1. ENHANCED OIL RECOVERY (EOR) AS A STEPPING STONE TO CARBON CAPTURE AND SEQUESTRATION (CCS)
Dana M Abdulbaqi, Saudi Aramco
Carol Dahl, Colorado School of Mines
& Luleo Technical University
Mohammed AlShaikh, Saudi Aramco
June 2016

2. Outline Motivations Workflow and Objectives Methodology
Reservoir Simulation Model
Dynamic Optimization Model
Results
Conclusions
Future Work 2

3. Motivation CO2-EOR’s commercial viability as a sequestration option:
Industry’s Expertise
Existing Infrastructure
Technical estimates of CO2 sequestration potential
Opportunity for development of CO2 Market
Carbon Capture Facilities = Suppliers
CO2-EOR Projects = Demanders
How CO2-EOR producer’s will co-optimize:
Oil Recovery & CO2 Sequestration 3

4. Motivation
Leach, Mason and van’t Veld, Co-Optimization of Enhanced Oil Recovery and Carbon Sequestration.
Only study found that uses a dynamic optimization model to address the co-optimization issue.
Analysis is limited to the productive life of the field.
van’t Veld, K, Wang, X, Alvarado, V, 2014 Economic Co-optimization of Enhanced Oil Recovery and CO2 Sequestration.
Make use of dynamic reservoir simulation model to enhance technical assumptions. 4

5. Stage-2: CO2 Sequestration Reservoir Simulation
Maximizing NPV of the producer during CO2 sequestration activities subject to resource constraints.
Reservoir Simulation
Dynamic Reservoir Simulation Model was built to mimic CO2-EOR process using WAG injection and estimate sequestration capacity.
Stage-1: CO2-EOR
Maximize NPV of the producer during CO2-EOR subject to resource constraints and tax policy.
δ(c(t))
Equations
Reservoir simulation model output was used to construct equations used in the dynamic optimization model.
Sim:
Decline:
Opt:
Dynamic Optimization
A 2-stage dynamic optimization model was developed to track total carbon movements during the CO2-EOR and beyond oil production activities.

6. Optimal Control: Stage 1 CO2-EOR
𝒎𝒂𝒙 𝝅= 𝟎 𝑻 𝒆 −𝒓𝒕 𝒑−𝜷𝝉 𝒒 𝒑 𝒐 𝒕 + 𝝉 𝒒 𝒔 𝒄 (𝒕) −[ 𝒘 𝑵𝑹 +𝝉 𝒒 𝑵𝑹 𝒄 (𝒕) − 𝒘 𝑪𝑨𝑷 𝒒 𝑪𝑨𝑷 𝒄 (𝒕) − 𝒘 𝒓 𝒒 𝒓 𝒄 (𝒕) −𝑭 𝒅𝒕
𝑝−𝛽𝜏 𝑞 𝑝 𝑜 ( 𝑡) – Revenues from Oil Production
𝜏 𝑞 𝑠 𝑐 (𝑡) – Revenues From Sequestration
𝑤 𝑁𝑅 +𝜏 𝑞 𝑁𝑅 𝑐 (𝑡)– Costs of Natural CO2 Usage
𝑤 𝐶𝐴𝑃 𝑞 𝐶𝐴𝑃 𝑐 (𝑡) – Costs of Captured CO2 Usage
𝑤 𝑟 𝑞 𝑟 𝑐 𝑡 – Costs of Recycling CO2
𝐹 – Costs not related to CO2 purchase and handling 6

7. Optimal Control: Stage 1 CO2-EOR
𝒎𝒂𝒙 𝝅= 𝟎 𝑻 𝒆 −𝒓𝒕 𝒑−𝜷𝝉 𝒒 𝒑 𝒐 𝒕 + 𝝉 𝒒 𝒔 𝒄 (𝒕) −[ 𝒘 𝑵𝑹 +𝝉 𝒒 𝑵𝑹 𝒄 (𝒕) − 𝒘 𝑪𝑨𝑷 𝒒 𝑪𝑨𝑷 𝒄 (𝒕) − 𝒘 𝒓 𝒒 𝒓 𝒄 (𝒕) −𝑭 𝒅𝒕
Constraints:
𝑶𝒊𝒍(𝒕) =− 𝒒 𝒑 𝒐 𝒕
𝑵𝒂𝒕𝒖𝒓𝒂𝒍 𝑪𝑶𝟐(𝒕) =− 𝒒 𝑵𝑹 𝒄 𝒕
𝑺𝒆𝒒𝒖𝒆𝒔𝒕𝒓𝒂𝒕𝒊𝒐𝒏(𝒕) = 𝒒 𝒔 𝒄 𝒕 7

8. Optimal Control: Stage 2 CO2 Seq.
𝒎𝒂𝒙 𝝅 = 𝒕 𝟏 𝑻 𝒆 −𝒓𝒕 ( 𝒑 𝒑 ) 𝒒 𝒔 𝒄 𝒄 𝒕 −𝑭𝒄 𝒕 𝒅𝒕
( 𝒑 𝒑 ) 𝒒 𝒔 𝒄 𝒄 𝒕 – Revenues from Selling Pore Space
𝑭𝒄 𝒕 – costs for CO2 purchase and handling
Constraint:
𝑺𝒆𝒒𝒖𝒆𝒔𝒕𝒓𝒂𝒕𝒊𝒐𝒏(𝒕) = 𝒒 𝒔 𝒄 𝒄 𝒕
𝑺𝒆𝒒𝒖𝒆𝒔𝒕𝒓𝒂𝒕𝒊𝒐𝒏 𝑻 ≤𝟏.𝟐∗ 𝟎 𝒕 𝟏 𝒒 𝒑 𝒐 𝒕 8

9. Results
Using various combinations of oil price (P) and tax levels (𝜏) to solve for the optimal time paths of:
CO2 usage from each source 𝑞 𝑁𝑅 𝑐 (𝑡) & 𝑞 𝐶𝐴𝑃 𝑐 𝑡
CO2 injection rate 𝑐 𝑡
CO2 sequestration 𝑞 𝑠 𝑐 (𝑡)
Oil production 𝑞 𝑝 𝑜 (𝑡)
Timing of the switch from Stage 1 to 2
Termination Time
Tax Threshold = 𝑤 𝐶𝐴𝑃 − 𝑤 𝑁𝑅 = $20 𝑡𝐶𝑂 2 (Stage 1) 9

10. If Tax < $20 𝑡𝐶𝑂 2 , tax on 𝑞 𝑁𝑅 𝑐 (𝑡) usage negates the credit received from 𝑞 𝑆 𝑐 (𝑡).
If Tax > $20 𝑡𝐶𝑂 2 , observe the benefits of the credit received from 𝑞 𝑆 𝑐 (𝑡).

12. Stage 2: Total Profits Over Both Stages in Millions of Dollars
Tax Level
Price Level 50
100
150
200 42 90
138
187 19 38 86
133
182 20 37 85
181 21
134 40 33 80
128
176 68
117
165
120 10 57
106
155

13. Conclusions Our model assists in
Tracking total carbon movements under a tax policy.
We observe
Transition from usage of natural to captured CO2.
Incentive to continue CO2 sequestration beyond oil production.
Reduce net CO2 emissions resulting from oil production.
Minimal Impact on Oil Production 14

14. ENHANCED OIL RECOVERY (EOR) AS A STEPPING STONE TO CARBON CAPTURE AND SEQUESTRATION (CCS)
Dana M Abdulbaqi, Saudi Aramco
Carol Dahl, Colorado School of Mines
& Luleo Technical University
Mohammed AlShaikh, Saudi Aramco
June 2016

15. Future Work
Co-manage of oil production and pore volume capacity while varying:
Market Parameters
Reservoir Parameters
Upscale to regional modeling effort
Allocation of natural and captured CO2 volumes across a portfolio of producing assets
Impacts on co-management of pore volume & oil production
Mechanics of supply and demand of CO2 16

16. How CO2-EOR Works? 18