WO2012044269A1 - Method for increasing in situ rock permeability - Google Patents

Method for increasing in situ rock permeability Download PDF

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Publication number
WO2012044269A1
WO2012044269A1 PCT/UA2011/000088 UA2011000088W WO2012044269A1 WO 2012044269 A1 WO2012044269 A1 WO 2012044269A1 UA 2011000088 W UA2011000088 W UA 2011000088W WO 2012044269 A1 WO2012044269 A1 WO 2012044269A1
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WO
WIPO (PCT)
Prior art keywords
wave
fluid
well
stratum
section
Prior art date
Application number
PCT/UA2011/000088
Other languages
French (fr)
Inventor
Anatoliy Gnatovich Bazhal
Original Assignee
Barak, Aleksandr Motelevich
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 Barak, Aleksandr Motelevich filed Critical Barak, Aleksandr Motelevich
Priority to RU2013113278/03A priority Critical patent/RU2013113278A/en
Publication of WO2012044269A1 publication Critical patent/WO2012044269A1/en

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/25—Methods for stimulating production
    • E21B43/26—Methods for stimulating production by forming crevices or fractures

Definitions

  • Invention refers to mining and can be used for mineral production through wells.
  • rock permeability determines efficiency of mineral production technologies applied. Depending on the kind of rock the process of permeability increase influences significantly productiveness of the mineral production, power intensity and deterioration of equipment applied at mineral production.
  • the method for increasing rock permeability by means of directed wave impact on the rocks in situ [1] comprising uncovering a mineral stratum with a well, supplying fluid into a well, impact on the rocks by the energy of the impulse structure wave fields emitted from the emitter installed in the well. At that the rocks are impacted by the impulses emitted from the well with periodically changed wave shape and unsymmetrical distribution of the energy as regard to zero amplitude.
  • the method allows to effect fragmentation of the rocks more efficiently and reduce time consumption for rock processing as well as the cost of the mineral produced.
  • the disadvantage of this method is low efficiency as a result of non-providing sufficient rock permeability that is caused by large losses of the wave energy delivered into the stratum.
  • the nearest analogue of the applied engineering solution is the method for increasing in situ rock permeability [2] comprising uncovering a mineral stratum with a well, supplying fluid into a well, impact on the fluid by static pressure as well as by the shock waves of the definite structure with their transfer along the fluid channel into the well with subsequent turning from the wave reflector to the stratum and wave dilatant decompaction of the rocks.
  • the disadvantage of this method is insufficient efficiency of rock permeability increase and high energy consumption caused by inconformity of static pressure in the fluid with pore pressure of the rock making impossible running of the dilatant process of the rock fragmentation as well as due to large losses of the wave energy delivered into the stratum.
  • the objective of the invention is creation of the method for increasing in situ rock permeability in which improvement of the efficiency of the process of rock permeability increase and energy consumption reduction at the work cost reduction is achieved by means of reduction of the wave energy losses.
  • the static pressure value is 1.3 times as much as the value of capillary pressure appearing in the pores the amount of which prevails in size in the rocks decompacted and the shock wave amplitude is chosen as equal or exceeding the compressive or tensile stress which is necessary for running of the process of dilatant decompaction of the rocks.
  • the wave length is defined as commensurable with the depth of the stratum and the wave processing time is determined on the basis of the defined depth of the crack created in the stratum according to the following formula:
  • L> Ta>A In where L - is depth of stratum;
  • ⁇ ⁇ - is wave length
  • Fa c e - is initial value of the fluid channel cross-section;
  • p-xT is current value of fluid density;
  • a* - is current value of wave velocity in the fluid;
  • F 3 ⁇ 4 - is current value of the fluid channel cross-section;
  • p M - is rock mass density;
  • a M - is wave velocity in the rock mass;
  • F M - is cross-section of the rock mass zone covered with wave; p xo - is initial fluid density; aj K o - is initial wave velocity in the fluid.
  • 3 ⁇ 4 0 - is initial fluid density; a*,, - is initial wave velocity in the fluid; p x - is current value of fluid density; a* - is current value of wave velocity in the fluid;
  • F JK - is current value of the fluid channel cross-section
  • F M - is cross-section of the rock mass zone covered with wave; p M - is rock mass density; a M - is wave velocity in the rock mass.
  • shock wave amplitude is chosen as equal or exceeding the compressive or tensile stress the necessary conditions for running of the dilatant decompaction of the rocks are provided.
  • the necessary condition for dilatant decompaction is non-uniform loading of the rock mass zone covered with a wave at every instant, in particular presence of tensile stresses caused by this non-uniformity in micro- and macrovolumes of the rock mass decompaction.
  • the wave length is defined as commensurable with the depth of the stratum and the wave processing time is determined on the basis of the defined depth of the crack created in the stratum thus providing the wave length conformity with the rock characteristics as a result of which the wave energy losses for diffusion beyond the stratum decrease and the process of increasing in situ rock permeability runs more efficiently.
  • the wave length is limited according to the minimal value in such a way that it would be not less than the depth of the cracks created in the rock mass as the low amplitude wave will not spread through such the cracks.
  • the wave is emitted along the fluid channel in the conditions of the wave conformance in the zones of section difference according to the equality of the wave (acoustic) impedance of the channels and the fluid channel section is changed towards the bottom in the wave emission zone according to the definite formula taking into account fluid density in the fluid channel, wave velocity in the fluid as well as wave velocity in the rock mass and the rock mass density the rock permeability increase is provided more efficiently.
  • the invention is carried out as follows.
  • a well is drilled in the rock mass and a mineral stratum is uncovered.
  • the fluid impacted simultaneously by static pressure and by the shock waves is supplied into the well.
  • the static pressure value is 1.3 times as much as the value of capillary pressure appearing in the pores the amount of which prevails in size in the rocks decompacted and compensates the rock pressure displacing the fluid from the capillars and pores towards the well.
  • the waves are supplied by the emitter from the surface with their transfer along the fluid channel with variable cross-section into the well with subsequent turning from the wave reflector to the stratum and the wave conformance conditions are provided in the zones of section difference according to the equality of the wave (acoustic) impedance of the channels thus creating conditions for full wave energy transmission.
  • the shock wave amplitude is chosen as equal or exceeding the compressive or tensile stress in the stratum plane providing dilatant strain and decompaction of the rock mass in the regime of non-uniform loading in the microvolumes caused by rock pressure difference on the lower and upper surfaces of the rock mass zone covered with the wave, and non-uniformities in the microvolumes caused by the capillary pressure difference due to different size of the pores and wave structure non- uniformity of the rock mass.
  • the wave length is defined as commensurable with the depth of the stratum and the wave processing time is determined on the basis of the defined depth of the crack created in the stratum thus reducing wave energy losses for diffusion beyond the stratum and improving efficiency of the process of increasing in situ rock permeability.
  • the process of the rock decompaction and permeability increase is controlled from the surface concerning the rock permeability - fluid adsorption during its injection into the well.
  • initially permeability is mainly up to 50mD for low- permeable rocks and in the process of simultaneous impact by the waves and by static pressure it gradually increases up to lOOOmD and more depending on the technological requirements. It can take from several minutes to several hours depending on the rock hardness.
  • the proposed engineering solution allows to improve efficiency of the process of increasing in situ rock permeability and decompaction, to reduce energy consumption at the work cost reduction.

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  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • Physics & Mathematics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Mattresses And Other Support Structures For Chairs And Beds (AREA)
  • Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
  • Earth Drilling (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)

Abstract

Invention refers to mining and can be used for mineral production through wells. The method for increasing in situ rock permeability comprises uncovering a mineral stratum with a well, supplying fluid into the well, impact on the fluid by static pressure as well as by the shock waves of the definite structure with their transfer along the fluid channel into the well with subsequent turning from the wave reflector to the stratum and wave dilatant decompaction of the rocks, at that the impact on the fluid by static pressure and by the shock waves is effected simultaneously, besides, the static pressure value is 1.3 times as much as the value of capillary pressure appearing in the pores the amount of which prevails in size in the rocks decompacted and the shock wave amplitude is chosen as equal or exceeding the compressive or tensile stress which is necessary for running of dilatant decompaction of the rocks. The proposed engineering solution allows to improve efficiency of the process of increasing in situ rock permeability and decompaction, to reduce energy consumption at the work cost reduction.

Description

METHOD FOR INCREASING IN SITU ROCK PERMEABILITY
Invention refers to mining and can be used for mineral production through wells.
An essential factor at mineral production is rock permeability which determines efficiency of mineral production technologies applied. Depending on the kind of rock the process of permeability increase influences significantly productiveness of the mineral production, power intensity and deterioration of equipment applied at mineral production.
There exist various methods for increasing rock permeability.
The method for increasing rock permeability by means of directed wave impact on the rocks in situ [1] is known comprising uncovering a mineral stratum with a well, supplying fluid into a well, impact on the rocks by the energy of the impulse structure wave fields emitted from the emitter installed in the well. At that the rocks are impacted by the impulses emitted from the well with periodically changed wave shape and unsymmetrical distribution of the energy as regard to zero amplitude. The method allows to effect fragmentation of the rocks more efficiently and reduce time consumption for rock processing as well as the cost of the mineral produced.
The disadvantage of this method is low efficiency as a result of non-providing sufficient rock permeability that is caused by large losses of the wave energy delivered into the stratum.
The nearest analogue of the applied engineering solution is the method for increasing in situ rock permeability [2] comprising uncovering a mineral stratum with a well, supplying fluid into a well, impact on the fluid by static pressure as well as by the shock waves of the definite structure with their transfer along the fluid channel into the well with subsequent turning from the wave reflector to the stratum and wave dilatant decompaction of the rocks.
The disadvantage of this method is insufficient efficiency of rock permeability increase and high energy consumption caused by inconformity of static pressure in the fluid with pore pressure of the rock making impossible running of the dilatant process of the rock fragmentation as well as due to large losses of the wave energy delivered into the stratum.
The objective of the invention is creation of the method for increasing in situ rock permeability in which improvement of the efficiency of the process of rock permeability increase and energy consumption reduction at the work cost reduction is achieved by means of reduction of the wave energy losses.
The above objective is achieved in that in the known method for increasing in situ rock permeability comprising uncovering a mineral stratum with a well, supplying fluid into a well, impact on the fluid by static pressure as well as by the shock waves of the definite structure with their transfer along the fluid channel into the well with subsequent turning from the wave reflector to the stratum and wave dilatant decompaction of the rocks, according to the invention,
impact on the fluid by static pressure and by the shock waves is effected simultaneously, at that the static pressure value is 1.3 times as much as the value of capillary pressure appearing in the pores the amount of which prevails in size in the rocks decompacted and the shock wave amplitude is chosen as equal or exceeding the compressive or tensile stress which is necessary for running of the process of dilatant decompaction of the rocks.
At that the wave length is defined as commensurable with the depth of the stratum and the wave processing time is determined on the basis of the defined depth of the crack created in the stratum according to the following formula:
L> =Ta>A In where L - is depth of stratum;
λ - is wave length;
T - time of wave processing;
a - wave velocity;
Δ 1 - increase of depth of the crack created within one wave passage n - number of wave passages for providing estimated crack depth. Besides, the fluid channel section is changed towards the bottom in the wave emission zone according to the following formula:
)KO ¾ 05
where:
Face - is initial value of the fluid channel cross-section; p-xT is current value of fluid density; a* - is current value of wave velocity in the fluid;
F¾- is current value of the fluid channel cross-section; pM- is rock mass density; aM - is wave velocity in the rock mass;
FM- is cross-section of the rock mass zone covered with wave; pxo- is initial fluid density; ajKo - is initial wave velocity in the fluid.
It is preferable when the wave is emitted along the fluid channel in the conditions of the wave conformance in the zones of the section difference according to the equality of the wave (acoustic) impedance of the channels:
F>KO PTKO ¾KO— P* ^IC JK + ?M aM FM where : F^- is initial value of the fluid channel cross-section;
¾0- is initial fluid density; a*,, - is initial wave velocity in the fluid; px- is current value of fluid density; a* - is current value of wave velocity in the fluid;
FJK- is current value of the fluid channel cross-section;
FM- is cross-section of the rock mass zone covered with wave; pM- is rock mass density; aM - is wave velocity in the rock mass.
Due to the fact that the impact on the fluid by static pressure and by the shock waves is effected simultaneously minimal losses of the wave energy delivered into the stratum are achieved thus reducing significantly energy consumption for running the process.
Due to the fact that the static pressure value exceeds the value of capillary pressure appearing in the pores the amount of which prevails in size in the rocks decompacted the conformity of the static pressure in the fluid with the capillary pressure of the rock is provided thus providing running of the dilatant process of the rock decompaction and improving efficiency of the rock permeability increase.
The dilatant process of the rock fragmentation takes place as a result of shearing strain along the crystal faces or crystal block faces. In consequence of such shear strain the rock mass is covered with the uniform crack network and existing cracks, pores and capillars grow in size. At that the volume of the decompacted rock mass part increases due to elastic compression of the neighboring rock mass.
At that experiments proved that when the static pressure value is at least 1.3 times as much as the capillary pressure value optimal running of the dilatant process of rock decompaction is provided.
At that due to the fact that the shock wave amplitude is chosen as equal or exceeding the compressive or tensile stress the necessary conditions for running of the dilatant decompaction of the rocks are provided.
It should be noted that the necessary condition for dilatant decompaction is non-uniform loading of the rock mass zone covered with a wave at every instant, in particular presence of tensile stresses caused by this non-uniformity in micro- and macrovolumes of the rock mass decompaction.
At that the wave length is defined as commensurable with the depth of the stratum and the wave processing time is determined on the basis of the defined depth of the crack created in the stratum thus providing the wave length conformity with the rock characteristics as a result of which the wave energy losses for diffusion beyond the stratum decrease and the process of increasing in situ rock permeability runs more efficiently.
At the shallow depth stratum the wave length is limited according to the minimal value in such a way that it would be not less than the depth of the cracks created in the rock mass as the low amplitude wave will not spread through such the cracks.
Due to the fact that the wave is emitted along the fluid channel in the conditions of the wave conformance in the zones of section difference according to the equality of the wave (acoustic) impedance of the channels and the fluid channel section is changed towards the bottom in the wave emission zone according to the definite formula taking into account fluid density in the fluid channel, wave velocity in the fluid as well as wave velocity in the rock mass and the rock mass density the rock permeability increase is provided more efficiently. The invention is carried out as follows.
A well is drilled in the rock mass and a mineral stratum is uncovered.
The fluid impacted simultaneously by static pressure and by the shock waves is supplied into the well. At that the static pressure value is 1.3 times as much as the value of capillary pressure appearing in the pores the amount of which prevails in size in the rocks decompacted and compensates the rock pressure displacing the fluid from the capillars and pores towards the well.
The waves are supplied by the emitter from the surface with their transfer along the fluid channel with variable cross-section into the well with subsequent turning from the wave reflector to the stratum and the wave conformance conditions are provided in the zones of section difference according to the equality of the wave (acoustic) impedance of the channels thus creating conditions for full wave energy transmission.
The shock wave amplitude is chosen as equal or exceeding the compressive or tensile stress in the stratum plane providing dilatant strain and decompaction of the rock mass in the regime of non-uniform loading in the microvolumes caused by rock pressure difference on the lower and upper surfaces of the rock mass zone covered with the wave, and non-uniformities in the microvolumes caused by the capillary pressure difference due to different size of the pores and wave structure non- uniformity of the rock mass.
The wave length is defined as commensurable with the depth of the stratum and the wave processing time is determined on the basis of the defined depth of the crack created in the stratum thus reducing wave energy losses for diffusion beyond the stratum and improving efficiency of the process of increasing in situ rock permeability.
At that the process of dilatant rock decompaction takes place at the stress values which are much lower than the stress values at the process of traditional fragmentation by crushing that allows to reduce energy consumption. For example, at presence of tensile stresses of up to 5 MPa in the granite the stresses of up to 0.5 - 3 MPa applied in the plane perpendicular to the direction of tensile stress are sufficient for dilatant shear of the crystals along the faces.
The process of the rock decompaction and permeability increase is controlled from the surface concerning the rock permeability - fluid adsorption during its injection into the well. Thus, initially permeability is mainly up to 50mD for low- permeable rocks and in the process of simultaneous impact by the waves and by static pressure it gradually increases up to lOOOmD and more depending on the technological requirements. It can take from several minutes to several hours depending on the rock hardness.
Thus, the proposed engineering solution allows to improve efficiency of the process of increasing in situ rock permeability and decompaction, to reduce energy consumption at the work cost reduction.
Information sources
1. USSR Certificate of Authorship No. 1030540 IPC3 E21 B43/28, 1980.
2. USSR Certificate of Authorship No. 1240112 IPC3 E21 B43/28, 1983.

Claims

1. The method for increasing in situ rock permeability comprising uncovering a mineral stratum with a well, supplying fluid into the well, impact on the fluid by static pressure as well as by the shock waves of the definite structure with their transfer along the fluid channel into the well with subsequent turning from the wave reflector to the stratum and wave dilatant decompaction of the rocks characterized in that the impact on the fluid by static pressure and by the shock waves is effected simultaneously, at that the static pressure value is 1.3 times as much as the value of capillary pressure appearing in the pores the amount of which prevails in size in the rocks decompacted and the shock wave amplitude is chosen as equal or exceeding the compressive or tensile stress which is necessary for running of dilatant decompaction of the rocks.
2. The method according to claim 1, characterized in that wave length is defined as commensurable with the depth of the stratum and the wave processing time is determined on the basis of the defined depth of the crack created in the stratum according to the following formula:
L>X=Ta>A In where L - is depth of stratum;
λ - is wave length;
T - time of wave processing;
a - wave velocity;
Δ 1 - increase of depth of the crack created within one wave passage;
n - number of wave passages for providing estimated crack depth.
3. The method according to claim 1, characterized in that fluid channel section is changed towards the bottom in the wave emission zone according to the following formula: F>KO— (ί½ <½F HC ^Pw FMV /½O ¾ O>
where:
FJKO - is initial value of the fluid channel cross-section; is current value of fluid density; ¾ - is current value of wave velocity in the fluid; Fw- is current value of the fluid channel cross-section; pM- is rock mass density; aM - is wave velocity in the rock mass; FM- is cross-section of the rock mass zone covered with wave; PKO- is initial fluid density; ¾0 - is initial wave velocity in the fluid.
4. The method according to claim 1, characterized in that wave is emitted along the fluid channel in the conditions of the wave conformance in the zones of section difference according to the equality of the wave (acoustic) impedance of the channels:
FJKO PVKO ¾to~ / κ ¾tF»c ~^Pu ¾ FMi where : F^- is initial value of the fluid channel cross-section;
PK0- is initial fluid density; a^o - is initial wave velocity in the fluid;
PK- is current value of fluid density; a* - is current value of wave velocity in the fluid;
F¾- is current value of the fluid channel cross-section; pM- is rock mass density; aM - is wave velocity in the rock mass;
FM- is cross-section of the rock mass zone covered with wave.
PCT/UA2011/000088 2010-10-01 2011-09-28 Method for increasing in situ rock permeability WO2012044269A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
RU2013113278/03A RU2013113278A (en) 2010-10-01 2011-09-28 METHOD FOR IMPROVING ROCK PERMEABILITY AT THE DEPOSIT PLACE

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
UAU201011708U UA54998U (en) 2010-10-01 2010-10-01 Method for increase of permeability of rocks in place of bedding
UAU201011708 2010-10-01

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WO2012044269A1 true WO2012044269A1 (en) 2012-04-05

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20190032454A1 (en) * 2017-07-28 2019-01-31 Galex Energy Corp. Apparatus and method for in-situ permeability enhancement of reservoir rock
CN114739883A (en) * 2022-03-31 2022-07-12 中铁十一局集团第五工程有限公司 Generalized analysis method for rock expansion

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4342484A (en) * 1973-12-06 1982-08-03 Kennecott Corporation Well stimulation for solution mining
SU1240112A1 (en) * 1983-08-16 1988-05-15 Предприятие П/Я В-8664 Method of increasing rock permeability
SU1701896A1 (en) * 1989-02-01 1991-12-30 Криворожский горнорудный институт Method of improvement of permeability of rocks in place of their occurrence and equipment for its realization
GB2439632A (en) * 2006-06-22 2008-01-02 Schlumberger Holdings Method of pulse treatment for a bottom-hole formation zone

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4342484A (en) * 1973-12-06 1982-08-03 Kennecott Corporation Well stimulation for solution mining
SU1240112A1 (en) * 1983-08-16 1988-05-15 Предприятие П/Я В-8664 Method of increasing rock permeability
SU1701896A1 (en) * 1989-02-01 1991-12-30 Криворожский горнорудный институт Method of improvement of permeability of rocks in place of their occurrence and equipment for its realization
GB2439632A (en) * 2006-06-22 2008-01-02 Schlumberger Holdings Method of pulse treatment for a bottom-hole formation zone

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20190032454A1 (en) * 2017-07-28 2019-01-31 Galex Energy Corp. Apparatus and method for in-situ permeability enhancement of reservoir rock
CN114739883A (en) * 2022-03-31 2022-07-12 中铁十一局集团第五工程有限公司 Generalized analysis method for rock expansion

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UA54998U (en) 2010-11-25
RU2013113278A (en) 2014-11-20

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