CN104912533A - Coal reservoir water locking damage control method - Google Patents
Coal reservoir water locking damage control method Download PDFInfo
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- CN104912533A CN104912533A CN201510238769.1A CN201510238769A CN104912533A CN 104912533 A CN104912533 A CN 104912533A CN 201510238769 A CN201510238769 A CN 201510238769A CN 104912533 A CN104912533 A CN 104912533A
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Abstract
The invention relates to a coal reservoir water locking damage control method, which comprises the following steps that:1, a ground coal-bed gas well subjected to fracturing transformation is selected; 2, reservoir coal samples are collected on sites, and the contact angle of water on the coal sample surface is tested in an indoor position; 3, quickly penetrating agents T and chlorine dioxides are added into fracturing fluid, the concentration of the quickly penetrating agents T is selected according to the contact angle of the water on the coal sample surface, and the concentration of the chlorine dioxide is selected according to the coal rank of the coal samples (the metamorphism degree of the coal samples); 4, after the quickly penetrating agents T and the chlorine dioxides are added, the uniformly stirred fracturing fluid can be used as ahead fluid, or is used as sand-carrying fluid to be subjected to joint hydraulic fracturing with non-active water fracturing fluid, and 20 to 30 cubic meters of active water fracturing fluid needs to be pumped between the ahead fluid and the sand-carrying fluid for isolation; and 5, the fracturing fluid return and discharging can start only after at least 3 hours from the hydraulic fracturing completion. The coal reservoir water locking damage control method has the advantages that the capillary resistance and the surface tension of a coal-bed gas reservoir layer are reduced; the reservoir layer water locking damage is reduced; the coal-bed gas reservoir layer is favorably protected; and the coal-bed gas recovery rate is favorably improved.
Description
Technical field
The invention belongs to CBM exploration and development coal bed gas well stimulation technology field, be specifically related to a kind of coal seam reservoirs water blocking damage control method.
Background technology
China's low-permeability, low face storage pressure ratio, low gas content saturation ratio conditions of coal bed gas reservoir be unfavorable for coal bed gas commercial development, domestic a lot of scholar reduces in close methane ability of coal seam reservoirs etc. in the anti-reflection technology of physics, chemical anti-reflection technology, chemical energy mode and is studied, and achieves certain effect to the transformation of coal seam reservoirs.But most achievement in research does not relate to or pays close attention to the formation damage problem that reservoir reconstruction causes.
Water-blocking effect is one of principal element causing coalbed methane reservoir to damage.Coalbed methane reservoir is a kind of porous media of complexity, outside fluid pushes gas in crack to reservoir deep after invading, and form a recessed meniscus to aqueous phase at gas-water interface, and then formation capillary resistance, when pressure differential between pore interior and external environment condition is not enough to overcome this capillary resistance, just hinder coal bed gas desorb and seepage flow, water lock occurs.Along with reservoir moisture content rises; coal bed gas desorption time extends and permeability reduction; have a strong impact on desorb diffuse seepage and the later stage exploitation of coal bed gas, therefore carry out the research of coal seam reservoirs water blocking damage control technology and be conducive to protecting coalbed methane reservoir, thus improve coal bed gas recovery ratio.
Summary of the invention
The object of the invention is to provide a kind of coal seam reservoirs water blocking damage control method, this method reduces coalbed methane reservoir surface tension and capillary resistance, decreases reservoir Water-blocking damage, is conducive to protection coalbed methane reservoir and improves coal bed gas recovery ratio.
For achieving the above object, the present invention adopts following technical scheme:
A kind of coal seam reservoirs water blocking damage control method, it comprises the steps:
1) the ground coal bed gas well carrying out fracturing reform is selected;
2) collection in worksite reservoir coal sample, indoor test water is at the contact angle on coal sample surface;
3) in fracturing fluid, add fast T and chlorine dioxide, select the concentration of fast T according to water at the contact angle on coal sample surface, according to the concentration of the selected chlorine dioxide in the coal rank (i.e. the degree of metamorphism of coal sample) of coal sample;
4) after adding fast T and chlorine dioxide and the fracturing fluid stirred can be used as prepad fluid, or carrying out associating fracturing as load fluid with nonactive water fracturing fluid, (namely between prepad fluid and load fluid) the active water fracturing fluid that need pump into 20-30 cubic meter is isolated between the two;
5) fracturing terminate after at least 3 hours, could start to return discharge fracturing fluid;
6) validity check, leading indicator comprises coal bed gas desorption time, reservoir permeability etc.
Concrete, in described step 3), the size of contact angle determines the concentration adding fast T, basic principle: 0 ° of < contact angle≤40 °, the fast T concentration≤500ppm of 100ppm <; 40 ° of < contact angle≤90 °, the fast T concentration≤1000ppm of 500ppm <; 90 ° of < contact angle≤180 °, the fast T concentration≤2000ppm of 1000ppm <.
In described step 3), the height on coal sample coal rank determines the concentration adding chlorine dioxide, basic principle: low-order coal, and chlorine dioxide concentration is 500-1000ppm; Scala media coal, the concentration of chlorine dioxide is 1000-2500ppm but does not comprise 1000ppm; High-order coal, the concentration of chlorine dioxide is 2500-5000ppm but does not comprise 2500ppm.
In described step 4), fracturing had both comprised the fracturing first of coal bed gas well, also comprised secondary fracturing transformation and the de-plugging construction of coal bed gas well.
Fast T and fast penetrant T, chemical name: disecoctylmaleate sodium sulfonate, belongs to anion surfactant.Nonactive water fracturing fluid can be conventional clean fracturing fluid, guanidine gum fracturing fluid, foam fracturing fluid etc.
A large amount of fracturing fluids can be injected coal seam reservoirs during fracturing, just water lock is there is in fracturing fluid after entering coal reservoir fracture, hinder coal bed gas desorb and seepage flow, cause coal bed gas desorption time to extend and permeability reduction, thus have a strong impact on desorb diffuse seepage and the later stage exploitation of coal bed gas.The present invention evenly admixes the fast T of surfactant of suitable concn in fracturing fluid, fracturing fluid is made to have more weak foaming characteristic and good surface-active, after using this fracturing fluid to carry out fracturing, reduce the contact angle on water and coal surface, reduce coalbed methane reservoir surface tension, capillary resistance and coal seam reservoirs free-boundary problem, add the desorption rate of coal bed gas, thus avoid the Water-blocking damage of fracturing fluid to coal seam reservoirs, improve coal bed gas recovery ratio.In addition, the present invention has evenly admixed the chlorine dioxide of selected concentration evenly admix the fast T of selected concentration in fracturing fluid while, fast T changes the wetability of hydrophobic coal seam reservoirs, chlorine dioxide along with fracturing fluid enter coal seam reservoirs hole and with coal seam reservoirs effect, reduce the close methane ability of coal seam reservoirs, add the desorption quantity of coal bed gas, add the permeability of coal seam reservoirs simultaneously.
Compared to the prior art, beneficial effect of the present invention:
After adding fast T, fracturing fluid has more weak foaming characteristic and good surface-active, reduces coalbed methane reservoir surface tension and capillary resistance, decreases reservoir Water-blocking damage, is conducive to protecting coalbed methane reservoir; Reduce reservoir free-boundary problem, add the desorption rate of coal bed gas, increase the permeability of reservoir, individual well daily output tolerance can be improved, thus improve coal bed gas recovery ratio.
Detailed description of the invention
Do to introduce in detail further to technical scheme of the present invention below in conjunction with embodiment, but protection scope of the present invention is not limited thereto.
embodiment 1
A kind of coal seam reservoirs water blocking damage control method, it comprises the steps:
1) the ground coal bed gas well carrying out fracturing reform is selected;
2) collection in worksite reservoir coal sample, indoor test water is at the contact angle on coal sample surface;
3) in fracturing fluid, add fast T and chlorine dioxide, select the concentration of fast T according to water at the contact angle on coal sample surface, select the concentration of chlorine dioxide according to the coal rank of coal sample; Specific Principles is: 0 ° of < contact angle≤40 °, the fast T concentration≤500ppm of 100ppm <; 40 ° of < contact angle≤90 °, the fast T concentration≤1000ppm of 500ppm <; 90 ° of < contact angle≤180 °, the fast T concentration≤2000ppm of 1000ppm <; Low-order coal, chlorine dioxide concentration is 500-1000ppm; Scala media coal, the concentration of chlorine dioxide is 1000-2500ppm but does not comprise 1000ppm; High-order coal, the concentration of chlorine dioxide is 2500-5000ppm but does not comprise 2500ppm.
4) after adding fast T and chlorine dioxide and the fracturing fluid stirred can be used as prepad fluid, or carry out associating fracturing as load fluid with nonactive water fracturing fluid, need the active water fracturing fluid pumping into 20-30 cubic meter to isolate between the two; In step 4), fracturing had both comprised the fracturing first of coal bed gas well, also comprised secondary fracturing transformation and the de-plugging construction of coal bed gas well;
5) fracturing terminate after at least 3 hours, could start to return discharge fracturing fluid;
6) validity check, leading indicator comprises coal bed gas desorption time, reservoir permeability etc.
Fracturing fluid after the present invention adds fast T has more weak foaming characteristic and good surface-active, reduces coalbed methane reservoir surface tension and capillary resistance, decreases reservoir Water-blocking damage, is conducive to protecting coalbed methane reservoir; Reduce reservoir free-boundary problem, add the desorption rate of coal bed gas, increase the permeability of reservoir, individual well daily output tolerance can be improved, thus improve coal bed gas recovery ratio.
Claims (4)
1. a coal seam reservoirs water blocking damage control method, is characterized in that, comprises the following steps:
1) the ground coal bed gas well carrying out fracturing reform is selected;
2) collection in worksite reservoir coal sample, indoor test water is at the contact angle on coal sample surface;
3) in fracturing fluid, add fast T and chlorine dioxide, select the concentration of fast T according to water at the contact angle on coal sample surface, select the concentration of chlorine dioxide according to the coal rank of coal sample;
4) after adding fast T and chlorine dioxide and the fracturing fluid stirred as prepad fluid, or carry out associating fracturing as load fluid with nonactive water fracturing fluid, need the active water fracturing fluid pumping into 20-30 cubic meter to isolate between the two;
5) fracturing terminate after at least 3 hours, could start to return discharge fracturing fluid.
2. coal seam reservoirs water blocking damage control method as claimed in claim 1, it is characterized in that, in described step 3), the size of contact angle determines the concentration adding fast T, basic principle: 0 ° of < contact angle≤40 °, the fast T concentration≤500ppm of 100ppm <; 40 ° of < contact angle≤90 °, the fast T concentration≤1000ppm of 500ppm <; 90 ° of < contact angle≤180 °, the fast T concentration≤2000ppm of 1000ppm <.
3. coal seam reservoirs water blocking damage control method as claimed in claim 1 or 2, it is characterized in that, in described step 3), the height on coal sample coal rank determines the concentration adding chlorine dioxide, basic principle: low-order coal, and chlorine dioxide concentration is 500-1000ppm; Scala media coal, the concentration of chlorine dioxide is 1000-2500ppm but does not comprise 1000ppm; High-order coal, the concentration of chlorine dioxide is 2500-5000ppm but does not comprise 2500ppm.
4. coal seam reservoirs water blocking damage control method as claimed in claim 1 or 2, is characterized in that, in described step 4), fracturing comprises the fracturing first of coal bed gas well, the secondary fracturing transformation of coal bed gas well and de-plugging construction.
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| CN201510238769.1A CN104912533B (en) | 2015-04-20 | 2015-05-12 | A kind of coal seam reservoirs water blocking damage control method |
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| CN104912533B CN104912533B (en) | 2017-10-24 |
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Cited By (3)
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| CN106867501A (en) * | 2017-02-22 | 2017-06-20 | 山西晋城无烟煤矿业集团有限责任公司 | A kind of coal seam reservoirs transparent agent based on aqueous sodium hypochlorite solution |
| CN107144671A (en) * | 2017-06-23 | 2017-09-08 | 中国电建集团贵阳勘测设计研究院有限公司 | Shale air water locks Effect Evaluation device and method under a kind of condition of high voltage |
| CN111271038A (en) * | 2020-03-12 | 2020-06-12 | 内蒙古科技大学 | Novel coalbed methane yield increasing method for low-permeability coal body |
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| CN111271038A (en) * | 2020-03-12 | 2020-06-12 | 内蒙古科技大学 | Novel coalbed methane yield increasing method for low-permeability coal body |
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