CN1014336B - In-situ steam drive oil recovery process - Google Patents

Abstract

An oil and water-containing subterranean reservoir can be heated in a manner capable of inducing an economically feasible production of oil from zones which were initially so impermeable as to be undesirably unproductive in response to injections of oil recovery fluids. Treatment zones of specified thickness are conductively heated from boreholes arranged in a specified pattern of heat-injecting and fluid-producing wells and heated to above about 600degree C.

Description

In-situ steam drive oil recovery process

The present invention is by conduction heating in-situ steam drive, method from the subsurface deposit oil recovery, more particularly, the present invention relates to the processing of following subsurface deposit, this type of reservoir pore degree is higher, contains big gauging and water, but permeability is extremely low consequently for injecting such as water, steam, the reaction of hot gas or oily miscible solvent displacement fluid is almost not have the fluid output.

Some kieselguhr/palm fibre (Diatomife/Brown) shale formations in the auspicious base of Bel (Belridge) oil field (U.S.) are typical case's representatives of this type of oil reservoir.The characteristics on these stratum are: the degree of depth is greater than 60 meters, about 300 meters of thickness, degree of porosity about 50%, the oil saturation ratio is about 40%, and the API severe of oil is about 30 degree, and water saturation is approximately 60%, although exist intrinsic fracture in inside, stratum, permeability is less than 1 millidarcy.Find these stratum, in the primary oil recovery process, the ratio that produced quantity takes up an area of layer oil content is very low, such as only being 5% or lower.And they do not have any reaction basically to the secondary or the tertiary oil recovery process of routine.Some publications, such as the SPE10773 paper of delivering in San Francisco March nineteen eighty-two, " reason that Bel Rui Ji-the kieselguhr field output is successively decreased: the investigation of rock mechanics " carried out this type of oil recovery problem the conclusion of typification.This piece article is a research of carrying out in order to explain oil yield to successively decrease rapidly.The SPE10966 paper of delivering in the New Orleans September nineteen eighty-two, " the auspicious base oil of Gary Fu Niya BellSouth field diatomite formations pressure break result " also discussed this production problem of successively decreasing.Article points out that the production curve shows cumulative recovery of representational calculating in the condition and range that is run into approximately only is the 1-14% of original oil in place.

Invent by F Jiang Si Tom (Ljungstroem) in Sweden with the oil recovery of heat transfer type of drive by subterranean oil shale.This method is in Swedish patent 121737,123136,123137,123138,125712 and No. 126674, some articles on No. 2732195, United States Patent (USP) and the magazine, such as IVA1953 the 24th volume, " shale oil being carried out underground Pintsch process " on 118～123 pages of the 3rd phases and be published on " the retrievable energy that has a net increase of of dielectric heating oil shale on the spot " article of oil shale proceeding the 11st volume 311～330 pages (1978) and all describe (the method once had small-scale industrialness to use in the invention forties in the fifties) to some extent by Jiang Si Tom method.In this method, heat injection well and the equal completion of solution extraction well are in subaerial same permeable oil shale formation, and the gap between the well is less than three meters.The heat injection well is equipped with electrical heating or other heating element, and the many materials of component ambient filling (such as sand or cement) make it the heat transferred oil shale, can prevent any inflow or the outflow of fluid simultaneously again.During at the design of the oil shale that has underground water to continuously flow into and test the method, just need pump water continuously, with avoid energy unnecessarily loss in evaporating underground water.

No. 3113623 patents of the U.S. have been described the method that heats the stratum and be convenient to hydrocarbon recovery, and this method is used a reverse flow ejector half burner, and fuel can ooze piping by a gas and flow into burner, so that the stratum can both cause burning for whole long and narrow section.

Virtually completely impermeable for those, relatively dark and thicker, and the deposition of possible produce oil, as sand asphalt or oil shale deposit (such as this deposition in the U.S. Piceance basin), the application diabatic process is recovered the oil, and is infeasible economically certainly according to former theory and view.Such as, Jiang Si Tom method is described to such method in above-mentioned oil shale proceedings, " ... by in high-grade shale deposition, embedding successfully extraction shale oil of tubular type heating." this method depends on common thermal diffusion shale is heated, obviously, the demanding temperature gradient of thermal diffusion, therefore heating is very inhomogeneous; Make the time of the required some months of the complete destructive distillation of shale piece of the such size in room.And because of shale zone underheat outside the destructive distillation belt edge, the shale at the most close thermal source place is overheated again and wasted a large amount of heat energy.The problem in back is particularly important for western shale, because the endothermic reaction takes place when being higher than about 600 ℃, and just can not be and reclaim (313 pages) fully at the heat energy of overheated zone by diffusion.

In impermeable substantially stratum, cause and keep warmed-up oil or high-temperature pyrolysis product can pass through its permeable band that flows, be a difficult task.Once chatted in No. 3468376 patents of the U.S. and (in the 1st and 2 hurdles): " conduct heat to have two mechanism by oil shale, i.e. heat transmission in the oil shale solid matrix that produces by conduction and the above-mentioned heat transmission of being undertaken by convection action.Heat transmission by conductivity is a process more slowly.The evenly heat coefficient of conductivity of oil shale and evenly heat diffusion coefficient and refractory brick close.The permeability of oil shale solid matrix is extremely low, and is very similar with unglazed porcelain.Thereby convection heat transfer' heat-transfer by convection only is confined to the heat effect that fluid produced that flowing in running through the communication passage of oil shale.These flow channels can be intrinsic fracture and artificial induction crack.When being heated, next-door neighbour's passage place forms the oil shale layer band of a Pintsch process.This layer is an inorganic mineral matrix, contains carbon in various degree.This layer is a barrier that constantly enlarges for for the hot-fluid that adds hot fluid in the passage ".This patent relates to by flow channel circulation heating oil shale-Pintsch process fluid, adds the Pintsch process oil shale layer that the material particle that rubs forms with erosion next-door neighbour passage simultaneously in circulation of fluid.No. 3284281 patents of the U.S. are referred to (first hurdle, 3～21 row): " the heating shale of attempting in all sorts of ways, such as ... resistance heater ..., the nearly all not success of from oil shale, recovering the oil.To the frac treatment of oil shale, also seldom successful, this is the shale expansion that takes place owing to heating before employing layer internal combustion or additive method heating, has caused the partially or completely closed of crack." this patents state a kind of method of formula in turn, comprise heating (thereby expand) oil shale, inject fluid then dilated shale carried out fracturing, repeat again these steps up to a heat-staple fracture propagation till the producing well.No. 3455391 patents of the U.S. disclose: waterpower induces the crack mostly to be vertical fracture in the stratum, and hot fluid is flowed by vertical fracture, rock fever is expanded and makes closing up of cracks, thereby can make a bet into fluid at the pressure that is enough to form horizontal fracture.

The object of the invention is to provide an improved method, and this method is the impermeable subsurface deposit of heated height, then extraction oil from oil reservoir.According to the present invention, at least two mouthfuls of wells want completion to handling interval, and this interval has about 30 meters thickness at least in the oil-containing water band of oil reservoir, and the displacement of reservoir oil fluid of this oil reservoir for injecting has disadvantageous impenetrability and non-productibility.The arrangement of well should make in heat injection well and the fluid withdrawal well has at least a bite to run through the entire process interval substantially, and well is substantially parallel, and is separated by about at least 6 meters basic distance that equates.For running through every mouthful of heat injection well handling interval substantially, in order to prevent fluid flowing between well and oil reservoir, the oil reservoir face is better relatively with heat conductivity, impermeable substantially solid material of fluid or cement seal.In running through every mouthful of fluid extraction well handling interval substantially, fluid is communicated with, so that these wells can be produced fluid from oil reservoir.Heat with a speed or several speed every mouthful of heat injection well inside of running through the entire process interval at least substantially, its firing rate is wanted and can (a) be made the well temperature inside be increased to about 600 ℃ at least, (b) keep about at least 600 ℃ of well internal temperature, but do not make the degree of the high equipment cause thermal damage in well of temperature, will make the speed that well is outwards conducted heat not be higher than the speed that oil reservoir conduction of heat itself is allowed significantly simultaneously.

The present invention to the small part be with following discovery as prerequisite, when promptly handling the oil reservoir of the specified type of the present invention according to the mode of the present invention's regulation, the function performance of processing procedure.It seems and relate to following mechanism.

The heat that injects only penetrates into the stratum by conduction.Yet, when the rising of stratum temperature, such as being elevated to 250～300 ℃, water and hydrocarbon all can form steam, because the expansion of these fluids produces high pressure.Under this barometric gradient effect that produces, fluid or under the low low speed that natural permeability allowed, flow to producing well, perhaps when pore pressure during near burden pressure by generation, or the crack that is interconnected because of progradation flows to producing well.

At water vapour and hydrocarbon steam when producing well moves, the position condensation that both are will be on the stratum colder, and the latent heat that discharges makes the stratum be preheated to what is called " steam " temperature, this temperature approximates the temperature of moist steam under the burden pressure greatly.Some heat is to transmit by convection current like this, thereby than the situation that net quantity of heat is only transmitted by conduction, has quickened process greatly.

Such water vapour and hydrocarbon vapours produce, pressurization and the displacement process by oil reservoir oil-containing position are exactly the steam flooding that produces on the spot.This displacement has the characteristics of many what is called " steam distillation displacement ", the latter is once by B.T. Weir graceful (Willman), V.V. Wa Leluoyi (Walleroy), G.W. Lun Boge (Runherg), A.J. Kona stays this (Cornelius) and L.W. bubble wet this (Powers) at American Society of Mining and Metallurgical Engineers (AIME) proceedings, in July, 1961, carried out description in " desk research that steam injection is recovered the oil " literary composition that 681 pages are delivered.Therefore, many phenomenons of finding in steam distillation drives are estimated also may take place in this process, particularly about the mixed problem of the colder part original oil of hydro carbons condensate and stratum.This hydro carbons condensate is easy to volatilization than original oil, and viscosity is lower.When evaporation front arrived the position that original oil diluted by the hydrocarbon condensate, the steam under pressure distillation and original oil of the flux oil of formation itself was heated to uniform temp and compares with pressure, can make more oil distillate vaporization.This mechanism can improve the displacement efficiency that produces steam flooding on the spot that this process proposes, and makes it to surpass from the simple steam distilled result of original crude oil.

In addition, the applicant has found that now using following steps in some cases has superiority.The best approach that forms the fluid impermeable barrier between the well at oil reservoir and heater place part is heater to be installed in the sleeve pipe or oil pipe tubing string of bottom sealing, around sleeve pipe or the tubing string around with thermally-stabilised and material heat conduction, such as cement.The optimum velocity that produces heat in the heat injection well is every meter per hour about 1200 to 2400 kJ (kilojoule)s, or when electrical heating, resistance heater should be every meter about 330 to 660 watts.Usually be suitable for the example of speed, be every meter from 264 to 726 watts or the corresponding speed represented with kJ (kilojoule).When the well fluid pressure is low relatively wellbore have through be squeezed and the oil reservoir of slump trend in (such as kieselguhr/brown rammell), the fluid pressure in the fluid extraction well should keep enough high and push preventing.In this case the heat injection well preferably continue heating when fluid being driven at least a bite fluid extraction well till.Fluid preferably is limited in certain degree from the discharge of every mouthful of fluid extraction well (that is fluid is to the well that wherein drives in), also is borehole fluid pressure to be increased to be enough to stop adjacent stratum obviously extruding to take place and necessary limit.In general, this increase of well fluid pressure should make reservoir fluid pressure increase to and surpass adjacent stratum natural fluid pressure 7 to 14 crust.The gas pressure (steam, methane or the like) that produces at the heat injection well is keeping high pore pressure and can prevent extruding.When effective pressure surpassed about 35 crust, no matter how temperature all may push, such as when burden pressure cuts the oil reservoir fluid pressure, promptly effective stress was about 35 crust or when higher, extruding will appear in this stratum in diatomite formations.

Therefore, although the present invention and do not rely on what concrete mechanism in office, its function performance has comprised the steam distillation displacement process at least aspect key issue, and steam is to be produced on the spot by the heat of coming from awfully hot injection well conduction.

Referring now to accompanying drawing the present invention is carried out more detailed explanation, wherein:

Fig. 1 is the schematic diagram that heat injection well ambient temperature distributes when typical phases of this process.

Fig. 2 has illustrated the Temperature Distribution in the different phase of process similarly, and the time t of process represents over year.

Fig. 3 is every mouthful of heat injection well rate of oil production P(bucket/sky) with time t() relation curve.

Fig. 4 is the time t(of process) with well spacing Dw(rice) curve that changes.

Fig. 5 is the relation curve that heat demand amount (kJ (kilojoule)/bucket oil) changes with process required time (year).

Fig. 6 and 7 shows the oil reservoir interval that contains different permeability layers and simulates oil production and the time relation curve that heat transfer process draws.

Fig. 1 has schematically illustrated in the typical phases of this process the Temperature Distribution of oil reservoir around the heat injection well.And supposition heat is Radial Flow, and old place layer temperature only is the function apart from heat injection well centre distance γ.

Band I among Fig. 1, it is positioned between wellbore radius (γ w) and the evaporation front (γ b), and wherein all water have all been vaporized.From the Practical significance heat only is to flow by conduction.The conduction-type that heat is radial symmetric flows and to make temperature be linear change with the logarithm of γ in extremely big scope usually.The above-mentioned fact can be described as of equal valuely: Temperature Distribution can accurately be described by the steady state solution of the differential equation in the band I.

Contain the heavy hydrocarbon residue of a spot of liquid or solid at the voids volume of band I.These residues only account for the seldom part of original geology oil reserve, are made up of that part of heavy hydrocarbon component that can not vaporize by steam distillation in the crude oil.(for example, 300～800 ℃) these hydro carbons generation cracking under the main temperature in the band I, and form coke and light hydrocarbon gas, these gases are with the most of unborn steam of displacement.In other words the interstitial space that do not occupied by heavy hydrocarbon in the band I of our supposition methane abrim, do not exist any type of moisture content in the band I for this reason.

The temperature of supposing the band II that is positioned at evaporation front (γ b) and condensation leading edge (γ f) among Fig. 1 is fixed.Steam zone in this band and the conventional steam flooding is suitable.Its pressure value of supposition equals overburden pressure in the band II, and temperature equals the vapor (steam) temperature under this pressure.As the theoretical foundation of this hypothesis be exactly the permeability of kieselguhr/brown shale formation be so low in many places, to such an extent as to for the flow channel of water and hydrocarbon vapours is provided, the pressure fracture pressure of may having to be raised to.

The same with steam flooding in this process, give the displacement of the most of oil of meter, comprise that the steam distillation of oil all may occur near the condensation leading edge (γ f).Therefore, we will suppose that the interstitial space in the band II will be by water and steam filling, its saturation ratio S ^II _wCorresponding to the initial condition saturation ratio, and to contain saturation ratio be S ^II _oOil.

In band III (being positioned at outside the condensation leading edge (γ f)), comprising the formation water and the oil that are in original temperature and saturation ratio substantially in the voids volume.

As previously mentioned, opposite with most of oil displacement processes, the vertical sweep efficiency of this process is not determined by formation properties, but determines (being like this for first approximation at least) by the character of heater.Desirable, be identical from the top of heater basically to bottom heat injection speed, thereby injection profile is uniform basically.When using electrical heating, the heat that the per unit formation thickness injects is P ⁵ _H=i ²ν/A, wherein i is the electric current by heater, and A is a basal area, and ν is the resistivity of heating electric wire.

As two stage approach, the resistivity of heating electric wire increases with temperature.That section heating electric wire corresponding to the low stratum of heat conductivity can be warmmer than that section heater wire corresponding to the higher stratum of heat conductivity, thereby its resistance is also higher.Like this, appear absurd, but the lower layer of heat conductivity will inject many slightly heats.

In the incipient stage of this process of carrying out, the injection well of heat in well pattern be outwards diffluence radially.This situation may be extended to two adjacent tropical leading edges and begin till the overlapping.The temperature of midpoint can be than distance heated well same distance but the temperature of the point on the producing well direction rises more hurry up (because this mid point is accepted heat from both direction) in the middle of two adjacent injection wells from this time.As if like this, we have had the absurd situation of another one, promptly the isotherm after injecting well circulation for the first time on every side and outside rapidly expansion intersects each other substantially, has so just promptly heated intermediate zone between the adjacent heat injection well.Here in oil displacement process, streamed usually just and let slip, and the position of causing sweep efficiency to reduce.

On the contrary, we can expect very high horizontal sweep efficiency in this process, since oily by the thermal gradient displacement, and this gradient is also pointed to producing well inwardly around optionally pointing to.

We supposed once in the past that as most steam floodings, (γ f) located the displacement of reservoir oil in steam condensation leading edge in this process.According to this kind model, cumulative recovery should be directly proportional with the size in the torrid zone.Because at the early stage heat injection velocity ratio of this process very fast (suppose the temperature constant in the heat injection), oil reservoir is heated expansion speed partly also can be than higher, thereby rate of oil production is bigger.Heat injection speed reduction rate of oil production has also just descended later on.

This process when beginning most oil reservoirs all near original oil and water saturation degree.Do not having under the situation of gas, this just means that the oil that is driven to cold belt from the oil reservoir torrid zone can not increase initial oily saturation ratio significantly.Therefore we can estimate can be made extraction oil in the production by the torrid zone soon by the liquid of displacement, are like this to gassiness those stratum seldom at least.For example, the kieselguhr/brown shale formation in the auspicious base oil of Bel field is about 360 meters in the degree of depth, and the temperature maintenance in the heat injection well is at about 500～700 ℃, and well spacing is when being about 15 meters, is driven to producing well just having liquid approximately in two years.

The two all is subjected to passing through with II the influence of back remaining oil quantity consumingly rate of oil production and cumulative recovery.Preliminary experiment shows, approximately 70%(is heavy) original oil, such as the oil of the auspicious based diatomite layer of Bel, be can be by steam distilled.If but the hydro carbons condensate mixes (and displacing a part) with original oil, more part can be vaporized in the mixture so, and has the oil more than 70% can be by extraction.We still suppose to have only 60% recovery ratio in the Numerical examples that but is discussed below.

May bring the factor of negative influence to cumulative recovery is the geometric shape of well pattern.Well spacing will be especially close so that can be in the suitably short time ground layer for heating to the needed temperature of process.It is little of 20 meters that well spacing may preferably be wanted.Obviously, the well of these wells should near vertical, and perhaps be parallel to each other at least substantially (at least on the interval of handling oil reservoir), perpendicular or parallel deviation surpasses 1 meter just may seriously be influenced horizontal sweep efficiency, thereby influences cumulative recovery.

The heat demand amount is defined as and whenever adopts the heat that 1 barrel of oil injects.This parameter is all in all from the economic point of view.Make to be heated by resistive, the heat of generation is expensive, and the cost of whenever adopting 1 barrel required electricity can be very high.Model described herein is optimistic a little for the heat demand amount of process.This is the cause of ignoring because of in the conduction of heat of condensation leading edge front (downstream).In the steam flooding that adopts steam injection, doing similarly to suppose can be more accurate, because the expansion rate of steam-front wants fast a lot.And all leading edges move all very slowly in this process, have the front that a large amount of heat moves to the condensation leading edge.We will estimate the back the size of this error.Heat waste to top, bed rock stone has also been ignored, but this heat loss amount to compare with the loss amount in condensation leading edge downstream be smaller.

When using electrical heating, electric current is big more in the heating electric wire, and heat injection speed is just high more.Thereby the temperature of heating electric wire is also high more.Heater wire will melt when temperature is too high, and the heat injection well can be damaged.

The electric heater that installation can be worked down up to 1200 ℃ in temperature is possible.But it is about below 900 ℃ that we still advise will remaining on the maximum temperature that heats electric wire, needs drilling well again to prevent to inject the well damage.In general, heat injection speed will be adjusted to the well internal temperature is remained on the selected numerical value, the degree of the device damage that does not allow its height attend the meeting to make well, the limit that the speed that concurrently injected heat passes away from well is not allowed faster than oil reservoir conduction of heat significantly.Following manner, very be beneficial to and cause above-mentioned firing rate, promptly in the sleeve pipe of bottom lock, install stratie make heater resistance along be heated pattern that interval arranges and with the interrelated concord of distribution pattern of the pyroconductivity on the contiguous stratum of this interval, and to start these heater elements along about 330 to the 660 watts average speed of every meter spacing of interval.

Below imaginary example provided the result of calculation of some important process variables, it is the auspicious base oil of Bel field kieselguhr/brown shale formation is represented in big activation at a cover a particular procedure calculation of parameter.This result of calculation has been estimated the average case that parameter values characterized that is provided by table 1.

Table 1 procedure parameter

Experiment area 4.05 * 10 ⁶Rice ²

335 meters of h formation thicknesses

C ^I _gThe specific heat 0.6 card/gram ℃ of gas in the band I

The specific heat 0.6 card/gram of Cm rock forming mineral ℃

C ^I _OThe specific heat 0.4 card/gram ℃ of non-pneumatic hydrocarbon in the band I

C ^II _OThe specific heat 0.4 card/gram ℃ of non-pneumatic hydrocarbon in the band II

C ^II _WSpecific heat of water 1.0 card/grams ℃ in the band II

The heat of Hs 1 gram steam contains 640 card/grams

10 centimetres of γ w heat injection well radiuses

S ^I _gHydrocarbon gas saturation ratio 0.9 in the band I

S ^I _ONon-pneumatic hydro carbons saturation ratio 0.1 in the band I

S ^II _ONon-pneumatic hydro carbons saturation ratio 0.145 in the band II

The initial oily saturation ratio 0.36 of Soi

Vapo(u)rous degree 0.255 in the Ss band II

S ^II _WWater saturation 0.6 in the band II

40 ℃ of To the original reservoir temperature

300 ℃ of Ts vapor (steam) temperatures

800 ℃ of Tw heat injection well temperature

φ degree of porosity 0.55

3 * 10/ ℃ of β stratum thermal conductivity temperature relation coefficients

10 card/seconds of numerical value of λ o λ in the time of 0 ℃ centimetre ℃

ρ ^I _gHydrocarbon gas density 0.04 gram per centimeter in the band I ³

ρ m rock forming mineral density 2.5 gram per centimeters ³

ρ ^I _ONon-pneumatic hydro carbons density 1.0 gram per centimeters in the band I ³

ρ ^II _ONon-pneumatic hydro carbons density 0.9 gram per centimeter in the band II ³

ρ s vapour density 0.04 gram per centimeter ³

ρ ^II _WDensity 0.7 gram per centimeter of water in the band II ³

Fig. 2 shows and distributes corresponding to the determined all temps of the γ b value of different condensation leading edge locus around the heat injection well that (come mark by separately dotted line and solid line, as shown in Figure 1), wherein solid line is represented evaporation front, and dotted line represents to roll over fixed attention leading edge.An obvious characteristic that is showed by Fig. 2 is to have only relative seldom a part of stratum to be heated to very high temperature.Such as, leaving moment of 15 meters in heat injection well at evaporation front, 500 ℃ of isotherms move to open from the heat injection well and approximately are no more than 3 meters.Fig. 2 further also illustrate steam zone size (band II, still be quite little as described in Figure 1).In view of we have ignored the heat content on stratum, condensation leading edge downstream, this point is a particular importance, and this mobile heat must need to be supplied by the size of further reduction steam zone by conduction before steam-front.Therefore, we may safely draw the conclusion, in fact has only seldom a part of stratum to be in vapor (steam) temperature.Most of stratum is in or is higher than (and doing) or is lower than vapor (steam) temperature.

Fig. 3 shows rate of oil production P(bucket/sky).Here it should be noted that this " oil production " in fact is exactly by near the oil mass of displacing the heat injection well.Has high sweep efficiency since can estimate this process, so can extraction be come by the oily major part of displacement.Every mouthful of injection well all has a bite producing well in the Five-point method pattern example, so Fig. 3 can describe the oil recovery situation of every mouthful of producing well relatively accurately.Owing to inject seldom appearance interference between the well before at the most of oil of extraction (80%), so situation especially as mentioned above.

In the seven-spat pattern example, the torrid zone of adjacent heat injection well begins to overlap when producing about 60% oil.On the other hand, every mouthful of corresponding two mouthfuls of heat injection wells of producing well in the seven-spat pattern, therefore the initial rate of oil production of every mouthful of producing well will double than Five-point method pattern.When the torrid zone of adjacent injection well began to overlap, heat injection speed and rate of oil production all will be with than begun decay by model gained calculated value faster rate radially.But generally speaking, under the situation of seven-spat pattern initial higher rate of oil production must than later decay comparatively rapidly even more important.Particularly the equipment owing to the heat injection well can be more cheap than producing well, so seven-spat pattern should be more better than Five-point method pattern.

Fig. 4 has set forth identical viewpoint, and this figure shows the well spacing Dw that application is identical, and seven-spat pattern (second curve) calculation process time t(represented with year) shorter significantly than Five-point method pattern (article one curve).This figure also shows, for the life-span that guarantees process is approximately 20-30, requires well spacing Dw to be approximately 20～21 meters.

Fig. 5 has illustrated the heat demand amount of process.Except early stage, whenever adopt the heat that 1 barrel of oil needs to inject about 460000 kJ (kilojoule)s.Because the conduction of heat in condensation leading edge downstream is ignored, the heat demand amount of calculating is relatively optimistic.

Because the cause of our model, all fluid (You Heshui) all supposes it is extraction under original reservoir temperature.In fact, because the steam-front downstream has conductive preheating, the fluid of output is heating gradually soon, up to reaching vapor (steam) temperature (just being through with in this moment process).Because conduction of heat is individual process slowly, will extraction under original reservoir temperature at the several years ago fluid that process is carried out.In fact can point out that at least 25% is cold in the fluid of extraction.

Do conservative estimation for the heat demand amount, we need suppose that 25% its temperature equals the prime stratum temperature in the produced fluid, and the extraction under vapor (steam) temperature of remaining 75% fluid.For our this example, this very conservative hypothesis just makes the heat demand amount be increased to 760000 kJ (kilojoule)/buckets from 460000 kJ (kilojoule)/buckets.Real numerical value (hypothesis of admitting other is correct) should be between these two numerical value, unless we have developed model more accurately, it is rational that the numerical value of about 600000 kJ (kilojoule)/buckets will be considered to.

So far, we have provided each independent well or the dynamic all results of well pattern that each is independent.In these cases, it seems that injection rate and speed of production all be very little.Suppose that well spacing density is per 4000 meters ²10～12 mouthfuls of wells are arranged, and we can estimate that the speed with about 730 megawatts is annotated electric heating in the time in 27 years, recover the oil with the speed that every day is average 100000 barrels, and accumulation can produce 1,000,000,000 barrels of oil.

Processed oil reservoir substantially can be for having any subsurface deposit of thicker oil-bearing layer, this oil reservoir has high degree of porosity, contain a large amount of You Heshui, but permeability is such low so that be the no fluid output that makes people's disappointment to the reaction of injecting common oil recovery fluid.The long-pending of best its degree of porosity in such stratum and oily saturation ratio will equal 0.15 at least.The API severe of oil is at least about 10 °, and water saturation is at least about equaling 30%.The present invention is for having special superiority from permeability less than recovering the oil the oil reservoir of about 10 millidarcies.Other example with other oil reservoir of similar characteristics has other diatomite formations in Gary Fu Niya (U.S.) and other places, and the white stratum of hydrocarbonaceous or the like.

The used heat injection well of this process mainly is to be made of any cased or not cased well, this well (1) will run through in the above-mentioned type stratum at least substantially handles interval at least about 30 meters, (2) arranging in well pattern makes each well substantially parallel on the entire process interval, be about 6～24 meters at interval with the well spacing of adjacent well, (3) contain heat-resisting, heat conduction and impervious substantially solid material shell of convection cell or barrier, in case the fluid stopping body well and oil reservoir exposure and/or with crack that well is communicated with between flow.It is obvious to the person skilled in the art that the heating that to be heated by resistive or to burn, in heating process, generally all want the fluctuation of allowable temperature.The firing rate that requires only is an average along the heating interval, the temporary transient shut-down, and fluctuations such as pressure fluctuating should not make thermal velocity produced to have a strong impact on.

The used fluid extraction well of the present invention can be any well in the afore mentioned rules well pattern substantially.On arranging, require it adjacent with a bite heated well at least, have fluid to be communicated with oil reservoir, and will run through the entire process interval basically at least.Under keeping the well fluid pressure and during the extraction fluid, borehole fluid pressure will be lower than the fracture pressure of oil reservoir.

In fact the means of the inner heating of heated well can be any temperature that can raise, and can keep the well heater of well internal temperature with above-mentioned stated number value.This heater can be electric heating or combustion type.Wherein best with electric calorifie installation.Electric elements, for relatively being convenient to keep in repair in the one section sleeve pipe that preferably is installed in bottom lock, this section sleeve pipe is sealed in a heat transfer, and in impervious shell, and shell contacts with oil reservoir.Mode of heating preferably can relatively promptly reach about at least 600 ℃ temperature (best 800 ℃), but keeping temperature to be lower than 1000 ℃ (900 ℃ better) for a long time, require the degree that can not be allowed faster than the oil reservoir capacity of heat transmission significantly simultaneously again by the outside heat transfer rate of well.

Those that constitute barrier between oil reservoir and heater have heat stability, and the impervious material of heat conduction and fluid is steel pipe preferably, and outer bread is with thermally conductive materials, and this material contacts with oil reservoir and/or with the crack of well connection.Because fluid, often presents the fluid flow pattern of the easiest generation trouble from the inflow on stratum between well and oil reservoir, therefore may in barrier or shell, pressurize in some cases, so that prevent and/or stop the fluid inflow of this mode.Used gas is preferably the gas of nitrogen or inert gas and so in the pressure process.The material that centers on this barrier and contact with oil reservoir should be heat-resisting in about 600 to 1000 ℃ of temperature ranges, and have thermal conductivity preferably.Thermal cement or concrete are the most available materials for this application in this process.In some patents, once narrated this suitable cement such as No. 3507332 patents of the U.S..

We find such as the diatomite formations of the auspicious base of Bel, may occur the failure phenomenon of many heat transfer processes at inhomogeneous formation.Stratum thermal conductivity difference may cause uneven heating-up temperature.Because the electrical properties of copper more heat can occur and be injected into heat conductivity poor " richness " layer, rather than be injected into heat conductivity " poor " layer preferably.Because thermal conductivity is the function of entity density, degree of porosity diatomite layer will receive more heat by the layer more relatively poor than degree of porosity.This is that we are undesirable, because the higher layer ground of degree of porosity is the better stratum of permeability, just can be effective if enter the relatively lower process of the fewer temperature of heat in these layers.

Under extreme case,, in rich layer, after finishing, process also can continue to have heat to inject if use the fixing heater of a cross section.And the heat that injects in the poor layer not enough.

Therefore, the injection rate that increases relatively in all relatively poor poor layer of degree of porosity and permeability can make the oil production of process and the thermal efficiency that great improvement is arranged.Use the copper heater of variable cross-section and/or use parallel heating cable, than arranging more cable, or use other method that can change firing rate and all can reach this purpose along rich layer along poor layer.

In order to illustrate that permeability influences dynamically to process, it is different that Fig. 6 and Fig. 7 show permeability, and three layers the mathematical simulation that other character is identical is produced dynamically.Difference between two examples is heat injection speed.Be identical for its heat injection speed of various permeabilities among Fig. 6.Speed is with every meter wattmeter, and 3 years is 500 watts, and following 3 years is 410 watts, back 2 years be 330 watts last 3 years two be 250 watts.

Heat injection speed among Fig. 7 is different, and heat injection speed reduces in the layer of 1 and 2 millidarcies, then increases in the layer of 0.3 millidarcy.The speed that is injected in the 1 millidarcy layer reduces by 10%, and the speed in the 2 millidarcy layers of being injected into reduces by 15% and the speed that is injected in the 0.3 milli west layer increases by 15%.

Under first kind of situation (Fig. 6), heat injection 11 years by a definite date.As can be seen, although from high permeability zone do not had oil again output heat continue to be injected into this layer, finish this process and also can not get enough heats at the minimum layer of permeability.

Under second kind of situation (Fig. 7), heat is annotated all each layers always and is all reached identical oil production, but total heat exhaustion has reduced.Though the time that 1 and 2 millidarcy layer process are finished postpones to some extent, the layer of 0.3 millidarcy is except the process deadline shifts to an earlier date, and recovery ratio also obtains very big improvement.

The recovery ratio and the thermal efficiency of process are summarized in the table 2.

Table 2. process recovery ratio and thermal efficiency overview

The hot injection rate of identical each layer of change of the hot injection rate of each layer

Layer (millidarcy) 0.3 1.0 2.0 0.3 1.0 2.0

Recovery ratio (%) 8 84 84 83 83 83

The thermal efficiency 421 398 400 427 380 339

(10 kJ (kilojoule)s/bucket ground oil)

The process deadline 22 12 10 14 13 12

(year)

The analog result explanation thermal efficiency has improved about 10%.This points out us, uses the hot injection mode that this has been adjusted, and the quantitative oil of extraction can be saved the about 10-15% of heat from the specified type oil reservoir.

In an optimum operation, determine to make basis with the whole character and the economic analysis on known stratum to the heat injection speed of each layer under the stable condition.In some cases, excessive being infused in also may be worthwhile economically in some layer for the oil of extraction earlier comes.

Claims (14)

1, descends the oil production method on oil-containing and water stratum heatedly, being included in heat injection well and the fluid extraction well each class all has at least flatly and handles completion on the interval on above-mentioned stratum, this oil reservoir is thick at least about 30 meters, while oil-containing and water, reaction for the oil recovery fluid that injects is both impermeable can not production, the method is characterized in that:

To make the well that runs through these wells of handling interval substantially parallel during by these wells of row, and separate with about at least 6 meters distance that equates substantially;

In running through every mouthful of heat injection well handling interval, come the Seal Oil aspect with the impervious substantially solid material barrier of the better convection cell of thermal conductivity;

In running through every mouthful of fluid extraction well handling interval, fluid is communicated with between well and oil reservoir, and to make fluid can be in oil reservoir output, and

In running through every mouthful of heated well handling interval at least substantially, heat, its firing rate requires can (a) to make the well internal temperature to be increased to 600 ℃ and (b) make the well internal temperature maintain about 600 ℃ at least at least, but can not make temperature high to making the well internal equipment because of the overheated degree of damaging, leave the limit that the heat transfer rate of well can not be allowed apparently higher than the oil reservoir capacity of heat transmission simultaneously.

By the described method of claim 1, it is characterized in that 2, the means of heating heat injection well well inside should be able to make temperature remain on about 600 to 900 ℃.

3, by the described method of claim 1, it is characterized in that heating at least, the means of a bite heat injection well inside are electric heater.

4, by the described method of claim 1, it is characterized in that the solid material of Seal Oil aspect is the cement or the concrete of heat conduction.

5,, it is characterized in that to handle the interval place be substantially parallel running through for described heat injection and fluid extraction well, and at least in this interval, about 6 to 24 meters of each interval by the described method of claim 1.

6, by the described method of claim 1, it is characterized in that, most of heat injection wells and fluid extraction well with basically in vertical direction by five-spot, 7 methods or ten line-of-sight course well pattern well spacing.

7, by the described method of claim 1, it is characterized in that, till heating will proceed to always and have fluid to drive in the well of a bite fluid extraction well at least, and every mouthful of fluid external flux of being driven to fluid extraction well wherein will be limited in and borehole fluid pressure is increased to be enough to stop the obviously desired degree of extruding of oil reservoir.

By the described method of claim 7, it is characterized in that 8, described fluid pressure need be increased to approximately higher by 7 * 10 than the natural hydrostatic pressure in next-door neighbour stratum ⁵To 14 * 10 ⁵Handkerchief.

9,, it is characterized in that firing rate is or in every meter about 1200 to 2400 kJ (kilojoule)s per hour by the described method of claim 1.

10, by the described method of claim 1, it is characterized in that described solid material barrier is made of heat-resisting sleeve pipe, the sleeve pipe lower end is tight sealing for fluid, and be cement around.

11, by the described method of claim 10, it is characterized in that, described for barrier around well inside be heated by resistive the device heating, its heating power is approximately 330 to 660 watts every meter.

12, by the described method of claim 1, it is characterized in that, described oil reservoir, contain a relatively not too layer of infiltration at least, the permeability of this layer to be lower than significantly at least one in handling interval other layer; This method further comprises the steps;

Definite edge is a bite heat injection well and run into the position of above-mentioned relative low-permeability layer at least; With

In the above-mentioned heat injection of a bite at least well, increase the relative velocity of heat injection along the lower layer of above-mentioned at least one permeability, make its speed above the speed along above-mentioned at least one permeability higher level, the quantity of its increase is relevant with permeability higher level permeability value added.

13, by the described method of claim 12, it is characterized in that, with resistive element heating heat injection well, and at least in a bite heat injection well, the arrangement of heating element will make the resistance of unit length heater higher relatively along the permeability lower level, so that above-mentioned high relatively heat injection speed is provided.

14, by the described method of claim 12, it is characterized in that, with resistive element heating heat injection well, and at least in a bite well, the arrangement of resistive element will comprise many parallel straties in handling interval, and the number along the resistive element of permeability lower level will be more than another layer at least in this interval, so that above-mentioned high relatively firing rate is provided.

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