CN110298047A - It is a kind of consider phase transformation concentric double pipe steam injection pit shaft mass dryness fraction determine method - Google Patents
It is a kind of consider phase transformation concentric double pipe steam injection pit shaft mass dryness fraction determine method Download PDFInfo
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Abstract
This application provides a kind of concentric double pipe steam injection pit shaft mass dryness fractions for considering phase transformation to determine method, method includes the following steps: step 1, five kinds of different phases occurring during flowing downward of inner and outer pipes hot fluid for concentric double pipe steam injection pit shaft, establish thermal physical property parameter equation model respectively；Concentric double pipe steam injection pit shaft is divided into multiple segmentations by step 2；Step 3, the mass dryness fraction that each segmentation is solved using section iterative method combination thermal physical property parameter equation model.By this method, so that analysis result is more in line with reality, an effective ways and means are provided for the evaluation of viscous crude steamed well cylinder heat utilization efficiency, the optimization of wellbore heat law study, well head injection parameter and steam injection conceptual design.
Description
Technical field
The present invention relates to oil exploration and development fields, and more particularly, to a kind of concentric double pipe for considering phase transformation
Steam injection pit shaft mass dryness fraction determines method.
Background technique
In recent years, viscous crude steam injection technology is constantly progressive, and other than the variation for taking heat carrier, there are also steam injection tubular column structures
Improvement.Earliest steam injection mode is single tube steam injection, but horizontal well single tube steam injection technology is easy to that steam is caused to refer to
Into phenomenon, and then oil reservoir is caused to heat and employ unevenly, particularly with the more serious heavy crude reservoir of heterogeneity.It is parallel double
Pipe steam injection is mainly used in dual horizontal well SAGD, and (Steam Assisted Gravity Drainage, steam assisted gravity are let out
Oil tech) in, i.e. length oil pipe steam injection simultaneously, it is ensured that horizontal well heel end and toe-end can effective heated oil reservoir, but it is this
There is also some shortcomings for steam injection mode, such as: completion casing size is big, and well head is more complicated, is suitable for buried depth than shallower
Heavy crude reservoir.Other than using parallel double tube steam injection, concentric double pipe steam injection can also be used.Concentric double pipe steam injection refers to
There are two steam injection tubing strings inside pit shaft, it is not parallel, concentric, wherein annular space (outer tube) terminates to heel, and nothing connects
Hoop oil pipe (inner tube) extends to tiptoe, respectively to horizontal well heel end and toe-end steam injection simultaneously.Due to this two steam injection tubing strings
Be it is concentric, completion casing size is smaller for parallel double tube, and therefore, this steam injection mode is in deep-layer heavy crude
It is also suitable in oil reservoir.In fact, shut out concentric double pipe steam injection technology 84 block horizontal well steam soak sides for Liaohe Oil Field at home
There have been fairly large application (Xing Ertao horizontal well high efficient injection steam tubing string and matching technique study: (master's degree opinion in face
Text) grand celebration: Daqing Petroleum Institute, 2009), in addition, in order to solve interlayer steam injection contradiction, the oil field Kern River is being layered
Steam drives aspect and also once used this steam injection technology (Hight MA, Redus CL, Lehrmann JK.Evaluation
of dual-injection methods for multiple-zone steamflooding.SPE Reservoir
Engineering, February 1992:45-51.), i.e. inner tube is to lower layer's steam injection, and outer tube is to upper layer steam injection, and upper and lower two
Layer carries out steam drive simultaneously.
For viscous crude concentric double pipe steam injection, inner and outer pipes hot fluid causes same because there are temperature differences, and heat exchange can occur
There are great differences in pit shaft greening in main road feature for the two-tube steam injection of the heart and traditional single tube steam injection, also, if it is considered that interior
The presence of phase-state change of outer tube hot fluid during flowing downward, phase-change heat transfer can make pit shaft greening in main road become more multiple
It is miscellaneous, therefore, it is necessary to determine the viscous crude concentric double pipe steam injection pit shaft mass dryness fraction for considering phase transformation.
Technique study is also fewer to be determined to viscous crude concentric double pipe steam injection pit shaft mass dryness fraction both at home and abroad at present, is especially considered
The phase transformation of hot fluid in pit shaft, the problem of being primarily present in terms of following two, are urgently to be resolved:
(1) it is different from traditional single tube steam injection, inner tube (integral joint tubing) and outer tube (ring during concentric double pipe steam injection
It is empty) in hot fluid because there are temperature differences, and heat exchange can occur, this heat exchange will affect hot-fluid in every root canal column in turn
Therefore how the mass dryness fraction of body for concentric double pipe steam injection, determines that pit shaft mass dryness fraction is a critical issue.
(2) five kinds of phases are likely to occur during concentric double pipe steam injection, and (unsaturated water, wet saturated steam, is done saturated water
Saturated vapor and superheated steam), and can occur mutually to convert during flows downward between different phase, in this feelings
Under condition, how to consider that influence of the phase-state change to pit shaft mass dryness fraction is a difficult point.
Summary of the invention
For above-mentioned the problems of the prior art, present applicant proposes a kind of concentric double pipe steam injection pit shafts for considering phase transformation
A kind of method that mass dryness fraction determines, for phase, it is contemplated that influence of the heat exchange to pit shaft mass dryness fraction between two-tube is kept by quality
Perseverance, wellbore heat, momentum balance and the conservation of energy obtain between inner and outer pipes heat transfer rate, fluid temperature (F.T.), pressure drop and mass dryness fraction
Implicit relationship, and the steam quality in integral joint tubing and in annular space is solved using section iterative method, it is infused for viscous crude concentric double pipe
Vapor solution design provides theory support.
It is a kind of consider phase transformation concentric double pipe steam injection pit shaft mass dryness fraction determine method, method includes the following steps: step
1, the five kinds of different phases occurred during flowing downward for the inner and outer pipes hot fluid of concentric double pipe steam injection pit shaft, point
Thermal physical property parameter equation model is not established, wherein the inner and outer pipes include inner and outer tubes, and said inner tube is integral joint tubing,
The outer tube is annular space；Concentric double pipe steam injection pit shaft is divided into multiple segmentations by step 2；Step 3 utilizes section iterative method
The mass dryness fraction of each segmentation is solved in conjunction with thermal physical property parameter equation model.
In a kind of possible implementation of the above method, five kinds of different phases are unsaturated water, saturated water, wet saturation
Steam, dry saturated steam and superheated steam.
In a kind of possible implementation of the above method, thermal physical property parameter equation model includes: the first equation model,
Its density for being used to characterize inner and outer pipes hot fluid and mass dryness fraction, temperature, the relationship between pressure；Second equation model, is used for table
Levy the heat transfer rate of inner and outer pipes hot fluid and the relationship of temperature；Third equation model is used to characterize the pressure of inner and outer pipes hot fluid
Power drop and the relationship between density, pressure；And the 4th equation model, it is used to characterize the mass dryness fraction and heat transfer of inner and outer pipes hot fluid
Speed, pressure, the relationship between temperature.
In a kind of possible implementation of the above method, the first equation model is obtained based on mass conservation law, the
Two-equation model is based on wellbore heat rule and show that third equation model is obtained based on the law of conservation of momentum, the 4th equation model
It is quantitatively obtained based on the conservation of energy.
In a kind of possible implementation of the above method, the first equation model includes:
Integral joint tubing:
Annular space:
Wherein, WijAnd WanThe mass flow of hot fluid, kg/s respectively in integral joint tubing and annular space；DiiFor no box cupling
The internal diameter of oil pipe；ρijAnd ρanThe density of hot fluid, kg/m respectively in integral joint tubing and annular space3；νijAnd νanRespectively without connecing
Bind round the flow velocity of hot fluid in oil pipe and annular space, m/s；r1iAnd rioThe respectively inside radius and integral joint tubing of instlated tubular inner tube
Outer radius, m, z are the distance of the upper bound identity distance well head of each segmentation, m.
In a kind of possible implementation of the above method, second equation model includes:
Rate of heat exchange in integral joint tubing in hot fluid and annular space between hot fluid are as follows:
Heat transfer rate of the hot fluid to cement sheath in annular space are as follows:
Heat transfer rate of the cement sheath outer rim to surrounding formation are as follows:
Wherein, dQij/ dz refers to the heat transfer rate of hot fluid hot fluid into annular space in integral joint tubing in unit length, W/
m；TijAnd TanRespectively represent the hot fluid temperature in the hot fluid temperature and annular space in integral joint tubing, K；UioFor based on rio's
Overall heat-transfer coefficient between integral joint tubing inside and outside wall, W/ (m2·K)；dQan/ dz is that the hot fluid in unit length in annular space arrives
The heat transfer rate of cement sheath, W/m；DQ/dz refers to the heat transfer rate of the peripherally layer of cement sheath outer rim in unit length, W/m；r2oIt is
The outer radius of instlated tubular outer tube, m；ThFor the temperature of cement sheath and stratum interface, K；U2oFor based on r2oAnnular space in hot fluid
Overall heat-transfer coefficient between cement sheath outer rim, W/ (m2·K)；λeFor stratum heat transfer coefficient, W/ (mK)；TeiFor initial stratum
Temperature, K；F (t) is zero dimension stratum thermal conduction time function.
In a kind of possible implementation of the above method, third equation model includes:
Integral joint tubing:
It is single-phase hot fluid in annular space:
It is two-phase hot fluid in annular space:
Wherein, pijAnd panPressure respectively in integral joint tubing with hot fluid in annular space, Pa；ftpFor the resistance of two phase flow
Force coefficient；f'tpFor the coefficient of frictional resistance of annular space tube wall；ρijAnd ρanHot fluid is close respectively in integral joint tubing and annular space
Degree, kg/m3；DiiAnd DanThe respectively internal diameter of integral joint tubing and annular space equivalent diameter, Dan=2 (r1i-rio), m；νsgijWith
νsganFor the superficial gas flow velocity in integral joint tubing and in annular space, m/s；CpmFor the specific heat at constant pressure of hot fluid in annular space, J/
(kg·K)；CJmFor the Joule-Thomson coefficient of hot fluid in annular space, K/Pa；dQij/ dz refers in unit length without box cupling oil
The heat transfer rate of hot fluid hot fluid into annular space, W/m in managing；dQan/ dz is the hot fluid in annular space in unit length to cement
The heat transfer rate of ring, W/m；νijAnd νanThe flow velocity of hot fluid, m/s respectively in integral joint tubing and annular space；θ is no box cupling oil
The angle of pipe and horizontal direction, rad.
In a kind of possible implementation of the above method, the 4th equation model includes:
Integral joint tubing:
Annular space:
Wherein, WijAnd WanThe mass flow of hot fluid, kg/s respectively in integral joint tubing and annular space；dQij/ dz refers to list
On bit length in integral joint tubing hot fluid heat transfer rate from hot fluid to annular space, W/m；dQan/ dz is annular space in unit length
Heat transfer rate of the interior hot fluid to cement sheath, W/m；hijAnd hanThe enthalpy of hot fluid, J/ respectively in integral joint tubing and annular space
kg；νijAnd νanThe flow velocity of hot fluid, m/s respectively in integral joint tubing and annular space；G is acceleration of gravity, m/s2；θ is that nothing connects
Bind round the angle of oil pipe and horizontal direction, rad.
In a kind of possible implementation of the above method, step 3 is specifically included: step 31 inputs no box cupling respectively
The well head injection parameter of oil pipe and annular space, the hot physical property of borehole size and stratum；Step 32 calculates pit shaft first using iterative method
The pressure drop of hot fluid in segmentation and temperature drop；Step 33 calculates under different phase hot fluid in integral joint tubing and annular space
Mass dryness fraction；Step 34 repeats the above steps, until calculating to the bottom of concentric double pipe steam injection pit shaft.
The concentric double pipe steam injection pit shaft mass dryness fraction of the considerations of the application phase transformation determines method, compared with the prior art, has
Following advantage:
Research object of the present invention is more novel, and analysis result is also more in line with reality.Such as: traditional single tube is infused and is steamed
Vapour, heat in pit shaft peripherally layer always by transmitting, and with the increase of well depth, steam quality can decline always in pit shaft, when
When well is deep, bottom steam dryness may be reduced to 0, still, for concentric double pipe steam injection, due between inner and outer pipes
There are heat exchange, be equivalent to wherein a root canal column heat absorption, an in addition root canal column heat release, and it is this heat absorption and exothermic direction and
Size can change during flows downward, cause in inner and outer pipes steam quality that can not only be reduced to 0 because of heat release, but also
1 can be increased to because of heat absorption, shown and traditional single tube steam injection difference.
Above-mentioned technical characteristic may be combined in various suitable ways or be substituted by equivalent technical characteristic, as long as can reach
To the purpose of the present invention.
Detailed description of the invention
The invention will be described in more detail below based on embodiments and refering to the accompanying drawings.Wherein:
Fig. 1 shows the determination method of the concentric double pipe steam injection pit shaft mass dryness fraction according to an embodiment of the present invention for considering phase transformation
Schematic flow chart.
Fig. 2 shows traditional single tube steamed well barrel structure schematic diagrames.
Fig. 3 shows concentric double pipe steamed well barrel structure schematic diagram.
Fig. 4 shows five kinds of different phases that concentric double pipe steam injection hot fluid occurs in flow process.
Fig. 5 shows the determination of the concentric double pipe steam injection pit shaft mass dryness fraction according to another embodiment of the present invention for considering phase transformation
The schematic flow chart of method.
Fig. 6 shows traditional single tube steamed well heat loss velocity distribution curve figure.
It is bent that Fig. 7 shows the concentric double pipe steam injection heat transfer rate distribution according to another embodiment of the present invention for considering phase transformation
Line chart.
Fig. 8 shows traditional single tube steam injection pit shaft greening in main road curve graph.
Fig. 9 shows the determination of the concentric double pipe steam injection pit shaft mass dryness fraction according to another embodiment of the present invention for considering phase transformation
The greening in main road curve graph of method.
In the accompanying drawings, identical component uses identical appended drawing reference.Attached drawing is not according to actual ratio.
Specific embodiment
The present invention will be further described with reference to the accompanying drawings.
Fig. 1 is to determine the schematic of method 100 according to the concentric double pipe steam injection pit shaft mass dryness fraction of phase transformation the considerations of the application
Flow chart.As shown in Figure 1, this method 100 includes:
S110, five kinds occurred during flowing downward for the inner and outer pipes hot fluid of concentric double pipe steam injection pit shaft
Different phase establishes thermal physical property parameter equation model respectively, wherein the inner and outer pipes include inner and outer tubes, and said inner tube is
Integral joint tubing, the outer tube are annular space；
Concentric double pipe steam injection pit shaft is divided into multiple segmentations by S120；
S130 solves the mass dryness fraction of each segmentation using section iterative method combination thermal physical property parameter equation model.
Firstly, in this application, for object be concentric double pipe steam injection, this under traditional research single tube steam injection
Pit shaft mass dryness fraction be completely different；Secondly, the pit shaft mass dryness fraction mentioned in this application determines that method considers inner and outer pipes hot-fluid
Complicated phase-state change of body during flowing downward, i.e. unsaturated water, saturated water, wet saturated steam, dry saturated steam and mistake
Mutually converting between 5 kinds of different phases of hot steam.
As shown in Fig. 2, hot fluid at most occurs three kinds during flowing downward in traditional single tube steam injection pit shaft
Phase (wet saturated steam, saturated water and unsaturated water), and heat is always transmitted from pit shaft into stratum.And in such as Fig. 3 and
In concentric double pipe steam injection pit shaft shown in Fig. 4, it is (unsaturated that five kinds of phases can occur during flowing downward in hot fluid
Water, saturated water, wet saturated steam, dry saturated steam and superheated steam), and heat is in addition to transmitting it into stratum from annular space
Outside, it can also be transmitted between integral joint tubing and annular space, and the heat exchange direction of the two is during flows downward
It can change.Therefore, when studying the mass dryness fraction of pit shaft in concentric double pipe steam injection pit shaft, need to consider that hot fluid flows down past
The variation of phase change and heat exchange direction in dynamic process.
In S110, thermal physical property parameter equation model includes the first equation model, is used to characterize inner and outer pipes hot fluid
Density and mass dryness fraction, temperature, the relationship between pressure；Second equation model is used to characterize the heat transfer rate of inner and outer pipes hot fluid
With the relationship of temperature；Third equation model is used to characterize the pass between the pressure drop and density, pressure of inner and outer pipes hot fluid
System；And the 4th equation model, it is used to characterize mass dryness fraction and heat transfer rate, pressure, the pass between temperature of inner and outer pipes hot fluid
System.
Wherein, because mass exchange do not occur in flow process with the stratum of surrounding for the hot fluid in pit shaft, in pit shaft
Flowing the quality streams such as may be considered, therefore mass conservation law can be based on, consider hot fluid in flow process
In the case where phase transformation, it can be deduced that the first following equation model:
Integral joint tubing:
Annular space:
Wherein, WijAnd WanThe mass flow of hot fluid, kg/s respectively in integral joint tubing and annular space；DiiFor no box cupling
The internal diameter of oil pipe；ρijAnd ρanThe density of hot fluid, kg/m respectively in integral joint tubing and annular space3；νijAnd νanRespectively without connecing
Bind round the flow velocity of hot fluid in oil pipe and annular space, m/s；r1iAnd rioThe respectively inside radius and integral joint tubing of instlated tubular inner tube
Outer radius, m, z are the distance of the upper bound identity distance well head of each segmentation, and m, as z=0, corresponding is well head.
Under different phases, the density function of the hot fluid in pit shaft are as follows:
Wherein, ρsAnd ρwThe respectively density of dry saturated steam and saturated water, kg/m3；X is mass dryness fraction.
For wet saturated steam, the density of hot fluid is the function of temperature (or pressure) and mass dryness fraction, can be dry using steam
The method of degree weighting is calculated；For dry saturated steam and saturated water, the density of hot fluid is the function of temperature (or pressure),
It can be calculated with the empirical equation that Ejiogu and Tortike is proposed；For superheated steam and unsaturated water, hot fluid it is close
Degree is the function of temperature and pressure, can be calculated using the density meter interpolation that Zhang Jiarong and Zhao Tingyuan is proposed, be steamed with overheating
For vapour, density is as shown in table 1.
By formula (1), (2) and (11), that is, establish hot-fluid volume density and pit shaft mass dryness fraction, temperature under five kinds of different phases
The implicit relationship between pressure.
1 superheated steam density meter of table
Second equation model can be obtained based on wellbore heat rule, i.e., right respectively according to Fourier (Fourier) law
Heat transfer of the hot fluid into stratum is characterized in heat exchange and annular space in integral joint tubing and annular space between hot fluid, is retouched
Various thermal resistances inside pit shaft are stated during concentric double pipe steam injection, wellbore heat coefficient expressions are established.
In concentric double pipe steam injection pit shaft, wellbore heat includes two parts, is flowed in fluid and annular space in integral joint tubing
Heat transfer of the fluid to cement sheath in heat exchange and annular space between body；And previous invention is infused primarily directed to traditional single tube and is steamed
Vapour, wellbore heat only include a part, the i.e. heat transfer of downhole well fluid to cement sheath.
Rate of heat exchange according to Fourier law, in integral joint tubing in hot fluid and annular space between hot fluid are as follows:
Heat transfer rate of the hot fluid to cement sheath in annular space are as follows:
Heat transfer rate of the cement sheath outer rim to surrounding formation are as follows:
Wherein, dQij/ dz refers to the heat transfer rate of hot fluid hot fluid into annular space in integral joint tubing in unit length, W/
m；TijAnd TanRespectively represent the hot fluid temperature in the hot fluid temperature and annular space in integral joint tubing, K；UioFor based on rio's
Overall heat-transfer coefficient between integral joint tubing inside and outside wall, W/ (m2·K)；dQan/ dz is that the hot fluid in unit length in annular space arrives
The heat transfer rate of cement sheath, W/m；DQ/dz refers to the heat transfer rate of the peripherally layer of cement sheath outer rim in unit length, W/m；r2oIt is
The outer radius of instlated tubular outer tube, m；ThFor the temperature of cement sheath and stratum interface, K；U2oFor based on r2oAnnular space in hot fluid
Overall heat-transfer coefficient between cement sheath outer rim, W/ (m2·K)；λeFor stratum heat transfer coefficient, W/ (mK)；TeiFor initial stratum
Temperature, K；F (t) is zero dimension stratum thermal conduction time function, and there are a variety of expression-forms by f (t), uses following public affairs herein
Formula is defined:
Wherein, τDFor non dimensional time.
It should be understood that concentric double pipe steam injection pit shaft fluid pressure drop calculates and needs to be divided to single-phase flow (unidirectional hot fluid) and two
Mutually stream (two-phase hot fluid) two kinds of situations, it may be assumed that
Fluid temperature (F.T.) calculating then needs to see Fluid pressure and fluid temperature (F.T.) under different phase in concentric double pipe steam injection pit shaft
Between whether meet one-to-one relationship, it may be assumed that for dry saturated steam, wet saturated steam and saturated water, fluid temperature (F.T.) and fluid
Meet one-to-one relationship between pressure, and for superheated steam and unsaturated water, fluid temperature (F.T.) and Fluid pressure are mutually indepedent,
It is unsatisfactory for one-to-one relationship.Therefore, it when constructing third equation model, according to the law of conservation of momentum, then needs to consider single-phase
Hot fluid and two-phase hot fluid, it may be assumed that
The flowing of hot fluid is Flow In A Circular Tube, its pressure drop under different phase in integral joint tubing are as follows:
For the flowing in annular space, if it is single-phase flow (dry saturated steam, superheated steam, saturated water and unsaturated water),
Can annular space is equivalent at round tube, the pressure drop of monophasic fluid in annular space is calculated using similar round tube systems approach, it may be assumed that
If being biphase gas and liquid flow (wet saturated steam) in annular space, pressure drop can be indicated are as follows:
Wherein, panFor the pressure of hot fluid in annular space, Pa；f'tpFor the coefficient of frictional resistance of annular space tube wall；DanFor annular space
Equivalent diameter, Dan=2 (r1i-rio), m；νsganFor superficial gas flow velocity, m/s, C in annular spacepmFor the level pressure of hot fluid in annular space
Specific heat, J/ (kgK)；CJmFor the Joule-Thomson coefficient of hot fluid in annular space, K/Pa, WsAnd WwRespectively steam and water
Mass flow, kg/s；CpsAnd CpwThe respectively specific heat at constant pressure of dry saturated steam and saturated water, J/ (kgK).
In addition, there are following one-to-one relationships between the temperature and pressure of saturated vapor:
Wherein, T is the temperature of saturated vapor, and p is the pressure of saturated vapor.
In pit shaft in flow process, enthalpy, kinetic energy and the potential energy of hot fluid change hot fluid with well depth.According to the conservation of energy
Principle, the energy conservation equation (the 4th equation model) of hot fluid is respectively as follows: in available integral joint tubing and annular space
Integral joint tubing:
Annular space:
Wherein, hijAnd hanThe enthalpy of hot fluid, J/kg respectively in integral joint tubing and annular space；G is acceleration of gravity, m/
s2；θ is the angle of integral joint tubing and horizontal direction, rad.
Wherein, under different phase hot fluid enthalpy function are as follows:
For wet saturated steam, the enthalpy of hot fluid is the function of temperature (or pressure) and mass dryness fraction, can use steam quality
The method of weighting is calculated；For dry saturated steam and saturated water, the enthalpy of hot fluid is the function of temperature (or pressure), can be with
It is calculated with the empirical equation that Ejiogu and Tortike is proposed；For superheated steam and unsaturated water, the enthalpy of hot fluid is temperature
The function of degree and pressure can be calculated using the enthalpy table interpolation that Zhang Jiarong and Zhao Tingyuan is proposed, by taking superheated steam as an example,
Enthalpy is as shown in table 2.
Enthalpy equation (12) is substituted into equation (9) and equation (10) respectively to be respectively obtained in integral joint tubing and annular space
Implicit governing equation of the hot fluid about temperature can calculate pit shaft stream by alternative manner under the conditions of single-phase hot fluid stream
Temperature drop.
2 superheated steam enthalpy of table
The above are mass conservation law, wellbore heat rule, the law of conservation of momentum and the energy by comprehensive hot fluid
The thermal physical property parameter equation model that law of conservation obtains.
In summary formula, it can be deduced that mass dryness fraction of the concentric double pipe steam injection after before phase change, it should be appreciated that when hot in pit shaft
When fluid is wet saturated steam, mass dryness fraction is greater than 0 less than 1, specific formula for calculation are as follows:
Wherein, xijIt (0) is well head steam quality in integral joint tubing；C1=Lv；
Steam quality in annular space:
Wherein, xanIt (0) is well head steam quality in annular space；C1'=Lv； With C3Unlike expression formula, C'3Expression formula
Right side of the equal sign first item represents the net heat loss speed of hot fluid in annular space, i.e. dQan/dz-dQij/dz。
In the step s 120, entire pit shaft is divided into N number of segmentation, iterative method is all made of on every section and carries out mass dryness fraction solution.
In step s 130, as shown in figure 5, may include steps of:
S131, the first segmentation for pit shaft, inputs the well head injection parameter (steam injection of every steam injection tubing string respectively
Pressure, temperature, mass dryness fraction and mass flow), steam injection time, the basic parameters such as the hot physical property of borehole size and stratum；
S132 calculates the pressure drop of the hot fluid in the segmentation of pit shaft first using iterative method and temperature drops；
Pressure drop and temperature drop for kth (k=1,2,3 ... N) segmentation, can be solved using following method.
On the one hand, the pressure drop and temperature drop in the segmentation of integral joint tubing are calculated.For biphase gas and liquid flow: first assuming one
A initial valueIt is calculated using formula (16)Then, this average pressure is calculated according to Beggs-Brill classical way and be averaged
At a temperature of fluid intermediate parameters, such as density, two phase flow resistance coefficient and enthalpy；It is calculated using formula (6) formulaAnd with vacation
If initial valueComparison, if the two not in the error range of permission, after calculatingIt is assigned toContinue to calculate,
Until meeting required precision.
For single-phase flow: first assuming an initial valueWithIt calculates under this average pressure and mean temperature in fluid
Between parameter, such as density, two phase flow resistance coefficient and enthalpy；(6) formula of utilization calculatesConsolidated equation (9) and equation (12) calculate
Hot fluid temperature drops in integral joint tubingAnd respectively with the initial value of hypothesisWithComparison, if the two is not allowing
Error range in, then will be after calculatingWithIt is assigned to respectivelyWithContinue to calculate, until meeting required precision.
In above-mentioned calculating process, steam quality using the initial value of upper node come approximate, for single-phase flow, pipe friction resistance
The calculation method that force coefficient can go out with reference to Yuan's grace stilb.
On the other hand, the pressure drop and temperature drop in the segmentation of annular space are calculated.
For single-phase flow, calculated using the algorithm of similar integral joint tubing；
For biphase gas and liquid flow: first assuming an initial valueSecondly, being calculated according to formula (16)According to (3) formula meter
It calculatesIt is calculated according to (4) formulaFinally, being calculated according to (8) formulaAnd the initial value with hypothesisComparison, if two
Person, then will be after calculating not in the error range of permissionIt is assigned toContinue to calculate, until meeting required precision.
In addition,For based onAnnular space in fluid to the overall heat-transfer coefficient between cement sheath outer rim, W/ (m2K),
It can be defined with following formula (17):
r1o、r2i、rcoAnd rhRespectively instlated tubular inner tube outer radius, instlated tubular inner tube inside radius, casing outer radius and cement
Ring outer edge radius, m；λinsAnd λcemThe respectively thermal coefficient of heat-barrier material and cement sheath, W/ (mK)；hcAnd hrIt is respectively oily
The aerial convection transfer rate of lantern ring and radiation heat transfer coefficient, W/ (m2·K)。
S133 calculates the mass dryness fraction of hot fluid in integral joint tubing and annular space under different phase according to formula (13) and (14),
I.e.With
By the above-mentioned mass dryness fraction result output of the first segmentation, and enter the calculating of next segmentation.
S134 repeats the above steps, until calculating to the bottom of concentric double pipe steam injection pit shaft.
For example, the well head injection parameter of integral joint tubing are as follows: steam injection pressure 11MPa, steam injection speed 8kg/h steam
Vapour mass dryness fraction 59%；The well head injection parameter of annular space are as follows: steam injection pressure 9MPa, steam injection speed 6kg/h, steam quality
59%, other pit shafts and formation parameter are shown in Table 3.
3 concentric double pipe steam injection pit shaft of table and formation parameter
Fig. 6 is traditional single tube steam injection wellbore heat loss VELOCITY DISTRIBUTION typical curve, and Fig. 7 is concentric double pipe steam injection in this example
Wellbore heat VELOCITY DISTRIBUTION as a result, comparison diagram 6 and Fig. 7 it can be seen that
1. for traditional single tube steam injection, heat in pit shaft peripherally layer always by transmitting, and with the increase of well depth,
Wellbore heat loss speed is gradually reduced；
2. wellbore heat shows different feature for concentric double pipe steam injection: at well head, due to integral joint tubing
Interior fluid temperature (F.T.) is higher than fluid temperature (F.T.) in annular space, so heat has just been initially to transmit from integral joint tubing into annular space, and two
Rate of heat exchange between person is gradually decreased with the increase of well depth；But due to fluid temperature (F.T.) suppression ratio in integral joint tubing
Fast in annular space, when well depth is more than certain value, the direction of heat exchange is changed, and hot fluid starts to no box cupling oil in annular space
Heat release in managing, from Fig. 5 it can be found that integral joint tubing to the heat transfer rate of annular space be negative value, that is to say, that for double with one heart
Pipe steam injection, heat transfer direction can change in hot fluid flow process between inner and outer pipes, and this variation depend primarily on it is every
The well head primary condition of root steam injection string and along Cheng Wendu drop.Annular space is in addition to there are heat exchanges between integral joint tubing hot fluid
Except, it can also conduct heat to cement sheath, therefore, be influenced in terms of the net heat loss speed two in annular space.
Fig. 8 is to be distributed typical plot along journey steam quality according to traditional single tube steam injection pit shaft.Fig. 9 is according to the application
Offer determines the obtained greening in main road curve graph for considering the method for the mass dryness fraction of concentric double pipe steam injection pit shaft of phase transformation.Such as figure
Shown in 8 and Fig. 9, for traditional single tube steam injection, with the increase of well depth, steam quality is gradually reduced, and is not in that steam is dry
The phenomenon that degree increases.And for concentric double pipe steam injection, during flowing downward, steam quality is not inner and outer pipes hot fluid
Reduce always, but have rise also have drop, mainly by between inside and outside pipe fluid heat exchange direction and size influenced, also, by
In considering phase transformation of pit shaft hot fluid during flowing downward, steam quality can increase to 1 in pit shaft, can also reduce
To 0, in this example, steam quality has reached 1 in well depth 470m in annular space.
Therefore, method is determined according to the concentric double pipe steam injection pit shaft mass dryness fraction provided by the present application for considering phase transformation, it is contemplated that
Five kinds of phase-state changes that inner and outer pipes hot fluid occurs during flowing downward, analysis result are more in line with reality, are thick oil filling
The evaluation of steam pit shaft heat utilization efficiency, the optimization of wellbore heat law study, well head injection parameter and steam injection conceptual design provide
One effective ways and means.
In the description of the present invention, it is to be understood that, term " on ", "lower", "bottom", "top", "front", "rear", "inner",
The orientation or positional relationship of the instructions such as "outside", "left", "right" is to be based on the orientation or positional relationship shown in the drawings, merely to just
In description the present invention and simplify description, rather than the device or element of indication or suggestion meaning must have a particular orientation, with
Specific orientation construction and operation, therefore be not considered as limiting the invention.
Although describing the present invention herein with reference to specific embodiment, it should be understood that, these realities
Apply the example that example is only principles and applications.It should therefore be understood that can be carried out to exemplary embodiment
Many modifications, and can be designed that other arrangements, without departing from spirit of the invention as defined in the appended claims
And range.It should be understood that different appurtenances can be combined by being different from mode described in original claim
Benefit requires and feature described herein.It will also be appreciated that the feature in conjunction with described in separate embodiments can be used
In other described embodiments.
Claims (9)
1. a kind of concentric double pipe steam injection pit shaft mass dryness fraction for considering phase transformation determines method, which comprises the following steps:
Step 1, for the concentric double pipe steam injection pit shaft inner and outer pipes hot fluid occur during flowing downward five
Kind different phase, establishes thermal physical property parameter equation model, wherein the inner and outer pipes include inner and outer tubes, said inner tube respectively
For integral joint tubing, the outer tube is annular space；
The concentric double pipe steam injection pit shaft is divided into multiple segmentations by step 2；
Step 3, the mass dryness fraction for solving each segmentation in conjunction with the thermal physical property parameter equation model using section iterative method.
2. the method according to claim 1, wherein five kinds of different phases be unsaturated water, it is saturated water, wet
Saturated vapor, dry saturated steam and superheated steam.
3. according to the method described in claim 2, it is characterized in that, the thermal physical property parameter equation model includes:
First equation model is used to characterize the density and mass dryness fraction, temperature, the relationship between pressure of the inner and outer pipes hot fluid；
Second equation model is used to characterize the heat transfer rate of the inner and outer pipes hot fluid and the relationship of temperature；
Third equation model is used to characterize the relationship between the pressure drop and density, pressure of the inner and outer pipes hot fluid；And
4th equation model is used to characterize mass dryness fraction and heat transfer rate, pressure, the pass between temperature of the inner and outer pipes hot fluid
System.
4. according to the method described in claim 3, it is characterized in that, first equation model is obtained based on mass conservation law
Out, the second equation model is based on wellbore heat rule and show that the third equation model is obtained based on the law of conservation of momentum,
4th equation model is based on the conservation of energy and quantitatively obtains.
5. the method according to claim 3 or 4, which is characterized in that first equation model includes:
Integral joint tubing:
Annular space:
Wherein, WijAnd WanThe mass flow of hot fluid, kg/s respectively in integral joint tubing and annular space；DiiFor integral joint tubing
Internal diameter；ρijAnd ρanThe density of hot fluid, kg/m respectively in integral joint tubing and annular space3；νijAnd νanRespectively without box cupling oil
The flow velocity of hot fluid, m/s in pipe and annular space；r1iAnd rioRespectively outer the half of the inside radius and integral joint tubing of instlated tubular inner tube
Diameter, m, z are the distance of the upper bound identity distance well head of each segmentation, m.
6. the method according to claim 3 or 4, which is characterized in that the second equation model includes:
Rate of heat exchange in integral joint tubing in hot fluid and annular space between hot fluid are as follows:
Heat transfer rate of the hot fluid to cement sheath in annular space are as follows:
Heat transfer rate of the cement sheath outer rim to surrounding formation are as follows:
Wherein, dQij/ dz refers to the heat transfer rate of hot fluid hot fluid into annular space in integral joint tubing in unit length, W/m；Tij
And TanRespectively represent the hot fluid temperature in the hot fluid temperature and annular space in integral joint tubing, K；UioFor based on rioNothing connect
Bind round the overall heat-transfer coefficient between oil pipe inside and outside wall, W/ (m2·K)；dQan/ dz is the hot fluid in annular space in unit length to cement
The heat transfer rate of ring, W/m；DQ/dz refers to the heat transfer rate of the peripherally layer of cement sheath outer rim in unit length, W/m；r2oIt is heat-insulated
The outer radius of pipe outer tube, m；ThFor the temperature of cement sheath and stratum interface, K；U2oFor based on r2oAnnular space in hot fluid to water
Overall heat-transfer coefficient between mud ring outer rim, W/ (m2·K)；λeFor stratum heat transfer coefficient, W/ (mK)；TeiFor initial stratum temperature
Degree, K；F (t) is zero dimension stratum thermal conduction time function.
7. the method according to claim 3 or 4, which is characterized in that the third equation model includes:
Integral joint tubing:
It is single-phase hot fluid in annular space:
It is two-phase hot fluid in annular space:
Wherein, pijAnd panPressure respectively in integral joint tubing with hot fluid in annular space, Pa；ftpFor the resistance system of two phase flow
Number；f′tpFor the coefficient of frictional resistance of annular space tube wall；ρijAnd ρanThe density of hot fluid respectively in integral joint tubing and annular space,
kg/m3；DiiAnd DanThe respectively internal diameter of integral joint tubing and annular space equivalent diameter, Dan=2 (r1i-rio), m；νsgijAnd νsganFor
Superficial gas flow velocity in integral joint tubing and in annular space, m/s；CpmFor the specific heat at constant pressure of hot fluid in annular space, J/ (kgK)；
CJmFor the joule thomson coefficient of hot fluid in annular space, K/Pa；dQij/ dz refer in unit length in integral joint tubing hot fluid to
The heat transfer rate of hot fluid, W/m in annular space；dQan/ dz is heat transfer speed of the hot fluid in unit length in annular space to cement sheath
Degree, W/m；νijAnd νanThe flow velocity of hot fluid, m/s respectively in integral joint tubing and annular space；θ is integral joint tubing and level side
To angle, rad.
8. the method according to claim 3 or 4, which is characterized in that the 4th equation model includes:
Integral joint tubing:
Annular space:
Wherein, WijAnd WanThe mass flow of hot fluid, kg/s respectively in integral joint tubing and annular space；dQij/ dz refers to that unit is long
On degree in integral joint tubing hot fluid heat transfer rate from hot fluid to annular space, W/m；dQan/ dz is in annular space in unit length
Heat transfer rate of the hot fluid to cement sheath, W/m；hijAnd hanThe enthalpy of hot fluid, J/kg respectively in integral joint tubing and annular space；
νijAnd νanThe flow velocity of hot fluid, m/s respectively in integral joint tubing and annular space；G is acceleration of gravity, m/s2；θ is no box cupling oil
The angle of pipe and horizontal direction, rad.
9. method according to claim 1 to 4, which is characterized in that step 3 specifically includes:
Step 31, well head injection parameter, borehole size and the stratum thermal physical property parameter for inputting integral joint tubing and annular space respectively；
Step 32, the pressure drop and temperature drop that the hot fluid that pit shaft first is segmented is calculated using iterative method；
Step 33 calculates the described first mass dryness fraction for being segmented hot fluid in upper integral joint tubing and annular space；
Step 34 repeats the above steps, until calculating to the bottom of the concentric double pipe steam injection pit shaft.
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