11

Oliver C. Mullins, Schlumberger

and One Zillion Collaborators

Reservoir Evaluation &

Reservoir Fluid Geodynamics (RFG)

1) RFG: DFA and Thermodynamics2) Connectivity and Equilibrated Asphaltenes3) Disequilibrium and RFG Processes4) Tar Formation5) GCxGC & Geochemistry

OUTLINE

Basin modeling gives fluid type, timing, volumes

INTO reservoir

Geologic Time Line

Almost No Modeling of in-Reservoir

Fluid Geodynamics

NoModeling

Modeling ofProduction in Eclipse

Production Time Line

Missing Component of Reservoir Understanding and Modeling

Reservoir Fluid Geodynamics

Petroleum SystemFILLS Reservoir

Reservoir Fluid GeodynamicsRedistributes Fluids & Tar Formation

Simulation Produces Reservoir

Reservoir Fluid Geodynamics Redistributes Fluids and Yields Tar Formation After Charge

Time Line

Geologic Past Present Day

Asphaltene Nanoscience

Asphaltene Thermodynamics

Diffusion

Fluid Mechanics

Reservoir Fluid Geodynamics Requirements:

ComprehensiveScience

DFA Data of Reservoir

Reservoir EvaluationCase Studies

Vertical, LateralFluid in Fields

ReservoirFluid Geodynamics

Fault block migration,Formation overturn,Gas charge into oil,Tar mat formation,Viscosity gradients,Biodegradation & diffusion

F = mg. Newton’s 2nd LawPeng-Robinson EoS 1976

HC Liquids

Gas-Liquid Fluid- (dissolved) Solid

Flory-Huggins-Zuo EoS 2010

Yen-Mullins Model 2010

Gas

Cubic EoS Gas-Liquid

Crude Oil Thermodynamics; Asphaltenes Now Included.No Predictions Without Asphaltenes of Heavy Oil, Tar, Viscosity…

Asphaltenes:

Van Der Waals EoS 1873

First High Resolution Images of Asphaltene Molecules Agree with Yen-Mullins Model

IBM Zurich IBM Zurich, Schlumberger… Published in J. Amer. Chem. Soc.

Nobel Prizefor STM

STM Expt.

AFM Expt. AFM Expt.Atoms and Bonds

MO TheoryElectron Orbital

7

2nd Optical

Analyzer

1st Optical

Analyzer

Pump

Sample

Bottles

Probes

Probe

(extended)

7

Downhole Fluid

Analysis (DFA)

Measure Oil Color

Reservoir Fluid Geodynamics

Petroleum SystemContext

Gas Charge into OilDiffusion GOR Gradient

Different Reservoir Realizations

Diffusion& Convection

Fault Throw

Biodegradation& Diffusion

Not Equilibrated

Gas Charge into Flank

Heavy Oil & Tar MatConnectivity

“Gas Flood” Local GOR Increase but Connected

Compartments

Reservoir Baffling;Low Production

Regional Viscosity Gradients

Spill-Fill withBiodegradation

Big Viscosity Trends

Tar in NaturalFractions

No Productionin Flank

Gas Sweep & Tar GOR Gradient, Mobile Tar

Geologic Time

Diffusion/Mixing Connectivity

Equilibrated Asphaltenes (FHZ EoS) Connected Reservoirs Proven in Production in all Fluid Types

Volatile OilCondensate

9

Heavy Oil:100 kilometer length, 60 Meter 10x Gradient.

Matches FHZ with Yen-Mullins. No Adjustable ParametersConvective Currents

Tar

No Adjustable Parameters

Asphaltene Equilibration Reservoir ConnectedProven in Production

Tar

Giant Asphaltene Gradient NOT a Maturity Gradient !From Convective Currents of Asphaltene-Enriched Oil.

12

CH

4

CH

4

CH

4

CH

4

High GORLow Asphltn

Low GORHighAsphtn

Diffusive Gas Front

0 1 2 3 4 5

0 0.1

0.2

0.3

0.4

0.5

0.6

0.7

02

04

06

08

01

00

He

igh

t (m

ete

rs)

ClusterGradient

0

GOR scf/bbl

2k 4k 6k 8k

4k 6k 8k 10k 12k

Saturation Pressure (psi)

CH

4

Connected Reservoir But Not Equilibrated.Recent Gas Charge Into Oil. Diffusion Large GOR Gradients.

Asphaltene Expulsion. Convection Large Asphaltene Gradients.

Gravity CurrentPumps Asphaltenes to Base

Diffusion Gives HUGE GOR

Gradient at Top

3 Adjacent Fault Blocks. Same Petroleum System.3 Entirely Different Realizations.

Asphaltene Content in Liquid Phase

• Well 1: – large disequilibrium – high Asphaltene Content

• Well 2 & Well 3: – oil equilibrated – low Asphaltene Content

Where did the Asphaltene go? How and Why?

Fault Block 1. GIANT Disequilibrium in 40 Meters !!!Pleistocene condensate charge into Oil ReservoirGas Diffusion and Asphaltene Migration Ongoing

DFA Asphaltenes

De

pth

(m

eter

s)

GOC

OWC

1) 1st Movie of Tar Mat Formation2) Different Gradients Due to Baffling. Production Differs by 10x.

Well 1. Baffled. NOT EquilibratedLow DST Production Rate

Well 2. Equilibrated.High Production.

Asph GOR Core Ex

Equilibrated; Tiny Fluid Gradients

Late Gas Charge

Into OilReservoir

InitialGas

Asphaltene

1 2OD

120 180GOR m3/m3

Asphaltenes GOR

TVD

Not Equilibrated; Huge Gradients

0OD

Tar

Tiny Asphtn

FHZ Eo

S

TAR

600%AsphGOR

200180

SLOW Diffusion FAST Diffusion

SEM. Tar Mat. Phase Separated Asphaltene

Trapped Oil

Shale Baffle

Well 3. Density Stacking / Vertical Charge Above Shale. “Tar Mat”Asphaltenes Throughout.

Core %Asphaltene

Tar onShale

FB/Well #3

Asphaltenes On Baffle

Methane diffusionAsphalteneDiffusion(Slow)

Lateral Gas

Sweep

H2O

Vertical Gas Sweep

Shale

Lateral Sweep in Trap Filling Below Shale.

FB 1. Baffled. BIG GradientsLow DST Rate

FB 2. Equilibrated.Tar MatHigh Production.

Late Gas

Charge

IntoOil

Resrvr

SAMEInitialPoint

Gas

Asphaltene

1 2OD

Asphaltenes

TVD

Not Equilibrated; Huge Gradients

Asph

Equilibrated; Tiny Fluid Gradients

0OD

Tar

Tiny Asphtn

FHZ Eo

S

Core Ex

TAR

600%Asph

%Aspht

FB 3. Equilibrated.Tar on Shale.Aspht Coating

Near Charge Point.Lateral ChargeGood SandPoor Sand, Many NF.

RFG: Late Gas into Oil. 3 Very Different Realizations.

Primary Sand Connected and Equilibrated Asphaltenes.Flank Not Equilibrated. Connected?

Well B: Mud gas isotope:dC13

Lateral Sweep. Surge in Gas, GOR Across Field. Connected.

DFA GORsurge across field

Well B: DFA GOR

GOR

Well AWell B

Reservoir Connected !!!

New ! Not in Literature.

280

300

320

340

360

380

400

420

440

460

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

TVDSS m

OD at ch[5]

Mud filtrate

No n-alkanes

Many n-alkanes

GC Confirms Biodegradation at/near OWC

OBM contamination

IMPACT OF BIODEGRADATION

DFA Color. Asphaltene Content

270

310

350

390

430

470

0.0 0.5 1.0 1.5 2.0

TVDss, m

OD & Asphaltene

Alkanes Consumed at OWC

FHZ w Diffusion

FHZ (2nm)Diffusion Has not yet reached this high

Biodegradation and Diffusion. Severe Biodegradation TRIPLED Asphaltene Content PM 06

3x

Oil Volume

Alkane Consumption

via BiodegradationConcentrates Asphaltenes

ALKANE Diffusion

DFA Color / Asphaltene Increase is 3X from Deep to Shallow Reservoir

Naphthalene

1-Methyl Naphthalene

2-Methyl Naphthalene

C2-Naphthalenes

C3-Naphthalenes

Hopanes

Resv:1

Thermal Maturity

Contamination

Water Washing

GCxGC

1st Column

2n

dC

olu

mn

Peters-Moldowan = 2

Resv: 1

Resv: 4

Peters-Moldowan = 4

Minimal Water Washing

Moderate Water Washing

Peters-Moldowan = 6(25-Norhopanes appeared)

Extensive Water WashingResv: 6

Naphthalene

Naphthalene

Naphthalene

C2-Naphthalene

C2-Naphthalene

C2-NaphthaleneC4-Naphthalene

C4-Naphthalene

C4-Naphthalene

3X Increase in Asphaltenes:• PM 2 6• Water Washing (Assisted by Biodegradation)• Some Maturity Variation

Asphaltenes

Early Oil Tar Stuck in Charge Plane Makes No Sense (to me).

60oC

1st Cold, Solid Bitumen Exits NanoDarcy! (Sink in Water?)

Then Heats Up !Reservoir (say 100oC)Greatly Decreasing Viscosity

Hot Roofing Tar

Drilling Hazard Tar.

Then the Hot Tar Gets Stuck in the Grand Canyon

(or giant fault). Can’t Get Out !!

(or JUST maybe there is another explanation)

Reservoir Fluid Geodynamics can provide the answer.

Conclusions

Reservoir Fluid Geodynamics (RFG): Redistribution of Fluids, Tar After Charge.A New Way to Evaluate Reservoirs

RFG Enabled by Asphaltene Thermodynamics, DFA & Case StudiesEquilibrated Asphaltenes Reservoir Connectivity.

Disequilibrium Geodynamic Processes. Charging, Baffling, Diffusion, Convection, Phase change /Tar etc.

Chemical Composition; GCxGC with GeochemistryCompare with Thermodynamics.

Drilling Hazard Tar Needs a New Look.

Universal DFA Workflows to Address Most Reservoir Concerns.

Petroleum SystemFILLS Reservoir

Present Day

0 Ma After Charge

3 Ma After Charge:Asphaltenes Equilibrated

~12 Ma After Charge:Biomarkers Equilibrate

Asphaltenes Equilibrate FASTER than BiomarkersDue to Charge Sequence.Same as Tornado…?

Diffusion

MoreDiffusion

ReservoirCharge

Liquids

Liquids

Liquids

TVD

SS

TVD

SS

TVD

SS

Gas

Gas

Gas

Geologic Past

Density Stacking of Crude Oils.First Heavy Oils, Then Light Oils.

No Tat Mat. Core Extracts Merely Contain Oil.

Fault Block 1.

Giant Disequilibrium in 40 Meters!!.

Late Gas

Charge

IntoOil

Reservoir

Initial

Gas

Asphaltene

Current

Asphaltene in Oil Asphaltene in Core Extracts

Gas Chargeinto Oil

Gas Charge into Oil Reservoir & Reservoir Fluid Geodynamics

DiffusionConvectionHeavy Oil /Tar

Flank Charge& Seal Failure

Tar Occlusion in Natural Fractures

DS Report

Independent

Low ProductionDrilling Hazard

OTC Paper

Different Production Concerns: Connectivity, PI, Tar Mat, Viscosity…

DFA Color / Asphaltenes r

g/ccGORPressure

Not EquilibratedPoor ProductionEquilibrated

Good Production

Connectivity, Baffling, Compartments; DFA Gradients and Production

Connectivity.Low GOR Black Oil.

Tahiti Field38

Pressure:Two Stacked Sands

Chevron

UpliftCausesFaulting

DW

0 2 3

x4

x6

x7

TVDFeet103

DFA Color %Asphtn

In Each Main Sand: Equilibrated Asphaltenes: CONNECTED.

Proven Correct in Production.

kT

hgVODhOD

rexp)0()(

Oil C

olu

mn

Dia ~ 2nm

1

FHZ EoS