000707 CBerto El Tordillo Field

7/29/2019 000707 CBerto El Tordillo Field

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Outline

El Tordillo Field Description.

Area Central Norte Waterflood Project Description.

Data Acquisition and Preparation.

Production and Injection Data Analysis.

Integration of Results. Conclusions and Recommendations


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Objectives

To present a description of El Tordillo Field and the AreaCentral Norte waterflood project.

To show the preparation of the production and injectiondata.

To analyze and interpret the reallocated production data.

To demonstrate the various analyses.

To integrate the results (as maps and crossplots). To make recommendations for future waterflood projects inEl Tordillo Field.


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El Tordillo FieldEl Tordillo Field islocated in The SanJorge Basin, Patagonia(Argentina)

COMODORO

RIVADAVIA

ARGENTINA

71 70 69 68 67 66

71 6970 68 67 66

ATLANTIC

OCEA

DESEADO MASSIF

SOMOCURA MASSIF44

45

46

47

44

45

47

0 30

MILES

CHILE

NORTH-WESTERN

AREA

NORTHCENTRAL

AREA

CENTRAL

BASIN

WESTERN

AREA

SOUTH

FLANK

SOUTH-

WESTERN

AREA

ANDEAN

BELT

OFFSHORE

COMODORO

RIVADAVIA

Area: 29000 Acres

El Tordillo Field isrecognized as one of

the major oil fields in

Argentina.


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El Tordillo FieldReservoir Data

Total numbers of wells 850

Production oil wells 420

Injection water wells 69

Average final depth 9,840 ft Area 29,000 acres

Cumulative oil (Aug. 1999) 189 MMSTB

OOIP 1,800 MMSTB


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Reservoir Description

El Tordillo Field reservoirconsists of acomplex of fluvial-dominated sandstonesequences comprised of multiple layers withdistinctive shale zones.

Sandstones bodies are concentrated ingroups, locally called complejos.

Normal faultsare the most common andmost important structures in the reservoir.

Trbol, Comodoro Rivadavia, Mina ElCarmenare principal producing formationsin the stratigraphic column in the reservoir.


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El Tordillo FieldWaterflood Performance

There are several producing regions within El Tordillo

Field with:

Excellent continuity of oil-bearing sands,

Sequence development, and A high cumulative oil recovery.

These three characteristics are sufficient to define El

Tordillo Field as feasible for waterflooding.


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Area Central Norte project (ACN) has an excellent secondary response.

0

200

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1000

1200

1400

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br-99

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ul-99

MESES

CA

UDAL[m3/d]

T.SUR TN ACN LPE BLOQUE D ACNE LPS ACNSOM TSPROF.

Waterflood Oil Rate in ACN (Aug 99) = 2200 STB/D

El Tordillo FieldWaterflood Performance


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Stratigraphic Cross Section A-A for ACN Project Area

MINA EL CARMEN FORMATION

S-667 S-678 S-537 S-691 S-694 S-637 S-624 S-572 S-634 S-632 S-631 S-682 S-782

EL TREBOL FORMATION

PATAGONIA FORMATION

SARMIENTO-RIO CHICO FORMATION

COMODORO RIVADAVIA FORMATION

SALAMANCA FORMATION

8141 ft

0 ft

1000 ft

2000 ft

3000 ft

4000 ft

5000 ft

6000 ft

7000 ft

8000 ft

10000 ft

9000 ft

0 ft 1300 ft 2600 ft 3900 ft 5200ft 6500 ft 7800 ft 9100 ft 10500 ft

8443 ft

8095 ft

8787 ft

7993 ft

8532 ft

8207 ft

8580 ft

8450 ft8532 ft 8472 ft 8561 ft 8521 ft

Dry Horizon (No production)

Gas, Oil, and Water production

Injection horizon

Gas production

Oil and Water production

Oil production

Converted water injection well

Project Area Cross-Sections


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Area Central Norte (Region Map)

Area Central Norte


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Reservoir Thickness Contour Plot (ft)ACN Study Region

El Tordillo FieldPatagonia, Argentina


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Data Preparation

Production Data

Injection Data

Static Reservoir Data


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Data PreparationProduction Data

The fact that the production data are commingledmay significantly affect our ability to analyze

and interpret the production for each well:

It is impossible to provide an analysis for eachindividual layer.

The production data is re-allocated in Area

Central Norte (ACN) zones: ComodoroRivadavia and Mina El Carmen formations


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Data Preparation - Steps

Identify errors or anomalies in the production andinjection data.

Locate and annotate changes in the completionpractices.

Reinitialize the production data in time.

Reallocate the total production for each reservoirinterval.


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1.E+00

1.E+01

1.E+02

1.E+03

1962 1966 1970 1974 1978 1982 1986 1990 1994 1998

Data PreparationRe-allocation

OilProductionRates,

STB/

D

Date, year

ACNsands

Oil Production Non -ACNsands

Oil Production

Production Performance Plot for Well 516Comparison of Total Oil Rate and ACN Project Zones Oil Rate


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Data Preparation

Production Data

Injection Data

Static Reservoir Data


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Data PreparationInjection Data

Although the injection wells are injecting in a

multi-stage fashion (i.e., injection over several

layers simultaneously), the total injection per well

is used in the analysis because the oil productioncould not be identified sand by sand.


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Data PreparationStatic Reservoir Data

To estimate the static reservoir pressure as a func-tion of date, we used the fluid level measured inswab tests (performed on individual sands (orgroups of sands)) during the productive life of each

well.

Although the pressure data show a poor correlationwith date, we believe that the data are reasonable,

and as such, we have used the average trend for ouranalysis.


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0

500

1000

1500

2000

2500

3000

1960 1965 1970 1975 1980 1985 1990 1995 2000

Data PreparationStatic Reservoir Data

Pressure (avg.) = 84426 - 41.8 * year

Datum : 7664 ft

StaticReservoirPressure,p

si

Date, year

Static Reservoir Pressure Assigned by DateEl Tordillo Field, ArgentinaACN Region

high

avg.

low


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1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1975 1979 1983 1987 1991 1995 1999

Production Performance Plot for Well S-677ACN Project - Blue, Junior, Brown Zones

ProductionRates,S

TB/D

Date, year

Workover(Aug.9

3)

PrimarySecondary

Oil

Water

Completion(Oct.7

6)

Workover(Jun.8

2)Trend #1


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Well S-677 (Oil)Match Trend #1

We note a good match of all the production data, for both the transientand boundary-dominated flow periods in trend #1.


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1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1975 1979 1983 1987 1991 1995 1999


ProductionRates,S

TB/D

Date, year

Workover(Aug.9

3)

PrimarySecondary

Oil

Water

Completion(Oct.7

6)

Workover(Jun.8

2)Trend #2


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1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1975 1979 1983 1987 1991 1995 1999


ProductionRates,S

TB/D

Date, year

Workover(Aug.9

3)

PrimarySecondary

Oil

Water

Completion(Oct.7

6)

Workover(Jun.8

2)

Secondary Trend


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Well S-677 (Oil)Match Secondary Trend

We note a good match of all the production data in the boundary-domi-nated flow periods during the secondary production trend.


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Estimated Ultimate Recovery Analysis

qovs.Np (Semi-Empirical-Approach) (S-677)

This plotting approach is used when bottomhole pressure data

are not available.

SecondaryPerformance

Extrapolating thetrends in the

waterflood period

to qo=0, thesecondary

movable oil isobtained.


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EUR Analysis: ResultsWell S-677 (Oil)

Primary PerformanceNp,mov: 328.9 MSTB

Recovery factor: 6.0 %

Secondary Performance

Np,mov: 201.7 MSTB

Recovery factor: 3.68 %

Secondary/Primary Recovery Ratio = 0.613


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Data Result Using Decline Type Curves

Injection WellsAs for oil cases performed previously, the material balancetype curve analyses yield two types of results: flow andvolumetric parameters.

Reservoir properties Skin factor for near well damage or stimulation, s Effective permeability, kw

In-place fluid volumes Total system volume available for injection, W

Injectable water, Winj Injection area,A


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1 . E + 0 1

1 . E + 0 2

1 . E + 0 3

1 . E + 0 4

1 . E + 0 5

1 . E + 0 6

9 4 01 9 5 01 96 0 1 97 0 1 9 8 0 1 9 9 0 1

0

5 0 0

1 ,0 0 0

1 ,5 0 0

2 ,0 0 0

2 ,5 0 0

3 ,0 0 0

3 ,5 0 0

4 ,0 0 0

4 ,5 0 0

5 ,0 0 0

5 ,5 0 0

6 ,0 0 0

Injection Performance Plot for Well S-638

ACN Project - Blue, Junior, Brown Zones

W

aterInjectionRates

,STB/D

Date, year

Workover(Oct.98)

Pwfqwi

Conversion(Oct.93)

Workover(Oct.95)

Workover(Apr.97)

Flow

ingBottomholePressure,psia


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Results: Well S-638 (Injection Well)

The injection rate (and pressure) functions were plottedversus material balance time on the Fetkovich/McCraytype curve .The following results were obtained:

Volumetric PropertiesTotal system volume

available for injection, W= 42,040 MSTBW

Injection Area, A = 439.6 acres

Flow PropertiesPermeability, kw = 1.848 mdSkin factor, s = -6.498


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Estimated Injectable Water AnalysisS-638

We note a reasonably linear trend with sig-nificant data scatter. The extrapolation of

this trend yields Winj= 11.1 x 106 STBW

InjectionPerformance

By plotting theinjectivity index,(qwi/Dp), versus

cumulative waterinjection, we can

estimate theinjectable watervolume when

(qwi/Dp)=0.

(qwi/Dp) vs. Wi


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Integration of Results - Maps

The following maps are presented as a mechan-ism to integrate the results from our individualwell analyses:

Flow Capacity, khOriginal Oil-in-Place,OOIP

Primary and SecondaryEUR

Total Recovery Factor

Secondary/Primary Recovery Ratio.


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Flow Capacity (kh) Contour Map

OOIP

EUR(p)


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Original-Oil-in-Place (OOIP) Contour Map

kh

EUR(p)


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SecondaryEUR - Contour Map


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Integration of Results - Crossplots

Crosplots are presented to estimate average values for theprimary and secondary recovery factors and secondary/primary recovery ratio:

EURPrimary vs. OOIP

EURSecondary vs. OOIP

EURSecondaryvs.EURPrimary

Log-log correlation plots were prepared as an attempt toobtain meaningful relations between the computed flowcapacity and the oil recovery versus initial oil rate in order

to estimate the performance of infill wells in the ACNRegion:

kh, OOIP,EURPrimary ,EURSecondaryvs. Oil Rates.


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C l t S d EUR P i EUR


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Crossplot: SecondaryEUR versus PrimaryEUR

Comparison of Secondary Estimated Ultimate Recovery

Versus Primary Estimated Ultimate Recovery

El Tordillo Field, Argentina

(ACN Region- Zones : Blue, Junior, and Brown)

1.E+04

1.E+05

1.E+06

1.E+07

1.E+04 1.E+05 1.E+06 1.E+07

Estimated Ultimate Recovery (Primary), STB

EstimatedUltimateRecovery

(Secondary),S

TB

EUR Secondary = 0.47 EUR Primary


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Crossplot: OOIP versus Initial Oil Rate (q )


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Crossplot: OOIPversus Initial Oil Rate (qoi)Comparison of Oil-in-Place (OOIP) Computed from DeclineType Curve Analysis

Versus Initial Oil Rate



1.E+05

1.E+06

1.E+07

1.E+08

1.E+01 1.E+02 1.E+03 1.E+04

Initial Oil Rate, STB/D

ComputedOil-in-P

lace,STB

OOIP(avg)

= 119017 q oi0.6681

Low

Avg

High

primary(q )


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(qoi)Comparison of Estimated Ultimate Recovery (Primary)

Versus Initial Oil Rate



1.E+04

1.E+05

1.E+06

1.E+07

1.E+01 1.E+02 1.E+03 1.E+04

Initial Oil Rate, STB/D

EstimatedUltimateRecovery

(Primary),ST

B

EUR(primary)(avg)

= 25010 q oi0.5243

High

Avg

Low


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Integration of Results Time Dependency


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Integration of ResultsTime Dependency


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Integration of ResultsTime Dependency

We note that the previous comparisons do notshow any specific trends. The lack of any specifictime dependency of the results clearly confirms

that the reservoir is highly heterogeneous and

probably of a low, to very low permeability.

C l i


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Conclusions

The following conclusions are noted:

The guidelines to set the production and injection realloca-tion are well established an all of the necessary information/

data was identified and sorted.

The decline type curve and volumetric analyses yieldedacceptable estimates of original oil-in-place, as well as

primary and secondary movable oil.

The calculation of movable oil volume using the q versusNpplot yields acceptable results (unlesspwfvaries significantly).


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Conclusions (Cont.)

Integrating the results of this study, we identified areas with

favorable conditions for additional oil reserves. We believe

that a detailed analysis (on a well-by-well basis) of these

zones will support the drilling of new infill wells in the ACN

Region.

We observed relatively constant trends ofOOIPand primaryEUR versus completion date, which confirms that the reser-

voir is highly heterogeneous, is of low permeability, and

infill wells should improve overall recovery.

Crossplots of results developed in this study can be used aspredictive tools for estimating the recovery of infill wells of

the ACN Region.


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Ackno ledgments


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I would like to thankTecpetrol S.A for providing me the

opportunity and the financial support to pursue my Master ofEngineering degree at Texas A&M University.

I would also like to thank the following individuals for their

contributions to this work:

Dr. T.A. Blasingame , for serving as Committee Chairman,

and for his advise, support, and encouragement during this

investigation.

Dr. A. Datta-Gupta, Dr. R. Thompsen andDr. J. Watkins

for serving as Committee Members.

Acknowledgments


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Documents

000707 CBerto El Tordillo Field