Bringing OLI MSE into PHREEQC for reservoir simulations Application to subsurface challenges OLI Simulation Conference 2016 Tim Tambach, Niko Kampman, and Jeroen Snippe Storage and Containment Technologies With acknowledgement to Lingli Wei (Shell) and Peiming Wang/other OLI staff 1
Definitions & Cautionary Note Reserves: Our use of the term reserves in this presentation means SEC proved oil and gas reserves. Resources: Our use of the term resources in this presentation includes quantities of oil and gas not yet classified as SEC proved oil and gas reserves. Resources are consistent with the Society of Petroleum Engineers 2P and 2C definitions. Organic: Our use of the term Organic includes SEC proved oil and gas reserves excluding changes resulting from acquisitions, divestments and year-average pricing impact. Shales: Our use of the term shales refers to tight, shale and coal bed methane oil and gas acreage. The companies in which Royal Dutch Shell plc directly and indirectly owns investments are separate legal entities. In this presentation Shell, Shell group and Royal Dutch Shell are sometimes used for convenience where references are made to Royal Dutch Shell plc and its subsidiaries in general. 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In light of these risks, results could differ materially from those stated, implied or inferred from the forward-looking statements contained in this presentation. We may have used certain terms, such as resources, in this presentation that United States Securities and Exchange Commission (SEC) strictly prohibits us from including in our filings with the SEC. U.S. Investors are urged to consider closely the disclosure in our Form 20-F, File No 1-32575, available on the SEC website www.sec.gov. 2
Introduction to reservoir simulation and reactive transport modelling (RTM) 1 3
Challenges in the oil and gas industry Subsurface activities that potentially involve geochemistry Water flooding CO 2 / H 2 S injection Geochemical impact attracts more attention Operational technical challenges (e.g. scaling, souring) Long-term storage and conformance (safety) Forecast using reactive transport modelling (RTM) Fluid and gas flow in porous media (which area is affected?) Geochemical impact of subsurface activities Source: TNO 4
RTM with MoReS-PHREEQC started in 2009 3D geology Oil-Gas-Water PVT Fluid flow Aqueous chemistry Water-rock interactions MoReS MoReS (Reservoir simulation) PHREEQC v3 (Geochemical modelling) The Shell reservoir simulator MoReS is coupled to open-source geochemical software PHREEQC 5
Which geochemical database to be used? Geochemical databases distributed with PHREEQC give different results (Dethlefsen et al., 2011) From: Dethlefsen et al., Environ. Earth Sci. 2011 Criteria for a MoReS-PHREEQC geochemical database Should be verified against experimental data Should be consistent with data used by various other disciplines involved in our projects (e.g. production chemistry, wells) 6
Link the OLI MSE database to MoReS-PHREEQC 3D geology Oil-Gas-Water PVT Fluid flow Aqueous chemistry Water-rock interactions MoReS MoReS (Reservoir simulation) PHREEQC v3 (Geochemical modelling) MSE geochemical database from OLI Stream Analyzer fulfills the criteria Stream Analyzer (MSE) (Production Chemistry) 7
Mapping of MSE geochemical reactions to PHREEQC 2 8
Description of geochemical reactions in PHREEQC and OLI Stream Analyzer Dissociation of dissolved calcite: CaCO 3 (aq) Ca 2+ (aq) + CO 3 2- (aq) K = m Ca 2+m CO 3 2 m CaCO3 γ Ca 2+γ CO3 2 γ CaCO3 K and are pressure/ temperature dependent depends on the aqueous Equilibrium constant (K) Molality (m) Activity coefficient ( ) composition PHREEQC and OLI use different models to parameterize K and 9
Mapping of K and Equilibrium constant (K) Stream Analyzer uses Helgeson-Kirkham-Flowers equation of state (HKF-EOS) PHREEQC uses expression (P=1 bar): log 10 K = A 1 + A 2 T + A 3 T + A 4 log 10 T + A 5 T 2 + A 6 T 2 Solved by fitting Stream Analyzer results to the PHREEQC expression PHREEQC uses HKF-EOS for P-dependency map parameters directly Activity coefficient ( ) Stream Analyzer uses MSE model [Wang et al., Fluid Phase Equilibria 203 (2002)] PHREEQC uses various activity models (incompatible with MSE) Solved by implementing MSE model into the PHREEQC source code Mapping done for ~100 aqueous species, ~300 minerals, and ~10 gases 10
Molality (mol/kgw) log K (-) Activity coefficieint (-) Mapping carried out successfully 10.0 P=1 bar 8.0 6.0 4.0 CaCO3 (OLI) 2.0 Fit (PHRQC) 0.7 P=300 bar 0.6 0.5 Ca+2 (OLI) 0.4 Ca+2(PHRQC) 0.3 0.2 0.1 0.0 0.05 0.04 0 100 200 300 T ( C) P=300 bar 0 0 100 200 300 T ( C) Very good of fit of K 0.03 0.02 Ca+2 (OLI) 0.01 Ca+2(PHRQC) 0 0 100 200 300 T ( C) Activity coefficient and molality well-reproduced Similar conclusions for other reactions and species 11
We carry out our own verification of OLI Stream Analyzer results with experimental data Palmer et. al 2001 Example - boehmite [AlO(OH)] Left equilibrium constant Right dissolution with ph at 1.0M NaCl 12
Forecast of reactive CO 2 injection into a carbonate formation 3 A brief insight 13
CO 2 is reactive, but how reactive? CO 2 storage to mitigate climate change Carbonate reservoirs are abundant in the Middle East Dissociation of CO 2 in the formation water (FW) of the reservoir CO 2 (aq) + H 2 O HCO 3- (aq) + H + (aq) Geochemical reactions in the reservoir Dissolution of initially present calcite (and dolomite) New minerals are formed (anhydrite and celestine) Simulations with RTM to study the dynamics 14
Long-term migration of CO 2 in the reservoir Modelling of 30 years of CO 2 injection + additional 970 years Based on geological model with spatial variation in porosity/permeability Geological sealing layer prevents upward migration injection well cross section through the well map view of upper layer From: T.J. Tambach, J. Lonnee, and J.R. Snippe. Forecast of reactive CO 2 injection into a carbonate formation, Middle East. Proceedings of the 13 th International Conference on Greenhouse Gas Control Technologies, GHGT-13, 14-18 November 2016, Lausanne, Switzerland 15
Long-term geochemical effects in the reservoir From: T.J. Tambach, J. Lonnee, and J.R. Snippe. Forecast of reactive CO 2 injection into a carbonate formation, Middle East. Proceedings of the 13 th International Conference on Greenhouse Gas Control Technologies, GHGT-13, 14-18 November 2016, Lausanne, Switzerland Map views of ph (left), change in calcite (middle), and change in porosity (right) ph reduces from 7.0 to 4.6 calcite dissolution (<0.1%) is the most dominant mineral reaction porosity change is up to 0.03% 16
Barite scaling due to waterflooding of an oil-producing field 4 A brief insight 17
SI BaSO4 (-) Geochemistry of waterflooding matters Oil and formation water (FW) are present in the reservoir rock Sea water (SW) is injected to stimulate oil production FW has a relatively high Ba 2+ concentration (SO 4 2- is small) SW has a relatively high SO 4 2- concentration (Ba 2+ is small) 3 Mixing of SW and FW could lead to barite (BaSO 4 ) precipitation (scaling) Reduces the permeability of the rock/well Productivity decline 2 1 0 Simulations with RTM to predict the impact -1 computed with Stream Analyzer (MSE) 0 0.2 0.4 0.6 0.8 1 Volume fraction SW (-) 18
SW plume reaches various production wells We use Cl - to monitor the SW plume Cl - does not react Cl - molality in the SW is ±70% of the Cl - molality in the FW BaSO 4 precipitation is simulated in the plume area 19
Ba (mol/kgw) S (mol/kgw) SI BaSO4 (-) Production data with time for a certain well 4.0E-03 3.0E-03 His His - EDTA Sim SimNoMin 1.0E+00 1.0E-01 1.0E-02 His His - EDTA Sim SimNoMin 4 3 2 His His - EDTA Sim SimNoMin 2.0E-03 1 1.0E-03 1.0E-03 1.0E-04 0-1 0.0E+00 1994 2000 2006 2012 2018 Time (yr) 1.0E-05 1994 2000 2006 2012 2018 Time (yr) -2 1994 2000 2006 2012 2018 Time (yr) Simulations show reasonable agreement to historical data Simulations predict that scaling could become a problem in the near future We recommended a scale squeeze (preventing BaSO 4 precipitation) to the responsible team of this specific field 20
Conclusions 5 21
Summary and conclusions Successfully mapped OLI MSE geochemical data to MoReS-PHREEQC Currently contains ~100 aqueous species, ~300 minerals, and ~10 gases Stimulates project work where other disciplines are involved Parts of the geochemical database are confidential Demonstrated the use of RTM with OLI MSE geochemical data for two case studies Relatively small geochemical impact of CO 2 storage in carbonate reservoirs Scale squeeze recommendation to prevent barite scaling and productivity decline Combination of RTM and OLI MSE geochemical data assists our decision making for various reservoir engineering challenges 22
Questions and Answers 23