Modelling Unconventional Wells
with Resolve and Reveal
Juan Biörklund (Gauloise Energía)
and
Georg Ziegler (Wintershall Holding)
Modelling Unconventional Wells
PVT Modelling
Reservoir Modelling
Well Modelling
Chemical EOR
Water Chemistry
Reveal Features
Adsorption
Diffusion
Rock Mechanics
Rock Failure
Fracturing
Designed to study specialized near well bore effects and assess their impact on the production from the reservoir
Modelling Unconventional Wells
Quick Calculations
Tight reservoirs with complex well geometries
Systems with up to 20,000 wells with 100 wells being drilled per month
Shale Oil / Gas Wells
Horizontal, inclined and fractured wells
Gas adsorption, diffusion, directional stress dependent permeability variations etc...
Capabilities (Resolve & Reveal)
Modelling Unconventional Wells
Dimensionless transient reservoir response capturing the well, fracture and reservoir geometry Dimensionless pseudo-pressure pseudo-time (pD tD)
Match this response to production history Modify reference parameters k and phi(rw
2)
Adjust PVT reference conditions for pD and tD
Concept
Modelling Unconventional Wells
Perform predictions Use matched pD tD and super-position to predict Pwf
Transient IPR for rate estimation
Well scheduling
Automate the procedures using visual workflows Model definition and workflow in Resolve
Indirectly access simulation capabilities of Reveal
Concept (cont.)
Modelling Unconventional Wells
7
Microseismic
Frac Xf is 3 -5 x longer than seen in FracPro, proved with Microseismic
Multi-Fracs does not interfear near wells (approx. 300m)(Sketch not same as seen)
Modelling Unconventional Wells
History Match
10
History match a shale well- Additional Input Data -
Young’s modulus (248000 bar).
Poisson’s ratio (0.275).
Biot’s coefficient (0.75).
Langmuir adsorption curve (70 scc/g).
Fracture permeability variation (no data).
Compaction table (Palmer & Mansoori – SPE 52607).
Fracture geometry and properties (NRT Log & Gohfer)
Modelling Unconventional Wells
History Match: Reveal Model
13
Calculated Pressure
Me
asu
red
Pre
ssu
re
Ra
te
Modelling Unconventional Wells
pD tD Curves - Resolve
14
pD tD curves
Why
A method that allows us to perform rapid calculations with complex well geometries
What they are
Dimensionless transient reservoir response that captures the well, fracture and reservoir geometry
Modelling Unconventional Wells
pD tD Curves - Resolve
15
pD tD curves (pseudo-pressure pseudo-time)
02103266.6 3
P
pD B
dp
Q
khp
t
TwD c
dt
r
kt
02
3102637.024
Modelling Unconventional Wells
pD tD Curves - Resolve
16
Optimization
Resolve - Powerful Optimizing Tool on Field Level Production
Why Resolve
Handles large number of wells
Easy to analyze well performance
Infinite scenarios to find best match
Modelling Unconventional Wells
pD tD Curves
17
Use GAP with Eclipse / Reveal / pD tD
One wellReveal Model
One wellpd td curve
Two wellEclipse Model
Modelling Unconventional Wells
Issues No gas break-through seen in the simulation
What is the frac geometry causing this behaviour?
Tight Reservoir Module uses only analytical method (pD tD)
3 Fracs simulated as one, inflow problems
Solutions Model the fracs explicitly with Reveal frac gridding option
Evaluate resulting pD tD curves from analytical vs. numerical
Detailed Resolve model explains where GOR increase when pressure is below Pb at certain fracs
Oil Models: Resolve & Reveal
Modelling Unconventional Wells
Setup Resolve model and ran several cases to test sensitivity on different parameters and interaction between them such as:
Porosity, Stimulated K, Matrix K
Fracture half length, Fracture height
Stimulated Rock Volume (SRV)
Compressibility
Control Reveal with Resolve
RESOLVE Logic
Modelling Unconventional Wells
Resolve / Reveal Sensitivities
24
Case_Name Porosity Permeability Compressibility Fracture Half Length Fracture Height SRV MatrixKCase_24 0.04 0.0008 1.00E-05 262 82 13 0.0001Case_25 0.04 0.0008 1.00E-05 262 82 13 0.0002Case_26 0.04 0.0008 1.00E-05 262 82 13 0.0003Case_27 0.04 0.0008 1.00E-05 262 82 13 0.0005
Modelling Unconventional Wells
What is different between a Resolve analytical and a
Reveal numerical model?
Transfer fracture model from Resolve tight module to
Reveal to back calculate geometry.
Oil Reservoir Model
Modelling Unconventional Wells
Pressure after one month
Reveal Oil Reservoir ModelModel variable compaction table, stress dependent
perm and changing cleat compressibility
Modelling Unconventional Wells
Porosity Reduction with Pressure
27/11/2013 02/03/2014 30/06/2014
Effect of Cleat Compressibility
4.01
3.96
3.90
3.65
3.80
3.74
Modelling Unconventional Wells
Reduction of Oil Density over Time
12/12/2013 31/01/2014 30/06/2014
Changing Oil Density over Time
41.5
40.4
39.3
38.2
37.1
36.0
Modelling Unconventional Wells
Porosity and compressibility have similar effects on BHP match
Changes on SRV affects the late match
Stress - Permeability function has an effect on the transient behaviour (early decline / build up)
BHP calculation need careful considerations due to the instability of low rate wells.
Stress dependent permeability needs to be included in the Reveal models to obtain a match
Reservoir Model - Conclusions