CN114854384A - Blocking remover system and blocking removing method - Google Patents
Blocking remover system and blocking removing method Download PDFInfo
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- CN114854384A CN114854384A CN202110147982.7A CN202110147982A CN114854384A CN 114854384 A CN114854384 A CN 114854384A CN 202110147982 A CN202110147982 A CN 202110147982A CN 114854384 A CN114854384 A CN 114854384A
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- 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
- C09K8/52—Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning
- C09K8/524—Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning organic depositions, e.g. paraffins or asphaltenes
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- 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
- C09K8/52—Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning
- C09K8/528—Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning inorganic depositions, e.g. sulfates or carbonates
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- 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
- C09K8/54—Compositions for in situ inhibition of corrosion in boreholes or wells
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B37/00—Methods or apparatus for cleaning boreholes or wells
- E21B37/06—Methods or apparatus for cleaning boreholes or wells using chemical means for preventing, limiting or eliminating the deposition of paraffins or like substances
Abstract
The invention discloses a blocking remover system and a blocking removing method, and relates to the technical field of oil and gas production. The blocking remover system comprises a preposed acid and a main acid, wherein the preposed acid comprises the following components in percentage by weight: 8 to 12 percent of hydrochloric acid, 0.2 to 0.6 percent of first clay stabilizer, 0.5 to 1 percent of first corrosion inhibitor, 0.5 to 1 percent of first iron ion stabilizer, 1 to 2 percent of first water-lock releasing agent, 0.1 to 0.6 percent of first strong oxidant and the balance of water; the main acid comprises the following components in percentage by weight: 8 to 12 percent of hydrochloric acid, 1 to 3 percent of hydrofluoric acid or fluoboric acid, 0.5 to 1 percent of second corrosion inhibitor, 0.5 to 1 percent of second iron ion stabilizer, 1 to 2 percent of second water-unlocking agent, 0.2 to 0.6 percent of second clay stabilizer, 0.1 to 0.6 percent of second strong oxidant and the balance of water. The blocking remover system achieves the purpose of removing the composite blocking of the fluid entering the well and the mud blocking.
Description
Technical Field
The embodiment of the invention relates to the field of oil and gas production, in particular to a blocking remover system and a blocking removing method.
Background
The northaceous gas field is located in three lake areas of the Qinghai province, the Chaudhur basin, the Meyer lake and the Dabunson lake, mainly comprises three gas fields of the first acerbit, the second acerbit and the south Taiwan, and is a typical loose sandstone gas reservoir in China. The harsh north gas field is affected by low pressure of a reservoir, water yielding, sand yielding and other reasons, clay migration blockage, pollution of fluid entering the well and deterioration of physical properties of the reservoir occur successively, and implementation of measures for increasing and stabilizing yield of the oil and gas field is affected, so that the blockage removal problem of the blockage removal is urgently needed to be solved.
Aiming at reservoir shale blockage, the related technology mainly adopts an acidification blockage removal method which mainly adopts earth acid to remove blockage, and aiming at blockage caused by leakage of xanthan gum and guanidine gum in well killing fluid, sand washing fluid and sand control fluid, the related technology mainly adopts modes of adding biological enzyme in an acid liquor system and the like to degrade in the aspects of removing filter cake of a guanidine gum fracturing fluid system and blockage of residues after gel breaking.
In the course of implementing the present invention, the inventor finds that the related art has at least the following technical problems:
the blockage caused by the leakage of xanthan gum in the well killing fluid, the sand washing fluid and the sand control fluid is not reported in a public way, and the blockage removing agent and the blockage removing method for the composite blockage caused by the leakage of the biogums such as the xanthan gum, the guanidine gum and the like in the reservoir shale and the well entering fluid are not reported in a public way.
Disclosure of Invention
The embodiment of the invention provides a composite blocking remover system and a blocking removal method, which aim to solve the problem that a method for removing the blocking of composite blocking of fluid blocking and argillaceous blocking in a reservoir is not provided in the related art.
The technical scheme is as follows:
in one aspect, the embodiment of the present invention provides a blocking remover system, which comprises a pre-acid and a main acid,
the pre-acid comprises the following components in percentage by weight: 8 to 12 percent of hydrochloric acid, 0.2 to 0.6 percent of first clay stabilizer, 0.5 to 1 percent of first corrosion inhibitor, 0.5 to 1 percent of first iron ion stabilizer, 1 to 2 percent of first water-lock releasing agent, 0.1 to 0.6 percent of first strong oxidant and the balance of water;
the main acid comprises the following components in percentage by weight: 8 to 12 percent of hydrochloric acid, 1 to 3 percent of hydrofluoric acid or fluoboric acid, 0.5 to 1 percent of second corrosion inhibitor, 0.5 to 1 percent of second iron ion stabilizer, 1 to 2 percent of second water-unlocking agent, 0.2 to 0.6 percent of second clay stabilizer, 0.1 to 0.6 percent of second strong oxidant and the balance of water.
Optionally, the host acid comprises the following components in percentage by weight: 8 to 10 percent of hydrochloric acid, 1 to 2 percent of hydrofluoric acid or 2 to 3 percent of fluoboric acid, 0.8 to 1 percent of second corrosion inhibitor, 0.8 to 1 percent of second iron ion stabilizer, 1.5 to 2 percent of second water-locking releasing agent, 0.3 to 0.5 percent of second clay stabilizer, 0.2 to 0.5 percent of second strong oxidant and the balance of water.
Optionally, the first strong oxidizer and the second strong oxidizer are both ammonium persulfate.
Optionally, the first corrosion inhibitor and the second corrosion inhibitor are both ketone aldehyde amine polycondensate corrosion inhibitors or quinoline acidification corrosion inhibitors; the first water-lock releasing agent and the second water-lock releasing agent are both silicon-fluorine water-lock releasing agents.
Optionally, the first iron ion stabilizer and the second iron ion stabilizer are isoascorbic acid type iron ion stabilizers, and the first clay stabilizer and the second clay stabilizer are trimethyl allyl ammonium chloride or potassium chloride.
Optionally, the main acid further comprises the following components in percentage by weight: 2 percent of foaming agent.
Optionally, the blowing agent is an imidazoline based blowing agent.
In another aspect, an embodiment of the present invention provides a deblocking method, where the deblocking method is performed using the deblocking agent system, and the deblocking method includes:
preparing the pre-acid according to the weight percentage of each component;
preparing the main acid according to the weight percentage of each component;
sequentially injecting the pre-acid and the main acid into the well to be unblocked;
and closing the well and reacting for 0.5-2h to finish the blockage removal of the well to be blocked.
Optionally, the volume ratio of the pre-acid to the host acid is 2: 3-20.
Optionally, the preparing the pre-acid or the main acid according to the weight percentage of each component comprises: and uniformly mixing other components except the first strong oxidant or the second strong oxidant in the pre-acid or the main body acid, adding the strong oxidant before injecting the pre-acid or the main body acid into the well to be unplugged, and uniformly mixing to obtain the pre-acid or the main body acid.
The technical scheme provided by the embodiment of the invention has the beneficial effects that at least:
(1) the blocking remover system provided by the embodiment of the invention comprises a front acid and a main acid, wherein the front acid and hydrochloric acid in the main acid can erode carbonate in a reservoir, hydrofluoric acid or fluoroboric acid in the main acid can erode argillaceous substances, and the front acid and a strong oxidant in the main acid can enhance the removal of biological gum blockage such as xanthan gum, guanidine gum and the like leaked from a fluid entering a well in an acid environment.
(2) In the blocking remover system of the embodiment of the invention, the water-releasing locking agent can reduce the capillary force and promote the flowback; the clay stabilizer can prevent the reservoir clay from swelling; the iron ion stabilizer achieves the effect of preventing iron ions from precipitating.
(3) The blocking remover system provided by the embodiment of the invention can achieve the purpose of removing the composite blocking of the fluid blocking and the argillaceous blocking of the well under the complex blocking condition of the reservoir stratum, is suitable for the complex blocking condition of the low-temperature low-pressure loose sandstone reservoir stratum, has the characteristics of preventing the secondary sedimentation of the reservoir stratum and being easy to flowback, is low in cost, and meets the requirement of the residual liquid flowback under the low formation pressure coefficient of the harsh north gas field.
(4) The blockage removing method adopting the blockage removing agent system provided by the embodiment of the invention has the characteristics of high efficiency, rapidness and simplicity in operation, and indicates the direction for removing the blockage of the stopped lying well caused by fluid loss in the well of the northbound gas field and the mud blockage of the near wellbore zone.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a graph showing the time-dependent changes of the pump pressure and the displacement in the field construction provided in example 1;
FIG. 2 is a graph showing the time-dependent changes in pump pressure and displacement during construction in the field as provided in example 2.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more clear, embodiments of the present invention will be described in further detail below.
The northbound gas field is a typical domestic low-temperature low-pressure loose sandstone gas reservoir, the total number of wells is 1031, more than 60 wells stop lying due to various reasons at present, wherein the wells stop lying due to clay migration blockage, well entering fluid pollution, poor reservoir physical property and the like are affected by reservoir low pressure, water outlet, sand outlet and the like, about 20-30 wells stop lying at present, and the blockage of the reservoir in which the wells stop lying is generally a composite blockage formed by well entering fluid blockage and mud blockage.
The plugging of the well entering fluid, such as the damage to the reservoir caused by the leakage of xanthan gum and guanidine gum in the well killing fluid, the sand washing fluid and the sand control fluid or the failure of large-dose fracturing fluid to flow back, causes the complex plugging of the low-temperature and low-pressure reservoir caused by the plugging of the well entering fluid and the muddy plugging.
The xanthan gum is acid-resistant and alkali-resistant, and is ineffective by biological enzyme gel breaking, so that the xanthan gum is difficult to degrade, and the xanthan gum can be degraded by adopting a strong oxidant gel breaking method, but because the temperature of a low-temperature low-pressure reservoir is lower, about 40-50 ℃, and the degradation effect of the strong oxidant on the xanthan gum in the temperature range is poor, a blocking remover system is required to be provided, and the blocking remover system is suitable for degrading the xanthan gum and the guanidine gum in the low-temperature low-pressure reservoir.
A first aspect of embodiments of the present invention provides a deblocking agent system, including a pre-acid and a bulk acid;
the pre-acid comprises the following components in percentage by weight: 8 to 12 percent of hydrochloric acid, 0.2 to 0.6 percent of first clay stabilizer, 0.5 to 1 percent of first corrosion inhibitor, 0.5 to 1 percent of first iron ion stabilizer, 1 to 2 percent of first water-lock releasing agent, 0.1 to 0.6 percent of first strong oxidant and the balance of water;
the main acid comprises the following components in percentage by weight: 8 to 12 percent of hydrochloric acid, 1 to 3 percent of hydrofluoric acid or fluoroboric acid, 0.5 to 1 percent of a second corrosion inhibitor, 0.5 to 1 percent of a second iron ion stabilizer, 1 to 2 percent of a second water-lock release agent, 0.2 to 0.6 percent of a second clay stabilizer, 0.1 to 0.6 percent of a second strong oxidant and the balance of water.
The blocking remover system provided by the embodiment of the invention comprises the preposed acid and the main acid, wherein the preposed acid can erode most of carbonate in a reservoir, and the main acid can erode argillaceous substances and residual carbonate, so that the reservoir damage caused by the secondary precipitation of calcium fluoride in the reservoir can be prevented, and the blocking removal effect is prevented from being poor. Under an acidic condition, the degradation performance of a strong oxidant (comprising a first strong oxidant and a second strong oxidant) can be enhanced, the strong oxidant can accelerate the degradation speed of xanthan gum and guanidine gum leaking into a reservoir stratum from a fluid entering a well at a low temperature of 40-50 ℃, and the blocking remover system can also remove the argillaceous blockage caused by loosening, falling, migration and the like of the reservoir stratum, so that the blocking remover system can realize the blocking removal of the composite blockage caused by the biogum and argillaceous blockage in the fluid entering the well from low-temperature loose sandstone.
Optionally, the main acid comprises the following components in percentage by weight: 8 to 10 percent of hydrochloric acid, 1 to 2 percent of hydrofluoric acid or 2 to 3 percent of fluoboric acid, 0.8 to 1 percent of second corrosion inhibitor, 0.8 to 1 percent of second iron ion stabilizer, 1.5 to 2 percent of second water-locking releasing agent, 0.3 to 0.5 percent of second clay stabilizer, 0.2 to 0.5 percent of second strong oxidant and the balance of water.
According to the embodiment of the invention, the hydrochloric acid can be selected to be industrial hydrochloric acid with the mass fraction of 30%, and hydrochloric acid in the front acid and the main acid is used for eroding the carbonate component in the plug.
The hydrofluoric acid is industrial hydrogen fluoride with the mass fraction of 30%, and the hydrofluoric acid and the fluoboric acid are used for corroding muddy components in the plug.
The hydrochloric acid, the hydrofluoric acid or the fluoboric acid can also provide an acid environment, so that the capability of degrading biological gums such as xanthan gum, guar gum and the like by the strong oxidant is enhanced under the low-temperature condition, and the blockage of the biological gums such as xanthan gum, guar gum and the like leaked from the fluid entering the well is removed.
According to the embodiment of the invention, the first corrosion inhibitor and the second corrosion inhibitor may be the same or different, and both the first corrosion inhibitor and the second corrosion inhibitor are acidizing corrosion inhibitors, illustratively, ketone-aldehyde amine polycondensate corrosion inhibitors or quinoline acidizing corrosion inhibitors.
For example, the ketoamine polycondensate corrosion inhibitor may be one as described in the paper by Zhang Hongyu et al (synthesis and performance study of a novel ketoamine aminated corrosion inhibitor), or a commercially available product such as LHSH-1, a ketoamine polycondensate corrosion inhibitor produced and sold by Xinjiang Hei and chemical Limited may be used.
The quinoline acidification corrosion inhibitor can utilize a compound acidification corrosion inhibitor which can resist the temperature of 120-140 ℃ as described in patent document CN107418549A, or a quinoline biquaternary ammonium acidification corrosion inhibitor as described in the paper (synthesis and performance evaluation of quinoline biquaternary ammonium acidification corrosion inhibitor) of Zhengyunxiang and the like. Or, the quinoline acidification corrosion inhibitor can also adopt a commercially available quinoline acidification corrosion inhibitor, for example, an acidification corrosion inhibitor QHS-H produced and sold by China Qinghai oil field integrity chemical auxiliary factory, and the chemical components of the acidification corrosion inhibitor QHS-H are as follows: quinolines. The appearance is transparent and uniform liquid, and the chemical properties are as follows: PH is less than or equal to 7, a uniform dispersion system can be formed in the earth acid, and the corrosion speed is less than or equal to 3 g/(m) in an acidification corrosion inhibitor system with the temperature of 60 ℃, the mass percent of 12% of HCl, the mass percent of 3% of HF and the mass percent of 0.5% 2 H). Or, the corrosion inhibitor can also be an acidification corrosion inhibitor QHS-M produced and sold by Asahi chemical technology Limited company of Jiang, Changzhou city.
According to the embodiment of the invention, the first clay stabilizer and the second clay stabilizer can be the same or different, optionally, the first clay stabilizer and the second clay stabilizer are acidizing clay stabilizers, and the acidizing clay stabilizer is added into an acid liquor system, so that damages such as reservoir clay expansion, migration and the like caused in the acidizing process can be prevented, and the clay stabilizer can also be used as an anti-expansion aid in working fluids with other measures.
Optionally, the first clay stabilizer and the second clay stabilizer are both trimethyl allyl ammonium chloride or potassium chloride. Or, the product can also be a commercial product, such as a clay stabilizer QNW-A produced and sold by Xian Jianxiang chemical company Limited, the anti-swelling rate of which is more than or equal to 85, the short-term anti-swelling rate is high, the flowback is easy to occur, the damage to the stratum is small, and the compatibility with various acid systems and other additives is good.
According to the embodiment of the invention, the first iron ion stabilizer and the second iron ion stabilizer can be the same or different, and optionally, the first iron ion stabilizer and the second iron ion stabilizer are both iron ion stabilizers for acidification, so that the secondary precipitation of iron ions after the pH value of an acid liquor system is increased can be prevented, and the secondary damage of a reservoir can be prevented.
Alternatively, the first iron ion stabilizer and the second iron ion stabilizer are isoascorbic acid type iron ion stabilizers, such as isoascorbic acid or sodium erythorbate, and may also be, for example, iron ion stabilizer isoascorbic acid VTW-II for acidification produced and sold by Weifang Tianyang oil technology Limited, or iron ion stabilizer QTW-C produced and sold by Cheng chemical assistant factory in China Petroleum Qinghai oilfield. The iron ion stabilizer has strong iron ion complexing capability, small damage to stratum and good compatibility with various acid systems and other additives.
The water-lock releasing agent has the characteristics of low density and low interfacial tension, can change the wettability of a reservoir, reduce the capillary force, is easy to flowback, and has good compatibility with clear water and formation water.
According to the embodiment of the invention, the first water-locking releasing agent and the second water-locking releasing agent can be the same or different, and optionally, the first water-locking releasing agent and the second water-locking releasing agent are both silicon fluorine type water-locking releasing agents, such as water-locking releasing agent QJW-O of China Petroleum Qinghai oilfield integrity chemical auxiliary factory, water-locking releasing agent WCX-005 produced and sold by Weifang Cheng Xiang chemical engineering Limited liability company, or QZP-A (surface tension (25 ℃, 1.0% aqueous solution) is less than or equal to 25mN/m, and interfacial tension (25 ℃, 1.0% aqueous solution) is less than or equal to 2.0mN/m) produced and sold by Semian Asian Petroleum science Limited company.
According to the embodiment of the present invention, the first strong oxidant and the second strong oxidant may be the same or different, and optionally, both the first strong oxidant and the second strong oxidant are (NH) 4 ) 2 S 2 O 8 The ammonium persulfate is widely used for fracturing fluid gel breaking and polymer degradation in the field of oilfield development.
In the embodiment of the invention, a strong oxidant ammonium persulfate is added into the blocking remover system, and under an acidic condition, the ammonium persulfate can degrade biogums such as xanthan gum, guanidine gum and the like leaked from fluid entering a well, so that the aim of removing biogum blocking is fulfilled.
According to the embodiment of the invention, when the reservoir pressure coefficient is low, such as the reservoir pressure coefficient is between 0.4 and 0.7, the main body acid further comprises the following components in percentage by weight: blowing agent 2%, optionally the bulk acid comprises a blowing agent. The foaming agent is an acidifying foaming agent, can be selected from imidazoline foaming agents, is also called imidazoline surfactants, such as lauryl amphoteric imidazoline, coco amphoteric imidazoline and the like, and can also be referred to imidazoline surfactants related to written papers (imidazoline surfactants and applications thereof) of the horse waves and the like ， Has the advantages of strong foaming ability, good stability, resistance to pollution of oil, salt and calcium ions, good compatibility with acid liquor, and no precipitation and delamination. For example, the foaming amount (1% of the amount) of the imidazoline-based acidification foaming agent is more than or equal to 450mL, and the half life period is more than or equal to 200 s.
The blocking remover system provided by the embodiment of the invention is convenient to use and can be flexibly applied according to the blocking type of the stopped lying well. If the well is stopped to lie, only the near-wellbore zone is muddy and blocked due to the falling and the transportation of loose sandstone particles, and the history of the leakage of the fluid entering the well due to various sand washing, killing and preventing operations is not combined, the blockage can be removed by directly applying an acid system without adding ammonium persulfate; if the well is stopped to lie down and the mud blockage and the history of the leakage of the fluid entering the well are combined, a certain amount of ammonium persulfate is added into an acid liquor system by referring to the leakage amount of the fluid entering the well, the type of the biogel and the application concentration, and the blockage removal work is carried out by an optimization process.
According to the blocking remover system disclosed by the embodiment of the invention, mud in the composite blocking object is corroded by hydrochloric acid, hydrofluoric acid or fluoroboric acid, and an acidic condition is provided, so that the capability of a strong oxidant for degrading biological gums such as xanthan gum, guar gum and the like under a low-temperature condition is enhanced, the well fluid leaked into a reservoir is degraded, and the purpose of composite blocking of the well fluid and the mud under the blocking removing condition is achieved.
The blocking remover system provided by the embodiment of the invention is suitable for removing the composite blocking of the well-entering fluid blocking and the argillaceous blocking of a low-temperature low-pressure loose sandstone reservoir, can be used for complex (well-entering fluid + argillaceous) blocking of loose sandstone gas reservoirs in harsh north gas fields according to the type, the preparation concentration and the leakage amount of the well-entering fluid and by combining the comprehensive consideration of the argillaceous blocking degree in the near wellbore region, can effectively remove biogums and argillaceous blockages lost by the well-entering fluids such as xanthan gum and guanidine gum, has the characteristics of preventing secondary sedimentation of the reservoir and being easy to flowback under the condition of low temperature and low pressure, and is low in preparation cost.
Another aspect of the embodiments of the present invention provides a deblocking method, which is implemented by using the above deblocking agent system, and the deblocking method includes:
And 2, preparing a main acid according to the weight percentage of each component.
and 4, closing the well and reacting for 0.5-2h to finish the blockage removal of the well to be blocked.
According to the blockage removing method provided by the embodiment of the invention, the preposed acid and the main acid are sequentially injected into the well to be blocked, and the well is closed for reaction, so that the blockage removing operation is completed, carbonate in a reservoir is corroded by hydrochloric acid, argillaceous substances are corroded by hydrofluoric acid or fluoroboric acid, and the biogum gum, guanidine gum and the like entering the well are degraded by strong oxidant ammonium persulfate under an acidic environment, so that biogums such as xanthan gum, guanidine gum and the like entering the reservoir due to sand prevention liquid, sand washing liquid and well killing leakage are broken, the viscosity of the biogum gum, guanidine gum and the like is reduced, and the aim of removing the blockage of the stratum along with the discharge of return fluid is fulfilled; and simultaneously, the mud blockage of the pore throat due to loose and falling of the reservoir and migration blockage is also removed, so that the aims of solving the mud blockage of the well to be unblocked and the composite blockage of the fluid (xanthan gum and guanidine gum) entering the well are fulfilled.
In the step 1, preparing the pre-acid according to the weight percentage of each component, comprising the following steps: and uniformly mixing other components except the first strong oxidant in the pre-acid, adding the first strong oxidant before injecting into the well to be unplugged, and uniformly mixing to obtain the pre-acid.
Illustratively, the process of formulating the pre-acid comprises: according to the weight percentage of each component, adding water into a liquid storage tank provided with a stirrer, then adding a corrosion inhibitor into the liquid storage tank through a dosing funnel, after uniformly stirring, sequentially adding hydrochloric acid, a water-releasing locking agent, an iron ion stabilizer, a clay stabilizer and optionally a foaming agent, uniformly stirring through the stirrer, adding a strong oxidizing agent before the blockage removal operation is started, and uniformly stirring to obtain the preposed acid.
In step 2, preparing a main acid according to the weight percentage of each component, comprising: and uniformly mixing other components except the second strong oxidant in the main body acid, and adding the second strong oxidant before injecting the main body acid into the well to be unplugged to obtain the main body acid.
Illustratively, the process of formulating the host acid comprises: according to the weight percentage of each component, adding water into a liquid storage tank provided with a stirrer, then adding a corrosion inhibitor into the liquid storage tank through a dosing funnel, after uniformly stirring, sequentially adding hydrochloric acid, hydrofluoric acid or fluoroboric acid, a water-unlocking agent, an iron ion stabilizer, a clay stabilizer and optionally a foaming agent, uniformly stirring through the stirrer, adding a strong oxidant before the blockage removal operation is started, and uniformly mixing to obtain a main acid.
In the step 3, a pre-acid and a main acid are injected into the blockage relieving well in sequence, wherein the volume ratio of the pre-acid to the main acid is 2:3-20, and can be 2:3-10, such as 2:3, 2:5, 2:6, 2:8, 2:10 and the like.
In the step 4, the well is closed for reaction for 0.5-2 h.
In the embodiment of the invention, after the pre-acid and the main acid are injected in sequence, the well is closed for reaction, the pre-acid is added into the well to be deblocked, the reservoir stratum of the well to be deblocked is pretreated by the pre-acid to erode most of carbonate, and the main acid plays a role in eroding argillaceous substances and residual carbonate, so that the reservoir stratum is prevented from being damaged due to secondary precipitation of calcium fluoride in the reservoir stratum, and the acidizing and deblocking effects are prevented from being deteriorated.
In the embodiment of the invention, the well closing reaction is carried out for 1-1.5h, such as 1 h. The purpose of removing the blockage of the to-be-removed well which is compositely blocked by the fluid and the argillaceous substances entering the well can be realized within the well closing reaction time, the blockage removing method adopting the blockage removing agent is efficient, quick and easy to operate, and the difficult problem of complex blockage removal of a reservoir is solved.
In an optional embodiment, after the well shut-in reaction is finished, the blockage removing operation of the well to be blocked is finished through gas lift flowback.
In another optional implementation mode, a blocking remover added with a foaming agent for acidification is injected into a well to be blocked, nitrogen is simultaneously injected in the process that the blocking remover enters the well, a uniform foam system is formed, flowback is carried out, and blocking removal operation is completed.
In the embodiment of the invention, when a gas lift flowback mode is adopted, the blocking remover system does not comprise a foaming agent, and for a well with a lower reservoir pressure coefficient, if the reservoir pressure coefficient is between 0.4 and 0.7, a foaming agent for acidification needs to be added into the blocking remover, and nitrogen is injected into the blocking remover in the well entering process to form a uniform foam system, so that the aim of improving the difficulty in flowback of residual acid of the acidizing fluid under the condition of low formation pressure coefficient is fulfilled.
The blockage removing method provided by the embodiment of the invention is efficient, quick and easy to operate, can solve the composite blockage of fluid entering a well and muddy blockage, adopts the blockage removing agent system and the blockage removing method provided by the embodiment of the invention to carry out blockage removing measures on the blocked wells in the harsh northern gas field, has the measure success rate of 100 percent, and successfully produces the blockage after the blockage removing of the composite blockage, as shown in the embodiment 1 and the embodiment 2, becomes a main measure means for solving the composite blockage removing for the complex blockage of the low-temperature low-pressure loose sandstone well, and points out the direction for the leakage of the fluid entering the well in the harsh northern gas field due to various reasons and the recovery of the blocked wells in the muddy blockage in the near well zone.
The following examples will illustrate the invention in further detail by way of example:
in the following examples:
HCl: industrial hydrochloric acid with a mass concentration of 30%, manufacturer: nanjing Linte chemical Co., Ltd;
HF: industrial hydrofluoric acid with a mass concentration of 30%, manufacturer: guangyo chemical Co., Ltd, Shandong Binzhou;
the corrosion inhibitor QHS-M for acidification is prepared by a manufacturer: changzhou city Jiangxu chemical technology Limited;
clay stabilizer QNW-a for acidification, manufacturer: sa Ann Jian Xiang chemical Co., Ltd;
iron ion stabilizer QTW-C for acidification, manufacturer: qinghai oilfield integrity aid factories;
the water-unlocking agent QJW-O is prepared by the following manufacturers: qinghai oilfield integrity aid factories;
ammonium persulfate, manufacturer: shanxi Baozi Tech Limited liability company.
Example 1
The embodiment 1 provides a blocking remover system and discloses application of the blocking remover system in a 2-25 well of a low-temperature low-pressure loose sandstone gas reservoir gas well.
The well 2-25 is a sand control well, production is stopped in the production process of 20 days in 5 months in 2020, and the well is not produced again after 0.3 percent xanthan gum sand washing liquid is used for conventional sand washing operation in 23 days in 5 months. And 5, 24 days after the well is developed for 5 months, gas lift air circulation is performed when skid-mounted gas lift operation is carried out, no gas is produced, and water is produced, so that the condition that sand washing liquid leakage and clay composite blockage occur in the well area close to the well is judged.
The blockage removing agent system provided by the embodiment of the invention is adopted to carry out blockage removing operation on the astringent 2-25 well, and the adopted blockage removing agent system comprises preposed acid and main acid.
The pre-acid comprises the following components in percentage by weight: 8% of HCl, 0.6% of QNW-A, 1% of QHS-M, 1% of QTW-C, 2% of QJW-O, 0.2% of ammonium persulfate and the balance of water.
The main acid comprises the following components in percentage by weight: 8% of HCl, 1.5% of HF, 0.6% of QNW-A, 1% of QHS-M, 1% of QTW-C, 2% of QJW-O, 0.2% of ammonium persulfate and the balance of water.
Preparing 10-square preposed acid according to weight percentage, adding water into a liquid storage tank provided with a stirrer, then adding 1% of QHS-M into the liquid storage tank through a dosing funnel, after uniformly stirring, sequentially adding 8% of HCL, 1% of QNW-A, 1% of QTW-C and 2% of QJW-O, uniformly stirring through the stirrer, pumping into a pulling transport vehicle through a centrifugal pump, adding 0.2% of ammonium persulfate before an injection well, and uniformly mixing to obtain the preposed acid.
Preparing 15-square main body acid according to weight percentage, adding water into a liquid storage tank provided with a stirrer, then adding 1% of QHS-M into the liquid storage tank through a dosing funnel, after uniformly stirring, sequentially adding 8% of HCL, 1.5% of HF, 1% of QNW-A, 1% of QTW-C and 2% of QJW-O, uniformly stirring through the stirrer, pumping into a pulling and transporting vehicle through a centrifugal pump, adding 0.2% of ammonium persulfate before an injection well, and uniformly mixing to obtain the main body acid.
Sequentially injecting 10-square preposed acid and 15-square main body acid into the astringent 2-25 well, and injecting a 25-square blocking remover system, wherein a blocking removal field construction curve of the astringent 2-25 well is shown in figure 1. As can be seen from figure 1, the pressure drop is obvious in the construction process, the pressure is reduced from more than 25MPa to 5MPa, after the well is closed and reacts for 1 hour, the well smoothly completes the blockage removing operation through gas lift flowback, the well successfully enters the station for production, and the situation that the blockage of the near-wellbore zone is completely removed and the construction is successful is shown.
The daily gas yield is 0.81 ten thousand after the blockage removal of 2-25 wells, and the current production condition is stable.
Example 2
This example 2 provides a deblocking agent system and discloses its application in low temperature low pressure open sand gas reservoir gas well astringency R28-3 wells.
The astringent R28-3 well is used for carrying out major repair and fracturing sand control operation in 5 months in 2020 and is injected with 300 formulations of fracturing fluid. And then the well can not be put into the station for production, the air lift has an empty circulation phenomenon, the pressure of the manual oil extraction assisting sleeve is reduced to 0MPa, no air or water is discharged, the phenomenon of reservoir blockage is shown, and the well is diagnosed to be compositely blocked due to large-dose guanidine gum fracturing fluid and clay migration.
The blocking remover system provided by the embodiment 2 of the invention is adopted for blocking removal, and the adopted blocking remover system comprises a preposed acid and a main acid.
The pre-acid comprises the following components in percentage by weight: 10% of HCL, 0.5% of trimethyl allyl ammonium chloride, 0.8% of ketone-aldehyde amine polycondensate corrosion inhibitor, 0.7% of sodium erythorbate, 1.5% of WCX-005, 0.5% of ammonium persulfate and the balance of water;
the main acid comprises the following components in percentage by weight: 10% of HCL, 2% of HF, 0.5% of trimethyl allyl ammonium chloride, 0.8% of ketoaldehyde amine polycondensate corrosion inhibitor, 0.7% of sodium erythorbate, 1.5% of WCX-005, 0.5% of ammonium persulfate and the balance of water.
The preparation method of the deblocking agent system provided in example 2 can be seen in the preparation method of the deblocking agent system provided in example 1.
Sequentially injecting 10-square prepositive acid and 50-square main body acid into the astringent R28-3 well, and forming a 60-square blocking remover system, wherein the 60-square blocking remover system is shown as an astringent R28-3 well blocking removal field construction curve in figure 2. As can be seen from figure 2, the pressure drop is obvious in the construction process, the pressure is reduced from 11.5MPa to 6.5MPa, after the well is closed and reacts for 1 hour, the well is smoothly subjected to blockage removal operation through gas lift flowback, and a large amount of gas-liquid phase fluid is continuously returned from the wellhead, so that the composite blockage of the well is removed, and the construction is successful once.
The daily gas production after plugging removal of the astringent R28-3 well is 1.0 ten thousand square, and the current production condition is stable.
The above description is only exemplary of the present application and should not be taken as limiting the scope of the present application, as any modifications, equivalents, improvements and the like that are within the spirit and principle of the present application should be included in the present application.
Claims (10)
1. A deblocking agent system, wherein the deblocking agent system comprises a pre-acid and a bulk acid;
the pre-acid comprises the following components in percentage by weight: 8 to 12 percent of hydrochloric acid, 0.2 to 0.6 percent of first clay stabilizer, 0.5 to 1 percent of first corrosion inhibitor, 0.5 to 1 percent of first iron ion stabilizer, 1 to 2 percent of first water-lock releasing agent, 0.1 to 0.6 percent of first strong oxidant and the balance of water;
the main acid comprises the following components in percentage by weight: 8 to 12 percent of hydrochloric acid, 1 to 3 percent of hydrofluoric acid or fluoboric acid, 0.5 to 1 percent of second corrosion inhibitor, 0.5 to 1 percent of second iron ion stabilizer, 1 to 2 percent of second water-unlocking agent, 0.2 to 0.6 percent of second clay stabilizer, 0.1 to 0.6 percent of second strong oxidant and the balance of water.
2. The deblocking agent system according to claim 1, wherein the bulk acid comprises the following components in weight percent: 8 to 10 percent of hydrochloric acid, 1 to 2 percent of hydrofluoric acid or 2 to 3 percent of fluoboric acid, 0.8 to 1 percent of second corrosion inhibitor, 0.8 to 1 percent of second iron ion stabilizer, 1.5 to 2 percent of second water-locking releasing agent, 0.3 to 0.5 percent of second clay stabilizer, 0.2 to 0.5 percent of second strong oxidant and the balance of water.
3. The deblocking agent system of claim 1, wherein said first strong oxidizer and said second strong oxidizer are each ammonium persulfate.
4. The deblocking agent system according to claim 1, wherein said first corrosion inhibitor and said second corrosion inhibitor are both ketoaldehyde amine polycondensate-based corrosion inhibitors or quinoline-based acidizing corrosion inhibitors;
the first water-lock releasing agent and the second water-lock releasing agent are both silicon-fluorine water-lock releasing agents.
5. The deblocking agent system according to claim 1, wherein said first iron ion stabilizer and said second iron ion stabilizer are isoascorbic acid-based iron ion stabilizers;
the first clay stabilizer and the second clay stabilizer are both trimethyl allyl ammonium chloride or potassium chloride.
6. The deblocking agent system according to any one of claims 1-5, wherein said host acid further comprises the following components in weight percent: 2 percent of foaming agent.
7. The deblocking agent system of claim 6, wherein said blowing agent is an imidazoline based blowing agent.
8. A deblocking method, wherein the deblocking method is performed using the deblocking agent system according to any one of claims 1 to 7, the deblocking method comprising:
preparing the pre-acid according to the weight percentage of each component;
preparing the main acid according to the weight percentage of each component;
sequentially injecting the pre-acid and the main acid into the well to be unblocked;
and closing the well and reacting for 0.5-2h to finish the blockage removal of the well to be blocked.
9. The deblocking method according to claim 8, wherein the volume ratio of the pre-acid to the bulk acid is 2: 3-20.
10. The blockage relieving method according to claim 8 or 9, wherein the preparation of the pre-acid or the main acid according to the weight percentage of each component comprises: and uniformly mixing other components except the first strong oxidant or the second strong oxidant in the pre-acid or the main body acid, adding the first strong oxidant or the second strong oxidant before injecting the mixture into the well to be unplugged, and uniformly mixing to obtain the pre-acid or the main body acid.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115785931A (en) * | 2022-10-25 | 2023-03-14 | 何振涛 | Chelating blocking remover system for removing inorganic scale of gas well and blocking removing method |
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| CN105505360A (en) * | 2015-12-28 | 2016-04-20 | 中国石油化工股份有限公司 | Fluoroboric acid blocking remover and acidification de-blocking method |
| CN110452680A (en) * | 2019-08-16 | 2019-11-15 | 西安博宏石油科技有限公司 | The method for removing blockage of acidification blocking remover and its preparation method and application acidification blocking remover |
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| CN103740353A (en) * | 2013-12-16 | 2014-04-23 | 中国石油化工股份有限公司 | Composite blocking remover and method for removing blockage of compact sandstone reservoir pressing crack commissioning horizontal well in composite manner |
| CN105505360A (en) * | 2015-12-28 | 2016-04-20 | 中国石油化工股份有限公司 | Fluoroboric acid blocking remover and acidification de-blocking method |
| CN110452680A (en) * | 2019-08-16 | 2019-11-15 | 西安博宏石油科技有限公司 | The method for removing blockage of acidification blocking remover and its preparation method and application acidification blocking remover |
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