January 12 Sc hlumberger Private 1 SIS Training ECLIPSE Black Oil Simulator – Advanced Options: Schlumberger Private Low Salinity Water Flooding Chuck Kossack Schlumberger Advisor January 12 Denver, Colorado Low Salinity Water Flooding 1 SIS Training NTNU Lecture Theory/Overview of Low Salinity Water Flooding ECLIPSE Modeling of LSWF Schlumberger Private ECLIPSE Modeling of LSWF Sensitivity Study of LSWF Economics January 12 Low Salinity Water Flooding 2
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Low Salinity Water Flooding - · PDF fileJanuary 12 Sc hlumberger Private 2 SIS Training Low Salinity Water Flooding (LSW) Simple concept – during water flooding inject fresh water
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January 12Schlum
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SIS Training
ECLIPSE Black Oil Simulator – Advanced Options:
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Low Salinity Water Flooding
Chuck KossackSchlumberger Advisor
January 12
gDenver, Colorado
Low Salinity Water Flooding 1
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NTNU Lecture
Theory/Overview of Low Salinity Water FloodingECLIPSE Modeling of LSWF
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ECLIPSE Modeling of LSWFSensitivity Study of LSWF Economics
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Low Salinity Water Flooding (LSW)
Simple concept – during water flooding inject fresh water – or at least water with lower dissolved salts that the
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connate water.
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Interest in LSW (Low-Salinity Waterflooding ) has increased
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LSE (Low-Salinity Effect)
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Key Reference Papers
SPE 129421 (Distinguished Author paper) – Improved Oil Recovery by Low-Salinity Waterflooding, Morrow & Buckley, 2011 – this includes a very extensive bibliography
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SPE 36680 – Salinity, Temperature, Oil Composition and Oil Recovery by Waterflooding, Tang & Morrow, 1997
Fresh water < 1 ppmDrinking Water – ppm (or mg/l as CaCO3)
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Drinking Water ppm (or mg/l as CaCO3)• 0 - 100 Soft• 100 - 200 Moderate• 200 - 300 Hard• 300 - 500 Very hard• 500 - 1,000 Extremely hard
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Sea Water = 36,850 ppmAquifers/oilfield Saturated ≅ 300,000 ppm
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Low Salinity Flooding Theory and Applications
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Low Salinity Flooding – Theory and Applications
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Two Possible Processes
LSW at initial water saturation (Swi)– Much higher oil recovery than with HS
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g yLSW at residual oil saturation (Sor)
– Requires very large water injection volume
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Mechanisms
Many proposed mechanisms – non agreed on by authorsMany SPE papers written over the last 10+ years
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Many SPE papers written over the last 10 years.Will give an overview of the various proposed
mechanisms.
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Key to Low Salinity Flood Increase in Oil Recovery
Residual oil saturation to water flood decreases as the salinity of the injected water decreases.
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Mechanisms
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Necessary but not Sufficient Conditions
From Morrow (1999) in Berea-sandstone cores: Significant clay fraction
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Significant clay fraction Presence of connate water Exposure to crude oil to create mixed-wet conditions
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Mechanisms
What do we know?:– Injection of low salinity water has a significant effect on
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j y grock wettability
– Oil recovery can increase by 10 to 40% over high salinity water flood.
– Increased oil recovery function of rock mineralogy, temperature, brine salinity, and oil type/composition.
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– This effect is NOT seen in clay free rock – note: Kaolinite is always oil wet in the reservoir
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Mechanism #1
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Fine Clay Migration and Permeability Reduction
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Fine Clay Migration and Permeability Reduction 1 of 2
Clay tends to hydrate and swell when contacting with fresh water
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Less-saline water affects the dispersion of clay and silt in the formationClay and silt then become mobile and follow the water into
the high permeability pathsMobile clay and silt become lodged in the smaller pore
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Mobile clay and silt become lodged in the smaller pore spaces of the high permeability paths
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Fine Clay Migration and Permeability Reduction 2 of 2
These high permeability paths become LESS permeableResulting formation more uniform and water flood
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Resulting formation more uniform and water flood performance is improvedClay is usually kaolinite and illite
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Mechanism #2
Mi ti f Cl P ti l d Ch f Schlumberger Private
Migration of Clay Particles and Change of Wettability of Rock
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Migration of Clay Particles and Change of Wettability of Rock
Detachment of mixed-wet clay particles (destabilized clays) from the pore walls because of lower salinity water –
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y ) p yresulting rock is more water wet.
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Mechanism #3
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pH Effect
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pH Effect
As low salinity water is injected into rock – hydroxyl ions generated through reactions with minerals in
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g greservoirEffectively like alkaline flooding – pH increases from 7+ to 9+Problems:
– Most alkaline floods have pH – 11 to 13
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Most alkaline floods have pH 11 to 13– No clear relationship between pH and oil recovery
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Mechanism #4
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Multicomponent Ion Exchange (MIE)
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Multicomponent Ion Exchange – Explanation 1 (short one)
Reduced salinity allows the electrical double layers to expand – allows bound multivalent ions to exchange –
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p gcomplex cations at the surface are replaced – rock goes from oil wet to water wet.(wettability modification depends on the amount of suited clay minerals and especially their distribution of the rock surface)
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Multicomponent Ion Exchange – Explanation 1 (short one)
Also called: DLVO theoryNamed after Derjaguin Landau Verwey and Overbeek
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Named after Derjaguin, Landau, Verwey, and Overbeek.
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Electrical double layer
A double layer (DL, also called an electrical double layer, EDL) is a structure that appears on the surface of an
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) ppobject when it is placed into a liquid. The object might be a solid particle, a gas bubble, a liquid droplet, or a porous body. The DL refers to two parallel layers of charge surrounding the object. The first layer, the surface charge (either positive or negative), comprises ions adsorbed di tl t th bj t d t h t f h i l
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directly onto the object due to a host of chemical interactions. The second layer is composed of ions attracted to the surface charge via the coulomb force, electrically screening the first layer…..
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Multicomponent Ion Exchange – Explanation 2
Status in oil-wet rock:– Different affinities of ions on rock surfaces
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– Multivalents or divalents such as Ca2+ and Mg2+ strongly adsorbed on rock surfaces
– Multivalent cations at clay surfaces are bonded to polar compounds present in the oil phase (resin and asphaltene) forming organo-metallic complexes and
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promoting oil-wetness on rock surfaces– Organic polar compounds are adsorbed directly to the
mineral surface - also oil wet
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Multicomponent Ion Exchange – Explanation 2
Low salinity water injection situation - MIE:– MIE removes organic polar compounds and organo-
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g p p gmetallic complexes from the surface and replacing them with uncomplexed cations
– Desorption of polar compounds from the clay/rock surface leads to a more water-wet surface
– Resulting in an increase in oil recovery
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Keys to Modeling Low Salinity Flooding
Exact mechanism not importantMust have appropriate relative permeability
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Must have appropriate relative permeability measurements
– Relperms with high salinity brine– Relperms with low salinity brine
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Brine and Low Salt Models in ECLIPSETheory and KeywordsAnd Examples from our Workshop Dataset
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Brine Model
The distribution of brine is modeled by solving a mass conservation equation for the salt concentration in each
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qgrid block. Brine is assumed to exist solely in the water phase and is
modeled internally as a water phase tracer using the equation:
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Brine EquationSchlum
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Low salinity option
Allows you to modify the saturation and relative permeability end points for water and
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relative permeability end points for water and oil phases as a function of the salt concentration as well as the water-oil capillary pressure.
This option is activated by the LOWSALT
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This option is activated by the LOWSALT keyword in the RUNSPEC section.
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LOWSALT Keyword
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It will automatically turn on the BRINEoption if this keyword is not already present.
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Interpolation Between High Salt End Points (H) and Low Salt End Points (L)
Given two sets of saturation functions, one for the low salinity and one for the high salinity, the saturation end points are first
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modified as:
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Where
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Interpolation Between High Salt Tables(H) and Low Salt Tables(L)
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LSALTFNC Example -- connate water is 100,000 PPM = 100 Kg/m3
LSALTFNC-- F1 = 0 for high salinity
F1 1 f l li it
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-- F1 = 1 for low salinity--Salt F1--conc factor--LSALTFNC Table --conc F1 F2 -- factor factor--kg/sm3
Low salinity injection RF 63%But cost of fresh water is very expensivePerhaps injecting a slug of fresh water followed by high
salinity water might recovery significantly more oil (than high salinity injection) but cost less because needs less fresh water
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fresh water.
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Slug Fresh Water Injection
Case 3: inject fresh water for 360 days followed by high salinity water
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Case 3: Slug Injection Low salt Flood – SALT Concentration
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Continuous and Slug Low Salinity Injection Comparison (Cases 2 and 3) of Cumulative Oil Produced Continuous low
salt injection
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Slug low salt injection
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Small difference in oil produced
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Continuous and Slug Low Salinity Injection Comparison (Cases 2 and 3) of Salt Production Rate
Slug low salt
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ginjection
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Continuous low salt injection
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Comparison (Cases 2 and 3) of Continuous and Slug Low Salinity Injection
Case 2 injects 107,700 Sm3 of low salinity waterCase 3 injects 34 900 Sm3 of low salinity water
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Case 3 injects 34,900 Sm of low salinity waterCase 2 recovers 62.7% of the oil in place (FOE)Case 3 recovers 60.7% of the oil in place (FOE)Conclusion – slug injection reduces the requirement for
fresh water but recovers nearly the same percentage of oil.
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Data Sets
Case 1 – highsalt-flood.dataCase 2 – lowsalt-flood data
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Case 2 lowsalt flood.dataCase 3 – lowsalt-slug-flood.dataYou will find these data sets in the distributed folder.
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Economic Sensitivity Study
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Economic Sensitivity Study – Details
The continuous high salinity water injection case produces 33,463 Sm3
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p ,We are interested in the incremental oil recovery from low
salinity flooding – incremental over the high salinity flood case.The continuous low salinity (fresh) water flood case
produces 56,651 Sm3 – that is an incremental recovery of
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p , y23,188 Sm3
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Economic Sensitivity Study – Details
Cost of produced oil (income) = $ 500 per Sm3
Cost of high salinity water = $ 0 per Sm3
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Cost of high salinity water $ 0 per SmCost of low salinity (fresh) water = $ 50 per Sm3
No discounting, oil price increase, interest rates, inflation will be considered.
Incremental Income from continuous low salinity flood is $ 6 207 350 00
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$ 6,207,350.00
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Economic Sensitivity Study
Starting with lowsalt-slug-flood-udq.data – vary the time of fresh water injection followed by high salinity water
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j y g yinjection – total water injection time must be 1110 days.Calculate the incremental income/profit for each case –
determine the injection case with the highest incremental income (incremental over the high salinity flood ).A UDQ is included in the data set.
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UDQ
UDQASSIGN FUOIL 500 / oil price ($/Sm3)ASSIGN FUFW 50 / fresh water cost ($/Sm3)ASSIGN FUSWOE 33463 / oil produced by high salt water (Sm3)
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ASSIGN FUSWOE 33463 / oil produced by high salt water (Sm3)DEFINE FUPROFIT (FOPT-FUSWOE)*FUOIL-(WWIT IFRESH)*FUFW / profit ($)UNITS FUPROFIT $ /UPDATE FUPROFIT ON //
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Results of Economic Sensitive Study
9.00E+06
9.10E+06
Incremental Profit Vs. Time of Fresh Water Injection390 day fresh water injectionIncremental profit = $8,989,000
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8 40E+06
8.50E+06
8.60E+06
8.70E+06
8.80E+06
8.90E+06
IncrementalProfit (US$)
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8.10E+06
8.20E+06
8.30E+06
8.40E+06
100 200 300 400 500 600 700Time of Fresh Water Injection (Days)
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End of Lo Salinit Water Flooding Schlumberger Private