CN1234472A - Steam chemical incoming-outcoming method for extracting superthick oil - Google Patents

Abstract

The steam chemical handling method for production of viscous crude comprises three technological processes of injection, well-covering and producing oil. It is characterized by that said injection process includes stages of preheating, preflush slug, lead steam section, emulsifier slug and post-treatment steam hollow injection, in which the preflush and emulsifier are carried by high-temp. steam, and simutaneusly passed through production well and fed into stratum, and then the well is covered and closed for above two days, then the production of crude can be made. Said invention possesses the following advantages of improving temp. distribution in oil reservoir, reducing heat loss, strengthening production period and raising yield of crude.

Description

A kind of steam chemistry of exploiting super viscous crude method of handling up

The present invention is a kind of method of commercial scale crude oil extraction, particularly a kind of steam soak and surfactant flooding the combine method of the super viscous crude of exploitation, i.e. steam chemistry method of handling up utilized.

On the oilfield exploitation history, the natural energy that utilizes oil reservoir self to be had, as solution gas, pneumatic jack etc. are called as primary oil recovery with the method on crude oil extraction ground; The method of strata pressure is kept in utilization, to oil-bearing stratum flooding, and the gas injection makeup energy, the method with crude oil extraction ground is called secondary oil recovery; After secondary oil recovery, by inject the method that unconventional material carries out crude oil extraction to oil reservoir, be called tertiary oil recovery, also be called and improve recovery ratio or intensified oil reduction (Enhanced Oil Recovery), be called for short the EOR technology.

At present, the tertiary oil recovery technology of having used mainly can be divided into three major types: 1, heat is driven

(1). steam-assisted recovery comprises steam soak and steam flooding;

(2). combustion in situ (inject air, make the oil reservoir burning).2, gas drive

(1) .CO ₂The MULTI CONTACT mixed phase drives or non-phase-mixing driving;

(2). lighter hydrocarbons drive;

(3). nitrogen or flue gas flooding.3, chemical flooding

(1). polymer flooding;

(2). surfactant flooding;

(3). alkali drives;

(4). (by above three kinds of methods, polymer, surfactant, alkali drive and combine combination flooding

Binary or three-component compound system flooding method);

(5). foam flooding.

Viscous crude, particularly super viscous crude, it has the density height and (approaches 1000Kg/m ³), the viscosity height is (in the time of 50 ℃, several ten thousand to hundreds thousand of Mpa.S), initial boiling point height (at 150-350 ℃ category), freezing point height (more than 30 ℃), characteristics such as colloid and asphalt content height, conventional once or the secondary oil recovery method, oil extraction can't be come out, must use the intensified oil reduction method, for example adopt the way of steam in jection or combustion in situ, reduce the viscosity of viscous crude, increase its flowability, Here it is, and heat is driven, and these two methods all make reservoir temperature raise, improved the flowability of viscous crude, deep fat is by gas and hot water injection, and gas and hot water have also produced certain barometric gradient, makes deep fat arrive producing well.But, the viscosity temperature of viscous crude is responsive especially, for example, the super viscous crude of Du of LiaoNing, China-84 block, its viscous flow activation energy is up to the 100kj/mol (see figure 1), so in the exploitation of viscous crude or special viscous crude, in order to guarantee the flowability of viscous crude, pit shaft also must be kept certain temperature, adopts electrical heating usually, and this makes the cost of thermal recovery improve once more undoubtedly, at present, the oily variable cost of ton of every mouthful of well is up to 400-500 unit (RMB), and this certainly will make the super viscous crude of exploitation infeasible economically behind crude oil price and international joint.

The steam injection oil recovery by heating is widely used in China and external each viscous crude field, in China, still is in the phase I of thermal recovery, the steam soak stage.Though steam soak aspect theoretical or the mining site application facet all accumulated a large amount of experiences.Nineteen fifty-nine Marx and Langeheim just set up and have proposed the equation of heat balance of steam soak and provided separating of equation, can obtain the heating tape area according to equation, Temperature Distribution in the oil reservoir, the heat waste of oil reservoir etc., Boberg in 1966 and Lantz have delivered the article (J.P.T.Dec.1966) of steam soak well potential calculating aspect again, the cyclic steam stimulation of domestic and international a large amount of viscous crude makes steam soak become a mature technique for many years.But steam soak is after several cycles, and strata pressure descends, and the cycle water recovery rate is low, and near the water saturation the shaft bottom increases, and drainage period prolongs with the increase of the round of handling up, and oil production descends.Therefore, the dependence cycle handles up that to increase ultimate recovery be limited.Abroad, all be in time to change steam flooding over to.And domestic because the recovery ratio of steam soak is not high, make steam flooding be difficult to realize.

Though steam soak is a more successful technology for general thickened oil recovery, but when being applied to the exploitation of special viscous crude, recovery percent further reduces, the big step of economic benefit glides, and this is objectively determining the further renewal and perfect of thermal recovery technology.

The purpose of this invention is to provide a kind of novel production practice at super viscous crude, it can overcome existing shortcoming in the prior art, improves the tar productivity for super viscous crude, reduces cost of winning.

The object of the present invention is achieved like this: it is made up of injection, stewing well, three sequences of recovering the oil, it is characterized in that injecting sequence was made up of the empty notes stage of preheating section, prepad fluid slug, leading steam section, emulsifier slug and post processing steam, prepad fluid and emulsifier carry by high-temperature vapor and enter the stratum through producing well simultaneously in prepad fluid slug and the emulsifier slug, stewing afterwards more than well 2-3 days, exploit again.

Prepad fluid and surfactant carry by steam and enter the stratum, two independently pipelines are set near well head, be steam injection pipeline and notes solvent (prepad fluid and emulsifier) pipeline, the prepad fluid slug is that prepad fluid and steam are together injected into well, preliminary treatment is carried out on the stratum, prevented clay swell, improve steam expansion rate and expanding surface, reduce steam injection pressure, thereby improve the emulsifying effectiveness in surfactant stage.The main effect of leading steam section is that the cold oil band is further heated, for necessary condition is created in next step emulsification.The emulsifier slug is the three phases that injects, and in this stage emulsifier is injected into well in company with steam, and its main purpose is to reduce the interfacial tension of profit, so that form stable ^O/ ^WEmulsion, the concentration of emulsifier must be an amount of, so that satisfy the consumption reaction needs in the oil reservoir, it is mobility control agent as steam that another of surfactant mainly acts on, and the viscosity of steam is increased.Because the stratum is with the increase of the round of handling up, the near wellbore zone oil saturation reduces gradually, can reduce or without emulsifier, so that this technology of more economical use, so adopt the empty notes stage of post processing steam, it can advance the emulsifier of front, the position that also can indicate emulsifier to advance simultaneously.

The vapor (steam) temperature of using in the above-mentioned oil production method is as between 300-400 ℃.

In common steam soak process, energy-balance equation can be expressed as:

The increase of injecting energy-spouting energy+inner produce power=interior energy wherein, the inner energy that produces is qdxdydzdt.Q is the thermal source of micro unit inside, owing to do not have thermal source in the micro unit, so q=0.But, in the steam chemistry is handled up, used emulsifier, when injecting, emulsifier is carried by steam, its temperature and vapor (steam) temperature equate, in oil reservoir, formed the emulsion of oil-in-water type rapidly, the diameter of oil droplet is greatly about 0.5-4 μ m, so the theory of hot water bank's heating surface (area) (HS and Marx and Langeheim has tangible difference, in the theory of Marx and Langeheim, the area of only considering hot water bank's external surface gets final product, but, in the steam chemistry is handled up, increased inner surface, and the area of inner surface is far longer than external surface.We are example with 1 kilogram of crude oil, and the density of supposing crude oil is 1000Kg/m ³, volume is a cube, so, its surface area is 0.06m ²If oil droplet is that average diameter is the sphere of 2 μ m, their surface area will be increased to 3000m so ², surface area has increased by 50000 times! As seen in Marx and the Langeheim theory, the consideration of heating tape area is not fitted into present steam chemistry fully handle up.Because the variation of heating tape area also causes a series of variations such as mother oil displacement speed.

In steam chemistry of the present invention is handled up process, because initial crude oil emulsification is the oil droplet of about 0.5～4 μ m of diameter, in emulsification system, the macroscopic thermodynamics function, in other words the correct thermodynamic characteristics of description system, should use the surface thermodynamics function, at this moment, the interior of system can be

U=u ^b+ u ^σWherein, u ^bBe the interior mutually energy of body, u ^σIt is the interior mutually energy in surface, energy equation during steam soak, when setting up, there is no need to consider this problem, but in the steam chemistry was handled up, this problem was extremely important, and system is when emulsification, by the example above us, surface area has increased by 50000 times, reaches 3000 square metres, is 50 * 10 by the interface tension force of water oil ^-3J/m ³Calculate, concerning 1kg crude oil, can 150J in increasing, to mother oil displacement, what this numerical value will be big is surprising, and this means that also except that latent heat, the surface can be another hot source of bank savings.So in the steam chemistry was handled up, internal energy was

n _γDAdt here, γ is the surface tension of oil-water interfaces, in other words the surface can, when temperature and pressure was constant, it was a constant, n is the number of emulsion droplet in the micro unit, A is a surface area, the total surface of system can be $U^{\mathrm{\σ}}=N\∫\∫\mathrm{\γdAdt}=\mathrm{n\γ}\underset{0}{\overset{1}{\∫}}\mathrm{Adt}$ Transmit and the surperficial energy that can produce owing to hot, make increasing to of the interior energy of micro unit $\frac{\∂}{\∂t}\[\mathrm{\φ}({\mathrm{\ρ}}_o{V}_o{H}_o+{\mathrm{\ρ}}_w{V}_w{H}_w+{\mathrm{\ρ}}_s{V}_s{H}_{\mathrm{sr}})+\mathrm{n\γA}+(1-\mathrm{\φ}){\left(\mathrm{\ρC}\right)}_{R}T)\]$ So, energy-balance equation is (K T)- (ρ _oV _oH _o+ ρ _wV _wH _w+ ρ _sV _sH _s)+ (n γ A)= $\frac{\∂}{\∂t}\[\mathrm{\φ}({\mathrm{\ρ}}_o{V}_o{H}_o+{\mathrm{\ρ}}_w{V}_w{H}_w+{\mathrm{\ρ}}_s{V}_s{H}_s)+\mathrm{n\γA}+(1-\mathrm{\φ}){\left(\mathrm{\ρC}\right)}_{R}T\]$

In the formula, K, formation thermal conductivity, KJ/md ℃

ρ _o, ρ _w, ρ _s, the density of oil, water, steam.

v _o, v _w, v _s, the volume flow rate of oil, water, steam, Kg/m ³

H _o, H _w, H _s, the heat content of oil, water, steam.

(ρ c) _R, the thermal capacitance of formation rock, kj/m ³℃.

φ, the oil reservoir degree of porosity.

T, temperature, ℃.

T, time, d (day).

From the derivation of above energy-balance equation as can be seen, the energy-balance equation of it and steam soak has had very big difference, so the invention has the advantages that as can be seen, it makes, and the heating tape area increases greatly in the oil reservoir, it is different with steam soak, stewing well only forms the O/W emulsion band and the cold oil band of heat when finishing, the temperature of emulsion band approaches steam in jection or hot water bank's temperature, the temperature that forms the deep fat band during than steam soak is much higher, Temperature Distribution in the layer is improved greatly, and heat waste significantly reduces.

Another advantage of the present invention is, the viscosity of the O/W emulsion of crude oil is significantly less than the pyrogen oil viscosity again, and wellhead temperature is higher, and the back pit shaft that drives a well needn't electrical heat tracing, and discharge opeing is normal, even when temperature was low to moderate 50 ℃, the load of oil pumper was still very normal.Because the increase of heating tape area, the temperature of emulsion is higher, the surface of emulsion droplet has the surfactant of trace again, although trace is very little, can significantly not change the physical property of fluid, can eliminate interior circulation, resistance is significantly increased, sharply reduce rate of heat transfer, the viscosity of adding emulsion is very low again, so the production cycle prolongs greatly.

In steam soak, owing to the viscosity of steam is very low, it is easy to cause steamchanneling, or the Gravity Separation of steam and cohesion water takes place, and causes that steam is to the super shoe in top of oil horizon.In the steam chemistry was handled up, emulsifier and steam injected simultaneously, and the density of steam and viscosity are increased, and this has been avoided channelling and super carrying out to a great extent.Simultaneously, steam has carried emulsifier liquid, can make heat-transfer fluid on the wall of cold oil band, form liquid film, under low wall surface temperature, form moisture film, constitute inner and outer boundary, like this, the film coefficient of heat transfer of vapour-liquid mist flow is improved a lot than gas, reach as high as 30 times, this also is one of advantage of the present invention.

Below in conjunction with embodiment and accompanying drawing thereof invention is described in further detail.

Fig. 1 is the crude oil viscosity-temperature curve of three mouthfuls of wells of Chinese Liaohe Oil Field Du's-84 blocks.

Fig. 2 is steam chemistry of the present invention the handle up contrast of each creation data of method of method and original steam of handling up.

Fig. 3 is steam chemistry of the present invention the handle up contrast of output of method of method and original steam of handling up.

The present invention has made large-scale field test at Liaohe Oil Field Du's-84 blocks that LiaoNing, China is economized, and has chosen altogether 13 mouthfuls of producing wells and has done test. This block is monoclinal structure, and structural high is positioned at Du84-33-54Jing near the 84-37-44 well of shutting out, and being inclined to east southeast by northwest (NW) does not have, structure is mild, and form is simple, stratigraphic dip 2.5-30, shut out-84 Xinglongtai oil reservoir lithology take glutenite as main, and the medium coarse sand rock takes second place, and the rock forming mineral composition is mainly quartz and feldspar, cementation type is the hole formula, contact, cement are shale, average shale content 15.8%, clay mineral is with montmorillonite, and illite is main. That high hole, height ooze reservoir. The reservoir properties data see the following form.

Table 1

Block	Maximum diameter of hole um	Average pore size um	Hole is divided	Maximum throat radius um	The average porosity	The pore structure type	Venturi is divided
								Du 84	288.3	100.9	Macropore	12.7	8.520	The thin larynx of macropore	Thin larynx

The viscosity of crude of Du's-84 blocks is large, and responsive especially to temperature, Fig. 1 is the temperature-viscosity curve of three mouthfuls of wells. Its viscosity-temperature dependency can approximate expression be $\mathrm{Ln\η}=-25+\frac{99\mathrm{kJ}}{\mathrm{RT}}$ In the formula, T is absolute temperature, (is viscosity.

Selected 13 mouthfuls of wells are positioned at the different series of strata of Du-84 block Xinglongtai oil reservoir, have different characteristics, and 2 mouthfuls of High Efficiency Wells are wherein arranged,, there are 2 mouthfuls to belong to the hyposmosis well, other wells belong to stripper well basically, therefore, have certain representativeness.

Embodiment one: the 58-58 well, and this is that a bite poor efficiency vapour is scurried well, has carried out the three-wheel steam soak, reservoir depth exists

678-718.3 rice is positioned at prosperous platform I and II group, 29.6 meters of core intersections.Adopt the steam chemistry of the present invention method of handling up, begin to annotate vapour, stopped November 29 then from November 24th, 1998.Annotate vapour total amount 1927m ³, steam quality 76%, 332 ℃ of vapor (steam) temperatures, pumpage 15m ³/ h, pressure are 13.6MPa.Steam injection process injects 50m at first opening steam injection pipeline in well ³Steam carries out preheating, opens the injectant pipeline then, is injecting 100m ³Carrying prepad fluid in the time of steam together injects, this process is the prepad fluid slug, prepad fluid adopts two octadecyl methyl ammonium chlorides or octadecyl 3 ammonio methacrylates or the cetyl 3 methyl ammonium bromides of cationic surfactant, its concentration about 4/1000ths, close the notes solvent line then, in well, squeeze into about 520m ³Steam is leading steam section, open the notes solvent line begins to inject emulsifier simultaneously with steam thereupon, it is the emulsifier slug, emulsifier by neopelex and op-10 or adopt lauryl sodium sulfate and OP-12 or employing neopelex and NP10-15 formulated, the ratio of weight is 2: 1 during preparation, the concentration of emulsifier is about 3/1000ths, and concurrently injected quantity of steam is 1677m ³, the about 100m of the empty steam injection section steam in jection of post processing ³Vexed well 17 days, on December 16th, 1998 drove a well, end of day epicycle time production March 10 in 1999.The condition of production contrast that the steam chemistry of the steam soak in three cycles of 58-58 well and one-period is handled up sees the following form.

Table 2.58-58 well condition of production statistics

Round	Layer position	Cyclic steam injection volume m 3	Cycle production fluid amount m 3	Cycle oil production m 3	Cycle aquifer yield m 3	Gas oil ratio	Water recovery rate
								?1	I and II	?1174	?1503	?926	?577	?0.79	????0.49
?2	?1912	?1739	?1424	?315	?0.74	????0.17
							?3	?1482		?1227	?454	?773	?0.31	????0.52
?4	?1927	?3510	?2388	?1122	?1.24	????0.58

First three cycle is a steam soak, and the 4th cycle is that the steam chemistry is handled up, and can obviously find out, the steam chemistry is handled up and is better than steam soak, and its oil-gas ratio is up to 1.24.

Embodiment 2.

The 57-53 well, this is the more serious middle effect well that shakes out flatly, has carried out the steam soak production in three cycles.Reservoir depth 702.2-749.2m is positioned at emerging II and emerging V layer, and core intersection 22.1m, steam chemistry handled up since on July 2nd, 1998, annotates vapour 1700m ³, 4.5 days times spent, steam quality 74-76%, temperature 328-334 ℃.Pumpage 15m ³/ h, pressure 12.7-15.6MPa.Inject sequence and consumption substantially with embodiment 1, stewing well 3 days, on July 12nd, 1998 opening well and making production, the same day lifting rate 102m ³, end of day production in October 19 then, the accumulative total condition of production that the steam chemistry of the steam soak in three cycles and one-period is handled up sees the following form.

Table 3.57-53 well condition of production statistics

Round	Layer position	Cyclic steam injection volume m 3	Cycle production fluid amount m 3	Cycle oil production m 3	Cycle aquifer yield m 3	Gas oil ratio	Water recovery rate
								????1	II and IV	????1197	????1464	?1102	????362	????0.92	????0.31
????2	????1478	????1585	?959	????529	????0.65	????0.43
							????3	????1622		????1644	?1112	????536	????0.68	????0.33
????4	????1700	????4557	?2564	????1993	????1.51	????1.17

Before this mouthful well the oil-gas ratio of three-wheel still can, but owing to shake out seriously, back production water is very low, after changing the steam chemistry into and handling up, oil-gas ratio is up to 1.51, water recovery rate reaches 1.17.

Embodiment 3.

Flat-11 wells, this is the water horizontal well, belongs to the pre-stage test active well, has carried out the steam soak production in two cycles.Oil reservoir is positioned at emerging VI layer at underground 944-1164.85m, and core intersection 193.85m, on November 5th, the 1998 beginning steam chemistry test of handling up was annotated vapour 11.4 days, notes vapour amount 2021m ³, steam quality 74%, 324 ℃ of temperature, pumpage 7.5m ³/ h, pressure 12.3MPa.Inject sequence and boiled in a covered pot over a slow fire wells 7 days with embodiment 1. substantially, November 30 drove a well, discharge opeing on same day 82m ³, end of day production in February 25 in 1999, the accumulative total that the steam chemistry of the steam soak in two cycles and one-period is handled up is produced statistics and is seen the following form.

Flat-11 well conditions of production statistics of table 4.

Round	Layer position	Cyclic steam injection volume m 3	Cycle production fluid amount m 3	Cycle oil production m 3	Cycle aquifer yield m 3	Gas oil ratio	Water recovery rate
								?1	Ⅲ	?4000	?1952	?1099	????428	?0.274	????0.11
?2	?3544	?2336	?1198	????1139	?0.338	????0.32
							?3	?2021		?2451.3	?1382.7	????1068.6	?0.564	????0.53

The condition of production to 13 mouthfuls of wells, we also add up, the result is shown in Fig. 2-3, among the figure, steam soak (on average) is represented the average of these 13 mouthfuls of wells steam soak production in the past, steam soak (the highest) represent these 13 mouthfuls of well steam soak productions in the past in the peak chosen, these two figure clearly reflect the superiority that the steam chemistry is handled up.

Claims (6)

1, a kind of steam chemistry of exploiting super viscous crude method of handling up, it is the steam chemistry method of handling up, it is made up of injection, stewing well, three sequences of recovering the oil, it is characterized in that injecting sequence was made up of the empty notes stage of preheating, prepad fluid slug, leading steam section, emulsifier slug and post processing steam, prepad fluid in prepad fluid slug and the emulsifier slug and emulsifier carry by high-temperature vapor and enter the stratum through producing well simultaneously, boil in a covered pot over a slow fire well afterwards more than two days, and then exploit.

2, oil production method according to claim 1 is characterized in that so-called high-temperature water vapor is to be produced by the steam producer, and its temperature is between 300-400 ℃.

3, oil production method according to claim 1 is characterized in that so-called prepad fluid and emulsifier, is in environment temperature before injection, is heated when being carried by high-temperature vapor after pump is defeated.

4, oil production method according to claim 1 is characterized in that high-temperature vapor and prepad fluid inject the stratum through producing well simultaneously.

5, oil production method according to claim 1 is characterized in that emulsifier is carried by high-temperature vapor simultaneously to enter the stratum through producing well.

6, according to claim 4 and 5 described oil production methods, it is characterized in that so-calledly injecting simultaneously, be meant steam injection pipeline to be set and to annotate solvent (prepad fluid and emulsifier) pipeline to have that twin pipeline is two to be blocked and bleeder near well head.

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