core based, 89% cemented)

SS Carb

MFI = 0.483 MFI = 1.003


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Fracture Intensity vs Porosity with Depth, MOW-4 Core

0.0

5.0

10.0

15.0

20.025.0

30.0

35.0

76

00

76

50

77

00

77

50

78

00

78

50

79

00

79

50

80

00

80

50

81

00

Measured Depth, ft

WholeCorePor

osity,

%

0

0.2

0.4

0.6

0.81

1.2

1.4

AllFractureInte

nsity,

#/0.5

ftPorosity, %

FIC, #/0.5 ft

Inverse Relationship Between Porosity &

Fracture Intensity


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Grain Size

Finer grained rocks are generally stronger

and more brittle and generally contain

closer spaced fractures

Nelson (1985)


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Strength vs Grain Size, Navajo Ss

Nelson (1985)


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Ward (1987)

Fracture Intensity vs Grain Size

Ls, Carbonates


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Bed Thickness

For bed-contained fractures, closer

spaced fractures in thinner beds

Nelson (1985)


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After Sowers (1970)

Fracture Spacing vs Bed Thickness


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06b intensity pt1

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