CA1048768A - Acidization process - Google Patents
Acidization processInfo
- Publication number
- CA1048768A CA1048768A CA75221843A CA221843A CA1048768A CA 1048768 A CA1048768 A CA 1048768A CA 75221843 A CA75221843 A CA 75221843A CA 221843 A CA221843 A CA 221843A CA 1048768 A CA1048768 A CA 1048768A
- Authority
- CA
- Canada
- Prior art keywords
- acid
- solvent
- water
- miscible
- slurry
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/60—Compositions for stimulating production by acting on the underground formation
- C09K8/62—Compositions for forming crevices or fractures
- C09K8/72—Eroding chemicals, e.g. acids
Abstract
ABSTRACT OF THE DISCLOSURE
A process is provided whereby a subterranean formation may be treated uniformly with acid at a controlled rate to a considerable distance from an injection point. The process includes the introduction of acid absorbed on colloidal silica which usually takes the form of a free flowing apparently dry powder. This powder is slurried in a solvent, such as a light hydro-carbon fraction, to form a composition which, on contact with water in the reservoir, will liberate acid. The process allows the acid to penetrate some distance into the formation before the acid is liberated, thus having an effect similar to retarded acid and effecting a large radius around the well bore.
A process is provided whereby a subterranean formation may be treated uniformly with acid at a controlled rate to a considerable distance from an injection point. The process includes the introduction of acid absorbed on colloidal silica which usually takes the form of a free flowing apparently dry powder. This powder is slurried in a solvent, such as a light hydro-carbon fraction, to form a composition which, on contact with water in the reservoir, will liberate acid. The process allows the acid to penetrate some distance into the formation before the acid is liberated, thus having an effect similar to retarded acid and effecting a large radius around the well bore.
Description
10~768 BACKGROUND OF l`HE INVENIION
Field o~ the Invention The invention relates to the treatment of subter-ranean formations in order to increase productivity or injectivity of such formations by an improved acidizing technique.
Description of the Prior Art Many petroleum-containing reservoirs are composed of limestone, dolomite or sandstone of low permeability.
Although limestone and dolomite formations may bontain large quantities of petroleum materials their permeabil-ities are generally quite low so that the oil production rates from them may be uneconomic because of resistance of the formations to fluid flow. Areas in the formation a substantial distance from the producing wells penetra-ting the formation may not be drained at all. A common method that has been used in an effort to stimulate pro-duction from such formations has been acidization. Thatis, acid is generally pumped down the well and displaced into the formation to dissolve a part of the formation and create channels of increased permeability thereby increasing fluid conductivity in the formation. Lime-stone or dolomite formations are generally best treated with hydrochloric acid or a similar acid and ~andstone formations are treated with a mixture of hydrochloric and hydrofluoric acid. It is often necessary to pump the acid into the formation at a rate that will fracture the formatisn thus conducting it rapidly therein to avoid expending the acid in the area near the well bore. If th~
_ 1 -104~761~
acid is expended only around the well hore it will have no beneficial effect in increasing transmissibility of fluid present a substantial distance fr~ the well bore.
However, the presence of fractures extending from the well into the surrounding formations does not nec-essarily greatly increase the amount of acid that reaches substantial distances from the well bore before being spent by reaction with the formation. The high temperature of most subterranean formations and the extremely rapid reaction of the mineral acids which are used causes most of the acid to be neutralized by reac-tion with the calcareous formation before it can traverse a great distance into the formation from the well bore.
One prior art method that has been used in an effort to acn'dize fractures more effectively has been to protect the faces of the fraetures by eoating them with a mater-ial such as a gel that will be slowly destroyed by the aeid as it is displaeed into the fraeture. However, these eoatings are only partially effeetive beeause the eoating cnthat portion of the fraeture closest to the well is the first to be contacted with acid and destroyed.
Acid subsequently displaced into the fracture passes and eontaets the exposed surfaee of the formation close to the well and is largely spent so that insufficient acid reaches the outer parts of the fraeture. Similarly, sometimes fluid-loss redueing additives such as fine silica flcur are added to control leak-off but the aeid ean quiekly sweep the siliea away and reaets rapidly 1041~768 with the thus exposed calcareous surface channels near the borehole so that much of the acid is again lost be-fore reaching the outer limits of the fracture.
The difficulties in acidizing fractures at substan-tial distances from the well are aggravated in hot car-bonate formations because the acid treatment methods heretofore available have resulted in little more than borehole enlargement at the high rate of reaction at the elevated temperature existing in such formations. The elevated temperature existing in hot carbonate reservoirs also aggravates the problem of inhibiting hydrochloric acid to prevent excessive corrosion by the acid of the casing and tubing in a well. Efforts have been made to pump large volumes of water ahead of -the acid to cool the tubing and fracture faces. However, this proced~re is not totally dependable and it is generally not desir~
able to pump large quantities of water into productive formations and especially not into gas reservoirs. U.S.
Patent 3,707,192 attempts to solve this problem by a multiple stage injection procedure whereby two substances are pumped into the formation sequentially; the second reactlng with the first to form an acid capable of reacting with at least a portion of the formation. This method, however, requires two reactants to mix within the fracture to produce the acid. Such a process would be wasteful and a high efficiency of mixing would be unexpected in porous media. More importantly, the cited reactions would be expected to be very rapid and thus spent very quickly as in most other prior art processes.
1~8768 The invention is a method for acidizing a subterranean for-mation comprising:
contacting the subterranean formation with a slurry compri-sing a solvent and a mixture of colloidal silica which is a fumed silica of surface area from about 50 to 400 meters2/gram and which has a particle size ranging from about 7 to 15 millimicrons and a liquid acid wherein said mix-ture resembles a free flowing dry powder.
The colloidal silica and the acid are mixed into a free flowing powder which is then slurried in a solvent such as a light hydrocar-bon. This slurry is then injected into the formation to be acidized. On contact with water in the reservoir acid will be liberated. The invention is also the free flowing powder mixture of colloidal silica and liquid acid.
The process of the invention is usually carried out by injec-ting the acid composition of the invention into a well penetrating and in communication with a subterranean reservoir so that the acid contacts the reservoir rock matrix. The reservoir usually contains petroleum or oil, but may contain other fluids such as water or a mixture of water and oil.
The composition of the process of the invention consists of three principal ingredients: colloidal silica, acid and solvents.
The colloidal silica useful in the invention is different ; from precipitated silica or silica gel. The colloidal silica useful in the invention is a fumed silica which is made up of chain-like formations sin-tered together. These chains are branched and have enormous external surface areas of from about 50 to about 400 meters2/gram. Although the exact mechan-- ism is not B _4_ .
Known~ Applicant believes that the acid adsorbs onto the silica particles and the resultant mixture resembles a powder. However, when an aqueous fluid contacts the acid-colloidal silica mixture the acid is liberated from the colloidal silica particles.
Colloidal silicas are readily available from manufacturers. One source is the Cabot Corporation of Boston, Massachusetts under the trade mark CAB-O~SII, Colloidal silica is also available from other commerc~al sources and the reference to one source is not intended to limit the seope of my invention.
The eolloidal siliea aeeeptable for use in the method of thi,s inventicnshould have a partiele size ranging from about 7 to 15 millimierons (mu). In this size range the eolloidal siliea will pass through even reservoirs with very small pore size. For example, a reservoir having very low permeability of say 0.016 milli-dareies (md) has a eorrespondingly small pore size of 25 to 100 mu. Thus, the eolloidal siliea suitable for use in the proeess ~ this invention will pass through even the smallest pores eneountered in hydroearbon reservoirs .
Colloidal siliea suitabe for the proeess of th s invention is deseribed in the literature. For example, U.S. Patent 3,993,809 deseribes the eolloidal siliea of the invention and a method for its manufaeture.
There are other methods for its manufaeture whieh produee eolloidal siliea as deseribed hePein.
Aeids useful in this invention are genera~lly those whieh will attaek reservoir matrix. Those ~048q68 skilled in the art of petroleum recovery will readily chose the acid or mixtures of acids most suitable for a particular reservoir rock. Examples of suitable acids include but are not limited to mineral acids such as hydrochloric, hydrofluoric, sulfuric, phosphoric, nitric, and organic acids such as formic, acetic, etc., and oxalic, malonic, succinic, etc. Mixtures of the above acids may also be used as well.
Solvents are useful in the process of this invention, both for providing a medium in which to slurry the collo-idal silica-acid powder and as a preflush fluid to be introduced ahead of the colloidal silica-acid-solvent slurry in the reservoir.
The solvent chosen to slurry the colloidal silica-acid powder may be of several broad types including sol-vents miscible with both water and oil, solvents miscible with oil but immiscible with water, and solvents miscible with water but not with oil. The choice of the solvent type will help dictate the character of acid treatment resulting. Once the connate water in the reservoir contacts the colloidal silica acid powder, the acid will be liberated and reaction with the reservoir rock matrix will begin. If the slurry solvent is of the type miscible with both water and oil or the type miscible with both water and oil or the type miscible with water and immiscible with oil connate water will ~uickly penetrate the slurry, release the acid and allow the acid to attack the rock matrix soon after the acid enters the formation. Thus, the acidizing effect will be near the well bore. If the slurry solvent is immiscible with water the ~04876~
connate water will have more difficulty penetrating to the acid powder allowing it to travel farther from the well bore before it is released. 'I'hus, the acidizing effect will be over a greater radius from the well bore. This has a similar effect to a retarded acid. In another embodiment of this invention this control of acid action on the formation may be supplemented by use of a preflush solvent in addition to a slurry solv~nt The preflush fluid solvent may be of the same broad types as the slurry solvent although in a given acidiz-ation process the type of preflush solvent may be the same as or different from the type of slurry solvent.
If a preflush solvent is used which is miscible with both water and oil or miscible with water and immi-scible with oil, the connate water will be pushed efficiently away from the well bore and, therefore, the acid slurry which follows will be able to penetrate far from the well bore before connate water liberates the acid resulting in acidization over a large radius from the well bore. Use of a preflush solvent immiscible with water would leave much connate water near the well bore and allow a more rapid connate water attack on the acid slurry resulting in acidization concentrated nearer the well bore.
Typical solvents miscible with water and oil and ~uitable for use to form the acid slurry or the preflush include but are not limited to acetone, higher alcohols, ethylene and polyethylene glyco]s, and glycerol.
104~76~
Typical solvents miscible with oil and immiscible with water and suitable for use to form the acid slurry or the preflush include but are not limited to LPG and other hydrocarbon fractions, base crude, aldehydes and ketones.
A typical solvent miscible with water and immiscible with oil includes but is not ~imited to methoanol.
The terms miscible and immiscible as used herein are not meant to be absolute but only to indicate a ten-dency. Thus, miscible may means completely miscible in all proportions to partial miscibi~ity. Immiscible may be little or no misciblity to slightly miscible. Whether a particular solvent is miscible or immiscible with a given oil must be determined in an individual case due to the infinite variety of reservoir oils.
Preparation of An Acid-Colloidal Silica Powder To a Waring Blender add:
(1) 180 gm Cab-0-Sil~
Field o~ the Invention The invention relates to the treatment of subter-ranean formations in order to increase productivity or injectivity of such formations by an improved acidizing technique.
Description of the Prior Art Many petroleum-containing reservoirs are composed of limestone, dolomite or sandstone of low permeability.
Although limestone and dolomite formations may bontain large quantities of petroleum materials their permeabil-ities are generally quite low so that the oil production rates from them may be uneconomic because of resistance of the formations to fluid flow. Areas in the formation a substantial distance from the producing wells penetra-ting the formation may not be drained at all. A common method that has been used in an effort to stimulate pro-duction from such formations has been acidization. Thatis, acid is generally pumped down the well and displaced into the formation to dissolve a part of the formation and create channels of increased permeability thereby increasing fluid conductivity in the formation. Lime-stone or dolomite formations are generally best treated with hydrochloric acid or a similar acid and ~andstone formations are treated with a mixture of hydrochloric and hydrofluoric acid. It is often necessary to pump the acid into the formation at a rate that will fracture the formatisn thus conducting it rapidly therein to avoid expending the acid in the area near the well bore. If th~
_ 1 -104~761~
acid is expended only around the well hore it will have no beneficial effect in increasing transmissibility of fluid present a substantial distance fr~ the well bore.
However, the presence of fractures extending from the well into the surrounding formations does not nec-essarily greatly increase the amount of acid that reaches substantial distances from the well bore before being spent by reaction with the formation. The high temperature of most subterranean formations and the extremely rapid reaction of the mineral acids which are used causes most of the acid to be neutralized by reac-tion with the calcareous formation before it can traverse a great distance into the formation from the well bore.
One prior art method that has been used in an effort to acn'dize fractures more effectively has been to protect the faces of the fraetures by eoating them with a mater-ial such as a gel that will be slowly destroyed by the aeid as it is displaeed into the fraeture. However, these eoatings are only partially effeetive beeause the eoating cnthat portion of the fraeture closest to the well is the first to be contacted with acid and destroyed.
Acid subsequently displaced into the fracture passes and eontaets the exposed surfaee of the formation close to the well and is largely spent so that insufficient acid reaches the outer parts of the fraeture. Similarly, sometimes fluid-loss redueing additives such as fine silica flcur are added to control leak-off but the aeid ean quiekly sweep the siliea away and reaets rapidly 1041~768 with the thus exposed calcareous surface channels near the borehole so that much of the acid is again lost be-fore reaching the outer limits of the fracture.
The difficulties in acidizing fractures at substan-tial distances from the well are aggravated in hot car-bonate formations because the acid treatment methods heretofore available have resulted in little more than borehole enlargement at the high rate of reaction at the elevated temperature existing in such formations. The elevated temperature existing in hot carbonate reservoirs also aggravates the problem of inhibiting hydrochloric acid to prevent excessive corrosion by the acid of the casing and tubing in a well. Efforts have been made to pump large volumes of water ahead of -the acid to cool the tubing and fracture faces. However, this proced~re is not totally dependable and it is generally not desir~
able to pump large quantities of water into productive formations and especially not into gas reservoirs. U.S.
Patent 3,707,192 attempts to solve this problem by a multiple stage injection procedure whereby two substances are pumped into the formation sequentially; the second reactlng with the first to form an acid capable of reacting with at least a portion of the formation. This method, however, requires two reactants to mix within the fracture to produce the acid. Such a process would be wasteful and a high efficiency of mixing would be unexpected in porous media. More importantly, the cited reactions would be expected to be very rapid and thus spent very quickly as in most other prior art processes.
1~8768 The invention is a method for acidizing a subterranean for-mation comprising:
contacting the subterranean formation with a slurry compri-sing a solvent and a mixture of colloidal silica which is a fumed silica of surface area from about 50 to 400 meters2/gram and which has a particle size ranging from about 7 to 15 millimicrons and a liquid acid wherein said mix-ture resembles a free flowing dry powder.
The colloidal silica and the acid are mixed into a free flowing powder which is then slurried in a solvent such as a light hydrocar-bon. This slurry is then injected into the formation to be acidized. On contact with water in the reservoir acid will be liberated. The invention is also the free flowing powder mixture of colloidal silica and liquid acid.
The process of the invention is usually carried out by injec-ting the acid composition of the invention into a well penetrating and in communication with a subterranean reservoir so that the acid contacts the reservoir rock matrix. The reservoir usually contains petroleum or oil, but may contain other fluids such as water or a mixture of water and oil.
The composition of the process of the invention consists of three principal ingredients: colloidal silica, acid and solvents.
The colloidal silica useful in the invention is different ; from precipitated silica or silica gel. The colloidal silica useful in the invention is a fumed silica which is made up of chain-like formations sin-tered together. These chains are branched and have enormous external surface areas of from about 50 to about 400 meters2/gram. Although the exact mechan-- ism is not B _4_ .
Known~ Applicant believes that the acid adsorbs onto the silica particles and the resultant mixture resembles a powder. However, when an aqueous fluid contacts the acid-colloidal silica mixture the acid is liberated from the colloidal silica particles.
Colloidal silicas are readily available from manufacturers. One source is the Cabot Corporation of Boston, Massachusetts under the trade mark CAB-O~SII, Colloidal silica is also available from other commerc~al sources and the reference to one source is not intended to limit the seope of my invention.
The eolloidal siliea aeeeptable for use in the method of thi,s inventicnshould have a partiele size ranging from about 7 to 15 millimierons (mu). In this size range the eolloidal siliea will pass through even reservoirs with very small pore size. For example, a reservoir having very low permeability of say 0.016 milli-dareies (md) has a eorrespondingly small pore size of 25 to 100 mu. Thus, the eolloidal siliea suitable for use in the proeess ~ this invention will pass through even the smallest pores eneountered in hydroearbon reservoirs .
Colloidal siliea suitabe for the proeess of th s invention is deseribed in the literature. For example, U.S. Patent 3,993,809 deseribes the eolloidal siliea of the invention and a method for its manufaeture.
There are other methods for its manufaeture whieh produee eolloidal siliea as deseribed hePein.
Aeids useful in this invention are genera~lly those whieh will attaek reservoir matrix. Those ~048q68 skilled in the art of petroleum recovery will readily chose the acid or mixtures of acids most suitable for a particular reservoir rock. Examples of suitable acids include but are not limited to mineral acids such as hydrochloric, hydrofluoric, sulfuric, phosphoric, nitric, and organic acids such as formic, acetic, etc., and oxalic, malonic, succinic, etc. Mixtures of the above acids may also be used as well.
Solvents are useful in the process of this invention, both for providing a medium in which to slurry the collo-idal silica-acid powder and as a preflush fluid to be introduced ahead of the colloidal silica-acid-solvent slurry in the reservoir.
The solvent chosen to slurry the colloidal silica-acid powder may be of several broad types including sol-vents miscible with both water and oil, solvents miscible with oil but immiscible with water, and solvents miscible with water but not with oil. The choice of the solvent type will help dictate the character of acid treatment resulting. Once the connate water in the reservoir contacts the colloidal silica acid powder, the acid will be liberated and reaction with the reservoir rock matrix will begin. If the slurry solvent is of the type miscible with both water and oil or the type miscible with both water and oil or the type miscible with water and immiscible with oil connate water will ~uickly penetrate the slurry, release the acid and allow the acid to attack the rock matrix soon after the acid enters the formation. Thus, the acidizing effect will be near the well bore. If the slurry solvent is immiscible with water the ~04876~
connate water will have more difficulty penetrating to the acid powder allowing it to travel farther from the well bore before it is released. 'I'hus, the acidizing effect will be over a greater radius from the well bore. This has a similar effect to a retarded acid. In another embodiment of this invention this control of acid action on the formation may be supplemented by use of a preflush solvent in addition to a slurry solv~nt The preflush fluid solvent may be of the same broad types as the slurry solvent although in a given acidiz-ation process the type of preflush solvent may be the same as or different from the type of slurry solvent.
If a preflush solvent is used which is miscible with both water and oil or miscible with water and immi-scible with oil, the connate water will be pushed efficiently away from the well bore and, therefore, the acid slurry which follows will be able to penetrate far from the well bore before connate water liberates the acid resulting in acidization over a large radius from the well bore. Use of a preflush solvent immiscible with water would leave much connate water near the well bore and allow a more rapid connate water attack on the acid slurry resulting in acidization concentrated nearer the well bore.
Typical solvents miscible with water and oil and ~uitable for use to form the acid slurry or the preflush include but are not limited to acetone, higher alcohols, ethylene and polyethylene glyco]s, and glycerol.
104~76~
Typical solvents miscible with oil and immiscible with water and suitable for use to form the acid slurry or the preflush include but are not limited to LPG and other hydrocarbon fractions, base crude, aldehydes and ketones.
A typical solvent miscible with water and immiscible with oil includes but is not ~imited to methoanol.
The terms miscible and immiscible as used herein are not meant to be absolute but only to indicate a ten-dency. Thus, miscible may means completely miscible in all proportions to partial miscibi~ity. Immiscible may be little or no misciblity to slightly miscible. Whether a particular solvent is miscible or immiscible with a given oil must be determined in an individual case due to the infinite variety of reservoir oils.
Preparation of An Acid-Colloidal Silica Powder To a Waring Blender add:
(1) 180 gm Cab-0-Sil~
(2) 1000 gm concentrated sulfuric acid and blend 15 seconds to prepare finely dispersed powder.
F;ield Example First, mix acid and colloidal silica as above to form dry powder. Then inject preflush of solvent to sweep water away from well bore. Use of a water immiscible solve~t will leave an irreducible ~048768 water saturation on the rock matrix which on contact with the adsorbed acid will liberate it and allow the acid to react with the rock matrix. For a more in depth treatment, a solvent such as acetone is used which is miscible with water and which will displace all the water from the rock matrix. In this example 200 barrels acetone in injected into the well to displace water out to a distance of 30 feet for the well bore. Next, inject lO0 barrels of a 10% by weight slurry of powdered acid in the water miscible solvent. After the acid injection overflush with lO0 barrels of solvent to carry powdered acid slurry out into the reservoir. Then if an injec-tion well is involved, return the well to water injec-tion. However, if an oil production well is involved overflush with lO0 barrels of water followed by 100 barrels lease crude and return the well to production, The purpose here is to use water to liberate acid and oil to reestablish oil permeability.
_ g
F;ield Example First, mix acid and colloidal silica as above to form dry powder. Then inject preflush of solvent to sweep water away from well bore. Use of a water immiscible solve~t will leave an irreducible ~048768 water saturation on the rock matrix which on contact with the adsorbed acid will liberate it and allow the acid to react with the rock matrix. For a more in depth treatment, a solvent such as acetone is used which is miscible with water and which will displace all the water from the rock matrix. In this example 200 barrels acetone in injected into the well to displace water out to a distance of 30 feet for the well bore. Next, inject lO0 barrels of a 10% by weight slurry of powdered acid in the water miscible solvent. After the acid injection overflush with lO0 barrels of solvent to carry powdered acid slurry out into the reservoir. Then if an injec-tion well is involved, return the well to water injec-tion. However, if an oil production well is involved overflush with lO0 barrels of water followed by 100 barrels lease crude and return the well to production, The purpose here is to use water to liberate acid and oil to reestablish oil permeability.
_ g
Claims (20)
1. A method for acidizing a subterranean formation comprising contacting the subterranean formation with a slurry comprising a solvent and a mixture of colloidal silica which is a fumed silica of surface area from about 50 to 400 meters2/gram and which has a particle size ranging from about 7 to 15 millimicrons and a liquid acid wherein said mixture resembles a free flowing dry powder.
2. A method of Claim 1 wherein the solvent is miscible with both water and oil.
3. A method of Claim 1 wherein the solvent is miscible with oil and immiscible with water.
4. A method of Claim 1 wherein the solvent is miscible with water and immiscible with oil.
5. A method of Claim 1 wherein the acid comprises a mineral acid.
6. A method of Claim 5 wherein the acid comprises sulfuric.
7. A method of Claim 5 wherein the acid comprises hydrochloric.
8. A method of Claim 5 wherein the acid comprises hydrofluoric.
9. A method of Claim 1 wherein the acid is an organic acid.
10. A method for acidizing a subterranean formation comprising introducing a solvent preflush acid into the formation and following the preflush fluid with a slurry comprising a solvent and a mixture of colloidal silica which is fumed silica of surface area from about 50 to 400 meters2/gram and which has a particle size ranging from about 7 to 15 millimi-crons and a liquid acid wherein said mixture resembles a free flowing dry powder.
11. A method of Claim 10 wherein the preflush fluid is miscible with water.
12. A method of Claim 11 wherein the slurry solvent is immiscible with water.
13. A method of Claim 10 wherein the acid comprises a mineral acid.
14. A method of Claim 10 wherein the acid comprises an organic acid.
15. A composition comprising colloidal silica which is a fumed silica of surface area from about 50 to 400 meters2/gram and which has a particle size ranging from about 7 to 15 millimicrons, a solvent and a liquid acid wherein the components are mixed until the composition resembles free flowing powder.
16. A composition as in Claim 15 wherein the acid comprises a mineral acid.
17. A composition as in Claim 16 wherein the acid comprises sulfuric.
18. A composition as in Claim 16 wherein the acid is hydrochloric.
19. A method of Claim 16 wherein the acid is hydrofluoric.
20. A method of Claim 15 wherein the acid comprises an organic acid.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US457156A US3876007A (en) | 1974-04-01 | 1974-04-01 | Acidization process |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1048768A true CA1048768A (en) | 1979-02-20 |
Family
ID=23815665
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA75221843A Expired CA1048768A (en) | 1974-04-01 | 1975-03-11 | Acidization process |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US3876007A (en) |
| CA (1) | CA1048768A (en) |
| DE (1) | DE2459296A1 (en) |
| DK (1) | DK135575A (en) |
| GB (1) | GB1469737A (en) |
| NL (1) | NL7501869A (en) |
| NO (1) | NO750732L (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4525285A (en) * | 1983-08-31 | 1985-06-25 | Halliburton Company | Method of preventing loss of an oil-base drilling fluid during the drilling of an oil or gas well into a subterranean formation |
| US4703803A (en) * | 1986-06-24 | 1987-11-03 | Cities Service Oil & Gas Corporation | Composition and method for slowly dissolving siliceous material |
| US5294353A (en) * | 1991-06-27 | 1994-03-15 | Halliburton Company | Methods of preparing and using stable oil external-aqueous internal emulsions |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3377275A (en) * | 1965-06-17 | 1968-04-09 | Nalco Chemical Co | Treatment for aqueous industrial process fluids |
| US3818989A (en) * | 1972-12-27 | 1974-06-25 | Texaco Inc | Method for preferentially producing petroleum from reservoirs containing oil and water |
-
1974
- 1974-04-01 US US457156A patent/US3876007A/en not_active Expired - Lifetime
- 1974-12-14 DE DE19742459296 patent/DE2459296A1/en active Pending
-
1975
- 1975-02-12 GB GB586675A patent/GB1469737A/en not_active Expired
- 1975-02-18 NL NL7501869A patent/NL7501869A/en not_active Application Discontinuation
- 1975-03-05 NO NO750732A patent/NO750732L/no unknown
- 1975-03-11 CA CA75221843A patent/CA1048768A/en not_active Expired
- 1975-03-26 DK DK135575A patent/DK135575A/da not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| NO750732L (en) | 1975-10-02 |
| DK135575A (en) | 1975-10-02 |
| NL7501869A (en) | 1975-10-03 |
| GB1469737A (en) | 1977-04-06 |
| US3876007A (en) | 1975-04-08 |
| AU7851475A (en) | 1976-08-26 |
| DE2459296A1 (en) | 1975-10-09 |
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