Reservoir Connectivity and Stimulated Gas Flow in Tight Sands “The Piceance Project”

Rulison Field, Piceance Basin

It is becoming more important than ever to know the facts and get them out there to avoid derailing the unconventional natural gas industry the way the nuclear energy industry was high-jacked and derailed by misinformation in the late

1970s.

Tom Davis photo

Ilya Tsvankin, Paul Sava, Andre Revil, Graham Mustoe, John Berger, Bruce Trudgill, Tom Davis, Piret Plink-

Bjørklund, Jennifer Aschoff and Dag NummedalColorado School of Mines, Golden, CO

Matt Pranter and Paul WeimerUniversity of Colorado, Boulder, CO

Jim Gilman and Reinaldo MichelenaiReservoir.com, Denver, CO

Rex ColeMesa State University, Grand Junction, CO

andMany Excellent Students!

The Piceance Basin Project Team

Bill Barrett Corporation Geology: Image logs (7) through 3000 ft of pay. More that 6000 well logs across the basin

Geophysics: 3D multi-component reflection seismic data set (from 2005) for an area of 25.6 mi2. Microseismic data cross-well tomographic data sets.

Whiting Petroleum 2D VSP surveys, image logs, and thin sections from 70 rotary sidewall cores from the Boies Ranch field in the northern Piceance basin, for a total value of $319,000.2D VSP surveys, image logs, and thin sections from 70 rotary sidewall cores

Seitel - Regional seismic lines

TGS-Nopec, Noble, others – Wireline logs

IHS-Petra, Landmark, Schlumberger – Software support

Project cost-share consortium members – Antero Resources, Bill Barrett, Antero, Berry Petroleum, ConocoPhillips, EnCana, ExxonMobil, Marathon, Noble Energy, Whiting, Williams

Data Donation and Financial Support

The Rock Framework

Tectonic Subsidence Across UT-CO Tied to Farallon Slab Migration

Farallon plate data from Gurnis’ team

Piceance Basin, StructureTop Rollins structure mapTop Rollins structure map

Mike Leibovitz, 2009

Basem ent(Pre-Pennsylvanian)

Cam bian to M ississipian(Leadv ille Lim estones )

P e n n s y l v a n i a nPerm ian -Triassic

Ju rass ic-Dakota

M ancos

M esaverd e G roupTo p C a m e o

To p R o l lin s

M an co s B

Cen ozo ic(Wasatch , G reen River and Uinta Fm s)

0

1 .5

3

0 .5

2

3 .5

1

2 .5

4

0

1 .5

3

0 .5

2

3 .5

1

2 .5

4

The Major Faults, Fluid Pathways

Divide CreekAnticline

Wolf CreekAnticline

• Ancestral Rockies deformation during Pennsylvanian to Triassic.• Erosion at base Jurassic. Local Pennsylvanian to Triassic missing.• Laramide reactivation of Paleozoic structures at Divide Creek.• Upper Mancos shale is the basal detachment for Wolf Creek Anticline.

NWSE

Tim

e (S

ec. T

WT

T)

Cozzette Mbr. of Iles Fm.

Top Cozzette Mbr. MancosParasequences

Waypoint 028

Rollins Ss. Mbr.

MancosTongue

Cozzette Mbr.

Cameo-Wheeler CZ

Middle Ss. Mbr.South Cyn. CZ

Upper Ss. Mbr.

Coal Ridge CZ

WasatchFormation

Mancos Shale

“Ohio Creek Interval”

(Dunrud, 1989)

Wil

lia

ms

Fo

rk F

orm

ati

on

Cozzette Mbr.

Undifferentiated

Ile

s F

m.

5,500 Ft

5,000

4,500

4,000

3,500

3,000

2,500

2,000

1,500

1,000

500

6248

Lo

we

rM

idd

leU

pp

er

Project From Outcrop to Subsurface

Fracture Analysis and DFN Modeling

Fracture Intensityand Lithology

+

Fracture Dip Angle and Dip Azimuth

DFN (discrete fracture network) model

Scale up fracture properties

Ki

Kj

Kk

The Fluid Flow

Hydraulic Fracture• Fracture mechanics is traditionally focused on preventing brittle

fracture• Oil and natural gas industry began commercially creating and

extending fractures to stimulate production in 1949 (Howard SPE 1970)

• Aims to increase the exposure of the well to the surrounding formation and provide channels for increased production

CHALLENGES (Shlyapobersky et al. SPE 1994)1. What fracture mechanisms take place

in hydraulic fracturing and how these mechanisms are affected by the rate of injection

2. How rock heterogeneity (inclusions,micro cracks, formation layers,etc.) affect fracture initiation

3. How porous properties of rock affect fracture mechanisms

Rock Fracture Modeling

INPUTS Material

Composition System Geometry Constituent

Properties Volume Fractions Layer Thicknesses Porosity (void freq.

& geometry) Confining Pressure Overburden

Pressure

OUTPUTS Effective

Mechanical Properties

Material Failure Strengths

Effective Material Strength

Failure Modes Fracture Initiation Predictive Tool

30-Year for Several 25 ft Intervals

Recovery after 30 years, “optimal” hydraulic fractures, 25~30 ft thickness

Hydraulic Fracture Orientation

30o

Zone 1 Big Kahuna

Paonia Zone 5

Some Things We Don’t Know1. In a recent poll of petroleum engineering professionals, 80% stated that they do

not really know where in the reservoir they are actually draining the gas from! This can be viewed as pretty scary, or as a positive indication that there is a lot of upside potential for increased gas production from tight sands.

2. The data in this poll are also pretty consistent with statements from several professionals in the service industry that in many cases more than 80% of the production comes from 20% of the well bore stimulation. This also seems scary, but it is also another indicator of the potential for cost reductions, increased flow, or both.

3. Several sophisticated reservoir modelers in some of the world’s most advanced companies harbor great uncertainties as to whether pore scale flow or fractures control most of the gas flow. High fracture densities actually work against gas production, because the fractures primarily increase water production – not gas. Many big fractures also end up being filled with drilling mud and cement – with big production losses.

4. There are big problems with the concept of “heterogeneity” of reservoirs. The choice of wording sends the message to a wide section of the industry community that the distribution of good quality reservoir rocks and sealing rocks is sort of random. That is not how the sedimentary rock record is built. There is a great deal of order. The very concept behind sequence stratigraphy has articulated this order. Not used much.

From CSM workshop, Oct. 22, 2010

Proposed Next RPSEA PhaseSubsurface Characterization Laboratory

• Inspired by 1980s MWX experiments• Several closely-spaced wells in Piceance basin

– from surface to base Mancos Shale• Drilling, stimulation and completion experiments• Geophysical monitoring (some permanent)• Open first for sponsors (RPSEA, majors and

independents) – in the long run for everyone• Major field research site for CSM faculty and

students and Colorado partner institutions