Steam Injection. Dr. Helmy Sayyouh Petroleum Engineering Cairo University

Transcription

1 Steam Injection Dr. Helmy Sayyouh Petroleum Engineering Cairo University 1

2 Increasing Temperature Lowers Viscosity... Fig

3 Single-Parameter Viscosity Correlation Fig Two-parameter correlation 2 Ae B / T Andrade equation 3

4 Thermal Properties of Water Table

5 Pressure-Specific Volume of Water Fig

6 Enthalpy of Water... Fig

7 Thermal Properties of Selected Rocks Table

8 Graphical Construction of Hot Water Flood Fig

9 How Heat is Lost... Heat management is the single most important factor in the commercial success of thermal recovery projects 9

10 Heat Loss Sources... Surface equipment Rock and water in formation From wellbore To adjacent strata 10

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 11

12 Losses to Rock and Water Usually the largest source of loss Avoid low porosity formations (f>0.3) Avoid high water saturation S o f >0.3 Use steam, not hot water 12

13 Schematic Temperature Profile in Drill Hole Fig

14 Wellbore Heat Loss Fig Fig

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) 15

16 Thermal Methods Process variations Physical properties Fractional flow in thermal floods Heat losses from wellbores Heat losses to over/underburden 16

17 Losses to Adjacent Strata... Fig

18 Thin Reservoirs Lose Heat 18

19 Effect of Oil Saturation, Reservoir Thickness, and Net/Gross Ratio 19

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 20

21 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 21 25/12/2017 Dr.Helmy Sayyouh

22 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 /12/2017 Dr.Helmy Sayyouh

23 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 /12/2017 Dr.Helmy Sayyouh

24 Zones in a Steam Drive... Fig

25 Midway Sunset Response From Jones (2007) 25

26 Kern River 10 Pattern Flood (Chevron) Depth, ft Oil gravity, o API 14 Original reservoir pressure, psi 225 Current reservoir pressure, psi 60 Average net sand thickness, ft 70 Oil viscosity at 85 o F, cp 2,710 Oil viscosity at 350 o F, cp 4 Average permeability, md 7,600 Average porosity, percent 35 Average oil saturation, percent 52 Residual oil saturation, percent 33 26

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 ~ % oil recovery 27

28 Ten-Pattern Performance Well... 1/OSR Cumulative Table

29 Gravity Override... Kern River Overburden Underburden T Fig Fig

30 Duri Field, Phase 1 Process type: Steamdrive Location: Sumatra, Indonesia Operator: P.T. Caltex Pacific Indonesia Lithology: Sandstone Subsurface depth: m Oil viscosity: 157 mpa-s Pressure: 750 kpa Sq. km/producer: 0.05 Water salinity: ppm NaCl Est. % IOR: na 1370 steam injectors, 3810 producers Oil prod. = 204x10 3 B/D Steam inj. = 730x10 3 B/D 30

31 Duri Field, Phase Oil Rate (BOPD) Injection Rate (BCWEPD) 1000 Injection Pressure (psia) 100 Water Cut (%) From Enhanced Oil Recovery Field Reports, SPE 31

32 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 32 25/12/2017 Dr.Helmy Sayyouh

33 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 /12/2017 Dr.Helmy Sayyouh

34 Reservoir rocks should not contain fresh watersensitive clays. Emulsification and sand production may be encountered /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 35

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 36

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 Sayyouh 37

38 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 /12/2017 Dr.Helmy Sayyouh

39 Cyclic steam stimulation process is widely used in Canada and Venezuela because of its applicability in very viscous oil formations, and quick payout /12/2017 Dr.Helmy Sayyouh

40 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 /12/2017 Dr.Helmy Sayyouh

41 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 /12/2017 Dr.Helmy Sayyouh

42 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 /12/2017 Dr.Helmy Sayyouh

43 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 /12/2017 Dr.Helmy Sayyouh

44 Design Criteria Typical design criteria for finding out whether an oil reservoir is a good candidate for steam injection were established: 44 25/12/2017 Dr.Helmy Sayyouh

45 Formation depth may be above 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 /12/2017 Dr.Helmy Sayyouh

46 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 API range with viscosity about 2000 cp at reservoir temperature /12/2017 Dr.Helmy Sayyouh

47 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% /12/2017 Dr.Helmy Sayyouh

48 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 /12/2017 Dr.Helmy Sayyouh

49 Properties of Tar Reservoirs at locations tested by steam injection Steam Drive Steam Soak Depth, ft Net Thickness, ft Gravity, ºAPI Temperature, ºF Oil Viscosity, cp 2, Million 25, Million 49 25/12/2017 Dr.Helmy Sayyouh