1.4 Physical Property of Reservoir Fluid

8/15/2019 1.4 Physical Property of Reservoir Fluid

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. p ys ca property o eservo rFluid

ys ca proper es o cru e o

ys ca proper es o orma on wa er

The application of high-pressure

material balance


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Problem

1. What is the definition of gas solubility in crudeoil , the unit and the factors for gas solubility?

2. In the liberation processes, what is the

-

stage liberation? And the relationship betweenmulti-stage liberation and differential liberation?


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Density of crude oil

Dissolved gas-oil ratio of crude oil

orma on vo ume ac or

oil

Viscosity of crude oil


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1.1 Densit and s ecific ravit

m

o

oV

= ρ

o ρ =

w ρ

5.1315.141−=

o

API oγ


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） 3

0 . 7 5

1 7 0 o

C 度（ g / c m

0 . 6 5

0 . 7 0

地层

油密

0 5 1 0 1 5 2 0 2 5 3 0 3 5

28 4 o

C

压力（ M P a ）density decreases with the increasing temperature;

, ,

density of crude oil decreases because of the increasing

Above the bubble pressure, with the increase of pressure,

density of crude oil increases because of the systemcompressed by pressure;


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1.2 Dissolved gas-oil ratio of crude oil 溶解气油比

Gas oil ratio (Rs) refers to the standard volume of

as which dissolves in one stock tank volume of oil

at formation pressure and temperature.

•Pi>Pb , R s= R si

•P =P R =R

•Pi


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1.3 Oil formation volume factor原油的地层体积系数

1)conception

The oil formation volume factor , Bo, is defined as the

ratio of the volume of oil lus the as in solution at

the prevailing reservoir temperature and pressure to

e vo ume o o a s an ar con ons. o s a ways

.

Expressed mathematically as:

T P f

o

V B

,)(=

os


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oo f os f B BV V V /)1(/)( −=−=

β

reflects the shrinkage of crude oil extracted from

e reservo r


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3) The relation between oil volume factor and pressure

•

•P= Pb, Bo= Bob

•P= Pb, Bo•P =0.1MPa Bo=1 at

standard conditions


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4)Two phase volume factor

(or Total formation volume factor)

Two phase volume factor containing oil and gas

refers to the ratio of the bulk volume of reservoir oil

.

g s si

os

f

os

g os s si f

t B R R

V

V

V

V V B )(

)(−+=

⋅−+= g s sio B R R B )( −+=


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(1)When formation pressure is greater B R R B B ( −+=

or equal to saturation pressure (that is

＝ — ＝＝ s s s s o ,

That is, two phase volume factor equal toB t

.

(2)When formation pressure decreases Bob

to standard pressure, dissolved gas will be completely evolved from crude oil, R s

＝0; at the time, B g ＝1, Bo＝1, get Bt ＝

1+R si，this is the maximum for Bt .P

bP

(3) Bt -P curve only exists when P ＜ P b.

When ＞ it is sin le hase oil.

Bt is the function of p.

,


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1.4 Crude oil compressibility coefficient

Crude oil compressibility coefficient refers

to the change in volume per unit volume for a

unit chan e in ressure.

V V V V C

f b f

T

f

o−

−−=

Δ⋅−≈

∂−=

11)(

1

b f f f

B BC oobo

−−=

1

bo

−


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地层原油的粘度

.地层原油的粘度

ru e o v scos y s an mpor an p ys ca

property that controls and influences the flow of oil

through porous media and pipes. The viscosity, in

general, is defined as the internal resistance of thefluid to flow.

The oil viscosity is a strong function of thetemperature, pressure, oil gravity, gas gravity, and

gas so u y.


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1) Chemical composition factors 化学组成的影响

Or Oil gravity

The chemical composition of crude oil is the internalcause and main factor that affects viscosity. Generally

speaking, high viscosity with high formula weight,

-

viscosity greatly.


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2) Temperature factors温度的影响

1000

10000

相对密度0.9861原油

100

， m

P a . s

相对密度

0.8762原油

1

10

粘

0.1

0 50 100 150 200 250 300

温度，℃

Oil viscosit is sensitive to tem erature variation. Theviscosity decreases with temperature increasing. The

sensitiveness to various kinds of crude oil is different. For

certain oil, when temperature increases 10 , the viscosity

may decrease 50%


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3)Pressure factors压力的影响


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1.6 The variation law of physical properties for typical

unsaturate reservo r o


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Ex r i :

fluids to evaluate fluid properties. An 320cm3 oil

.

reservoir conditions. When pressure reduced to

. a, e o samp e vo ume n ce ncrease o335.2cm3. After evolved 4.1 L gas, the remaining oil

in cell was 303cm . The pressure and temperature

reduced to 0.1MPa and 20 , respectively, theremaining oil was 230cm3 and released gas was

16.4 L.

Calculate: Rs, Bo, Bg, Z, Bt at 13.6MPa


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, g , .

320cm3 Vo,303cm3g2

, .

Vs

Pf, Tf P, T P0, T0


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2 The following is the PVT analysis at 93.3℃

Pressure ,MPa 27.579 20.684 17.237 13.790 10.342

System volume, cm3 404 408 410 430 450

After compressed, the system is expanded to 13.79MPa again.The remaining liquid volume is 388 cm3 and the evolved gas

5.275 L (measured at standard conditions). Then system

pressure decreased to 0.1MPa, temperature 20 ℃, theremaining liquid volume is 295 cm3, liberated gas volume

measured at standard conditions is 21 L, calculate:

1 the bubble ressure of the s stem.(2)Co, Bg at 20.684 MPa

o, , s . , .

(4)Bg, Z at 13.790 MPa


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2 Ph sical Pro erties of Formation ater

FormationFormation waterwater refers to edge and bottom water,

interlayer water and bound water.

water that remains in reservoir after the generation of

reservoir. It coexists with oil and gas but does not join

in the flow.


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Formation water is a kind of formation fluid that has

are considered as driving forces. Though bound water

doesn’t join in flowing, its distribution has direct impact

on o sa ura on.


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The following purpose is:

（1）to judge edge water flow, block connectivity

producing well;

（2）to study the compatibility conditions with

water and to analyze the causes and extents of

damage;


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（3）to provide references to the treatment and

（

4）

to judge sedimentary environment according

to reservoir water type.


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2 Physical Properties of Formation Water

.

•Water formation volume factor

•Water viscosity

•Gas solubility in water

•


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2.1 Chemical Composition and Classification of

Formation Water

1

Chemical Composition

s nown as sa wa er .

• 阳离子 + + 2+ 2+ 阳离子

• Common anions阴离子

: Cl-, SO42-, HCO3

- CO32-

, NO3-, Br -, I -


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• 微生物生物.

sulfate reducer 厌氧硫酸还原菌

, which contributes to

t e cas ng corros on an ormat on p ug n water

injecting. They may be present in the closedreservoir, or entering into the formation while

.

• 有机物质机物质

acid环烷酸 , fatty acid脂肪酸 and other more

x u , .

have a direct impact on oil sweep efficiency .


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1 Salinity

The salinity of water refers to the bulk concentration of

／, ／ .

The total salinity is expressed by the sum of cations andanions content in water.

离子毫克当量浓度子毫克当量浓度

on zeon ze m normam norma contentcontent 离子毫克当量浓度子毫克当量浓度

equa s tothe ratio of the concentration of a certain ion and its

equivalent weight.

／，

E g: upposed that the content o l- s mg／

L，

and

equivalent weight (化合当量) of Cl- is 35.3， the millinormal

content(毫克当量浓度

)7896／

35.3＝

225.6 mg／

L


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In primary condition, formation water with

high salinity is in saturated solution state. When it

,

formation water with the de ression of tem erature

and pressure. Seriously, the salt will crystallize (结晶

in well bore and bring great difficulties for

production.


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calcium, magnesium and other divalent cations(二价阳

离子

).

In chemical driving (such as polymer or active agent

injection), sediments formed by chemical injection will

a ec e sp acemen e c ency e ar ness s oo

hi h.


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1 Water t e1 Water t e水型型——Surin methodSurin method

(1) sodium sulfate type硫酸钠

(Na2

SO4

)水型

：reflects

水型型

a s ruc ure c osure , w c s un avora e or o

&gas accumulation and preservation;

(2) sodium bicarbonate type重碳酸钠

(NaHCO3)水型：

reflects water under continental environment,

widel s read in oilfield roduced water whichcould be symbol of oil distribution.


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(3) magnesium chloride type氯化镁

(MgCl2)水型

：

,

exist in interior layer of oilfield

氯化钙水型

(4) calcium chloride type氯化钙

(CaCl2)水型

：

reflectswater under closed structure, which is favorable for

oil&gas accumulation and preservation, and symbol

o goo o s r u on.


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22 WaterWater T eT e ud mentud ment

Combined Order of Anions and CationsCombined Order of Anions and Cations

Na K+ + -+ 12

3

2

3

2+ 2-Mg SO 4

2+ -Ca HCO 3


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formation water

The solubility of gas in

formation water refers to the

standard volume of dissolved

water at formation pressure

an empera ure s an ar

m3／m3).


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ormat on water compress ty coe c ent

refers to the change in volume per unit volumefor a unit change in pressure.

T

w

ww P V C )( ∂

−=

w

—— compressibility of formation water, MPa－1；

w

—— volume of formation water, m3；

T w

P

V )(

∂

∂——volume variance ratio of formation water with pressure

variation under constant pressure condition, m3 /MPa


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4 Formation Water Viscosit 地层水的粘度地层水的粘度

3 Th li ti f hi h


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3 The application of high-pressure

parame ers o u ——equ r umequation of reservoir material

The material balance equation (MBE) has long been

engineers for interpreting and predicting reservoir

per ormance.

• Estimate initial h drocarbon volumes in lace

• Predict future reservoir performance

• Predict ultimate hydrocarbon recovery under

various t es of rimar drivin mechanisms


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Reservoir material balance equation is based on

the material balance principle.

(1) The gas phase balance :

Original gas reserve in reservoir


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(2) The volumetric balance :


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supposed that a saturated reservoir with gas

with the pressure depletion the volume of

u , w w .


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p n a reservo r pressure, ap Volumetric average reservoir pressure, MPa

Δp Change in reservoir pressure = pi − p, MPa

N Initial (original) oil in place, m3

- - v v u

initial reservoir oil volume

Np Cumulative oil produced, m3

G Cumulative as roduced m3

Wp Cumulative water produced, m

3

p - ,


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GOR Instantaneous gas-oil ratio, sm3 /m3

Rsi Initial gas solubility, sm3 /m3R Gas solubility, sm3 /m3 Boi Initial oil formation volume factor, m

3 /sm3

B Oil formation volume factor, m3 /sm3 Bgi Initial gas formation volume factor, m

3 /sm3

B Gas formation volume factor m3 /sm3

Winj Cumulative water injected, m3

G Cumulative as in ected m3

We Cumulative water influx, m3

G Initial as-ca as m3

P.V Pore volume, m3

C Water com ressibilit MPa-1

Cf Formation (rock) compressibility, MPa-1


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The volume occupied by initial oil place :

NBoi (OIIP)

e vo ume occup e y n a gas p ace:

The total gas reserve in original bulk:

Bm ⋅⋅ o s

B+⋅


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The remaining gas volume at p in reservoir: G ?

The solution gas volume at p in the remaining oil :

s p R N N ⋅− )(

The evolved gas volume at p in gas cap:

w po poi BW W B N N B N m ])()()1[( ⋅−−⋅−−⋅⋅+

g


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R N ⋅

Original gas reserve in reservoir＝

t e output gas

the residual gas in reservoir


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)(])([ w p g si pt p BW W B R R B N N −−−+=

)()( gi g

titit

B

mB B B−

+−

g

u y u

R R , B B , B B , B , B B etc.

2) production data , such as N p , W p and R p.

3) unknown static, such as N, m, W .

exercises


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exercises：

1 Derived the expression of calculating reserves in a certainsa ura e o reservo r y us ng ma er a a ance pr nc p e.Supposed an original reservoir with no gas cap and no bottom

,developed by solution gas driving. During the process ofproducing, no water of bottom and badge was influxed and a

gas cap occured with the decreasing pressure. given thatreservoir volume is constant.xpresse parame ers:

Original oil reserve: No, accumulate producing oil volume: Np,

,solution gas to oil:Rpoil volume factor at pb: Boi ratio of solution gas to oil at p:Rsoil volume factor at p: Bo gas volume factor at p: Bg

2 Given that the oil initially in place (OIIP) 2 305×106m3 of some


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2. Given that the oil initially in place (OIIP) 2.305×10 m of somesaturate o reservo r, t e o ow ng s t e eta pro uc ng

information about the reservoir:

P, MPa R s, sm3/m3 Bo, m

3/sm3 Bg, sm3/m3 Bt, m

3/sm3 R p, sm3/m3 N p, m

3

12.755* 122.89 1.363 0.00696 1.363 ---- 0

11.032 110.60 1.333 0.00892 1.437 156.37 272660

8.963 95.28 1.300 0.01067 1.594 177.39 545330

6.895 87.89 1.258 0.01404 1.748 195.91 ?

Notes: * refers as the bubble pressure

Calculate:

producing oil volume was 272660 m3 and 545330 m3 ,

res ectivel ?2)If the pressure reduced to 6.895MPa, the water influx was

1.0135×106m3 , how much was the accumulate producing oilvolume?

Documents

1.4 Physical Property of Reservoir Fluid