Cyclic Steam InjectionPresented by

Ahmed Hassan Shehata

Kareem Ahmed Gamal El-Din Moussa

Mahmoud Hussein Mohamed Aboulfotouh

Mohannad Mostafa

Mostafa Ahmed Mostafa Mohamed Ragab

Omar Ahmed Badr El-Din

Omar El-Toukhy

Taher El-Moataz Bellah Abdel Salam Farghaly

Cairo UniversityFaculty of engineeringCairo University-MPM-Engineering Dept.Enhanced Oil recovery

Presented to: Dr. Sayed El-Tayeb. Dr. Mahmoud Abo Elella.

Cairo University-MPM Engineering Dept.

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Agenda1- Introduction.

2- Cyclic steam injection.

3- Mechanism of action.

4- Cyclic steam results.

5- Design Process & Computations.

6- Screening criteria

7- New advances.

8- Conclusion.

9- References.

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Introduction

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What is cyclic steam ?

1. It is a single well operation.

2. Steam is injected in producer well.

3. Steam is left to soak for a period.

4. Well is returned on production with more recovery.

Even if the oil is not heated efficiently at all, increased production can result through the removal of skin damage and cleaning of the tubing string.

N.B. also called: steam soak, steam stimulation, or huff and puff.

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Mechanism of Action

1. Reduction in the oil viscosity In-Situ.

When Oil Viscosity decreases the displacement efficiency increases, Since the water-oil mobility ratio is decreased and oil mobility ratio is increased.

M =

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Mechanism of Action

2- Reducing residual oil saturation, improving oil relative permeability. When oil relative permeability increase ,the water oil mobility ratio decrease ,and the sweep efficiency increase.

M =

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Mechanism of Action

3- Oil swelling ,Increasing FVF

and Vaporizing and distilling condensable

hydrocarbon from the crude.

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Mechanism of Action

4- Sometimes , the cyclic steam injection

in shallow reservoirs with thick

productive zone or high dip with high

lateral permeability results in a high oil

recovery. In these cases the steam cycles

repeated at the beginning

(in closely spaced wells) transmit the

heat through the oil beyond the

normal drainage area of the well.

In this figure , cyclic steam stimulated

Producers With drainage area overlapped and

gravitational effect in place.

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Cyclic steam results

1. Increase the ultimate recovery factor and Stimulate the formation to

produce at higher rate.

Typically 10-20% recovery is obtained

2. Increase the displacement efficiency. Since the water-oil mobility ratio is

decreased and oil mobility ratio is increased.

3. thermal expansion of the oil takes place and the heated oil increases in

volume so that the residual oil saturation is reduced.

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Cyclic steam results

4. Efficiency peaks in early stages and becomes redundant with time.

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Design Process and Computations

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Generic Optimization Guidelines

Evaluate and quantify thermodynamic requirements.

Minimize heat exchange by selecting operating conditions similar to reservoir conditions.

Select high efficiency equipment.

Minimize transportation of hot fluids.

Design Process & Computations

Heat Transfer

Governing Heat Loss Equations

Surface Pipes Heat Losses:

Wellbore Heat Losses:

Design Process & Computations

Heat Transfer

Heat Losses:

Special completion string to be used

Cement composition revisited

Tubing design

Thermal packers

Tuning insulation

Casing stress

Design Process & ComputationsHeat Transfer and oil PVT

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Effect of Heat on Reservoir Properties

Temperature increase causes thermal expansion in sand grains and sand structure.

Pore volume expansion affect permeability, which affect water and hydrocarbon mobility.

Confining stresses decrease due to increase in volumes, which causes hydrocarbon unloading.

Design Process & ComputationsHeat Transfer and oil PVT

Know oil API and composition.

Compute heat capacity of fluid-saturated rock

-

Two thirds of injected heat is lost to grains.

Nearby formations will be heated pending on thermal conductivities

Design Process & ComputationsHeat Transfer and oil PVT

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Heat Losses

Adjacent formations

As advancing in formation

Design Process & ComputationsHeat Transfer and oil PVT

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SOR computation:

Special Core Experiment (Thermal Flood Experiment)

- Heated core handler

- Steam with known quality injected to core with existing saturations

- Condensates are measured

- Vaporized water/oil measured

- Measuring extracted fluids volumes in + and P (i.e. injection production)

Design Process & Computations

Rock Properties Alteration SOR

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Water-Oil Relative permeability alteration

Design Process & Computations

Rock Properties Alteration SOR

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.2 0.4 0.6 0.8 10

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.2 0.4 0.6 0.8 1

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Kro Krw

Before After

SOR:

Quantity of PV injected to completely displace oil

Repeat process with different steam qualities, recording:

- relative permeability vs. water saturation

- PV injected vs. oil extracted

- volumes of water condensate

- Thermal Efficiency

Design Process & Computations

Rock Properties Alteration SOR

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Well Model on ECLIPSE

Design Process & Computations

Rock Properties Alteration SOR

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Source of water and steam

Facilities sizing

Combined purpose facilities

Thermal/Power efficiencies

QC of steam

Reservoir management at abandonment

Design Process & ComputationsSteam Preparation

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Design Process & Computations

Steam Preparation

Steam Properties:

Steam quality:

X=

, near 0.8 is optimum.

Saturation temperature with respect to Ps and Tref given by:

Ts=a + bPs0.225, where a=0, b=115.1 if T is F and P is psia

where a=-17.8 and b=41.1 if T in C and P in kPa

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Design Process & ComputationsSteam Preparation

Wet Steam Generators

Straight or coil shaped

Nearby water supply

Salinity treatment

Steam quality control

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Dual/Mutual benefit:

Electricity generation in addition to oil recovery

At abandonment, reverse processes can be implemented

- injecting water to heated reservoirs

- hot fluids reproduction

- yielding slightly higher recovery factors

- generating electricity

Design Process & ComputationsSteam Preparation

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Process Efficiencies:

Thermal efficiency; (Q inj-Qlost)/Qinj

Production efficiency; Vo,increment /Vo, do nothing

Volumetric efficiency; Vinj/Vprod

Economic efficiency pre and post abandonment

Design Process & Computations

Steam Preparation

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Screening Criteria

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New Advances

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New Advances

Fracturing With Viscoelastic Surfactant Fluid in Cyclic Steam Injection

Not a case study

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Hydraulic-Fracturing

By fracturing the high-permeability sand-producing formations, two combined

conditions are achieved:

1.The permeability-damaged zone is bypassed

2.Water can dissolve one of the most frequently found cementing materials

3.The fluid velocity is reduced

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Anionic Viscoelastic gels

1. Temporarily creates an inverse emulsion, having a viscosity lower than both the crude oil and the fracturing fluid

2. Viscoelastic fluids dont contain any solids to build viscosity, there is no filter cake damage

3. One of the best carrying fluid for good Proppant transport feature

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Comments

The synergy of two production improvement techniquescyclic steam injection

and hydraulic fracturingresults in improved high-rate production for high-

permeability formations with heavy oil.

Cyclic steam injection, well completion and the stimulation fluid all can create

formation damage in the wellbore. This problem can be addressed a careful

selection of the fracturing fluid.

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Conclusion

To sum up Steam injection a very important steam recovery method. Many field studies and researched are made in order to improve it and make it an effective recovery method.

Also, Steam injection is the most effective enhanced oil recovery process based on the amount of oil produced. Although cyclic steam injection has contributed much to oil production, its future use will be for stimulating and preparing wells for steam flood and in situ combustion.

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References

1- Khairy, M. (2005). Enhanced Oil Recovery. Society Of Petroleum Engineers, 15.

2- Carcoana, A. (1992). Applied Enhanced Oil recovery. New Jersey: Prentice Hall.

3- Lake, L. W. (1989). Enhanced Oil Recovery. New Jersey: Prentice Hall.

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