the research and application of co 2 flooding in low-permeability reservoirs, china

1/00Canberra.Sept. 21-23,2009

The Research and Application of COThe Research and Application of CO22 Flooding Flooding

in Low-permeability Reservoirs, Chinain Low-permeability Reservoirs, China

Canberra, Australia, Sept. 21-23, 2009

State Key laboratory of EOR (Research Institute of Petroleum Exploration & Development , PetroChina)

Presented by: Yang [email protected]


Outline

The advantages of COThe advantages of CO22 flooding in low K flooding in low K

reservoir reservoir

Typical characteristics of low K reservoirs Typical characteristics of low K reservoirs

in China in China Part1Part1

Part2Part2

SummarySummaryPart4Part4

Analysis of the COAnalysis of the CO22 flooding effect flooding effect Part3Part3


30% 30% OOIP deposited in the low-OOIP deposited in the low-

permeability reservoirs in China.permeability reservoirs in China.

2/3 undeveloped oil in place deposited in 2/3 undeveloped oil in place deposited in

low-permeability reservoirs ( K<10mD).low-permeability reservoirs ( K<10mD).

95% oil in CNPC produced from 95% oil in CNPC produced from

waterflooding reservoirs.waterflooding reservoirs.

Low permeability reservoir Low permeability reservoir account for a large percentage account for a large percentage


Small pore throatSmall pore throat ，， low P&K, poor reservoir low P&K, poor reservoir qualityquality

lithologic trap lithologic trap ，， poor reservoir continuitypoor reservoir continuity thin interbedded sandstone and mudstone thin interbedded sandstone and mudstone variable reservoir thickness and physical variable reservoir thickness and physical

properties properties well-developed micro-fracture well-developed micro-fracture strong heterogeneitystrong heterogeneity higher water saturation higher water saturation

Micro-pore with fracture (thin section) great lateral variation

Reservoir characteristics of low Reservoir characteristics of low permeability reservoirs in permeability reservoirs in ChinaChina

thin interbedded sandstone and mudstone


No natural flowNo natural flow ，， Put into Put into production after fracturingproduction after fracturing ；；weak natural energy weak natural energy ，， the the production decline production decline quicklyquickly ，， supply artifical supply artifical energyenergystrong flow strong flow resistance resistance ，， high throat high throat pressure gradientpressure gradient ，， difficult difficult to keep the injection-to keep the injection-production balanceproduction balance

Development characteristics of Development characteristics of low permeability reservoirs in low permeability reservoirs in ChinaChina

0

1

2

3

4

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time(Year)

Oil

rate

(t/d

)Slow water flooding response,low sweep efficiencySlow water flooding response,low sweep efficiencyLow oil recoveryLow oil recovery （（ <20%<20% ），）， low oil production low oil production raterate （（ <1%<1% ））High investment ,great economic risk High investment ,great economic risk


Non-linear flow with throat pressure Non-linear flow with throat pressure gradient gradient The relationship between TPG & Permeability

The comparison of the oil production between the computed

data and the actual data

BLOCK

4.38

2.35 2.18

4.73

2.50 3.22

4.76

2.24 2.21

4.55

2.41

3.71

6.34

4.123.65

10.81

5.95

8.30

0

2

4

6

8

10

12

C45 C5 C64 C50 C55 C522

Oil

pro

du

cti

on

(m3 /

d)

Actual productionActual production

Computed production with ND methodComputed production with ND method

Computed production with D methodComputed production with D method

Displacement pressure gradientDisplacement pressure gradientD

isp

lac

em

en

t ve

loc

ity

Dis

pla

ce

me

nt v

elo

city

Darcy Darcy flowflow

Non-Darcy Non-Darcy flowflow

△ p/Lp/L0

d

e

△

ν

0 a

d

e

c b

d


压差 25MPa， k=1mD, λ＝ 0.12MPa/m

Well distance:190m SC: 0Well distance:190m SC: 0

Startup coefficient: at certain drawdown , the area displaced by Startup coefficient: at certain drawdown , the area displaced by injected water is divided by the total well pattern areainjected water is divided by the total well pattern areathe critical well distance decreases with the TPG increasesthe critical well distance decreases with the TPG increasesAt the certain drawdown and TPG, the SC increases with well At the certain drawdown and TPG, the SC increases with well distance decreases distance decreases

Well pattern influences the TPGWell pattern influences the TPG

Well distance:180m SC: 0.23Well distance:180m SC: 0.23

Well distance:160m SC: 0.58Well distance:160m SC: 0.58 Well distance:150m SC: 0.72Well distance:150m SC: 0.72


Part 2Part 2

The advantages of COadvantages of CO22 flooding in flooding in

low permeability reservoirlow permeability reservoir


Daqingzijing

oil field, CO2

flooding pilot

Natural gas field with CO2 over 20%

Xinli oil field ,CO2

flooding pilot

Da an oil field, CO2 flooding

pilot

In recent years, there is a major breakthrough in natural gas In recent years, there is a major breakthrough in natural gas exploration in the deep reservoirs of Songliao Basin. A large amount exploration in the deep reservoirs of Songliao Basin. A large amount of natural gas resources has been discovered and COof natural gas resources has been discovered and CO22 resources resources

are amounted to more than 100 billion cubic meters. are amounted to more than 100 billion cubic meters.

CNPC promise CNPC promise “0” CO“0” CO22

emission in emission in developing the developing the Gas FieldGas Field


The slope of Hall curves The slope of Hall curves indicates that the capability indicates that the capability of gas injection is 6.2 times of gas injection is 6.2 times than water injection. than water injection. COCO22 absorption index is absorption index is

5 times5 times than water than water absorption index.absorption index.

The slope of Hall curves The slope of Hall curves indicates that the capability indicates that the capability of gas injection is 6.2 times of gas injection is 6.2 times than water injection. than water injection. COCO22 absorption index is absorption index is

5 times5 times than water than water absorption index.absorption index.

Flooding modeFlooding mode Injection Injection pressurepressure

absorption indexabsorption index （（ t/d.MPa)t/d.MPa)

Slope of the Hall Slope of the Hall curvecurve (t/MPa)(t/MPa)

Water floodingWater flooding 44↗↗10MPa10MPa 18.718.7 3.14723.1472

COCO22 flooding flooding 11MPa11MPa 93.593.5 0.550.55

黑59-4-2井注水与注气hall曲线对比

y = 3.1472x + 0.0474

y = 0.5529x - 0.0023

0

1

2

3

0 0.2 0.4 0.6 0.8 1累计注入量（气/水）

∑△

p•t

Hall curves Hall curves

Cumulative injection (COCumulative injection (CO2 2 /water)/water)

Water injectionWater injection

CO2 injectionCO2 injection

1. To be injected easily to supply formation energy1. To be injected easily to supply formation energy，， to be used to solve the problems for water to be used to solve the problems for water injection in low-permeability reservoirinjection in low-permeability reservoir


2. CO2. CO22 has strong dissolution and expansion in has strong dissolution and expansion in

formation fluids, and has a key role in oil formation fluids, and has a key role in oil viscosity decreaseviscosity decrease

oilfieldoilfieldFormationFormation

TemperatureTemperature（℃）（℃）

FormationFormationPressurePressure

MPaMPa

Solubility Solubility of COof CO

22

mol%mol%

Volume Volume Factor of Factor of

Formation Formation OilOil

Decreasing of Decreasing of Formation oil Formation oil

ViscosityViscosity%%

Type of Type of displcementdisplcement

H87-2H87-2 101.6101.6 21.2021.20 48.3048.30 1.231.23 56.7056.70 non-misciblenon-miscible

QIQI 76.076.0 18.5018.50 45.9045.90 1.271.27 58.4058.40 non-misciblenon-miscible

H59H59 98.998.9 24.2024.20 63.9663.96 1.471.47 63.2063.20 misciblemiscible

H79H79 97.397.3 23.1123.11 63.5863.58 1.411.41 59.6259.62 misciblemiscible

F48F48 83.983.9 20.2620.26 59.359.3 1.231.23 73.9373.93 non-misciblenon-miscible

Cao SheCao She 103103 3232 7777 1.321.32 8080 misciblemiscible


3. To greatly improve the oil displacement 3. To greatly improve the oil displacement efficiency in low-permeability reservoir efficiency in low-permeability reservoir

0

20

40

60

80

100

0 0.2 0.4 0.6 0.8 1 1.2 1.4

CO2 Inj. PV(f)

Re

co

ve

ry(%

)

water flooding

CO2 miscible flooding

Displacement efficiency of long core displacement testDisplacement efficiency of long core displacement test

K = 1.43mD


Part 3Part 3 Analysis of the COAnalysis of the CO22 flooding effect flooding effect


Oilfiled Oilfiled TimeTime depthdepth/m/m

KK/md/md φφ//％％ γγ/g/cm/g/cm33

uuoo//

mPa.smPa.sT/℃T/℃ PatternPattern

SaNan DaqingSaNan Daqing 19671967 11401140 16281628 27.627.6 0.8680.868 9.89.8 4949 22

F14 JiangSuF14 JiangSu 19981998 30513051 7.57.5 11.811.8 0.8320.832 1.61.6 102.5102.5 11

Block228 JilinBlock228 Jilin 20002000 15001500 0.350.35 12.312.3 0.7870.787 6.76.7 7070 11

F48P DaqingF48P Daqing 20032003 17421742 1.41.4 14.514.5 0.8050.805 6.66.6 85.985.9 11

Caoshe Caoshe JiangSuJiangSu 20052005 30653065 241241 21.321.3 0.8220.822 77 110110 22

H87-2 JilinH87-2 Jilin 20062006 23002300 0.360.36 1010 0.7370.737 1.761.76 108.5108.5 11

H59JilinH59Jilin 20072007 24002400 2.652.65 11.4411.44 0.7620.762 1.861.86 9797 55

F48 DaqingF48 Daqing 20072007 17421742 1.41.4 14.514.5 0.8050.805 6.66.6 85.985.9 1515

S101 DaqingS101 Daqing 20072007 21202120 1.061.06 10.6510.65 0.790.79 3.63.6 108108 88

G89-1ShengliG89-1Shengli 20072007 30003000 4.74.7 1313 0.7390.739 1.591.59 110110 55

The COThe CO22-EOR Projects in PetroChina -EOR Projects in PetroChina


0

5

10

15

20

06-10 07-1 07-4 07-7 07-10 08-1 08-4 08-7 08-10 09-1 09-4 09-7

Time (y-m)

oil

pro

du

ctio

n r

ate

(t/d

)li

qu

id p

rod

uct

ion

rat

e(t/

d)

0

20

40

60

80

100

wat

er c

ut(

%)

liquid production rateoil production ratewater cut

water flooding CO2 flooding

1.Oil production increases and water cut decreases after 1.Oil production increases and water cut decreases after COCO22 flooding flooding The water cut of producers obviously decreases before the COThe water cut of producers obviously decreases before the CO22

arrives at the producers, which indicates that it is easier to drive oil arrives at the producers, which indicates that it is easier to drive oil with COwith CO22 than water in the case of the co-existence of oil and water than water in the case of the co-existence of oil and water

in the reservoir, and COin the reservoir, and CO22 can drive oil bypass water to increase oil can drive oil bypass water to increase oil

production and decrease water cut. production and decrease water cut.


1.Oil production increases and water cut decreases after 1.Oil production increases and water cut decreases after COCO22 flooding flooding

waterbreakthrough

CO2

breakthrough

0

20

40

60

80

100

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

注入体积，PV

reco

very

(%)

wat

er c

ut(

%）

0

100

200

300

400

500

GO

R （m

3/m

3）

Recovery %OOIP

Water Cut %

GOR cm3/cm3

WaterFlooding CO2 Flooding

Silmtube test also confirmed this phenomenon, in the tubules Silmtube test also confirmed this phenomenon, in the tubules saturated with oil, 0.3PV of water was injected to drive the oil, then saturated with oil, 0.3PV of water was injected to drive the oil, then COCO22 was injected, in the outlet, CO was injected, in the outlet, CO22 was produced firstly with a little was produced firstly with a little

bit water, after CObit water, after CO22 broke through, water production increased greatly, broke through, water production increased greatly,

which indicates that COwhich indicates that CO22 can pass through water plug to drive oil. can pass through water plug to drive oil.


2.Comparing with the water injection, the displacement 2.Comparing with the water injection, the displacement pressure for COpressure for CO22 flooding is low and CO flooding is low and CO22 flooding is an flooding is an

effective way for low permeability reservoir development effective way for low permeability reservoir development

From the gas and water injection profiles ,the interval From the gas and water injection profiles ,the interval with low water injection has higher gas injection, and all with low water injection has higher gas injection, and all intervals have balanced gas injection. The interval intervals have balanced gas injection. The interval heterogeneity is relatively weakened for gas injection, and heterogeneity is relatively weakened for gas injection, and the sweep area is expanded.the sweep area is expanded.


y = 0.243Ln(x) + 0.5784

R2 = 0.8703

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 2 4 6 8 10 12 14Per（10-3um2)

av

era

ge

po

re t

hro

at

rad

ius

(u

m)

y = -0.2621Ln(x) + 0.7486

R2 = 0.5027

0

0.5

1

1.5

2

0.1 2.1 4.1 6.1 8.1 10.1 12.1 14.1Per（10-3um2)

dis

pla

ce

me

nt

pre

ss

ure

(Mp

a)

In the pilot area, the average permeability of the reservoir is In the pilot area, the average permeability of the reservoir is about 3mDabout 3mDthe average pore throat radius is about 1um; and when the the average pore throat radius is about 1um; and when the permeability is less than 1mD, the corresponding average pore permeability is less than 1mD, the corresponding average pore throat radius is about 0.5um, and the displacement pressure will throat radius is about 0.5um, and the displacement pressure will increase one time than that for permeability of 3mDincrease one time than that for permeability of 3mDUnder the condition of formation, interfacial tension for the COUnder the condition of formation, interfacial tension for the CO22--oil or COoil or CO22-water system is lower than oil-water system-water system is lower than oil-water systemCOCO22 can get into small throats of low permeability reservoir to can get into small throats of low permeability reservoir to drive oil, so the gas injection profile is relatively more uniform than drive oil, so the gas injection profile is relatively more uniform than water injectionwater injection


3.Great difference of displacement efficiency among wells 3.Great difference of displacement efficiency among wells mainly caused by the strong lateral heterogeneity of mainly caused by the strong lateral heterogeneity of reservoirs reservoirs

一期受效井二期受效井

24.5MP24.5MPaa

19.5MP19.5MPaa

22.5MP22.5MPaa

24.4MP24.4MPaa

20.6MP20.6MPaa

自喷抽油产量大于 10吨


1.1. A larger amount of hydrocarbon resources is A larger amount of hydrocarbon resources is preserved in the low- permeability reservoirs in preserved in the low- permeability reservoirs in China, due to the poor reservoir quality and China, due to the poor reservoir quality and strong heterogeneity, it is difficult for the strong heterogeneity, it is difficult for the conventional water injection to supply the conventional water injection to supply the formation energy, which results in low formation energy, which results in low production, poor developing effect and low oil production, poor developing effect and low oil recovery.recovery.

2. CO2. CO22 flooding has some advantages for the flooding has some advantages for the development of low permeability oilfield, which development of low permeability oilfield, which can effectively supplement the formation can effectively supplement the formation energy and improve displacement efficiency.energy and improve displacement efficiency.

SummarySummary


3. Recent years, many natural gas reservoirs were 3. Recent years, many natural gas reservoirs were discovered in China, contained 10~20%mol discovered in China, contained 10~20%mol COCO22, the CO, the CO22 resources was estimated more resources was estimated more

than 100 billion cubic meters, which will be than 100 billion cubic meters, which will be used to develop low-permeability oilfield.used to develop low-permeability oilfield.

4. The oil resources are very big which can be 4. The oil resources are very big which can be developed with COdeveloped with CO22 flooding, only in the flooding, only in the

Songliao basin, such resources are estimated 2 Songliao basin, such resources are estimated 2 billion tons, CObillion tons, CO22 flooding is very prospective flooding is very prospective

for low-permeability oilfields.for low-permeability oilfields.

SummarySummary


5. Based on the CO5. Based on the CO22 flooding projects in China, flooding projects in China,

COCO22 injection is better and more effective in injection is better and more effective in

low water-cut stage than high water-cut stage low water-cut stage than high water-cut stage in the low-permeability reservoirs, COin the low-permeability reservoirs, CO22 EOR EOR

pilots are proven to be a technical success pilots are proven to be a technical success (due to the increase in oil production) , but (due to the increase in oil production) , but exists an economic risk in some projects at exists an economic risk in some projects at the current oil price.the current oil price.

6. The sufficient CO6. The sufficient CO22 sources and better sources and better

understanding of reservoirs are the key understanding of reservoirs are the key important factors for COimportant factors for CO22-EOR.-EOR.

SummarySummary


7. From the preliminary results in pilot areas, CO7. From the preliminary results in pilot areas, CO22

flooding as the primary recovery, the oil flooding as the primary recovery, the oil

recovery in low-permeability reservoir with recovery in low-permeability reservoir with

difficulty in development by water flooding, will difficulty in development by water flooding, will

reach 25% by COreach 25% by CO22 miscible flooding, and as the miscible flooding, and as the

method for enhance oil recovery after water method for enhance oil recovery after water

flooding, the oil recovery can be improved flooding, the oil recovery can be improved

8~13% by CO8~13% by CO22 flooding. flooding.

SummarySummary

the research and application of co 2 flooding in low-permeability reservoirs, china

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