Optimized Recovery from Unconventional Reservoirs: How ... · Shale Gas Production Analysis...
Transcript of Optimized Recovery from Unconventional Reservoirs: How ... · Shale Gas Production Analysis...
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Optimized Recovery from Unconventional Reservoirs: How Nanophysics, the Micro-Crack Debate, and Complex Fracture Geometry Impact Operations
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Salt Lake City | Bratislava | Calgary | Houston | Jammu | London | Sydney
~120 EGI Staff & Affiliated Scientists
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Large
Small
Fast
Slow
Rasoul Sorkhabi | Global Systems
Michal Nemčok | Orogenic Systems
Lansing Taylor | Prospect- to Seismic-scale Structure
John McLennan | Reservoir Geomechanics
Ian Walton | Well-bore Geomechanics
Milind Deo | Pore to Nano-scale Engineering
2 New Books
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• Near Wellbore
• Well-to-Well
• Field Development
150 ft
1000 ft
miles
Ne
t p
rese
nt
valu
e
Completion Technology
Ne
t p
rese
nt
valu
e
Pressure Maintenance
Ne
t p
rese
nt
valu
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Spacing / Geometry
Optimized Recovery from Unconventional Reservoirs
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Liquids from Shales
Milind Deo, Ph.D.Professor and ChairChemical Engineering
Palash Panja, Ph.D.Post-Doctoral ResearcherEnergy & Geoscience Institute
• Probability density functions (PDFs)• Obtained using Monte Carlo simulations
kmRsiℓfpiCfdRs/dppwfng
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Oil Recovery from Shales1 yr 10 yrs 20 yrs Economic Rate
5 bbl/d/fracture
*Xf Km Km Km
Km *Xf *Xf Rsi
Rsi Rsi Rsi *Xf
Pi dRs/dp dRs/dp Pi
dRs/dp Pi Pi Cf
*Pwf ng Cf dRs/dp
ng Cf *Pwf *Pwf
Cf *Pwf ng ng
Symbol Property
Km Matrix perm
Xf Hydraulic Fracture spacing
Rsi Initial dissolvedgas oil ratio
dRs/dp Slope of dissolved GOR
Pi Initial pressure
ng Gas rel. perm exponent
Cf Compressibility
Pwf Producing BHP Only 2 of the variables are operationally
controllable parameters
Most important
Least important
Ranking
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Bryony Richards, Ph.D.Senior PetrologistEnergy & Geoscience Institute
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• Pressure – 15,000 psi• Temperature 300oF• High-resolution Volume and
Pressure Measurements
Absolute permeability
1 Day, 200 nD 14 days, 5 nD
Relative permeability
Shale Interrogator
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Manas Pathak, Ph.D.Energy & Geoscience Institute
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rockporerock
Micro
rockporerock
Nano
Surface Interaction
At the Nano-scale, permeability is not a rock property but also depends on fluid-rock interaction
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rockporerock
Nano
rockporerock
Nano
RestrictionMolecular Dynamics
Dro
p b
elo
w b
ub
ble
po
int
Bubble point is suppressed in nano-pores
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Shale Gas Production Analysis
Cumulative production and production rate
where depends on:– Pressures (bhfp, pore or reservoir pressure)– Reservoir quality/ GIP (permeability, porosity)– Gas properties (viscosity, compressibility, equation of state)– Productive fracture surface area
t
CqtCQ
p
p 21,
pC
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0.2
0.4
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1.2
1.4
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pro
du
ctio
nra
te (
bsc
/ye
arf)
time (years)
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200000
400000
600000
800000
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0 1 2 3
cu
mu
lati
ve p
rod
uc
tio
n (
ms
cf)
sqrt(time) years^0.5
Ian Walton, Ph.D.Research ScientistEnergy & Geoscience Institute
Gas Production Model
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• Measure the production coefficient• Estimate pressures, porosity etc• Infer productive fracture surface area
Productive fracture surface area in the Barnett: 1-5 MM sq ft.
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0 100 200 300 400 500
Su
rfac
e a
rea
(MM
sq
ft)
matrix permeability (nD)
Typical Productive Fracture Surface For Barnett Wells
poor producer
average producer
good producer
Estimate of Productive Fracture Surface Area
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Example15 transverse hydraulic fracs each 200 ft high and 500 ft across
Frac surface area = 2*15*200*500 sq ft= 3 MM sq ft
Mass balance
• Frac fluid: Frac surface area ~ 100 MM sq ft
• Proppant: Propped frac surface area ~ 1-5 MM sq ft
Estimate of Created Fracture Surface Area
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• Gas is produced from the volume defined by extent of primary fracture network
• Most of the fracture fluid resides in the large secondary fracture network and is eventually imbibed into the matrix
Large scale slickwater fracturing is very inefficient: thevolume of the productive fractures represents only asmall percentage of the volume of the fluid pumped.
Productive Reservoir Volume
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Oil Recovery from Shales1 yr 10 yrs 20 yrs Economic Rate
5 bbl/d/fracture
*Xf Km Km Km
Km *Xf *Xf Rsi
Rsi Rsi Rsi *Xf
Pi dRs/dp dRs/dp Pi
dRs/dp Pi Pi Cf
*Pwf ng Cf dRs/dp
ng Cf *Pwf *Pwf
Cf *Pwf ng ng
Symbol Property
Km Matrix perm
Xf Hydraulic Fracture spacing
Rsi Initial dissolvedgas oil ratio
dRs/dp Slope of dissolved GOR
Pi Initial pressure
ng Gas rel. perm exponent
Cf Compressibility
Pwf Producing BHP Only 2 of the variables are operationally
controllable parameters
Most important
Least important
Ranking
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Greater penetration, lower fracture density?
Idealized Conception
www.halliburton.com
Lower GRV, higher fracture density?
Plausible Complexity
www.drillingcontractor.org
Interaction with hoop stress
Interaction with natural fractures
Interaction with bedding
Lans Taylor, Ph.D.Research ScientistEnergy & Geoscience Institute
Large Scale Geologic Controls on Hydraulic Stimulation
John McLennan, Ph.D.Associate Professor of Chemical EngineeringEnergy & Geoscience Institute
Mechanical Stratigraphy for Hydraulic Stimulation
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Does bedding plane slip explain diffuse zones of micro-seismicity during frac jobs?
Jim Rutledge, SLB Microseismic Services, “The Signature of Shearing Driven by Hydraulic Opening”, HGS Mudrocks Conf. 2015
Systematic Chaotic
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North Sea
Karoo, S. Africa
Photo: Alan Cooper, www.otago.ac.nz
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Compressional Crossing
Process Zone
Material 1
Material 2
Material 1
Material 2
σK1 σK1
σT σT
Modified from Renshaw & Pollard, 1995
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Rigid but compressible vs.Flexible but incompressible
Initial condition
Vertical loadunconfined
Vertical loadlateral confinement
σHflexible > σHrigid
as Poisson Ratio decreases, Young’s Modulus increases
Rigid
Flexible
Rigid
Flexible
Rigid
Differential Motion
Con
stan
t st
ress
Con
stan
t st
rain
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How is present day stress influenced by basin form and topography?
Does creep enhance stress heterogeneity?
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FLEXIBLE
RIGID
FLEXIBLE
RIGID
FLEXIBLE
RIGID
Pressure
Shale
Sandstone
Sandstone
Sandstone
Shale
Shale
Horizontal Stress Magnitude
MostCompressive
LeastCompressive
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Stratigraphic arrangement matters
Horizontal Stress Magnitude
MostCompressive
LeastCompressive
FLEXIBLE
RIGID
Shale
Sandstone
FLEXIBLE
RIGID
Shale
Sandstone
Sandstone
Hydraulic Fracture
FLEXIBLERIGID
Shale
Un
ifo
rm P
ress
ure
thin sandencasedin shale
thin shaleencasedin sand
Co
arse
nin
g u
pw
ard
se
qu
en
ceC
oarse
nin
g u
pw
ard se
qu
en
ce
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Horizontal Stress Magnitude
MostCompressive
LeastCompressive
FLEXIBLE
RIGID
Un
ifo
rm P
ress
ure
Shale
Sandstone
FLEXIBLE
RIGID
RIGID
Shale
Sandstone
Sandstone
Hydraulic Fracture
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Different placement of horizontal wells will lead to different hydraulic fracture patterns
Net PressureNet Pressure
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Finite Element
Behavior of gradational interfaces
Direct measurement
Discrete Element Models
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Curvature Analysis
SLB: Dynel2DCourtesy of Laurent Maerten
1) Input horizon 3) Stress prediction2) Bending model
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Curvature for Unconventional Targets
Rigid layers isolated
Flexible layers isolated
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Dislocation Analylsis
(Maerten, et al., AAPG Bull, 2006)
Fault Locking
Regional / Counter-regional Faulting
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1972 2017
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