Simulating gelation of silica for in-depth reservoir plugging using IORSim as an add on tool to ECLIPSE

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The Challenge

• We know fluid chemistry affects flow properties on core scale (~10 cm) 1. Compaction and wettability in chalk

2. Water diversion

• How to translate core scale knowledge/processes to field scale? • Implementation of IOR processes in the field

• Interpretation of field data

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Example: Effect of sulphate on oil production

NaCl

NaC

l

NaCl

Na 2

SO4

Na2SO4

Na 2

SO4

R. Ahsan, M. V. Madland , F. Bratteli, A. Hiorth “A STUDY OF SULPHATE IONS - EFFECTS ON AGEING AND IMBIBITION

CAPILLARY PRESSURE CURVE” – SCA, 34 (2012) ‹#› 3

Mature Field Challenges

Complex flow

pattern

Multiple Wells

Temp. gradients

Geo-chemistry

Oil Displacement

Water Chemistry

• Mature fields • Chemical EOR

• Need (geo)-chemistry to translate core to field • Need history matched field scale reservoir models for upscaling

Remaining oil ~55% • Poor sweep • High Sor

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The Approach – IORSim Technology

Eclipse Reservoir simulator

IORSim

advect components

Geo-chemistry

Restart Files Sw, Po, Pw, qw

…

Oil Rate

SO4

Mg

Silicate

Modular interface

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A modular interface:

• Advection calculations separate from reactions

– Implicit formulation

• 1D :

0 1 N 2 𝒄𝑖𝑛,0

𝒄𝑖𝑛,1(𝑡 + Δ𝑡) 𝒄𝒊𝑛,2(𝑡 + Δ𝑡) 𝒄𝑖𝑛,𝑁(𝑡 + Δ𝑡)

Block-by-block upstream integration ‹#› 6

The IORSim methodology on a complex computational problem:

• Fast full geochemical calculations

• Robust, efficient solution:

– Transport and geochemistry solved separately and implicitly

• Global level (Flow) & Local (Block) level (non-linear physics chemistry)

– Decompose reservoir into separate flow paths

– Flow path is solved on a block sequentially:

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Synthetic Ekofisk Case

WIII

PI

water

oil

WII

WI

• Only forward coupling • Add geochemistry to ECLIPSE 8

Oil and water production rates

2X & 4X grid refinement

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Magnesium

Calcium

Sulphate

No reactions

Temperature

Chlorine - Ekofisk field data

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Reactions in the reservoir

Dissolution close to injectors

Reservoir pH

Temperature Surface potential

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To summarize:

• Forward coupling to ECLIPSE: – Calibrate reservoir model to ions in the formation water

– Predict reservoir textural alterations

– compare with field compaction data (ongoing in the National IOR Centre of Norway)

• Next: Backward coupling to ECLIPSE – Sodium silicate system (green chemical)

– Used offshore Norway to block water pathways and improve sweep

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Sodium Silicate Chemistry

5wt% Sodium Silicate

Na2O:(SiO2)n +

HCl

Oligomeric silicic acid

Phase separation

Nano sized

aggregation

gelation Gelation time

A. Stavland, H. Jonsbråten, O. Vikane, K. Skrettingland and H. Fischer, In-depth Water Diversion Using Sodium Silicate – Preparation for Single Well Field Pilot on Snorre, 16th European Symposium on Improved Oil Recovery Cambridge, UK, 12-14 April 2011

B. Sebastian Wilhelm and Matthias Kind, Polymers 2015, 7, 2504–2521; doi:10.3390/polym7121528

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4 aqueous species + 1 mineral phase

1. Silica 2. HCl 3. Mobile Gel 4. Calcium 5. Immobile Gel

Sodium Silicate

Activator

Nano size gel particles

Divalent ions

Rigid gel

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Permeability modification

• Gel formed as nanoparticles

• Nanoparticles aggregate

• Specific surface area increased, and permeability reduced

• Partial blocking of pore throats above critical saturation

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SATN

UM

1-

12

Stop Eclipse process

Update SATNUM

IORSim Backward Coupling

• X = EOR response, e.g.: • Low sal reduce Sor

• Silicate reduce Perm

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Synthetic fractured reservoir

View from the side

100mD 4000mD

240x30x7 = 50400 blocks

injecto

r

pro

du

cer

View from top

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Production & Pressure without treatment Injector Producer

BHP

BHP

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5wt% silica injection for 65 days

Silicate wt% Calcium wt%

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Permeability reduction

Perm reduction – View from top Perm Reduction – View from side

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Perm reduction – View from top Perm Reduction – View from side

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Perm reduction – View from top Perm Reduction – View from side

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Water Saturation Profile

injecto

r

pro

du

cer

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Water Saturation Profile

injecto

r

pro

du

cer

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Water Saturation Profile

injecto

r

pro

du

cer

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Water Saturation Profile

injecto

r

pro

du

cer

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Production & Pressure data with treatment

Injector Producer

Water Rate

BHP

Water Rate

Oil Rate

BHP

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Increased recovery and reduced water cut

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Effect of grid size

240x30x7 cells

60x15x7 cells

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Conclusions

• Coupling between IORSim and ECLIPSE works well

– Block sorting implicit & modular solver

– Can be extended to other simulators

• ECLIPSE is slow compared to IORSim, can be solved by:

– Run ECLIPSE once

– Use IORSim without backward coupling to design optimal slug

– Then run full simulation

• Great potential for realistic field cases

– Analyse offshore two-well silicate pilot on the Snorre field

– Analyse Ekofisk field data for chemistry induced compaction

• Simulation grid could have a huge impact on the EOR effect

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Further work

• Further testing on full field cases

• Advanced silicate model with geochemistry

• Implementation of 2nd order numerical schemes

• Separate grid refinement for chemical species

• Back coupling controller integrated in IORSim

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The National IOR Centre of Norway

Acknowledgement:

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