# US 10,119,374 B2 · Method for simulating fluid flows, a computer program and a computer readable medium

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- Number: US 10,119,374 B2
- Document ID: US10119374B2
- Status: Granted
- Kind: B2
- Application number: 14/385,055
- Filed: 2013-03-11
- Published: 2015-03-12
- Granted: 2018-11-06
- Earliest claimed: 2012-03-12
- Assignees: Total SA
- Applicants: Total SA
- Inventors: Leonardo Patacchini; Romain De Loubens; Arthur Moncorge
- Web page: https://patentgrep.com/patent/US10119374B2

## CPC

- E21B 43/16: Enhanced recovery methods for obtaining hydrocarbons
- G06F 30/20: Design optimisation, verification or simulation (optimisation, verification or simulation of circuit designs G06F30/30)
- G06F 30/28: using fluid dynamics, e.g. using Navier-Stokes equations or computational fluid dynamics [CFD]
- G06F 2111/10: Numerical modelling
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

A method for simulating fluid flows in a petroleum reservoir to improve final oil recovery. The fluid comprises water, hydrocarbon, and surfactant components. The method comprises a flash step for calculating compositions via two stages. A first stage comprises a first flash to determine first compositions of the water, oil and gas phases and is performed by omitting the surfactant component in the fluid. A second stage comprises a second flash to determine a microemulsion composition of the microemulsion phase.

## Claims

### Claim 1

A method for improving a recovery of a hydrocarbon from a petroleum reservoir, wherein the method comprises:
creating a model of said petroleum reservoir in which a reservoir fluid can be split in a plurality of physical phases, said plurality of physical phases comprising a gas phase, an oil phase, a water phase and a microemulsion phase, each physical phase comprising a plurality of components, the plurality of components comprising at least water, a hydrocarbon, and a surfactant,
performing a simulation on the model with a flash step for calculating at least compositions of each physical phase by evaluating a concentration and a quantity of each component in said physical phases,
wherein the flash step comprises:
a first stage comprising at least a first flash to determine compositions of a group of phases, said group of phases being the water phase, the oil phase and the gas phase, and said first flash being performed by omitting the surfactant component in the fluid,
a second stage wherein, in case the water phase and the oil phase are simultaneously present in the group of phases determined at the first stage, said second stage comprises at least a second flash to determine a microemulsion composition of the microemulsion phase,
optimizing a surfactant flooding procedure in the petroleum reservoir using the simulation output obtained after the flash step to optimize the timing for injection and the amount of injected surfactant;
initiating the optimized surfactant flooding procedure; and
recovering the hydrocarbons from the petroleum reservoir utilizing the optimized surfactant flooding procedure.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the second stage comprises the following:
lumping the gas phase, the water phase and oil phase into pseudo-phases, the pseudo-phases comprising an oleic pseudo-phase, an aqueous pseudo-phase and a chemical pseudo-phase,
performing the second flash on the bases of the pseudo-phases to determine updated compositions of the water phase, oil phase, and to determine the microemulsion composition of the microemulsion phase.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the second flash is performed by omitting the gas phase in the group of phases determined at the first stage, and the second stage comprises the following:
lumping the water phase and oil phase into pseudo-phases, the pseudo-phases comprising an oleic pseudo-phase, an aqueous pseudo-phase and a chemical pseudo-phase,
performing the second flash on the bases of the pseudo-phases to determine updated compositions of the water phase, oil phase, and to determine the microemulsion composition of the microemulsion phase.

### Claim 4 (depends on 3)

The method according to claim 3, wherein the second stage further comprises merging the gas phase determined at the first stage with the water phase, oil phase and microemulsion phase determined during the second stage.

### Claim 5 (depends on 2)

The method according to claim 2, wherein lumping comprises:
a first lumping operation wherein a first fraction of the surfactant component is lumped into the aqueous pseudo-phase so as for the surfactant concentration in said aqueous pseudo-phase to be below the critical micelle concentration, and
a second lumping operation wherein a second fraction of the surfactant component, said second fraction remaining after the first lumping operation, is lumped into the chemical pseudo-phase.

### Claim 6 (depends on 1)

The method according to claim 1, further performing the following steps after the flash step:
building reservoir equations based on the compositions of the physical phases determined by the flash step,
solving the reservoir equations to determine reservoir variables at the end of the time step.

### Claim 7 (depends on 6)

The method according to claim 6, wherein solving the reservoir equation is performed with a fully implicit solving method or with an adaptive implicit solving method.

### Claim 8 (depends on 6)

The method according to claim 6, further including a storing step for storing the reservoir variables onto a medium.

### Claim 9 (depends on 6)

The method according to claim 6, wherein the reservoir equations comprise:
molar balance equations for each component in the fluid, and
thermodynamic constraint equations corresponding to an equilibrium of all the physical phases that are present in the fluid.

### Claim 10 (depends on 9)

The method according to claim 9, wherein the molar balance equations write for each component of the fluid:
∂
∂
t
⁢
(
ϕ
⁢
∑
j
=
1
n
p
⁢
⁢
S
j
⁢
ρ
j
⁢
c
i
,
j
)
+
▽
_
·
(
∑
j
=
1
n
p
⁢
⁢
u
_
j
⁢
ρ
j
⁢
c
i
,
j
)
=
0
where
i is an index corresponding to a component in the fluid,
j is an index corresponding to a phase,
ci,j is the molar fraction of component i in phase j,
Sj is the saturation of phase j,
ϕ is the rock porosity,
ρj is the molar density of phase j,
nP is the maximum number of phases present in the fluid,
∇ is the nabla operator,
uj is the Darcy velocity that writes:
u
_
j
=
-
k
_
_
⁢
k
rj
μ
j
⁢
(
▽
_
⁢
⁢
P
j
-
ρ
_
j
⁢
g
_
)
where
Pj is the pressure of phase j,
k is the absolute permeability tensor of the petroleum reservoir,
krj is the relative permeability of the phase j,
μj is the viscosity of the phase j
g is the gravity acceleration,
ρj is the mass density of phase j.

### Claim 11 (depends on 9)

The method according to claim 9, wherein the thermodynamic constraints equations comprise oil-microemulsion thermodynamic constraints equations that write:
∀iϵ[1:nc]:Γom(oi−xi)+κo=0
where
nc is the number of components in the fluid,
oi is the molar fraction of component i in the oleic pseudo-phase constitutive of the microemulsion phase,
xi is the molar fraction of component i in the oil phase,
κo is a volumetric microemulsion constraint,
Γom is the molar fraction of oleic pseudo-phase in the microemulsion phase.

### Claim 12 (depends on 9)

The method according to claim 9, wherein the thermodynamic constraint equations comprise water-microemulsion thermodynamic constraints equations that write:
∀iϵ[1:nc]:Γam(ai−wi)+κa=0
where
nc is the number of components in the fluid,
ai is the molar fraction of component i in the aqueous pseudo-phase constitutive of the microemulsion phase,
wi is the molar fraction of component i in the water phase,
κa is a volumetric microemulsion constraint, and
Γam is the molar fraction of aqueous pseudo-phase in the microemulsion phase.

### Claim 13 (depends on 1)

A computer program comprising program code instructions for processing the method steps according to claim 1, said computer program being run by a computer.

### Claim 14 (depends on 1)

A computer readable medium having a computer program recorded on it, said computer program comprising program code instructions for processing the method steps according to claim 1.