EP0097149A4 - Process for increasing the water discharge of water delivering drilled wells. - Google Patents

Process for increasing the water discharge of water delivering drilled wells.

Info

Publication number
EP0097149A4
EP0097149A4 EP19820900127 EP82900127A EP0097149A4 EP 0097149 A4 EP0097149 A4 EP 0097149A4 EP 19820900127 EP19820900127 EP 19820900127 EP 82900127 A EP82900127 A EP 82900127A EP 0097149 A4 EP0097149 A4 EP 0097149A4
Authority
EP
European Patent Office
Prior art keywords
well
acid
water
less
dissociation constant
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.)
Withdrawn
Application number
EP19820900127
Other languages
German (de)
French (fr)
Other versions
EP0097149A1 (en
Inventor
Pal Gomory
Janos Hegedus
Ferenc Kiss
Attila Simon
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Generalimpex
Original Assignee
Generalimpex
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Generalimpex filed Critical Generalimpex
Publication of EP0097149A1 publication Critical patent/EP0097149A1/en
Publication of EP0097149A4 publication Critical patent/EP0097149A4/en
Withdrawn legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D29/00Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/62Regenerating the filter material in the filter
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09KMATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K8/00Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
    • C09K8/52Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning
    • C09K8/528Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning inorganic depositions, e.g. sulfates or carbonates

Definitions

  • the invention relates to a process for increasing the water discharge of water delivering drilled wells in case of the decrease of the water discharge with wells having been exploited for a longer period, furtheron in case of new wells having been deepened with mud, for restoring i.e. increasing the water permeability of the original rocks by reducing the well-resistance, by using a chemical treatment.
  • the water discharge of the water delivering drilled wells depends in addition to the layer conditions on the mode of the well formation, the age of the well, the methods of water production and on the quality of water.
  • Themode of well formation includes the structural solutions to be applied, e.g. the piping, the arrangement and construction of the filter, as well as the drilling methods and pumping with the purpose of cleaning being utmost important from the point of view of water discharge.
  • the pumping serving for purification may decisively influence the quality of well formation, which can be characterized numerically by the wellresistance.
  • the components of well-resistance a re the following: the dam effect, i.e.
  • the changed resistance of the zone around the well the layer resistance, the filter resistance, the resistance resulting from the instrustation, the resistance-surplus of a more or less turbulent stream - compared to the linear stream - at higher flow velocities and at least the flow resistance of the piping in the well.
  • the increase of the water discharge can be achieved by the considerable decrease of the dam effect - the more, by converting it into an effect with a different sign (achieving a lower resistance in the zone around the well, than the original one), by the reduction of the resistance resulting from incrustation and indirectly by the reduction of the resistance-surplus of the turbulent stream.
  • detrimental effects of the mud can be eliminated by removing the mud increasing the layer resistance with a high efficiency from the infiltered zone and by increasing the original water permeability of the confining zone.
  • Incrustation i.e. clogging is caused by the deposition of different compounds; said compounds contain mainly iron and calcium in form of carbonates, oxydes, hydroxydes, sulfates and silicates. Due to biological effects, e.g. as a consequence of the activity of iron- and manganese bacteria organic compounds may also deposit.
  • the rate of incrustation is increasing in dependence of the age of the well, at the same time the mode of operation and the quality of water are also considerably influencing the rate of incrustation.
  • the so-called “ochre-formation” is of the largest extent, accordingly, it is to be considered as the most dangerous phenomenon; in course of this process iron compounds, mainly ferric(III)hydroxyde are segregated.
  • hydrochloric acid is highly damaging all the fittings made of iron.
  • Improvement of wells with a reduced water discharge is mostly performed by using hydrochloric acid (Technical Directives of the Office of Water conserveancy, 136/4-73/4.2).
  • the layer purification with hydrochloric acid is causing corrosional damages in the metal parts and in case of glassf ⁇ bre reinforced synthetic casing pipes the risk is extraordinarily high and may lead to the early ageing of the well.
  • the advantageous effect of the weak acids may be explained probably by the fact that said acids dissolve far slower the carbonates and oxydes, than the hydrochloric acid, accordingly, they are penetrating far deeper into the zones confining the filter.
  • the slower dissolution is accompanied by a less vigorous gas formation, as a consequence, the danger of layer collapse is also less.
  • the weak acids having been used in course of the process according to the invention do not destruct the material of the filter and the pipes, the mechanical properties of the glassfibre-reinforced synthetic pipes are not deteriorated either.
  • the treatment having the character of an alkaline reaction i.e. using the sodium hypochlorite and/or sodium bicarbonate solutions after the treatment with the acids is highly increasing the efficiency of the process according to the invention, in the majority of cases a productivity far excessing the original one could be achieved.
  • Example 1 The well having been started in 1938 with an initial water discharge of 180 1/min (MALEV well II), with no yield at the start of the process, was subjected to a frad.it ⁇ onal treatment for 48 hours by using a Mammoth-pump and a compressor. As a result of the treatment a water discharge of 120 1/minute could be obtained. Thereafter, through the pipe penetrating to the filter concentrated acidic acid in a quantity of 1o kg was introduced Into the well; in the following operational phase, through the closed well-head, air pressure of 3 to 5 bar was produced for four hours by means of a compressor; after a pressure-free period lasting an hour, a pressure of 7 bar and of the duration of six hours was applied onto the well.
  • MALEV well II initial water discharge of 180 1/min
  • the concentrated aquaeous solution of 15 Kg tartaric acid was introduced through the pipe penetrating to the filter. After a dwelling period of 24 hours and compressing, flushing by means of a scavenging pump was performed, thereafter the solution of sodium bicarbonate (5 kg sodium bicarbonate have been diluted with 4o litres water) was introduced into the filter zone. After a dwelling period of six hours scavenging was performed. After the chemical treatment the water discharge of the well amounted to 1750 1/m ⁇ nute, being by 25 % higher, than the original yield.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Treatment Of Water By Oxidation Or Reduction (AREA)
  • Cleaning By Liquid Or Steam (AREA)

Abstract

Process for increasing the water discharge of water delivering drilled wells, which can be characterized in that into the filter section of the well weak acids with a dissociation constant being less, than Kd = 10<-3> are introduced. Afer a dwelling period of longer duration, expediently 10 to 48 hours, as well as compressing, flushing is performed by means of a scavenging pump. Thereafter the solution of sodium bicarbonate and/or sodium hypochlorite is introduced into the filter section. After a longer dwelling period, expediently one to thirty-six hours, flushing is performed by means of the scavenging pump. As weak acids with a dissociation constant being less than Kd = 10<-3> acetic acid, tartaric acid, citric acid, metaboric and/or tetraboric acid is used.

Description

Process for increasing the water discharge of water delivering drilled wells
Technical field
The invention relates to a process for increasing the water discharge of water delivering drilled wells in case of the decrease of the water discharge with wells having been exploited for a longer period, furtheron in case of new wells having been deepened with mud, for restoring i.e. increasing the water permeability of the original rocks by reducing the well-resistance, by using a chemical treatment.
Background art
As it is a well known fact, the water discharge of the water delivering drilled wells depends in addition to the layer conditions on the mode of the well formation, the age of the well, the methods of water production and on the quality of water.
Themode of well formation includes the structural solutions to be applied, e.g. the piping, the arrangement and construction of the filter, as well as the drilling methods and pumping with the purpose of cleaning being utmost important from the point of view of water discharge. The pumping serving for purification may decisively influence the quality of well formation, which can be characterized numerically by the wellresistance. As it is known, the components of well-resistance a re the following: the dam effect, i.e. the changed resistance of the zone around the well, the layer resistance, the filter resistance, the resistance resulting from the instrustation, the resistance-surplus of a more or less turbulent stream - compared to the linear stream - at higher flow velocities and at least the flow resistance of the piping in the well.
By the application of the process according to the invention the increase of the water discharge can be achieved by the considerable decrease of the dam effect - the more, by converting it into an effect with a different sign (achieving a lower resistance in the zone around the well, than the original one), by the reduction of the resistance resulting from incrustation and indirectly by the reduction of the resistance-surplus of the turbulent stream.
In course of well formation the optimal development of the zone around the well is of utmost importance. This represents an especially difficult task, when flush-dril I Ing is applied, since the mud is penetrating into the zone around the well in a depth of 10 to 50 cm and reduces water permeability of the confining zone. Water permeability may be considerably decreased, it may even reach the fhousandth-fenthousandth of the original value.
In accordance with the invention detrimental effects of the mud can be eliminated by removing the mud increasing the layer resistance with a high efficiency from the infiltered zone and by increasing the original water permeability of the confining zone.
It is a fact of common knowledge, that the resistance of the zone around the filter can be reduced by pumping, for this purpose the so-called Mammoth pump or a compressor is used. The pumping method in itself is rarely yielding satisfactory results and in particular it used to be unsuccessful, when the infiltrate contains bentonϊte. In the majority of cases the reason for the insufficient effect of pumping is, that the pressure drop in the well is not entirely breaking up the conglomerated mud layer in the clogged zone around the filter, but only on certain places. The water streaming along the lowest resistance in the initially small channels having been formed in such a manner - is forming more and more larger ducts resulting finally in the collapse of the layer. In this case the whole cleaning process is to be repeated.
Incrustation, i.e. clogging is caused by the deposition of different compounds; said compounds contain mainly iron and calcium in form of carbonates, oxydes, hydroxydes, sulfates and silicates. Due to biological effects, e.g. as a consequence of the activity of iron- and manganese bacteria organic compounds may also deposit. The rate of incrustation is increasing in dependence of the age of the well, at the same time the mode of operation and the quality of water are also considerably influencing the rate of incrustation. The so-called "ochre-formation" is of the largest extent, accordingly, it is to be considered as the most dangerous phenomenon; in course of this process iron compounds, mainly ferric(III)hydroxyde are segregated. According to our experiences, the intensity of draw-off is playing an important role in ochre-formation. The partial or total turbulence arising with higher flow velocities considerably increases the rate of ochre-formation, while with wells being out of operation ochre-formation usually could not be observed. In order to be able to eliminate the layer purification by means of pumping, mostly a treatment with hydro-chloric acid has been used (E. Bieske: Handbuch des Brunnenbaus, Berlin, 1965). Hydrochloric acid dissolves the oxydes and carbonates and elution of the ferrous and calciferous deposits in form of chlorides from the filter zone becomes possible. However, treatment with hydrochloric acid may be disadvantageous in several cases, e.g. where the relatively rapid and strong dissolving effect may result in the collapse of layers, in addition to this, due to its metal dissolving effect, hydrochloric acid is highly damaging all the fittings made of iron. In spite of the known damaging effects, Improvement of wells with a reduced water discharge is mostly performed by using hydrochloric acid (Technical Directives of the Office of Water Conservancy, 136/4-73/4.2). The layer purification with hydrochloric acid is causing corrosional damages in the metal parts and in case of glassfϊbre reinforced synthetic casing pipes the risk is extraordinarily high and may lead to the early ageing of the well.
Disclosure of Invention In course of our examinations aiming the elimination of the disadvantageous features of the known processes serving for the increase of the water discharge of drilled wells, we have found, that the water discharge of the drilled wells can be increased with a surprisingly good result - with a yield mostly surpassing the original one - by introducing weak acids into the filtering section, the dissociation constant of which is less, than Kd = l0-3 and after a longer dwelling period, expediently 1o to 48 hours and compression, flushing by means of a scavenging pump is performed. Thereafter, the solution of sodium dicarbonate and/or sodium hypochlorite is introduced into the filtering section. After a longer dwelling period, expediently lasting 1 to 36 hours, repeated flushing is performed by means of the scaveng ing pump.
The weak acids to be used in course of the process according to the invention, having a dissociation constant less than Kd = 10-3 are the following: acetic acid, citric acid, tartaric acid, metaboric acid and tetraboric acid, all are giving excellent results (Lengyel, Proszt, Szarvas: General and Organic Chemis-try, Budapest, 1960, pp. 198-201). Very weak acids, as e.g. orthobor icaci d, require a dwelling period of several days for yielding proper results.
The advantageous effect of the weak acids may be explained probably by the fact that said acids dissolve far slower the carbonates and oxydes, than the hydrochloric acid, accordingly, they are penetrating far deeper into the zones confining the filter. The slower dissolution is accompanied by a less vigorous gas formation, as a consequence, the danger of layer collapse is also less.
The weak acids having been used in course of the process according to the invention do not destruct the material of the filter and the pipes, the mechanical properties of the glassfibre-reinforced synthetic pipes are not deteriorated either.
According to our experiences, the treatment having the character of an alkaline reaction, i.e. using the sodium hypochlorite and/or sodium bicarbonate solutions after the treatment with the acids is highly increasing the efficiency of the process according to the invention, in the majority of cases a productivity far excessing the original one could be achieved.
Best Mode of Carrying out the Invention
The process according to the invention will be explained in details by the way of examples.
Example 1 The well having been started in 1938 with an initial water discharge of 180 1/min (MALEV well II), with no yield at the start of the process, was subjected to a frad.itϊonal treatment for 48 hours by using a Mammoth-pump and a compressor. As a result of the treatment a water discharge of 120 1/minute could be obtained. Thereafter, through the pipe penetrating to the filter concentrated acidic acid in a quantity of 1o kg was introduced Into the well; in the following operational phase, through the closed well-head, air pressure of 3 to 5 bar was produced for four hours by means of a compressor; after a pressure-free period lasting an hour, a pressure of 7 bar and of the duration of six hours was applied onto the well. After having scavenged the well with the pump for an hour, loo litres of commercially available hypo-solution were introduced into the well; after a dwelling period of eight hours cleaning was performed by means of the scavenging pump. After a treatment with chemicals the water discharge of the well could be incresed to 900 1/mϊnutes, amounting to the fivefold of the original yield and to the seven and half-fold of the value having been obtained by the traditional pumping process. Example 2
Into the well having been started in 1938, with an original water discharge of 1400 1 /minute, the concentrated aquaeous solution of 15 Kg tartaric acid was introduced through the pipe penetrating to the filter. After a dwelling period of 24 hours and compressing, flushing by means of a scavenging pump was performed, thereafter the solution of sodium bicarbonate (5 kg sodium bicarbonate have been diluted with 4o litres water) was introduced into the filter zone. After a dwelling period of six hours scavenging was performed. After the chemical treatment the water discharge of the well amounted to 1750 1/mϊnute, being by 25 % higher, than the original yield.
Example 3
Into a 40 years old well of the depth of 300 m with no water discharge at all, into the filter zone the solution of citric acid (30 kg citric acid have been dissolved in 200 I water) introduced. After a dwelling period of 36 hours and compressing, flushing was performed by means of a scavenging pump and 100 liters commercially available hypo- -solution were introduced into the well. After a dwelling period of eight hours, scavenging pumping was performed. As a consequence of the chemical treatment the water discharge amounted to 600 1/minute, equalling about to the double of the original yield.
Example 4
Into a well of the depth of 150 m, having been deepened with mud and with a water discharge of 190 1/minute, following the traditional treatment, the solution of tetraboric acid (1 kg tetraboric acid has been dissolved in 20 I warm water) was introduced into the well. After a dwelling time of 48 hours and compressing, flushing by means of the scavenging pump was performed, thereafter 5 kg sodium bicarbonate having been dissolved in 40 I water were introduced into the filter zone. After two hours of compressing and the following cleaning with the scavenging pump the water discharge amounted to 280 1/mϊnute, equalling to nearly one and a half of the water discharge having been measured prior to the chemical treatment.

Claims

Claims
1. Process for increasing the water discharge of water delivering drilled wells by using a chemical treatment, c h a r a c t e r i z e d in that into the filter section of the well weak acids are introduced, the dissociation constant of which is less, than Kd = l0-3 and after a dwelling period of longer duration, expediently 1o to 48 hours, as well as compressing, flushing is performed by means of a scavenging pump, thereafter the soluion of sodium bicarbonate and/or sodium hypochlorite is introduced into the filter section; after a dwelling time of longer duration, expediently 1 to 36 hours, flushing is performed by means of a scavenging pump.
2. Process as claimed in claim 1, c h a r a c t e r i z e d in that as a weak acid with a dissociation constant being less than Kd = l0-3 acetic acid is used.
3. Process as claimed in claim 1, c h a r a c t e r i z e d in that as a weak acid with a dissociation constant being less than Kd = l0-3 tartaric acid is used,
4. Process as claimed in claim 1, c h a r a c t e r i z e d in that as a weak acid with a dissociation constant being less than Kd = l0-3 citric acid is used.
5. Process as claimed in claim 1, c h a r a c t e r i z e d in that as a weak acid with a dissociation constant being less than Kd = l0-3 metaboric acid and/or tetraboric acidis used .
EP19820900127 1981-12-23 1981-12-23 Process for increasing the water discharge of water delivering drilled wells. Withdrawn EP0097149A4 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/HU1981/000049 WO1983002296A1 (en) 1981-12-23 1981-12-23 Process for increasing the water discharge of water delivering drilled wells

Publications (2)

Publication Number Publication Date
EP0097149A1 EP0097149A1 (en) 1984-01-04
EP0097149A4 true EP0097149A4 (en) 1985-06-06

Family

ID=10980426

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19820900127 Withdrawn EP0097149A4 (en) 1981-12-23 1981-12-23 Process for increasing the water discharge of water delivering drilled wells.

Country Status (5)

Country Link
US (1) US4541488A (en)
EP (1) EP0097149A4 (en)
JP (1) JPS59500323A (en)
BR (1) BR8109052A (en)
WO (1) WO1983002296A1 (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4778006A (en) * 1987-05-04 1988-10-18 Derowitsch Richard W Process for removing carbonate from wells
US5145012A (en) * 1990-12-21 1992-09-08 Union Oil Company Of California Method for selectively reducing subterranean water permeability
US5203834A (en) * 1990-12-21 1993-04-20 Union Oil Company Of California Foamed gels having selective permeability
US5268112A (en) * 1990-12-21 1993-12-07 Union Oil Company Of California Gel-forming composition
US5291950A (en) * 1992-08-27 1994-03-08 Petrosakh U.S.A. Method of well treatment
GB9308884D0 (en) * 1993-04-29 1993-06-16 Archaeus Tech Group Acidising oil reservoirs
US10068484B2 (en) * 2017-01-23 2018-09-04 Garden Technologies Llc Parking assisting device

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2425415A (en) * 1945-12-05 1947-08-12 Pure Oil Co Acidizing earth bores
US3122503A (en) * 1961-03-20 1964-02-25 Dow Chemical Co Dispersing clayey deposits
US3441085A (en) * 1967-09-07 1969-04-29 Exxon Production Research Co Method for acid treating carbonate formations
US3556221A (en) * 1969-01-06 1971-01-19 Marathon Oil Co Well stimulation process
US4325433A (en) * 1980-06-27 1982-04-20 University Of Southern California Pre-caustic flood treatment

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1984668A (en) * 1934-03-10 1934-12-18 Alfred W Knight Method of cleaning the walls of mudded bore-holes
US2045899A (en) * 1935-04-30 1936-06-30 Texas Co Method of increasing production from wells
US2059459A (en) * 1936-06-05 1936-11-03 Walter J Hund Method of treating wells with acids
US2852077A (en) * 1955-04-27 1958-09-16 Nat Aluminate Corp Process of improving and maintaining the water permeability of geological formations
US2933137A (en) * 1957-04-10 1960-04-19 Ranney Method Water Supplies I Plastic well screen and wells utilizing the screens and method of operation
US2978026A (en) * 1958-01-07 1961-04-04 California Research Corp Well wash fluid
US3307630A (en) * 1964-06-12 1967-03-07 Shell Oil Co Acidizing oil formations
US3482636A (en) * 1967-04-06 1969-12-09 Dow Chemical Co Method of lessening the inhibitory effects to fluid flow due to the presence of solid organic substances in a subterranean formation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2425415A (en) * 1945-12-05 1947-08-12 Pure Oil Co Acidizing earth bores
US3122503A (en) * 1961-03-20 1964-02-25 Dow Chemical Co Dispersing clayey deposits
US3441085A (en) * 1967-09-07 1969-04-29 Exxon Production Research Co Method for acid treating carbonate formations
US3556221A (en) * 1969-01-06 1971-01-19 Marathon Oil Co Well stimulation process
US4325433A (en) * 1980-06-27 1982-04-20 University Of Southern California Pre-caustic flood treatment

Also Published As

Publication number Publication date
EP0097149A1 (en) 1984-01-04
WO1983002296A1 (en) 1983-07-07
BR8109052A (en) 1983-11-22
US4541488A (en) 1985-09-17
JPS59500323A (en) 1984-03-01

Similar Documents

Publication Publication Date Title
CA2646533C (en) A method for dissolving oilfield scale
US7615518B2 (en) Composition for denaturing and breaking down friction-reducing polymer and for destroying other oil well contaminants
US7897063B1 (en) Composition for denaturing and breaking down friction-reducing polymer and for destroying other gas and oil well contaminants
JP2005087887A (en) Membrane washing method
US7563377B1 (en) Method for removing iron deposits in a water system
US4541488A (en) Process for increasing the water discharge of water delivering drilled wells, previously used for water delivery, and having decreased water discharge
US4778006A (en) Process for removing carbonate from wells
CN106833576A (en) Scale cleaning and preventing agent and preparation method thereof
CN106833577A (en) Construction method for cleaning and preventing scale on-line acidification multi-section plug
AU553167B2 (en) Process for increasing the water discharge of water delivering drilled wells
AU7936982A (en) Process for increasing the water discharge of water delivering drilled wells
KR100954571B1 (en) Method for prevention composition of MnO2 in water treatment using membrane filtration
CN103206192A (en) Method for rapidly cleaning insoluble dirt in oil wells and oil reservoirs close to oil wells
SU1519531A3 (en) Method of restoring permeability of well or its adjoining area in fluid communications of underground formation
Nada et al. Experience on pre-and post-treatment from sea water desalination plants in Saudi Arabia
RU2726089C1 (en) Method of processing gas wells of underground gas storages
CN111871217A (en) PVDF ultrafiltration membrane cleaning method
US4270802A (en) Permeability restoration and lowering of uranium leakage from leached ore beds
Rahman et al. Pursuing the effect of aeration, pH increment, and H2O2 coupled with UV irradiation on the removal efficiency of manganese by microfilter membrane
RU2101481C1 (en) Method for acid treatment of bottom-hole zone of injection well
RU2195545C1 (en) Method of isolating flushed zones in producing and injection wells
RU2717163C1 (en) Treatment method of borehole zone of productive formation
CN217490440U (en) Cleaning device for filtering membrane of water purification process
CN111195484B (en) Surfactant for cleaning plate-type ceramic membrane for oilfield wastewater treatment and cleaning method
SU1481378A1 (en) Method of reducing the permeability of formations

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT DE FR GB LU NL

17P Request for examination filed

Effective date: 19840109

RBV Designated contracting states (corrected)

Designated state(s): AT DE FR GB LU NL

17Q First examination report despatched

Effective date: 19870217

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19870728

RIN1 Information on inventor provided before grant (corrected)

Inventor name: GOEMOERY, PAL

Inventor name: KISS, FERENC

Inventor name: HEGEDUES, JANOS

Inventor name: SIMON, ATTILA