CN1043766A - Strengthen the method for potassium hydroxide treatment well with nitrogen - Google Patents

Abstract

Making method to the clay stabilization of the subsurface formations of water sensitive is that inert gas (preferably nitrogen) with q.s injects the stratum, so that contain the basic upper reaches of the clay bodyization of transportable particulate, thus it is removed from the stratum.After this, the soft water solution that will contain potassium chloride injects the stratum, so that the sodium in potassium and the expandable clay carries out cation exchange, to reduce its expansion.Soft water solution with potassium hydroxide injects the stratum then.Potassium hydroxide makes clay more insensitive to the aqueous solution with the ion composition that is different from the connate water in the stratum.Can not suffer damage when like this, this method makes the stratum run into water than connate water " lighter ".This method can be handled well and inject well or producing well.

Description

Strengthen the method for potassium hydroxide treatment well with nitrogen

The present invention relates to improve the method that sodium hydrate aqueous solution is stablized argillic horizon with nitrogen.

The sandstone formation that contains particulate can suffer damage when its contained particulate contacts with the aqueous solution that contains the ion composition that is different from connate water.This can make permeability reduction, thereby the fluid flow by injecting well and producing well is reduced.This phenomenon gradually becomes particularly general in the stratum of fresh water at salt solution.Described " carefully " grain is not limited to clay, but comprise all expansions in the sandstone pores body with the particulate that may flow.The example of this particulate has the silica (SiO of clay mineral, high surface area ₂) sand thing, feldspar, mica and barite.

The mode of the salt water intrusion sandstone formation of " lighter " can be diversified.For example, the intrusion of the oil recovery process of the intrusion in following aquifer, enhancing, be used to handle the intrusion or the like of the fluid of nearly well phenomenon.This intrusion can cause two kinds of different clay infringements.First kind to be expandable clay (montmorillenite that for example has the crack interbed) expanding when lighter salt solution contacts with it, thereby make permeability reduction, and the flow of the fluid by the there is reduced.Second kind is that freshet makes transportable clay (getting bad kaolinite and illite clay particle as gluing) break away from sandstone formation when sandstone formation, and these clay particles are captured between the crack on stratum in the venturi slit, thereby reduced permeability, the Fluid Volume there of flowing through is reduced.The infringement of these two kinds of infiltrations is caused on lighter salt water intrusion clay-containing sandstone stratum.

In order to overcome this problem, United States Patent (USP) the 3rd, 640 has been introduced a kind of method No. 343, and this method is to inject to contain SiO ₂The aqueous solution of alkali silicate so that this stratum is stable, particularly inject in drilling well or when producing fluid.United States Patent (USP) the 4th, 536 has been introduced the stable method of particulate that makes in the stratum by nitrogenous cation full fluorine compound is contacted with particulate No. 304.This processing can be carried out with acidization.Technically adopt organic polycationic polymer to prevent to reduce expanded clay or the particulate of migration or the illeffects of the composition of the two in the subsurface formations in addition.Can be referring to United States Patent (USP) 4,366,071; 4,366,072; 4,366,073; 4,366,074; 4,374,739; 4,460,483 and 4,462, No. 718.

United States Patent (USP) the 4th, 534, introduced a kind of method that increases the flow of water in the well for No. 413, this method be inject liquid state or gas nitrogen and (or) liquid carbon dioxide, and alternately make well supercharging and decompression, so that the stratum between the borehole wall and the water source is subjected to the effect and the generation fracture of high pressure, thereby the discharge that enters in the well is increased.

United States Patent (USP) the 4th, 280, introduced for No. 560 with potassium hydroxide and made the stable method of sandstone formation that contains the particulate of water sensitive, this potassium hydroxide and particulate interact to prevent owing to the intrusion of the water with the ion composition that the is different from connate water permeability on stratum being suffered damage basically.Potassium hydroxide can not flow particulate.

Method to the injection well that is subjected to the infringement of transportable particulate or producing well are handled is at first under pressure nitrogen to be injected the stratum, and nitrogen is sprung up in well back and forth to remove loosening particulate.This step handles and can repeat, and number of repetition is decided on the character and the injured degree thereof on handled stratum.After, well is carried out bailing, to remove all external particles.The potassium chloride that then will be solubilized in the soft water injects well, and makes it soak time enough, so that the sodium in potassium and the reservoir rock carries out cation exchange.After this, inject potassium hydroxide, and with its displacement to the oil reservoir that is subjected to the particulate adverse effect, make it soak time enough, form and chemical property with the silicate that changes clay, make it insensitive to fresh water.

Be subjected to responsive clay infringement, more particularly, be subjected to the producing well of transportable particulate infringement and inject well and handle with method of the present invention.This well contains transportable particulate, and these particulates are to break away from this stratum during through sandstone formation and be trapped in the slit of venturi between the crack on stratum at freshet, thereby the permeability on stratum is suffered damage.These particles not only comprise clay, also comprise the silica (S of clay mineral, high surface area _iO ₂) mineral, feldspar, mica and barite; These particles are easily owing to the change of the ionic nature of interstitial water or connate water is expanded.

At first nitrogen or similar inert gas are injected the stratum during processing.The pressure that is adopted during injecting gas will be enough to make gas can flow back in the stratum away from well.After this, reduce pressure rapidly, this gas is pushed back in the well inwards, at this moment gas is being carried transportable particulate secretly.This operation can repeat, and number of repetition is decided according to the injured degree of well.Time interval length between same gas boosting and the explosive decompression also depends on the radial distance of injured degree and well, oil reservoir to be processed.After this, well is carried out bailing, pumping or anti-circulation to remove the particle that the gas that springs up is taken out of.

Use the soft water solution-treated well of potassium chloride (KCl) then, the KCl solution of soft water and generation is preferably not silica containing.The sodium in potassium and the clay make KCl contact the enough time with sandstone formation, so that can carry out cation exchange.Be about 4～64 hours time of contact that is enough to carry out cation exchange, is preferably about 8～32 hours.The KCl injection rate should be about 100～10,000 pound/porosity foot, preferably is about 500～5,000 pound/porosity foot.The definition of " pound/porosity foot " is that the dry weight of product (being KCl) or 100% effective weight are divided by total porosity foot.The definition of porosity foot is porosity or the mean porosities that the line degree of depth of well multiply by reservoir rock.Therefore, 1 porosity foot, 10 feet vertical depths that can equal rock multiply by 10% porosity.Water in order to dissolving KCl does not contain bivalent cation, and the amount that contained E contains the salt of monovalent cation should be less than about 1000ppm, most preferably less than about 100ppm.This water is referred to as " soft water " here.The KCl aqueous solution that injects capacity also is in order to want displacement or to water down any bivalent cation, away from stratum to be processed.For a typical well, this consumption is about 100～10,000 pound/porosity foot KCl(dry weight), preferably be about 500～5000 pounds/porosity foot KCl(dry weight).The concentration of KCl can be 2%(weight in the aqueous solution) about, until reaching saturation point, preferably be about 3～5%(weight), but under any circumstance all should be above the concentration of connate water.

After this, potassium hydroxide (KOH) solution is injected into well.Have 100～100 approximately, 000(is preferably 500～50, about 000, is preferably about 10,000) potassium hydroxide of pound/porosity foot injects the stratum.Potassium hydroxide is soluble in water, does not preferably contain bivalent cation in the water, and the amount that is more preferably the salt that contains monovalent cation contained in the water will be less than about 1000ppm.In addition, this aqueous solution does not preferably contain silica.The concentration of potassium hydroxide aqueous solution is preferably 1～50%(weight) about or reach the saturation point of potassium hydroxide in water.This concentration should be in 2～45%(weight) about scope in, preferably be about 15～30%(weight).

When injecting potassium hydroxide it is radially penetrated and enter reservoir rock, the degree of depth that enters is at least about 25 feet, is preferably about 50 feet; But this radial distance depends on the undermined degree on stratum.

Importantly, the operation of potassium hydroxide aqueous solution being injected the stratum Once you begin must be carried out continuously.Concerning general well, charge velocity should be about 2～20 barrels per hours, preferably is about 5～10 barrels per hours.But charge velocity depend on the thickness on stratum to be processed.For example, if the thickness on handled stratum is 50 feet, charge velocity is about 10～100 barrels per hours so.If but formation thickness is about 10 feet, charge velocity is about 2～10 barrels per hours so.As previously mentioned, Once you begin inject potassium hydroxide, had better not interrupt.If stop to inject, connate water just may reflux and be diffused in the handled stratum, mixes with potassium hydroxide solution, makes bivalent cation and potassium hydroxide generate undesirable precipitation.

Inject a kind of displacing fluid that reinjects behind the potassium hydroxide,, make it enter stratum to be processed so that the potassium hydroxide displacement is gone out.This displacing fluid can adopt the KCl aqueous solution or weak inorganic acid (for example 7.5%(weight) HCl solution), preferably used water should not contain bivalent cation, and the amount that is more preferably its contained salt that contains monovalent cation will be less than about 1000ppm.Nitrogen or carbon dioxide or similar inert gas also can be used as the displacement fluid, and they are applicable to carries out preliminary treatment to prevent the injured producing well of clay.

When the potassium hydroxide displacement is gone out well and enters the stratum, all surfaces to the clay sensitivity on stratum are all contacted with potassium hydroxide.After this, closing well, and make particulate contact about 4～64 hours with potassium hydroxide, and be more preferably contact 8～32 hours, preferably contact about 16 hours.The silicate that has time enough to make potassium hydroxide energy " for good and all " change clay is formed and chemical property, makes it insensitive to fresh water.After handling like this, this clay all is insensitive to fresh water in for a long time.

After this, this well recovers normal to be used, and for example, if producing well just can be produced, just can again water be injected into well if inject well.When the such fluid of oil or water during by the stratum, well has improved their permeability.

Embodiment 1

Present embodiment is that the thickness to a stratum is about 20 feet, the porosity on stratum and is about 23% injured injection well and handles.Nitrogen with 5000 standard cubic foots (SCF) during processing injects the stratum, and the pressure that is adopted during injection is enough to make nitrogen to flow out well and enters the stratum, is deep into well radially, 25 feet places of distance.Removal is applied to aboveground pressure, so nitrogen regurgitates again in the well, has brought transportable particulate simultaneously.Well is carried out bailing to remove the particle in the well.Then the KCl aqueous solution is injected, well is handled, this KCl aqueous solution is water-soluble and get by 12,500 pounds of KCl, and the amount of the contained salt that contains monovalent cation is about 1000ppm in the water.The concentration of KCl in water is about 3.5%(weight).The charge velocity of potassium chloride is about 40 barrels per hours (BPH).Closing well 20 hours, the interior sodium cation of particulate that potassium cationic is contacted with KCl solution carries out ion-exchange.After this, with about 48 hours time about 340 barrels of (BBLS) potassium hydroxide aqueous solutions are injected the stratum continuously.The concentration of potassium hydroxide in water is about 30%(weight).Then, the soft water injection well with about 1000BBLS goes out potassium hydroxide with displacement, makes it enter the stratum.Closing well is 20 hours then.After this recover the use of well.Compare with the well before handling, well has improved the permeability of current, and the charge velocity of water has also improved.

Embodiment 2

Present embodiment is that the thickness to a stratum is about 60 feet, porosity and is about 17% injured producing well and handles.During processing under the pressure of about 2000PSi with 10, the nitrogen of 000SCF injects the stratum.After this, removal is applied to aboveground pressure, and nitrogen is regurgitated in the well.Well is carried out pumping with the sliding particle that removes in the well.Inject the KCl aqueous solution then well is handled, this KCl water solution system is dissolved in water by 30,000 pounds of KCl and gets, and contains the salt that contains monovalent cation of the 80ppm that has an appointment in the water in order to dissolving KCl, and this concentration than salt in the connate water is much lower.The concentration of KCl in water is about 5%(weight).The charge velocity of KCl is about 100BPH.Closing well 24 hours makes potassium cationic carry out ion-exchange with the sodium cation in the particulate that KCl solution is contacted.After this, with time of 48 hours will about 600BBLS potassium hydroxide aqueous solution inject the stratum continuously.The concentration of potassium hydroxide in water is about 15%(weight).Then, with about 10, the CO of 000SCF ₂Inject into well, go out potassium hydroxide, make it enter the stratum with displacement.Closing well 72 hours.Recover then to use.At this moment well has improved the permeability of oil stream and current.Total fluid-withdrawal rate of well is less than 25BPD before handling, and increases to 200BPD after handling.The average product of well is the 185BPD fluid after one month.

Embodiment 3

A bite sharply descends from producing well output behind water breakthrough of the oil-bearing stratum flooding produce oil of clay sensitivity, from original 260BOPD(produce oil every day barrelage) reduce to below the 50BOPD.The thickness on this oil recovery point stratum is 16 feet, and porosity is 14%.At 3200PSig(pound/inch ², gauge pressure) surface pressing down handle this well with the nitrogen of 4000SCF so that near the clay particle fluidisation of well, and be transported at least in 25 feet of wells (preferably 50 feet beyond) stratum far away.Speed with 25BPH is pumped into 300 barrels of potassium chloride solutions that contain water body (Slng) in the well, this potassium chloride solution system is dissolved in through in the demineralized water of filtration and get by 6000 pound of 100% effective KCl, the content of monovalent cation is less than 1000PPm then immediately with the speed of the 6BPH 15%(weight with 300 barrels in this water) potassium hydroxide aqueous solution is pumped in the stratum, the used water of this solution is the demineralized water through filtering, not bivalent cation of calcic, magnesium and so on and silica in the water, the amount of its contained monovalent cation is below 1000PPm.With 150 barrels of lease oils KOH is gone out near the regional displacement the well then, and closing well 36 hours.This well is resumed production by the productive rate before handling, and owing to the expansion and the displacement effect of the nitrogen that injected in the past recovers oily overflush.After reclaiming the movable KCl and the KOH aqueous solution, output can increase, and increases 50BPD weekly.Sustained yield reaches 150BFPD, is 3 times of the injured well yield before handling.

Embodiment 4

Generation well in flatly will oil reservoir water filling, that be in the clay sensitivity is carried out preliminary treatment, suffer damage when the water breakthrough to prevent it.

The thickness on the stratum of this well is that 18 feet, porosity are 14% to be to inject the nitrogen of 5000SCF to its method of handling, and the pressure that is adopted during injection will be enough to make nitrogen to flow out and enter the stratum from well, is deep into 50 feet places of radial distance of well.

Handle this well with the KCl aqueous solution then, this solution system is dissolved in the soft water of process filtration by 10,000 pounds of KCl and gets, and the amount of the salt of the monovalent cation that this water is contained is below 1000ppm.The concentration of the KCl aqueous solution is 2.5%(weight), and allow this solution flow in the well by the speed of hydrostatic head with 10BPH.Closing well 16 hours is so that potassium cationic can carry out ion-exchange with the sodium cation of clay in the oil reservoir district that is contacted.After this, containing soft water and 15%(weight with 48 hours time with 200 barrels) aqueous solution of potassium hydroxide injects the stratum continuously.Then about 500 barrels of softened water pumps are sent in the well, so that KOH solution is gone out near the regional displacement the well.Closing well is after 16 hours once again, and suction lures stream.

This well is produced one long period by the productive rate that is similar to before processing, and is 220BPD at during this period maximum dry oil feeling ability. Because water filling and water breakthrough, the water of generation increases. It is stable that oil productivity still keeps. Do not compare with the pretreated oil well of potassium hydroxide with neighbouring, its oil productivity is much higher. And most of oil reclaims behind water breakthrough from treated oil well. Compare near the water-oil factor of untreated oil well or the control well water-oil factor of the oil of the specified rate that reclaims behind the water breakthrough is lower than with other producing well.

Claims (14)

1, near a kind of stable method in subterranean sandstone stratum that is penetrated by the well of well of well that makes, circulate in described well and subterranean sandstone stratum, inflatable and transportable particulate is contained on the stratum, when this particulate when having liquid, aqueous contact that the ion that is different from connate water forms, be easy to make the stratum to suffer damage, make permeability reduction, this method may further comprise the steps successively:

What a. inject effective dose under pressure is inert gasses basically, makes it enter the stratum from well again through well, and the pressure that is adopted during injection will be enough to take away the transportable particulate that is present near the stratum of well;

B. reduce the injection pressure of gas, near the stratum of gas well of carrying transportable particulate secretly flow back in the well;

Transportable particulate is deposited in well;

D. from well, remove transportable particulate;

E. inject first kind of aqueous solution, make it flow out again and enter near the well stratum through well, be deep into the about 25 feet places of average radial distance of well, this aqueous solution contains soft water, the potassium chloride of about 100～10,000 pound/porosity foot in the soft water;

F. closing well, the length of its time be enough to make first kind in the aqueous solution potassium ion and the sodium ion in the expandable particulate near the stratum the well carry out cation exchange, the expandable particulate of this cation exchange since with contain the aqueous solution that the ion that is different from connate water forms and contact the expansion minimizing that causes;

G. inject second kind of aqueous solution water body (Slug) continuously, make it flow out and enter the stratum through well, its speed will be enough to prevent that connate water from flowing back near the well the stratum, and the described aqueous solution contains soft water, have an appointment in the soft water potassium hydroxide of 100～100,000 pound/porosity foot;

H. with a kind of displacing fluid second kind of aqueous solution displacement arrived away from outside the well, the average radial distance of this place and well is greater than about 25 feet at least, to contact in the well near zone and this extra-regional inflatable particulate and the outer transportable particulate of well near zone;

I. the transportable particulate that closing well, the length of its time will be enough to make in the well near zone and this extra-regional expandable particulate and well near zone are outer is later can to suffer damage the stratum owing to liquid, aqueous contact the with the ion composition that is different from connate water again;

J. make well recover operate as normal.

2, the process of claim 1 wherein step I, in closed-in time be about 4～64 hours.

3, the process of claim 1 wherein step f, in closed-in time be about 4～64 hours.

4, the process of claim 1 wherein that first kind of potassium chloride solution is substantially free of silica.

5, the process of claim 1 wherein that first kind of aqueous solution is substantially free of bivalent cation, but contain the non-potassium chloride salt that contains monovalent cation of about 1000ppm.

6, the process of claim 1 wherein that the concentration of potassium chloride in first kind of aqueous solution is from about 2%(weight) to the saturation point of potassium chloride soft water.

7, the process of claim 1 wherein step e, in have the potassium chloride of 500～5000 pounds/porosity foot to be injected into the stratum approximately.

8, the process of claim 1 wherein that the displacement fluid is soft water, oil, carbon dioxide, nitrogen or weak inorganic acid.

9, the process of claim 1 wherein that the concentration of potassium hydroxide is about 15～30%(weight in second kind of aqueous solution).

10, the method for claim 8, wherein well is a producing well, displacing fluid is a crude oil.

11, the process of claim 1 wherein it is that inert gasses is a nitrogen basically.

12, near a kind of stable method in subterranean sandstone stratum that is penetrated by the well of well of well that makes, circulate in described well and subterranean sandstone stratum, inflatable and transportable particulate is contained on the stratum, when this particulate when having liquid, aqueous contact that the ion that is different from connate water forms, be easy to make the stratum to suffer damage, make permeability reduction, this method may further comprise the steps successively:

What a. inject effective dose under pressure is inert gasses basically, makes it enter the stratum from well again through well, and the pressure that is adopted during injection will be enough to take away the transportable particulate that is present near the stratum of well;

B. inject first kind of aqueous solution, make it flow out and enter near the well stratum through well, be deep into the about 25 feet places of average radial distance of well, this aqueous solution contains soft water, the potassium chloride of about 100～10,000 pound/porosity foot in the soft water.

C. closing well, the length of its time to be enough to make first kind in the aqueous solution potassium ion and the sodium ion in the expandable particulate near the stratum the well carry out cation exchange, this cation exchange make expandable particulate since with contain the aqueous solution that the ion that is different from connate water forms and contact the expansion minimizing that causes;

D. inject second kind of aqueous solution water body continuously, make it flow out and enter the stratum through well, its speed will be enough to prevent that connate water from flowing back near the well the stratum, and the described aqueous solution contains soft water, have an appointment in the soft water potassium hydroxide of 100～100,000 pound/porosity foot;

E. with a kind of displacing fluid second kind of aqueous solution displacement arrived away from the well part, the average radial distance of this place and well is greater than about 25 feet at least, to contact in the well near zone and this extra-regional inflatable particulate and the outer transportable particulate of well near zone;

F. closing well, the length of its time will be enough to make in the well near zone and extra-regional expandable particulate and the outer transportable particulate of well near zone can suffer damage the stratum owing to liquid, aqueous contact the with the ion composition that is different from connate water later on;

G. make well recover operate as normal.

13, the method for claim 12, wherein inert gas is a nitrogen, the nitrogen of the 5000SCF that has an appointment is injected into well.

14, the method for claim 12, step f wherein, in closed-in time be about 4～64 hours.