steam injection - cairo university...injection pressure (psia) water cut (%) 32 25/12/2017 dr.helmy...
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1
Steam Injection
Dr. Helmy Sayyouh
Petroleum Engineering
Cairo University
2
Increasing Temperature Lowers Viscosity...
Fig. 11-1
3
Single-Parameter Viscosity Correlation
Fig. 11-5
Two-parameter correlation
2 AeB/T
Andrade equation
4
Thermal Properties of Water
Table 11-2
5
Pressure-Specific Volume of Water
Fig. 11-4
6
Enthalpy of Water...
Fig. 11-3
7
Thermal Properties of Selected Rocks
Table 11-3
8
Graphical Construction of Hot Water Flood
Fig. 11-6
9
How Heat is Lost...
Heat management is the single most
important factor in the commercial success
of thermal recovery projects
10
Heat Loss Sources...
Surface equipment
Rock and water in formation
From wellbore
To adjacent strata
11
Water Issues...
Requires fresh water source (not produced water)
Scaling in surface boiler…
Chemical treatments
Restricted to 80% quality steam
Intensive surface purification needed
12
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
13
Schematic Temperature Profile in Drill Hole
Fig. 11-7
14
Wellbore Heat Loss
Fig. 11-11 Fig. 11-12
15
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)
16
Thermal Methods
Process variations
Physical properties
Fractional flow in thermal floods
Heat losses from wellbores
Heat losses to over/underburden
17
Losses to Adjacent Strata...
Fig. 11-13
18
Thin Reservoirs Lose Heat
19
Effect of Oil Saturation, Reservoir Thickness, and
Net/Gross Ratio
20
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
25/12/2017 Dr.Helmy Sayyouh21
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
25/12/2017 Dr.Helmy Sayyouh22
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.
25/12/2017 Dr.Helmy Sayyouh23
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.
24
Zones in a Steam Drive...
Fig. 11-18
25
Midway Sunset Response
From Jones (2007)
26
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
27
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
28
Ten-Pattern Performance Well...
Table 11-5
1/OSR
Cumulative
29
Gravity Override...Kern River
Fig. 11-23 Fig. 11-24
Overburden
Underburden
T
30
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
Steam inj. = 730x103 B/D
31
Duri Field, Phase 1
From Enhanced Oil Recovery Field Reports, SPE
10
100
1000
10000
100000
1000000
1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
Oil Rate (BOPD)
Injection Rate (BCWEPD)
Injection Pressure (psia)
Water Cut (%)
25/12/2017 Dr.Helmy Sayyouh32
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
25/12/2017 Dr.Helmy Sayyouh33
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.
25/12/2017 Dr.Helmy Sayyouh34
Reservoir rocks should not contain fresh water-
sensitive clays.
Emulsification and sand production may be
encountered.
25/12/2017 Dr.Helmy Sayyouh 35
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 36
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 37
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 Sayyouh38
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.
25/12/2017 Dr.Helmy Sayyouh39
Cyclic steam stimulation process is widely
used in Canada and Venezuela because of
its applicability in very viscous oil
formations, and quick payout.
25/12/2017 Dr.Helmy Sayyouh40
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.
25/12/2017 Dr.Helmy Sayyouh41
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.
25/12/2017 Dr.Helmy Sayyouh42
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.
25/12/2017 Dr.Helmy Sayyouh43
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.
25/12/2017 Dr.Helmy Sayyouh44
Design Criteria
Typical design criteria for finding out whether
an oil reservoir is a good candidate for steam
injection were established:
25/12/2017 Dr.Helmy Sayyouh45
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.
25/12/2017 Dr.Helmy Sayyouh46
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.
25/12/2017 Dr.Helmy Sayyouh47
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%.
25/12/2017 Dr.Helmy Sayyouh48
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.
25/12/2017 Dr.Helmy Sayyouh49
Properties of Tar Reservoirs at locations tested by steam injection
Steam Drive Steam SoakDepth, 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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