CN112574732A - Sandstone reservoir water injection well modified depressurization acidification method - Google Patents

Sandstone reservoir water injection well modified depressurization acidification method Download PDF

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CN112574732A
CN112574732A CN201910947606.9A CN201910947606A CN112574732A CN 112574732 A CN112574732 A CN 112574732A CN 201910947606 A CN201910947606 A CN 201910947606A CN 112574732 A CN112574732 A CN 112574732A
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acid
water
balance
reservoir
percentage
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张江
田相雷
冯庆伟
张丁涌
张秀生
万惠平
周杨
游龙潭
张伟
张世诚
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China Petroleum and Chemical Corp
Sinopec Shengli Oilfield Co Xianhe Oil Production Plant
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China Petroleum and Chemical Corp
Sinopec Shengli Oilfield Co Xianhe Oil Production Plant
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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
    • 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
    • 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
    • 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 or limiting, e.g. eliminating, the deposition of paraffins or like substances
    • 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

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Abstract

The invention relates to the field of oil and gas field development, in particular to a method for modifying, depressurizing and acidifying a water injection well of a sandstone reservoir. The modified depressurization acidification method is based on reservoir difference investigation, optimizes injection rate, keeps lower pH value of stratum, inhibits the precipitation of soil acid products, enlarges swept volume and improves effective acidification seepage section; the method has the advantages of optimizing the acid using procedure based on the research of secondary injury, avoiding secondary blockage, improving the utilization rate of acid liquor, reducing the measure cost, improving the operation timeliness and realizing safe and environment-friendly production.

Description

Sandstone reservoir water injection well modified depressurization acidification method
Technical Field
The invention relates to the field of oil and gas field development, in particular to a method for modifying, depressurizing and acidifying a water injection well of a sandstone reservoir.
Background
In recent years, with continuous innovation and development of acidizing plugging removal technologies, under the guidance of a regional differentiation injection concept, conventional acidizing technologies adopted for type I (permeability >20md, porosity > 18%) and type II (permeability 20md >10md, 19% > porosity > 10%) reservoirs are all four-step methods of acid treatment, washing, soaking and draining, and become the main technologies of old oilfield formation reformation, but at present, with the increase of acidizing frequency, the acidizing effect gradually deteriorates for the following reasons:
firstly, in the conventional acidification process, in a range slightly far away from a shaft, a primary reaction product slowly performs a secondary reaction to form a silica gel precipitate;
secondly, three reactions occur at a place farther away from the acid liquor injection area to form more silica gel precipitates;
thirdly, in the process of back drainage after acid liquor is injected into the stratum for reaction, the dredged near-wellbore area is easily blocked by secondary sedimentation and backflow of tertiary sediment;
fourthly, the closer the sediment is to the wellbore during the acidizing process, the more severe the pressure loss is caused.
Chinese patent application (CN104629712A) discloses a deep acidizing acid liquid and a method for realizing deep acidizing of a low-permeability sandstone reservoir, which are applied to acidizing transformation of the low-permeability sandstone reservoir of a Changqing oil field. The deep acidizing acid solution comprises: the acid liquid a comprises the following components in percentage by weight: hydrochloric acid, 10%; formic acid, 2%; acetic acid, 6%; 1% of corrosion inhibitor; 0.5 percent of cleanup additive; clay stabilizer, 0.5%; 0.1% of iron ion stabilizer; the balance of clear water; the deep acidizing acid liquid b comprises the following components in percentage by weight: 2% of hydrofluoric acid; 1.5 percent of corrosion inhibitor; CJ1-6, 0.1%; surfactant, 4%; salt, 0.2%; the balance being clear water. The deep acidification process comprises the following steps: low substitution of active water → low substitution of acid liquor a → closing of the sleeve gate → acidification of acid liquor a → acidification of acid liquor b → acidification of acid liquor a → substitution of active water → well closing and open flow.
Chinese patent application (CN104031625A) discloses a blocking remover for a hypotonic heterogeneous sandstone reservoir and a using method thereof. The blocking remover comprises an agent A, an agent B and an agent C, wherein the agent A, the agent B and the agent C comprise the following components in percentage by weight:
the agent A consists of 10-25% of oxidant, 8-12% of activating agent and the balance of water, wherein the oxidant is sodium nitrite, ammonium nitrite or potassium nitrite; the activator is hydrochloric acid or phosphoric acid or a mixture of hydrochloric acid and phosphoric acid;
the agent B consists of 10 to 15 percent of reducing agent, 0.3 to 1.2 percent of foaming agent, 0.3 to 0.6 percent of foam stabilizer and the balance of water, wherein the reducing agent is urea or sodium carbonate or ammonium bicarbonate; the foaming agent is betaine or sodium dodecyl sulfate; the foam stabilizer is polyacrylamide;
the C agent consists of 8-12% of HCL, 6-10% of organic acid, 22-5% of NH4HF, 0.5-1.5% of corrosion inhibitor, 0.5-1.5% of iron ion stabilizer and the balance of water, wherein the organic acid is organic phosphoric acid or acetic acid or organic sulfonic acid or citric acid; the corrosion inhibitor is hexadecylamine or sodium nitrate or hydroxyethylidene diphosphonic acid or diethylenetriamine penta phosphonic acid; the iron ion stabilizer is ethylenediamine tetraacetate, citrate or diethylenetriamine pentacarboxylate. The blocking remover is applied to depressurization and injection increase of a water injection well and deep blocking removal of an oil well, a large amount of gas and heat are generated after an agent A and an agent B react in a stratum, the gas and a foaming agent act to generate uniform stable bubbles, a high permeable layer can be effectively blocked, uniform acid distribution can be realized when subsequent acid liquid is injected, drilling mud pollution, scale pollution and solid particle blocking of the stratum can be eliminated, the stratum permeability is improved, and deep effective acidification is realized; the generated heat can remove organic blockage such as asphaltene, colloid and the like; the generated gas foam has high viscosity and strong carrying capacity, and can carry out the particles and secondary sediment generated after acidification out of a shaft during flowback, thereby increasing the effective rate of acidification.
The technology mainly solves the problems of deep pollution and deep acidification of the low-permeability reservoir, and acid liquor components are various and complex. In practical application, most oil fields still commonly use four-step acidification technologies of acid, washing, soaking and draining, and the problems that the effect of I, II hypotonic reservoir layers is poor and the effective period is shortened after multiple rounds of conventional acidification are not effectively solved.
Disclosure of Invention
The invention aims to provide a sandstone reservoir water injection well modified depressurization acidification method, which is used for solving the problem that the effect is poor after multiple rounds of acidification in the prior acidification technologies of I-type and II-type reservoirs by improving a construction method on the basis of simply adjusting an acid solution formula.
The object of the invention can be achieved by the following technical measures:
providing a plugging removal liquid, wherein the plugging removal liquid comprises a pretreatment acid liquid, a pre-acid liquid, a main treatment acid liquid and a post-acid liquid;
the pretreatment acid solution is 10-12% HCl solution;
the preposed acid solution comprises the following components in percentage by weight: 10-12% of HCl, 1-2% of iron ion stabilizer and the balance of water;
the main treatment acid solution comprises the following components in percentage by weight: HCl 10-12%, HF 1.5-2%, CH32% -4% of COOH and the balance of water;
the post acid solution comprises the following components in percentage by weight: HCl 10% -12%, CH32 to 4 percent of COOH and the balance of water.
Preferably, the IRON ion stabilizer is IRON-2066A.
The object of the invention can also be achieved by the following technical measures:
the method for realizing the modified depressurization acidification of the sandstone reservoir water injection well by using the plugging removal liquid comprises the following steps:
step one, the pressure test of the well head of the original water injection well is qualified, no leakage exists, the pump truck is connected with the oil pipe gate of the well head through a pipeline which is qualified in pressure test, and the pretreatment acid liquor is replaced by 5-15m3Replacing the injected water with the volume 0.5-1.0 times of that of the underground oil pipe, closing the casing gate, extruding the injected water with the volume 0.1-0.5 times of that of the underground oil pipe, closing the oil pipe gate, and reacting for 15-20 min; the positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads;
the pretreatment acid solution is an HCl solution with the concentration of 10% -12%, and is mainly used for rapidly reacting with oil, impurities and scales in a sleeve, removing pollution blockage of a shallow layer of a reservoir and opening a channel for subsequent acidification construction;
secondly, connecting a pump truck with a wellhead casing gate, discharging not less than 500L/min, replacing injected water with the volume 1.0-2.0 times of that of the underground casing, connecting an outlet with a gas-liquid separation tank, and thoroughly backwashing through the casing to clean residual acid and acidification reaction products in a shaft;
step three, replacing the pre-acid solution, wherein the using amount of the pre-acid solution is 25-30% of the acid amount used for acidizing the radius of the reservoir, and the discharge amount is not less than 200L/min; the preposed acid solution comprises the following components in percentage by weight: 10% -12% of HCl, 1% -2% of an iron ion stabilizer and the balance of water, wherein the preposed acid liquid is mainly used for preposing and dredging a reservoir, reducing the squeezing-in construction pressure of main acid and simultaneously preventing iron ions from entering a stratum to generate iron gel precipitation;
step four, replacing the main treatment acid liquor, wherein the using amount of the main treatment acid liquor is 40-50% of the acid used for the reservoir acidification treatment radius, the discharge capacity is not lower than 200L/min, after the shaft is filled with the acid liquor, the sleeve gate is closed, the discharge capacity is increased to be not lower than 500L/min, and all the main treatment acid liquor is left in a positive extrusion mode; the positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads; the main treatment acid solution comprises the following components in percentage by weight: 10% -12% of HCl, 1.5% -2% of HF, 2% -4% of CH3COOH and the balance of water; the main treatment acid liquor mainly erodes silicate minerals such as quartz, clay, slurry particles, mud cakes and the like in pores
Step five, positive squeezing in post acid liquor, wherein the using amount of the post acid liquor is 25-30% of the acid used for acidizing the radius of the reservoir, and the discharge amount is not less than 500L/min; the positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads; the post acid solution comprises the following components in percentage by weight: 10% -12% of HCl, 2% -4% of CH3COOH and the balance of water, wherein the post-acid solution is mainly used for preventing hydrofluoric acid from reacting with silicates such as clay and carbonate to generate precipitates, and meanwhile, the hydrochloric acid reacts with carbonate minerals in a sandstone reservoir, so that the hydrofluoric acid can fully play a role in eroding the clay;
and step six, positively extruding injected water with the volume of 1.0-1.5 times of that of the underground oil pipe, wherein the positive extrusion force is required to be controlled within the rated working pressure range of various well mouths according to different well mouth types.
Seventhly, closing the well and reacting for 1-2 h;
and step eight, after the procedures are finished, thoroughly flushing the ground flow pipeline, and normally injecting water after opening the well.
Preferably, the pre-acid, the main treatment acid and the post-acid are used according to different reservoir mud contents to be augmented, and the pre-acid, the main treatment acid and the post-acid are as follows in percentage by weight:
the content of reservoir mud to be injected is less than or equal to 15 percent, the weight percentage of each component of the preposed acid liquid is HCl8 percent, IRON-2066A1 percent, and the balance is water; the main treatment acid solution comprises the following components in percentage by weight of HCl 8%, HF 1.5%, and CH34% of COOH, and the balance of water; the concentration ratio of the post acid solution is HCl8 percent and CH34% of COOH, and the balance of water;
15-25% of reservoir shale content to be augmented and injected, wherein the preposed acid liquor comprises the following components, by weight, HCl 10%, IRON-2066A 1.5%, and the balance of water; the main treatment acid liquid comprises the following components in percentage by weight of HCl 10%, HF 2% and CH34% of COOH, and the balance of water; the weight percentage of each component of the post acid solution is HCl10 percent and CH34% of COOH, and the balance of water;
the content of reservoir mud to be injected is more than 25 percent, the weight percentage of each component of the preposed acid liquid is HCl12 percent, IRON-2066A2 percent, and the balance is water; the main treatment acid liquid comprises HCl12 wt% and HF2％，CH34% of COOH, and the balance of water; the weight percentage of each component of the post acid solution is HCl12 percent and CH34% of COOH, and the balance of water.
Preferably, the acid amount formula for the reservoir acidizing radius is as follows:
Q＝π×R2×h×Φ×β
in the formula: q: acid liquor dosage m3(ii) a R: processing the radius m; phi: porosity of the target layer; h: the effective thickness of the target layer; pi: the circumference ratio is 3.14; beta: the dosage is added with a coefficient, and 1.3 to 1.8 times of the pollution radius of the reservoir of the underinjection well is taken.
According to the plugging removal liquid, acetic acid components with certain concentrations are added in the main treatment acid liquid and the post-acid liquid, so that the effective acidification action time can be prolonged; on the other hand, the reservoir can keep weak acidity for a long time, reaction precipitation products are reduced, and multiple acidification is facilitated.
The invention relates to a method for modifying, depressurizing and acidifying a water injection well of a sandstone reservoir, which is characterized in that a preposed acid solution, a main treatment acid solution and a postposition acid solution in a specific ratio are selected according to different mud contents of reservoirs to be injected, and the displacement is not lower than 500L/min when the main treatment acid solution, the postposition acid solution and injected water are required to be squeezed in for construction.
Compared with the prior art, the invention has the following advantages:
the plugging removal solution has simple components, does not need other auxiliary reagents, can realize deep acidizing plugging removal by matching the pretreatment acid solution, the preposed acid solution, the main treatment acid solution and the postposed acid solution, and has long validity period.
And secondly, the post-acid solution is adopted, the precipitation of second and third precipitates can be inhibited under the condition of keeping a lower pH value, the soil acid corrosion product is pushed to a position far away from a shaft in an ionic state, the higher permeability of a near wellbore area is ensured, the pressure drop loss is smaller, and the adverse effect of silica gel precipitation and pressure loss on each acidification effect is effectively avoided.
And thirdly, the whole process of the acidic reservoir environment is guaranteed, large discharge capacity is rapidly squeezed into the reservoir without backflow, the well is directly opened for water injection, blowout and reverse discharge are not needed, the utilization rate of acid liquor is improved, and secondary pollution is reduced.
In conclusion, the method solves the problem that the effect of the I, II hypotonic reservoir is poor after the conventional acidification is carried out for multiple times. The modified depressurization acidification method provided by the invention has the advantages that reservoir difference investigation is carried out, the injection rate is optimized, the lower pH value of the stratum is kept, the precipitation of soil acid products is inhibited, the swept volume is enlarged, and the effective acidification seepage section is improved; the method has the advantages of optimizing the acid using procedure based on the research of secondary injury, avoiding secondary blockage, improving the utilization rate of acid liquor, reducing the measure cost, improving the operation timeliness and realizing safe and environment-friendly production.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of the stated features, steps, operations, and/or combinations thereof, unless the context clearly indicates otherwise.
In order to make the technical solutions of the present invention more clearly understood by those skilled in the art, the technical solutions of the present invention will be described in detail below with reference to specific embodiments.
Example 1 sandstone reservoir water injection well modified depressurization acidification method
The thickness h of an oil layer used in the experiment is 10m, the processing radius R is 1.8m, the size of a casing is 139.7mm, the wall thickness is 9.17mm, the permeability is more than 10md, the porosity phi is 18%, and the shale content of a reservoir is 12%.
The formula of the acid amount used for treating the radius of the reservoir acidizing is as follows:
Q＝π×R2×h×Φ×β
in the formula: q: acid liquor dosage m3(ii) a R: processing the radius m; phi: porosity of the target layer; h: effective thickness of target layerDegree; pi: the circumference ratio is 3.14; beta: the additional coefficient of the dosage is taken to be 1.3 times of the pollution radius of the reservoir of the underinjection well.
Acid solution usage was calculated according to experimental data as follows:
Q＝3.14×1.82×10×0.18×1.3＝23.8≈24
the method is implemented according to the following steps in sequence:
step one, the pressure test of the well head of the original water injection well is qualified, no leakage exists, the pump truck is connected with the oil pipe gate of the well head through a pipeline which is qualified in pressure test, and pretreatment acid liquor (10% HCl)8m is replaced3And replacing the injected water with the volume 0.8 time of that of the underground oil pipe, closing the casing pipe gate, extruding the injected water with the volume 0.2 time of that of the underground oil pipe, closing the oil pipe gate, and reacting for 20 min. The positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads.
And step two, connecting the pump truck with a wellhead casing gate, wherein the discharge capacity is not less than 500L/min, and replacing injected water with the volume 1.2 times of that of the underground casing. The outlet is connected with a gas-liquid separation tank, and the residual acid and the acidification reaction products in the shaft are cleaned by thorough back flushing of a sleeve.
Step three, replacing the preposed acid liquor by 4.8m3The discharge capacity is not lower than 200L/min.
The preposed acid liquid comprises the following components in percentage by weight: HCl 10%, IRON-2066A 1.5%, the rest is water.
Step four, replacing the main treatment acid liquor by 10.8m3The discharge capacity is not lower than 200L/min, after the shaft is filled with the acid liquor, the sleeve gate is closed, the discharge capacity is increased to be not lower than 500L/min, and all the residual main treatment acid liquor is positively squeezed; the positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads.
The main treatment acid solution comprises the following components in percentage by weight: HCl 10%, HF 2%, CH34% of COOH, and the balance of water.
Step five, extruding the post-acid liquor into the extruder for 4.8m3The discharge capacity is not lower than 500L/min; the positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads.
The post acid solution comprises the following components in percentage by weight: HCl 10%, CH34% of COOH, and the balance of water.
And step six, positively extruding injected water with the volume of 1.5 times of that of the underground oil pipe, wherein the positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads.
And seventhly, closing the well and reacting for 1 h.
And step eight, after the procedures are finished, thoroughly flushing the ground flow pipeline, and normally injecting water after opening the well.
Embodiment 2 sandstone reservoir water injection well modified depressurization acidification method
The thickness h of an oil layer used in the experiment is 10m, the processing radius R is 2.0m, the size of a sleeve is 139.7mm, the wall thickness is 9.17mm, the permeability is more than 10md, the porosity phi of a target layer is 20 percent, and the mud content of a reservoir is 20 percent
The formula of the acid amount used for treating the radius of the reservoir acidizing is as follows:
Q＝π×R2×h×Φ×β
in the formula: q: acid liquor dosage m3(ii) a R: processing the radius m; phi: porosity of the target layer; h: the effective thickness of the target layer; pi: the circumference ratio is 3.14; beta: the dosage is added with a coefficient, and 1.5 times of the pollution radius of the reservoir of the underinjection well is taken.
Acid solution usage was calculated according to experimental data as follows:
Q＝3.14×2.02×10×0.20×1.5＝37.7≈38
the method is implemented according to the following steps in sequence:
step one, the pressure test of the well head of the original water injection well is qualified, no leakage exists, the pump truck is connected with the oil pipe gate of the well head through a pipeline which is qualified in pressure test, and pretreatment acid liquor (12% HCl)8m is replaced3And replacing the injected water with the volume 0.8 time of that of the underground oil pipe, closing the casing gate, extruding the injected water with the volume 0.2 time of that of the underground oil pipe, closing the oil pipe gate, and reacting for 15-20 min. The positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads.
And step two, connecting the pump truck with a wellhead casing gate, wherein the discharge capacity is not less than 500L/min, and replacing injected water with the volume 1.2 times of that of the underground casing. The outlet is connected with a gas-liquid separation tank, and the residual acid and the acidification reaction products in the shaft are cleaned by thorough back flushing of a sleeve.
Step three, replacing the preposed acid liquid with 11.4m3The discharge capacity is not lower than 200L/min.
The preposed acid liquid comprises the following components in percentage by weight: HCl 12%, IRON-2066A 2%, the rest is water.
Step four, replacing the main treatment acid liquor by 20.9m3The discharge capacity is not lower than 200L/min, after the shaft is filled with the acid liquor, the sleeve gate is closed, the discharge capacity is increased to be not lower than 500L/min, and all the residual main treatment acid liquor is positively squeezed; the positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads.
The main treatment acid solution comprises the following components in percentage by weight: HCl 12%, HF 2%, CH34% of COOH, and the balance of water.
Step five, extruding the post-acid solution into the container for 11.4m3The discharge capacity is not lower than 500L/min; the positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads.
The post acid solution comprises the following components in percentage by weight: HCl 12%, CH34% of COOH, and the balance of water.
And step six, positively extruding injected water with the volume of 1.2 times of that of the underground oil pipe, wherein the positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads.
Step seven, closing the well and reacting for 1.4 h.
And step eight, after the procedures are finished, thoroughly flushing the ground flow pipeline, and normally injecting water after opening the well.
Embodiment 3 sandstone reservoir water injection well modified depressurization acidification method
The thickness h of an oil layer used in the experiment is 10m, the processing radius R is 2.2m, the size of a casing is 139.7mm, the wall thickness is 9.17mm, the permeability is more than 10md, the porosity phi of a target layer is 22%, and the mud content of a reservoir is 30%.
The formula of the acid amount used for treating the radius of the reservoir acidizing is as follows:
Q＝π×R2×h×Φ×β
in the formula: q: acid liquor dosage m3(ii) a R: processing the radius m; phi: porosity of the target layer; h: the effective thickness of the target layer; pi: the circumference ratio is 3.14; beta: the additional coefficient of the dosage is taken to be 1.8 times of the pollution radius of the reservoir of the underinjection well.
Acid solution usage was calculated according to experimental data as follows:
Q＝3.14×2.22×10×0.22×1.8＝60.1≈60
the method is implemented according to the following steps in sequence:
step one, the pressure test of the well head of the original water injection well is qualified, no leakage exists, the pump truck is connected with the oil pipe gate of the well head through a pipeline which is qualified in pressure test, and 10m of pretreatment acid liquor (12% HCl) is replaced3And replacing the injected water with the volume 0.8 time of that of the underground oil pipe, closing the casing pipe gate, extruding the injected water with the volume 0.2 time of that of the underground oil pipe, closing the oil pipe gate, and reacting for 15 min. The positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads.
And step two, connecting the pump truck with a wellhead casing gate, wherein the discharge capacity is not less than 500L/min, and replacing injected water with the volume 1.2 times of that of the underground casing. The outlet is connected with a gas-liquid separation tank, and the residual acid and the acidification reaction products in the shaft are cleaned by thorough back flushing of a sleeve.
Step three, replacing the preposed acid liquor by 15m3The discharge capacity is not lower than 200L/min.
The preposed acid liquid comprises the following components in percentage by weight: HCl 8%, IRON-2066A 1%, and water in balance.
Step four, replacing the main treatment acid liquor by 30m3The discharge capacity is not lower than 200L/min, after the shaft is filled with the acid liquor, the sleeve gate is closed, the discharge capacity is increased to be not lower than 500L/min, and all the residual main treatment acid liquor is positively squeezed; the positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads.
The main treatment acid solution comprises the following components in percentage by weight: HCl 8%, HF1.5％，CH34% of COOH, and the balance of water.
Step five, extruding the post-acid liquor into the extruder for 15m3The discharge capacity is not lower than 500L/min; the positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads.
The post acid solution comprises the following components in percentage by weight: HCl 8%, CH34% of COOH, and the balance of water.
And step six, positively extruding injected water with the volume of 1.2 times of that of the underground oil pipe, wherein the positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads.
Step seven, closing the well and reacting for 1.6 h.
And step eight, after the procedures are finished, thoroughly flushing the ground flow pipeline, and normally injecting water after opening the well.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims (5)

1. The blockage removing liquid is characterized by comprising a pretreatment acid liquid, a pre-acid liquid, a main treatment acid liquid and a post-acid liquid;
the pretreatment acid solution is 10-12% HCl solution;
the preposed acid solution comprises the following components in percentage by weight: 10-12% of HCl, 1-2% of iron ion stabilizer and the balance of water;
the main treatment acid solution comprises the following components in percentage by weight: HCl 10-12%, HF 1.5-2%, CH32% -4% of COOH and the balance of water;
the post acid solution comprises the following components in percentage by weight: HCl 10% -12%, CH32 to 4 percent of COOH and the balance of water.
2. The unblocking fluid of claim 1, wherein the IRON ion stabilizer is IRON-2066A.
3. The method for realizing the modified depressurization acidification of the sandstone reservoir water injection well by the plugging removal liquid according to claim 1 or 2 is characterized by comprising the following steps:
step one, the pressure test of the well head of the original water injection well is qualified, no leakage exists, the pump truck is connected with the oil pipe gate of the well head through a pipeline which is qualified in pressure test, and the pretreatment acid liquor is replaced by 5-15m3Replacing the injected water with the volume 0.5-1.0 times of that of the underground oil pipe, closing the casing gate, extruding the injected water with the volume 0.1-0.5 times of that of the underground oil pipe, closing the oil pipe gate, and reacting for 15-20 min; the positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads;
secondly, connecting a pump truck with a wellhead casing gate, discharging not less than 500L/min, replacing injected water with the volume 1.0-2.0 times of that of the underground casing, connecting an outlet with a gas-liquid separation tank, and thoroughly backwashing through the casing to clean residual acid and acidification reaction products in a shaft;
step three, replacing the pre-acid solution, wherein the using amount of the pre-acid solution is 20% -30% of the acid amount used for acidizing the radius of the reservoir, and the discharge amount is not less than 200L/min;
step four, replacing the main treatment acid liquor, wherein the using amount of the main treatment acid liquor is 45% -55% of the acid used for the reservoir acidification treatment radius, the discharge capacity is not lower than 200L/min, after the shaft is filled with the acid liquor, the sleeve gate is closed, the discharge capacity is increased to be not lower than 500L/min, and all the main treatment acid liquor is left in a positive extrusion mode; the positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads;
step five, positive squeezing in post acid liquor, wherein the using amount of the post acid liquor is 20% -30% of the acid used for acidizing the radius of the reservoir, and the discharge capacity is not lower than 500L/min; the positive extrusion force is required to be controlled within the rated working pressure range of various wellheads according to different types of the wellheads;
and step six, positively extruding injected water with the volume of 1.0-1.5 times of that of the underground oil pipe, wherein the positive extrusion force is required to be controlled within the rated working pressure range of various well mouths according to different well mouth types.
Seventhly, closing the well and reacting for 1-2 h;
and step eight, after the procedures are finished, thoroughly flushing the ground flow pipeline, and normally injecting water after opening the well.
4. The method as claimed in claim 3, wherein the pre-acid, the main treatment acid and the post-acid are used according to different mud contents of reservoirs to be injected, and the pre-acid, the main treatment acid and the post-acid comprise the following components in percentage by weight:
the content of reservoir mud to be injected is less than or equal to 15 percent, the weight percentage of each component of the preposed acid liquid is HCl8 percent, IRON-2066A1 percent, and the balance is water; the main treatment acid solution comprises the following components in percentage by weight of HCl 8%, HF 1.5%, and CH34% of COOH, and the balance of water; the concentration ratio of the post acid solution is HCl8 percent and CH34% of COOH, and the balance of water;
15-25% of reservoir shale content to be augmented and injected, wherein the preposed acid liquor comprises the following components, by weight, HCl 10%, IRON-2066A 1.5%, and the balance of water; the main treatment acid liquid comprises the following components in percentage by weight of HCl 10%, HF 2% and CH34% of COOH, and the balance of water; the weight percentage of each component of the post acid solution is HCl10 percent and CH34% of COOH, and the balance of water;
the content of reservoir mud to be injected is more than 25 percent, the weight percentage of each component of the preposed acid liquid is HCl12 percent, IRON-2066A2 percent, and the balance is water; the main treatment acid liquid comprises the following components in percentage by weight of HCl 12%, HF 2% and CH34% of COOH, and the balance of water; the weight percentage of each component of the post acid solution is HCl12 percent and CH34% of COOH, and the balance of water.
5. The method of claim 3, wherein the acid amount formula for the reservoir acidizing radius is as follows:
Q＝π×R2×h×Φ×β
in the formula: q: acid liquor dosage m3(ii) a R: processing the radius m; phi: porosity of the target layer; h: the effective thickness of the target layer; pi: the circumference ratio is 3.14; beta: the dosage is added with a coefficient, and 1.3 to 1.8 times of the pollution radius of the reservoir of the underinjection well is taken.
CN201910947606.9A 2019-09-30 2019-09-30 Sandstone reservoir water injection well modified depressurization acidification method Pending CN112574732A (en)

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Citations (3)

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Publication number Priority date Publication date Assignee Title
US4151878A (en) * 1977-08-15 1979-05-01 The Dow Chemical Company Method for acidizing a subterranean formation
RU2121563C1 (en) * 1998-02-27 1998-11-10 Мамедов Борис Абдулович Method of cleaning the producing formation channels
CN101781982A (en) * 2010-02-25 2010-07-21 中国石油化工股份有限公司 Short-injection water injection well acidation injectivity process

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4151878A (en) * 1977-08-15 1979-05-01 The Dow Chemical Company Method for acidizing a subterranean formation
RU2121563C1 (en) * 1998-02-27 1998-11-10 Мамедов Борис Абдулович Method of cleaning the producing formation channels
CN101781982A (en) * 2010-02-25 2010-07-21 中国石油化工股份有限公司 Short-injection water injection well acidation injectivity process

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张洪涛等: "有机缓速酸在大庆外围东部油田的研究与应用", 《大庆石油地质与开发》 *
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Application publication date: 20210330