CN102278103A - Method for improving oil deposit recovery ratio of deep extremely-viscous oil by gravity drainage assisted steam flooding - Google Patents

Abstract

The invention relates to a method for improving the oil deposit recovery ratio of deep massive extremely-viscous oil in an extraction mode of gravity drainage assisted steam flooding. In the method, superposition horizontal wells are arranged among wells by combining results of researches on the fine contrast of small geological strata of massive oil deposit, the distribution rule of interlayer, the distribution rule of remaining oil and the like and a fine research on numerical simulation; an upper superposition horizontal well is used for injecting steam, a peripheral vertical shaft is used for production, and a lower superposition horizontal well is used for discharging liquid (crude oil between condensate water and the horizontal wells); and thus, a production-injection ratio of high-speed steam injection of deep oil deposit is improved, the dryness of steam on the well bottom is improved, the pressure of an oil layer is reduced, a steam cavity is easy to expand, the swept volume is improved, a development effect is improved, and the aim of improving the recovery ratio finally is fulfilled.

Description

A kind of gravity sluicing assisted steam flooding improves deep layer super-heavy oil deposit recovery ratio method

Technical field

The invention belongs to the oil reservoir development field, relate to the exploitation of bulk or thick-layer shape super-heavy oil deposit, be specifically related to a kind of gravity sluicing assisted steam flooding technology, the present invention is applicable to the recovery ratio that improves the super-heavy oil deposit that oil reservoir buries deeply, viscosity of crude is big.

Background technology

The viscosity of crude oil be inner certain part of crude oil when mobile with respect to another part the tolerance of frictional resistance be the important parameter of oil-gas field development.For heavy crude reservoir, China's sorting technique of viscous crude at present is that degassed crude viscosity is classified under the reservoir temperature condition: common heavy oil viscosity of crude 50～10000mPas; Special viscous crude viscosity of crude 10000～50000mPas; Super viscous crude viscosity of crude is greater than 50000mPas.Super viscosity of thickened oil height, fluid ability is poor, and the exploitation difficulty is the highest.The exploitation of heavy crude reservoir mainly is hot fluid to be injected oil reservoir carry out oil recovery by heating, reduces viscosity of crude, improves the fluid ability of crude oil.

Steam soak (Cyclic Steam Stimulation) is to point to the steam that a bite producing well injects some in a short time continuously, then closing well (stewing well) a couple of days, heat is spread, and opening well and making production is again seen Fig. 1, Fig. 2 afterwards.After instantaneous oil production is reduced to certain level, carry out the notes vapour of next round, stewing well, oil recovery, so repeatedly, loop cycle is invalid or change other mining type into until oil well production increasing oil mass economy.

SAGD (Steam Assisted Gravity Drainage) adopts a pair of horizontal well the earliest, and top horizontal well is annotated vapour, following horizontal well production.The steam that the injects onlap that makes progress forms the vapour chamber on the stratum, the crude oil of heating and the steam water that agglutinates depends on action of gravity to let out output in the following producing well, sees also shown in Figure 3ly, and Fig. 3 is a SAGD oil recovery mechanism schematic diagram.

Steam flooding (Steam Flooding/Drive) is exactly the steam that is continuously injected high mass dryness fraction by the injection well toward oil reservoir, and steam constantly heats oil reservoir, thereby greatly reduces the viscosity of in-place oil.The steam that injects becomes the fluid of heat on the stratum, around crude oil displacement producing well, and adopted on the ground.Fig. 4 represents that traditional steam flooding well pattern is to annotate vapour by straight well, the inverted nine-spot pattern that Fig. 5-1 recovers the oil for straight well, and Fig. 5-2 is anti-seven spot pattern, in the drawings ● for annotating the vapour well;

For producing straight well.

It mainly is at shallow-layer that at present external steam flooding, SAGD use, and is generally less than 600m, domestic being applied in the 1000m.And steam flooding generally is applicable to common heavy oil reservoir, and SAGD is applicable to super-heavy oil deposit.

Yet steam soak, steam flooding, SAGD face a following difficult problem:

For the heavy crude reservoir of 50 ℃ of following degassed crude viscosity less than 50000mPas, the exploitation of main at present employing steam soak is influenced by reservoir buried depth, and shallow layer thick oil can be developed by SAGD.For the deep layer super-heavy oil deposit of reservoir buried depth, have following exploitation difficult point greater than 1300m:

(1) deep-layer heavy crude reservoir buries deeply, and heat waste is bigger, steam flooding, SAGD general requirements shaft bottom mass dryness fraction height, and the deep-layer heavy crude development difficulty is big;

(2) deep-layer heavy crude enters after high round handles up, and cycle produce oil, gas oil ratio descend, the economic benefit variation, if do not adopt effective development tool, oil reservoir is about to discarded;

(3) the super viscous crude stage development degree of handling up is low, the stage recovery percent of reserves less than 30% of generally handling up;

(4) effective heated perimeter only is about 30m on the plane, is circular substantially, the relative enrichment of remaining oil between well;

(5) oil reservoir buries deeply, and heat waste is serious in the steam injection process, and the shaft bottom steam quality is low, can not form effective vapor chamber.

From super in the world heavy oil development is technical at present,,, except that the development technique of handling up, still there is not other effective development tool because of wellbore heat loss in the heat injection process is big for deep-layer heavy crude reservoir (reservoir buried depth is greater than 1300m).

Summary of the invention

For solving the super viscous crude of the deep layer exploitation contradiction that the later stage oil reservoir faces of handling up, the present invention proposes to adopt the technology of gravity sluicing assisted steam flooding SGWD (Steam-flooding assisted by Gravity Water Drainage) raising deep layer super-heavy oil deposit recovery ratio.

According to the present invention, a kind of gravity sluicing assisted steam flooding improves deep layer super-heavy oil deposit recovery ratio method and may further comprise the steps:

(1) oil reservoir of selection gravity sluicing assisted steam flooding: the oil reservoir of gravity sluicing assisted steam flooding will meet the following conditions: reservoir buried depth 1000-2000 rice, core intersection 20-180 rice, remaining oil saturation＞30%, degree of porosity＞18%, permeability＞200md (millidarcy), 50 ℃ of stock tank oil viscosity＞50000mPas (milli handkerchief second, viscosity unit), oil reservoir is every the interlayer agensis;

(2) estimation Fuel Oil Remaining: at first, in the vertical,, revert to oil-producing formation, calculate the output of each reservoir productivity and crude oil by oil mass with output according to oil well production situation and oil reservoir physical characterization data; Secondly, according to the difference of the former oil mass of output in the reserves of crude oil in every layer and every layer, obtain the reserves of remaining oil; According to following substratum production split model, the former oil mass of output is reduced to payzone:

Substratum production split model $N_{\mathrm{pi}}=\frac{k_i\·h_i\·{\mathrm{\φ}}_i}{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{k}_i\·h_i\·{\mathrm{\φ}}_i}\×N_p$

N _Pi---substratum cumulative production, t; (ton)

N _p---individual well stage cumulative production, t; (ton)

k _i---reservoir permeability, * 10 ^-3μ m ²(square micron)

H---effective pay thickiness, m; (rice)

φ---oil reservoir degree of porosity, decimal; (this value is the ratio of voids volume and rock volume)

N---penetrate out the number of plies;

At a certain concrete block, the Fuel Oil Remaining of estimation oil reservoir:

1. find vertical oil reservoir physical parameter of certain mouthful of well from the static database of oil field, this well has 2 oil reservoirs, i.e. No. 1 oil reservoir and No. 2 oil reservoirs, and No. 1 reservoir permeability is 1000 * 10 ^-3μ m ², effective pay thickiness is 10m, corresponding degree of porosity is 30%; No. 2 reservoir permeability is 500 * 10 ^-3μ m ², effective pay thickiness is 5m, corresponding degree of porosity is 20%;

2. find the tired product information of this well from dynamic data base, tired produce oil is as 3.5 ten thousand tons of the tired produce oils of this well.

3. calculate the k of No. 1 oil reservoir _iH _iφ _iValue: 1000 * 10 * 0.3=3000;

4. calculate the k of No. 2 oil reservoirs _iH _iφ _iValue: 500 * 5 * 0.2=500;

5. calculate total k _iH _iφ _iValue: $\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{k}_i\·h_i\·{\mathrm{\φ}}_i=3500;$

That 6. calculates No. 1 oil reservoir splits the branch coefficient: $\frac{{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="HDA0000086116810000021.png,HDA0000086116810000041.png"\; state="\{\{state\}\}">k</figure-callout>}}_1\&CenterDot;{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000086116810000021.png,HDA0000086116810000041.png"\; state="\{\{state\}\}">h</figure-callout>}}_1\&CenterDot;{\mathrm{\&phi;}}_1}{\underset{i=1}{\overset{2}{\mathrm{\&Sigma;}}}{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="HDA0000086116810000021.png,HDA0000086116810000041.png"\; state="\{\{state\}\}">k</figure-callout>}}_1\&CenterDot;{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000086116810000021.png,HDA0000086116810000041.png"\; state="\{\{state\}\}">h</figure-callout>}}_1\&CenterDot;{\mathrm{\&phi;}}_1}=3000/3500;$

That 7. calculates No. 1 oil reservoir splits the branch coefficient: $\frac{k_2\&CenterDot;h_2\&CenterDot;{\mathrm{\&phi;}}_2}{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{k}_2\&CenterDot;h_2\&CenterDot;{\mathrm{\&phi;}}_2}=500/3500;$

8. the substratum that calculates No. 1 oil reservoir is split the oil mass of branch: ${\mathrm{<figure-callout\; id="1"\; label="N\; p"\; filenames="HDA0000086116810000021.png,HDA0000086116810000041.png"\; state="\{\{state\}\}">N</figure-callout>}}_p=\frac{{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="HDA0000086116810000021.png,HDA0000086116810000041.png"\; state="\{\{state\}\}">k</figure-callout>}}_1\&CenterDot;{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000086116810000021.png,HDA0000086116810000041.png"\; state="\{\{state\}\}">h</figure-callout>}}_1\&CenterDot;{\mathrm{\&phi;}}_1}{\underset{i=1}{\overset{2}{\mathrm{\&Sigma;}}}{k}_i\&CenterDot;h_i\&CenterDot;{\mathrm{\&phi;}}_i}\&times;N_p=3.5\&times;\frac{3000}{3500}=3$ Ten thousand tons;

9. the substratum that calculates No. 2 oil reservoirs is split the oil mass of branch:

$N_{p2}=\frac{k_2\&CenterDot;h_2\&CenterDot;{\mathrm{\&phi;}}_2}{\underset{i=1}{\overset{2}{\mathrm{\&Sigma;}}}{k}_i\&CenterDot;h_i\&CenterDot;{\mathrm{\&phi;}}_i}\&times;N_p=3.5\&times;\frac{500}{3500}=0.5$ Ten thousand tons.

(3), gravity sluicing assisted steam flooding well pattern is set according to the Fuel Oil Remaining that estimates in the step (2):

At buried depth 1000-2000 rice, in the massive super heavy oil reservoirs of core intersection 20-180 rice, be arranged to right stacked horizontal well (S1 up and down, S2), many mouthfuls of straight wells (Z1-Zn), wherein horizontal well (S1) is used for annotating vapour on the oil reservoir, and following horizontal well (S2) is used for assisting discharge opeing, at stacked horizontal well periphery many mouthfuls of straight wells that are used for producing is set;

(4) optimize notes carbonated drink horizontal well and produce the straight well well spacing, adopting distance is the well spacing of 30m-100m;

(5) optimize notes carbonated drink horizontal well and discharge opeing horizontal well fore-and-aft distance, adopting distance is the fore-and-aft distance of 5m-30m;

(6) last stacked notes carbonated drink horizontal well is designed, go up the horizontal section length 200-600m of stacked notes carbonated drink horizontal well, go up stacked notes carbonated drink horizontal well tiptoe and exceed heel end 3-5m;

(7) following stacked sluicing horizontal well is provided with and drilling well, following stacked sluicing horizontal well horizontal section length 220-620m slightly is longer than stacked notes carbonated drink horizontal well;

(8) the perforation position that produces straight well is provided with: straight well divides two sections perforations, the corresponding carbonated drink horizontal well of annotating of perforation epimere, the corresponding discharge opeing horizontal well of perforation hypomere, keep at a certain distance away between the last hypomere (generally 3-10m) is beneficial to straight well and handles up and can implement layer steam injection in the process;

(9) preheating before gravity sluicing auxiliary steam turns has dual mode, a kind of preheating of handling up, another kind of circulation preheating.Straight well, horizontal well completion mode are provided with, adopt prestressing force thermal recovery completion;

(10) the stacked horizontal well before gravity sluicing auxiliary steam turns carries out preheating, makes oil reservoir reach thermal communication.

(11) design annotating vapour well notes vapour amount, day fluence 300-600t/d (ton/sky), steam injection pressure is controlled in the 10MPa;

(12) producing well production fluid amount is designed, total lifting rate of producing well is 1.1-1.2 a times of notes vapour amount;

(13) carry out the production of gravity sluicing assisted steam flooding according to the well pattern that is provided with.

Develop gravity sluicing assisted steam flooding technology in the present invention and be the deep-layer heavy crude reservoir exploitation back of handling up and adopted the development mode of straight well and horizontal well combination, this technology and traditional steam flooding have obvious difference, notes carbonated drink horizontal well and sluicing horizontal well have been increased, stacked horizontal well is annotated vapour in the employing, the auxiliary discharge opeing of stacked horizontal well down, straight well produce oil development scheme on every side, break traditional well pattern patterns such as the common areal well pattern (as the inverted nine-spot pattern steam flooding) that adopts, row well pattern, ring-type well pattern in original development scheme conversion, form three-dimensional development.This technology is disposed horizontal well and is annotated vapour well and discharge well in the development late stage of handling up between the straight well well.After realizing that commentaries on classics is driven, by the self gravitation of the condensed water behind the Steam Heating oil reservoir and stacked horizontal well and the upward producing pressure differential between stacked horizontal well down, fully realize stacked horizontal well discharge opeing (crude oil between condensed water and horizontal well) down, improve the production-injection ratio of gravity sluicing assisted steam flooding well group, and then improve the shaft bottom steam quality, fully expand the vapour cavity volume, improve the steam swept volume, be fit to the deep-layer heavy crude reservoir exploitation.

Brief Description Of Drawings

Fig. 1 annotates vapour stage schematic diagram for steam soak;

Fig. 2 is a steam oil production stage schematic diagram;

Fig. 3 is the SAGD schematic diagram;

Fig. 4 is traditional steam flooding schematic diagram;

Fig. 5-1 is traditional steam flooding inverted nine-spot pattern and anti-seven spot pattern;

Fig. 5-2 is the anti-seven spot pattern of traditional steam flooding;

Fig. 6 is a gravity sluicing assisted steam flooding well pattern stereogram;

Fig. 7 is gravity sluicing assisted steam flooding section (along a Z2-Z7 well profile among Fig. 6);

Fig. 8 is a gravity sluicing assisted steam flooding mechanism schematic diagram (along Z2-Z7 well profile among Fig. 6).

The specific embodiment

The invention solves the super viscous crude of the deep layer exploitation contradiction that the later stage oil reservoir faces of handling up, the present invention proposes to adopt gravity sluicing assisted steam flooding to improve the technology of deep layer super-heavy oil deposit recovery ratio.

Improve in the deep layer super-heavy oil deposit recovery ratio method at gravity sluicing assisted steam flooding of the present invention, may further comprise the steps:

(1) oil reservoir of gravity sluicing assisted steam flooding will meet the following conditions: reservoir buried depth 1000-2000m, core intersection 20-180m, remaining oil saturation＞30%, degree of porosity＞18%, permeability＞200md, 50 ℃ of stock tank oil viscosity＞50000mPas, oil reservoir is every the interlayer agensis;

(2) handle up exploitation heavy crude reservoir through too much take turns handle up after, there is very big-difference before formation pressure, remaining oil distribution and the exploitation, carry out the viscous crude development late stage Study on residual oil distribution of handling up, can further to define remaining oil distribution characteristics and material base, provide the basis for improving the development scheme conversion effect.Remaining oil distribution research is at present mainly calculated and method for numerical simulation by reservoir engineering.The handle up formula of heating radius of viscous crude mainly contains 3 kinds of Marx-Langenheim method, willman method and Frouq.Ali methods etc., can select different computational methods according to the oil reservoir characteristics.Wherein, the Marx-Langenheim method is considered waste heat amount and the oil reservoir non-homogeneity that many rounds are handled up, and the supposition heating surface (area) (HS is that rule is circular in the calculating, and its design formulas is as follows:

$A=\frac{i_s{\mathrm{hh}}_m{M}_R{\mathrm{\&alpha;}}_s}{4{\mathrm{\&lambda;}}_s^2(T_s-T_i)}(e^{t_D}\&CenterDot;\mathrm{erfc}\sqrt{t_D}+2\sqrt{\frac{t_D}{\mathrm{\&pi;}}}-1)$

Wherein: $t_D=\frac{{4\mathrm{\&lambda;}}_s^2}{M_R^2\&CenterDot;h^2\&CenterDot;{\mathrm{\&alpha;}}_s^2}\&CenterDot;t$

The A-heating surface (area) (HS, m ²

i _s-steam charge velocity, Kg/h;

h _mThe enthalpy of-saturated vapour, Kcal/Kg;

The h-core intersection, m;

M _R-oil reservoir heat capacity, Kcal/ (m ³℃);

α _s-top bottom thermal diffusion coefficient, m ²/ h;

λ _s-top seat rock coefficient of thermal conductivity, Kcal/ (hm ℃);

T _s-vapor (steam) temperature, ℃;

T _i-prime stratum temperature, ℃;

t _D-non dimensional time;

Ercf-error compensation function;

The t-steam in jection time, h.

Owing to calculate resulting heating surface (area) (HS is that rule is circular, and the actual oil reservoir thermal treatment zone is irregularly shaped, therefore, introduces sweep efficiency E _A, obtain the maximum heating radius and be:

$r_h=\sqrt{A/(E_A\&CenterDot;\mathrm{\&pi;})}$

Wherein:

$E_A=0.01\&times;[-220.43-11.29\&times;\ln \frac{{\mathrm{\&mu;}}_{\mathrm{oi}}}{{\mathrm{\&mu;}}_{\mathrm{os}}}-0.85196\&times;(T_s-T_i)+90.167\&times;\ln (T_s-T_i)]$

μ _OiViscosity of crude under-the original reservoir temperature, mPas;

μ _OsViscosity of crude under the-vapor (steam) temperature, mPas.

But, adopt this kind method the inside parameter to determine to have certain difficulty, the stage of the handling up heating radius error that calculates is relatively large.

In the vertical, usually according to the individual well condition of production and oil reservoir physical characterization data, the oil mass of output is reverted to oil-producing formation, and this method is familiar with the contribution of each reservoir productivity and the output situation of crude oil, just obtains the reserves of remaining oil again according to the difference of the reserves of crude oil in every layer and the former oil mass of output.The process that the former oil mass of output is reduced to payzone is exactly a production split, and substratum production split model is $N_{\mathrm{pi}}=\frac{V_i}{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{V}_i}\&times;N_p$

N _Pi---substratum cumulative production, t

N _p---individual well stage cumulative production, t

V _i---substratum heating volume, m ³

N---penetrate out the number of plies.

When carrying out production split between different oil reservoirs, only consider the value of oil reservoir effective thickness and permeability usually, just the KH value is split separating method.Adopt calculating of heating radius formula and KH value to split branch and all have error, go to be forbidden as if parameter, far from each other with actual conditions.Therefore, be necessary to improve present remaining oil research technology method.

In the present invention, the degree of porosity factor is considered that in the middle of the production split, promptly output is split branch by kh φ, splits sub-model and is converted into:

$N_{\mathrm{pi}}=\frac{k_i\&CenterDot;h_i\&CenterDot;{\mathrm{\&phi;}}_i}{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{k}_i\&CenterDot;h_i\&CenterDot;{\mathrm{\&phi;}}_i}\&times;N_p$

N _Pi---substratum cumulative production, t;

N _p---individual well stage cumulative production, t;

k _i---reservoir permeability, * 10 ^-3Um ²

H---effective pay thickiness, m;

φ---oil reservoir degree of porosity, decimal;

N---penetrate out the number of plies.

(3) gravity sluicing assisted steam flooding well pattern design

In the design of gravity sluicing assisted steam flooding well pattern, adopt many to paired horizontal well setting.For clarity, as referring to shown in Fig. 6, Fig. 7 simplified schematic, the main well pattern combining form of gravity sluicing assisted steam flooding is to adopt 2 mouthfuls of water horizontal wells up and down, is stacked relation up and down, go up stacked horizontal well S1 and annotate vapour, following stacked horizontal well S2 and many mouthfuls of straight well Z1-Zn oil recoveries on every side.In Fig. 6,7, S1 is for annotating the carbonated drink horizontal well, and S2 is a gravity sluicing assisted steam flooding drainage sump; Z1-Zn is the producing well in the gravity sluicing assisted steam flooding.

In this well pattern, the distance between straight well and the straight well is at 60-200m, and stacked up and down horizontal well fore-and-aft distance is at 5-30m.

(4) in the heavy crude reservoir development late stage of handling up, great changes will take place for the underground remaining oil enrichment state of oil reservoir and the original reservoir, and oil saturation, reservoir temperature, reservoir pressure are more complicated.How effectively to employ the distance between distance, straight well and the straight well between remaining reserves and straight well and the horizontal well and annotate the vapour well and discharge well between distance dependent, whether the size of inter-well distance is directly connected to the displacement of steam in jection back plane effective.Because the viscosity of crude height, the big requirement of well spacing drives the energy height; Distance between stacked notes vapour well and the discharge well is big, below discharge well need the time long, can not guarantee bottom pressure; Distance is too small, and steam can cause the thermal efficiency to reduce directly from discharging the stacked discharge well down.Therefore, in this well pattern, the distance of the distance between straight well and the straight well, horizontal well and straight well, stacked horizontal well fore-and-aft distance are this technological core.Distance between straight well and the straight well directly has influence on the straight well distribution of residual oil in the process of handling up, and directly exerts an influence for the exploitation long-term stability of later stage gravity sluicing assisted steam flooding mode after changing.In the present invention, draw through test of many times, the general employing of the distance between straight well and the straight well is the twice of straight well and horizontal well distance.

(5) straight well and horizontal well inter-well distance directly influence be to change the key factor of driving success in the handle up formation of temperature between the warm-up phase well of rotation gravity sluicing assisted steam flooding;

(6) distance of notes vapour well S1 and following stacked sluicing horizontal well S2 directly has influence on the utilization rate of injecting hot water in the stacked horizontal well, distance is too small, the steam in jection heated perimeter is little, the hot water of temperature higher temperature or even steam can directly directly be discharged from following stacked horizontal well behind the vapor condensation, the heat utilization efficiency of steam in jection descends, fore-and-aft distance is excessive, steam in jection can not in time diffuse to form the vapour chamber, cause and build the pressure, do not have the effect that steam flooding replaces, therefore annotating the economic benefit that carbonated drink horizontal well S1 and sluicing horizontal well S2 fore-and-aft distance directly have influence on gravity sluicing assisted steam flooding well group, is the key that maximization of economic benefit ultimate aim be realized in the oil field can.

Particularly, technical scheme of the present invention adopts following steps:

(1) oil reservoir of selection gravity sluicing assisted steam flooding, oil reservoir will meet the following conditions: reservoir buried depth 1000-2000m, core intersection 20-180m, remaining oil saturation＞30%, degree of porosity＞18%, permeability＞200md, 50 ℃ of stock tank oil viscosity＞50000mPas, oil reservoir is every the interlayer agensis;

(2) arrangement dynamic data, clear and definite individual well accumulation produce oil, cumulative water production, exploitation knowledge of regularity;

(3) collect static data, different oil reservoir degree of porosity, permeability, effective pay thickiness are carried out the super viscous crude development late stage Study on residual oil distribution of handling up, further clear and definite remaining oil distribution characteristics and material base.Remaining oil distribution research is mainly calculated and method for numerical simulation by reservoir engineering.Wherein, the Marx-Langenheim method is considered waste heat amount and the oil reservoir non-homogeneity that many rounds are handled up, and the supposition heating surface (area) (HS is that rule is circular in the calculating, and its design formulas is as follows:

$A=\frac{i_s{\mathrm{hh}}_m{M}_R{\mathrm{\&alpha;}}_s}{4{\mathrm{\&lambda;}}_s^2(T_s-T_i)}(e^{t_D}\&CenterDot;\mathrm{erfc}\sqrt{t_D}+2\sqrt{\frac{t_D}{\mathrm{\&pi;}}}-1)$

Wherein: $t_D=\frac{{4\mathrm{\&lambda;}}_s^2}{M_R^2\&CenterDot;h^2\&CenterDot;{\mathrm{\&alpha;}}_s^2}\&CenterDot;t$

The A-heating surface (area) (HS, m ²

i _s-steam charge velocity, Kg/h;

h _mThe enthalpy of-saturated vapour, Kcal/Kg;

The h-core intersection, m;

M _R-oil reservoir heat capacity, Kcal/ (m ³℃);

α _s-top bottom thermal diffusion coefficient, m ²/ h;

λ _s-top seat rock coefficient of thermal conductivity, Kcal/ (hm ℃);

T _s-vapor (steam) temperature, ℃;

T _i-prime stratum temperature, ℃;

t _D-non dimensional time;

Ercf-error compensation function;

The t-steam in jection time, h.

Owing to calculate resulting heating surface (area) (HS is that rule is circular, and the actual oil reservoir thermal treatment zone is irregularly shaped, therefore, introduces sweep efficiency E _A, obtain the maximum heating radius and be:

$r_h=\sqrt{A/(E_A\&CenterDot;\mathrm{\&pi;})}$

Wherein:

$E_A=0.01\&times;[-220.43-11.29\&times;\ln \frac{{\mathrm{\&mu;}}_{\mathrm{oi}}}{{\mathrm{\&mu;}}_{\mathrm{os}}}-0.85196\&times;(T_s-T_i)+90.167\&times;\ln (T_s-T_i)]$

μ _OiViscosity of crude under-the original reservoir temperature, mPas;

μ _OsViscosity of crude under the-vapor (steam) temperature, mPas.

Can calculate the heating radius in the stage of handling up by above method.

In the vertical, adopt the production split method to carry out the description of remaining oil.At first carry out the calculating of single well controlled reserves according to known geological conditions.Dynamic according to individual well production then, rerum natura such as oil reservoir permeability, core intersection and record steam entry profile with reference to the scene and carry out production split:

Its substratum production split model is $N_{\mathrm{pi}}=\frac{V_i}{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{V}_i}\&times;N_p$

N _Pi---substratum cumulative production, t

N _p---individual well stage cumulative production, t

V _i---substratum heating volume, m ³

N---penetrate out the number of plies.

Method for numerical simulation is set up geological model of oil accumulation, and is realized the individual well history matching by the reservoir engineering computational methods according to the real brill data of actual oil well, revises oil deposit parameter, makes it to be consistent with oil reservoir is actual.On the basis of history matching, realize the quantification of Remaining Oil Distribution and oil saturation by software.

(4) carry out the design of gravity sluicing assisted steam flooding well pattern.Referring to Fig. 6, in the gravity sluicing assisted steam flooding well group many mouthfuls of straight wells are arranged, 2 mouthfuls of horizontal wells.2 mouthfuls of water horizontal wells are up and down over against stacked relation, at many mouthfuls of straight wells of equidistant section deploy of vertical water horizontal well; In 2 mouthfuls of stacked up and down water horizontal wells, go up stacked horizontal well and annotate vapour, following stacked horizontal well discharge opeing, many mouthfuls of straight well produce oils on every side.

(5) optimize notes carbonated drink horizontal well and produce the straight well well spacing.Annotate the carbonated drink horizontal well and directly have influence on the preheating time and the later development effect of changeing before driving, adopt certain oil field gas injection horizontal well and produce straight well well spacing optimization result, see Table 1 with the distance of producing straight well.

Certain block of table 1 is annotated the carbonated drink horizontal well and is produced straight well well spacing optimization result

From annotating the vapour well and producing straight well well spacing optimization result, along with the increase of well spacing, the preheating time of handling up is elongated, and well spacing increases to 100m from 30m, and increase to 3117 day from 923t the preheating time of handling up.Have a net increase of oily effect, gas oil ratio from well group oil production, well group, see on the stage recovery percent of reserves, when annotating carbonated drink horizontal well and straight well well spacing when being 50m, the well group oil production reaches 8.35 * 10 ⁴T, have a net increase of oil 6.91 * 10 ⁴T, gas oil ratio 0.193, stage recovery percent of reserves are the highest by 22.3%.

(6) be provided with and carry out site operation annotating the carbonated drink horizontal well, require horizontal section length 200-600m, the horizontal well tiptoe exceeds heel end 3-5m;

(7) the discharge opeing horizontal well is provided with net horizontal section length 220-620m, effectively shaft bottom steam quality in the safeguard level well steam injection process; At present stacked discharge opeing horizontal well outline is longer than stacked notes carbonated drink horizontal well together, can effectively improve horizontal well discharge opeing ability down; Down require track maintenance level in the stacked horizontal well drilling process, can reduce the breakthrough probability of hot water behind the vapor condensation; Stacked notes carbonated drink horizontal well 5-30m can give full play to the entrained heat content of steam on the distance, improves the heat energy utilization rate;

(8) straight well and horizontal well plan range are provided with: adopt apart from 30-100m, can effectively realize the preheating of handling up before the gravity sluicing assisted steam flooding, improve the crude oil flow ability;

(9) the perforation position that produces straight well is optimized.Adopt numerical simulation to contain well section and carry out the perforating effect contrast annotating aboveground side 1/3,2/3 of vapour and the aboveground side of whole notes vapour respectively, comparing result sees the following form 3.

The relation of certain block perforation position of table 3 and well group oil production

From top optimization result, when penetrating out bottom oil reservoir 2/3rds, gas oil ratio is the highest, and the stage recovery percent of reserves reaches 22.86%, and development effectiveness is better.

(10) design of notes carbonated drink horizontal well and discharge opeing horizontal well fore-and-aft distance

Under core intersection 60m condition, calculate the oil production under the different fore-and-aft distance conditions according to steam injection rate, notes steam gauge, see Table 2.

The relation of certain block fore-and-aft distance of table 2 and well group oil production

From the optimization result of fore-and-aft distance as can be seen, when fore-and-aft distance was 20m, the well group recovery percent of reserves was up to 22.5%, and gas oil ratio reaches 0.19, therefore, selected 20m as the best fore-and-aft distance of annotating carbonated drink horizontal well and discharge opeing horizontal well.

(11) straight well, horizontal well completion are provided with, require all wells to carry out prestressing force thermal recovery completion;

Can the preheating before (12) gravity sluicing assisted steam flooding mode is changed be the key that realize displacement, adopts the circulation preheating or the preheating of handling up usually.Be preheated to and realize the oil reservoir thermal communication.Not preheating, the viscosity of crude height, mobile poor, vapour drives weak effect.Therefore, before gravity sluicing assisted steam flooding, need to guarantee anaphase effect to carrying out the preheating viscosity reduction around the pit shaft;

(13) be provided with annotating carbonated drink horizontal well notes vapour amount, annotate vapour well day fluence 300-600t/d, produce straight well lifting rate 30-80t/d, horizontal well lifting rate 80-240t/d.The well head steam injection pressure is controlled at about 10MPa when annotating vapour.

Embodiment 1

This well group reservoir buried depth-1390～-1410m, average effective pay thickiness 56.9m, inner Restraining barrier, average pore 24.5%, mean permeability 1463md, 50 ℃ of ground viscosity of crude 194000mPas are a thick-layer massive super heavy oil reservoirs.

At first, develop effect assessment at this piece, clear and definite remaining oil distribution characteristics and potentiality to be exploited adopt the remaining oil of kh φ to split separating method.Split the branch result and show, oil saturation is more than 65% between the straight well well, and the average oil saturation of oil reservoir is more than 47%.

On this basis, according to the oil field geologic parameter, carry out coarse screening.This oil reservoir meets the following conditions: reservoir buried depth 1000-2000m, core intersection 20-180m, remaining oil saturation＞40%, degree of porosity＞18%, permeability＞200md, degassed crude viscosity＞50000mPas under the formation condition meets the screening criteria of gravity sluicing assisted steam flooding.

By reservoir engineering design, calculate annotate the carbonated drink horizontal well with produce straight well apart from 50m, produce the well spacing 100m between the straight well, annotate vapour well and stacked horizontal well fore-and-aft distance 20m down.

Gravity sluicing assisted steam flooding can improve recovery ratio 22.6%, and the oil reservoir ultimate recovery can reach 49%, improves recovery ratio 19% on earth than steam soak.

Embodiment 2

This well group reservoir buried depth-1370～-1690m, average effective pay thickiness 72m, average pore 23.2%, mean permeability 1760md, 50 ℃ of ground viscosity of crude 78960mPas are a thick-layer massive super heavy oil reservoirs.

Carry out remaining oil distribution research at this piece, production split is the result show, change drive before remaining oil saturation more than 0.58 between well.

According to oil field geologic feature and exploitation present situation, carry out coarse screening.This oil reservoir meets the following conditions: reservoir buried depth 1000-2000m, core intersection 20-180m, remaining oil saturation＞30%, degree of porosity＞18%, permeability＞200md, degassed crude viscosity＞50000mPas under the formation condition.

Reservoir engineering design annotate the carbonated drink horizontal well with produce straight well apart from 35m, produce the well spacing 70m between the straight well, annotate vapour well and stacked horizontal well fore-and-aft distance 18m down.This piece gravity sluicing assisted steam flooding can improve recovery ratio about 23%, and the oil reservoir ultimate recovery can reach 53%.

As above-mentioned, the clear method that has described the present invention's proposition in detail, and the technique effect of application technical scheme of the present invention.But this area those skilled in the art are appreciated that under the situation of the spirit and scope of the present invention that do not deviate from the claims definition, can make multiple modification in form and details.

Claims (5)

1. a gravity sluicing assisted steam flooding improves deep layer super-heavy oil deposit recovery ratio method, and it may further comprise the steps:

(1) oil reservoir of selection gravity sluicing assisted steam flooding: the oil reservoir of gravity sluicing assisted steam flooding will meet the following conditions: reservoir buried depth 1000-2000 rice, core intersection 20-180 rice, remaining oil saturation＞30%, degree of porosity＞18%, permeability＞200md (millidarcy), 50 ℃ of stock tank oil viscosity＞50000mPas (milli handkerchief second, viscosity unit), oil reservoir is every the interlayer agensis;

(2) estimation Fuel Oil Remaining: at first, in the vertical,, revert to oil-producing formation, calculate the output of each reservoir productivity and crude oil by oil mass with output according to oil well production situation and oil reservoir physical characterization data; Secondly, according to the difference of the former oil mass of output in the reserves of crude oil in every layer and every layer, obtain the reserves of remaining oil; According to following substratum production split model, the former oil mass of output is reduced to payzone:

$N_{\mathrm{pi}}=\frac{k_i\&CenterDot;h_i\&CenterDot;{\mathrm{\&phi;}}_i}{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{k}_i\&CenterDot;h_i\&CenterDot;{\mathrm{\&phi;}}_i}\&times;N_p$

N _Pi---substratum cumulative production, t; (ton)

N _p---individual well stage cumulative production, t; (ton)

k _i---reservoir permeability, * 10 ^-3μ m ²(square micron)

H---effective pay thickiness, m; (rice)

φ---oil reservoir degree of porosity, decimal; (this value is the ratio of voids volume and rock volume)

N---penetrate out the number of plies;

(3), gravity sluicing assisted steam flooding well pattern is set according to the Fuel Oil Remaining that estimates in the step (2):

At buried depth 1000-2000 rice, in the massive super heavy oil reservoirs of core intersection 20-180 rice, be arranged to right stacked horizontal well (S1 up and down, S2), many mouthfuls of straight wells (Z1-Zn), wherein horizontal well (S1) is used for annotating vapour on the oil reservoir, and following horizontal well (S2) is used for assisting discharge opeing, at stacked horizontal well periphery many mouthfuls of straight wells that are used for producing is set;

(4) optimize notes carbonated drink horizontal well and produce the straight well well spacing, adopting distance is the well spacing of 30m-100m;

(5) optimize notes carbonated drink horizontal well and discharge opeing horizontal well fore-and-aft distance, adopting distance is the fore-and-aft distance of 5m-30m;

(6) stacked notes carbonated drink horizontal well is designed, and carry out site operation, require horizontal section length 200-600m (rice), the horizontal well tiptoe exceeds heel end 3-5m (rice);

(7) following stacked sluicing horizontal well is provided with and drilling well, horizontal section length 220-620m (rice) slightly is longer than stacked notes carbonated drink horizontal well;

(8) the perforation position that produces straight well is provided with: perforation is set at the 1/3 or 2/3 height section of annotating carbonated drink horizontal well top oil layer section, perforation position and horizontal well are in same interval, the corresponding carbonated drink horizontal well of annotating of first perforation, second perforation is corresponding to the discharge opeing horizontal well, the first perforation position and the second perforation location interval certain distance; Reserve not perforated zone in the relatively poor part of oil layer section permeability, in the process of handling up, can implement layer steam injection;

(9) straight well, horizontal well completion mode are provided with, adopt prestressing force thermal recovery completion;

(10) before gravity sluicing auxiliary steam turns, carry out preheating, make oil reservoir reach thermal communication.

(11) design annotating vapour well notes vapour amount, day fluence 300-600t/d (ton/sky), steam injection pressure is controlled in the 10MPa;

(12) the producing well liquid measure is designed, the lifting rate of producing well is 1.1-1.2 a times of notes vapour amount.

(13) carry out the production of gravity sluicing assisted steam flooding according to the well pattern that is provided with.

2. improve deep layer super-heavy oil deposit recovery ratio method according to the sluicing of gravity described in the claim 1 assisted steam flooding, wherein the distance between straight well and the straight well is at 70-210m, and stacked up and down horizontal well fore-and-aft distance is at 5-30m.

3. improve deep layer super-heavy oil deposit recovery ratio method according to the sluicing of gravity described in the claim 2 assisted steam flooding, wherein the distance between straight well and the straight well is at 60-200m.

4. improve deep layer super-heavy oil deposit recovery ratio method according to the sluicing of gravity described in the claim 1 assisted steam flooding, estimate the Fuel Oil Remaining of a certain concrete oil reservoir therein:

1. find vertical oil reservoir physical parameter of certain mouthful of well from the static database of oil field, this well has 2 oil reservoirs, i.e. No. 1 oil reservoir and No. 2 oil reservoirs, and No. 1 reservoir permeability is 1000 * 10 ^-3μ m ², effective pay thickiness is 10m, corresponding degree of porosity is 30%; No. 2 reservoir permeability is 500 * 10 ^-3μ m ², effective pay thickiness is 5m, corresponding degree of porosity is 20%;

2. find the tired product information of this well from dynamic data base, promptly tired oil production is as 3.5 ten thousand tons of the tired produce oils of this well.

3. calculate the k of No. 1 oil reservoir _iH _iφ _iValue: 1000 * 10 * 0.3=3000;

4. calculate the k of No. 2 oil reservoirs _iH _iφ _iValue: 500 * 5 * 0.2=500;

5. calculate total k _iH _iφ _iValue: $\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{k}_i\&CenterDot;h_i\&CenterDot;{\mathrm{\&phi;}}_i=3500;$

That 6. calculates No. 1 oil reservoir splits the branch coefficient: $\frac{k_1\&CenterDot;h_1\&CenterDot;{\mathrm{\&phi;}}_1}{\underset{i=1}{\overset{2}{\mathrm{\&Sigma;}}}{k}_1\&CenterDot;h_1\&CenterDot;{\mathrm{\&phi;}}_1}=3000/3500;$

That 7. calculates No. 1 oil reservoir splits the branch coefficient: $\frac{k_2\&CenterDot;h_2\&CenterDot;{\mathrm{\&phi;}}_2}{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{k}_2\&CenterDot;h_2\&CenterDot;{\mathrm{\&phi;}}_2}=500/3500;$

8. the substratum that calculates No. 1 oil reservoir is split the oil mass of branch: $N_{p1}=\frac{k_1\&CenterDot;h_1\&CenterDot;{\mathrm{\&phi;}}_1}{\underset{i=1}{\overset{2}{\mathrm{\&Sigma;}}}{k}_i\&CenterDot;h_i\&CenterDot;{\mathrm{\&phi;}}_i}\&times;N_p=3.5\&times;\frac{3000}{3500}=3$ Ten thousand tons;

8. the substratum that calculates No. 2 oil reservoirs is split the oil mass of branch:

$N_{p2}=\frac{k_2\&CenterDot;h_2\&CenterDot;{\mathrm{\&phi;}}_2}{\underset{i=1}{\overset{2}{\mathrm{\&Sigma;}}}{k}_i\&CenterDot;h_i\&CenterDot;{\mathrm{\&phi;}}_i}\&times;N_p=3.5\&times;\frac{500}{3500}=0.5$ Ten thousand tons.

5. improve deep layer super-heavy oil deposit recovery ratio method according to the sluicing of gravity described in the claim 1 assisted steam flooding, the preheating before wherein gravity sluicing auxiliary steam turns has dual mode, a kind of preheating of handling up, another kind of circulation preheating.

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