Steam Injection

Dr. Helmy Sayyouh

Petroleum Engineering
Cairo University

1
Increasing Temperature Lowers Viscosity...

Fig. 11-1 2
 Single-Parameter Viscosity Correlation
Fig. 11-5

Two-parameter correlation

B/T
 2  Ae
Andrade equation

3
Thermal Properties of Water

Table 11-2
4
Pressure-Specific Volume of Water

Fig. 11-4

5
Enthalpy of Water...

Fig. 11-3

6
Thermal Properties of Selected Rocks

Table 11-3 7
Graphical Construction of Hot Water Flood

Fig. 11-6
8
 How Heat is Lost...

Heat management is the single most

important factor in the commercial success
of thermal recovery projects

9
Heat Loss Sources...

 Surface equipment
 Rock and water in formation
 From wellbore
 To adjacent strata

10
Water Issues...

 Requires fresh water source (not produced water)

 Scaling in surface boiler…
 Chemical treatments
 Restricted to 80% quality steam

 Intensive surface purification needed

11
Losses to Rock and Water

 Usually the largest source of loss

 Avoid low porosity formations (f>0.3)
 Avoid high water saturation
 Sof >0.3
 Use steam, not hot water

12
Schematic Temperature Profile in Drill Hole

Fig. 11-7
13
Wellbore Heat Loss

Fig. 11-11 Fig. 11-12 14

Controlling Wellbore Loses...

 Inject as fast as possible

 Consider downhole generators
 Evacuate annulus
 Insulate tubing…. Steam depths
 <1500 ft. for uninstalled tubing
 <7000 ft. for insulated tubing
 In situ combustion (high pressure air injection)

15
 Thermal Methods

 Process variations

 Physical properties

 Fractional flow in thermal floods

 Heat losses from wellbores

 Heat losses to over/underburden

16
Losses to Adjacent Strata...

Fig. 11-13 17
Thin Reservoirs Lose Heat

18
Effect of Oil Saturation, Reservoir Thickness, and
Net/Gross Ratio

19
Ways to Control Heat Loss...

 Restrict application
 Avoid deep reservoirs
 Avoid low porosity reservoirs

 Isolate injection string

 Insulate tubing
 Evacuate annulus

 Operational considerations
 Inject at large rate
 Reduce rate after breakthrough

20
 Steam Quality Drop in Steam Pipelines

 If the steam quality at the generator is

Xgen, fraction, then the wellhead steam
quality is given by
 Xwh = Xgen - Q.L/M. Lv
 Where:
 Q = heat loss rate, Btu/hr-ft
 L = pipe length, ft
 M = mass flow rate of steam, lb/hr
 Lv = enthalpy of vaporization, Btu/lb

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 Steam Quality Drop in the Wellbore

 Given the wellhead steam quality, Xwh,

the formation face steam quality is given
by

 Xsf = Xwh - Q L/ M Lv

 Where, L is casing/tubing length.

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Thermal Stress in Casing

 Wellbore heat loss leads to an increase in the

casing temperature, and the thermal stress is
given by

 S = ά E (Tc-Tf)

 Where ά is the coefficient of expansion for

steel and E is Young’s modulus for steel.

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Zones in a Steam Drive...

Fig. 11-18 24
Midway Sunset Response

From Jones (2007)

25
Kern River 10 Pattern Flood (Chevron)

Depth, ft 700- 770

Oil gravity, oAPI 14
Original reservoir pressure, psi 225
Current reservoir pressure, psi 60
Average net sand thickness, ft 70
Oil viscosity at 85 oF, cp 2,710
Oil viscosity at 350 oF, cp 4
Average permeability, md 7,600
Average porosity, percent 35
Average oil saturation, percent 52
Residual oil saturation, percent 33

26
 Kern River 10 Pattern

 In seven yr test
 18.6 MM bbls steam inj
 3 MM bbls oil recovered
 Cum OSR = 0.16
 SOR ~ 6.15
 37% oil recovery

27
Ten-Pattern Performance Well...

1/OSR
Cumulative

Table 11-5
28
Gravity Override...
Kern River

Overburden

Underburden

Fig. 11-23 Fig. 11-24 29

 Duri Field, Phase 1

Process type: Steamdrive

Location: Sumatra, Indonesia
Operator: P.T. Caltex Pacific Indonesia
Lithology: Sandstone
Subsurface depth: 150-240 m
Oil viscosity: 157 mPa-s
Pressure: 750 kPa
Sq. km/producer: 0.05
Water salinity: 900 - 4500 ppm NaCl
Est. % IOR: na

1370 steam injectors, 3810 producers

Oil prod. = 204x103 B/D 30
Steam inj. = 730x103 B/D
 Duri Field, Phase 1
1000000

100000
Oil Rate (BOPD)

10000 Injection Rate (BCWEPD)

1000 Injection Pressure (psia)

100
Water Cut (%)

10
1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992

From Enhanced Oil Recovery Field Reports, SPE

31
 Advantages and Limitations

 Steam flooding has emerged as the major thermal

recovery process because of its relative low front-end
cost, ease of steam generation on site, low operating
cost, and proven success

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  However, it may suffers from the
following limitations:

 Lack of availability of large quantities of high

quality fresh water.

 Completion of producers with equipment to

accommodate high temperature fluctuations
creates many problems.

 Reservoirs should be shallower than 5,000 ft.

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  Reservoir rocks should not contain fresh water-
sensitive clays.

 Emulsification and sand production may be

encountered.

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 Steam Cycling Process

Injection Phase:
High quality steam is
injected into a producer.

Injection is achieved at the

highest practical injection
rate, to minimize heat
loss.

25/12/2017 Dr.Helmy Sayyouh 35

Soaking Phase:
Well is shut-in for some time
allowing steam to heat the
region.
Optimum soaking duration is
programmed to achieve a
balance between maximizing
the heated volume around
the well and minimizing the
loss of heat to the formations
above and below.

25/12/2017 Dr.Helmy Sayyouh 36

Production Phase:
producer is put back on
production until the oil
rate declines to the
economic limit.
The above cycle is repeated
(two to three times, in
general) until oil rate
response becomes
uneconomical.

25/12/2017 Dr.Helmy Sayyouh 37

 Cycling steam stimulation is one oil recovery
method which is known to be effective in
recovering oil from heavy oil reservoirs.

 The field use of this technique dates back to

1958, when Shell Oil Company steamed a
well of the Yorba Linda oilfield of California.

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 Cyclic steam stimulation process is widely
used in Canada and Venezuela because of
its applicability in very viscous oil
formations, and quick payout.

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  The total oil recovery by steam
stimulation averages about 10 to
15% of the oil-in-place.

 In Cold Lake, Alberta, it is over

25% or higher.

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  In Venezuela, cycling steaming is a
well established procedure for
recovering heavy oil and recoveries
from this process as high as 40%
have been noted.

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 Advantages and Limitations

 Well Stimulation by Huff-&-Puff is a widely

process because of its relative low front-end
cost, ease of steam generation, low operating
cost, quick pay-out, and proven success.
 Well stimulation is now a commonly used
method to prepare wells for inter-well steam
flood projects.

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  Wells designed as steam injectors provide
current income from the oil produced. And,
subsequent oil injectivity is improved.

 Wells designated as oil producers provide

higher current income. And, subsequent oil
productivity is improved.

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 Design Criteria

Typical design criteria for finding out whether

an oil reservoir is a good candidate for steam
injection were established:

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 Formation depth may be above 200-400 ft
(200 ft in Charco Redondo, Texas) to
avoid parting pressure of adjacent
formations and should be limited to 5000
ft ( Brea, California) due to heat loss.

 Higher limit possible using downhole

generators.

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 To minimize heat loss, formation thickness
should be not less than 30 ft (Slocum, Texas).

 Formation permeability should be high

(between 250 and 1000 md) and porosity
should be higher than 18 to 20 %( Shiells,
California).

 The oil gravity should be in the 12-25 API

range with viscosity about 2000 cp at
reservoir temperature.

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 The upper limit can be decreased to 4000
cp or less by cyclic steam injection.

 Steam injection is applied also to light

oils (Brea, California, with 24ºAPI and 6
cp and El Dorado, Kansas, with 37º API
and 4 cp).

 Oil saturation at the start of steam

injection project should be higher than 40
to 50%.

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 The injection should be as rapid as possible.

 Shallow and dip oil reservoirs, thick pay

zones with very good permeability, cheap
and high quality water source are some
favoring factors to steam injection, while
strong nonuniformity, highly water-sensitive
clay content, and low interwell
communication are adverse factors.

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 Properties of Tar Reservoirs at locations
tested by steam injection

 Steam Drive Steam Soak

Depth, ft 935 – 3800 269 – 2500
Net Thickness, ft 110 – 210 52 -110
Gravity, ºAPI 5 – 9.3 2-9
Temperature, ºF 52 – 140 55 – 110
Oil Viscosity, cp 2,159 – 1.6 Million 25,000 – 20 Million

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