CN110924926A - Method and apparatus for wellbore-based ion concentration determination - Google Patents

Method and apparatus for wellbore-based ion concentration determination Download PDF

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CN110924926A
CN110924926A CN201811024530.4A CN201811024530A CN110924926A CN 110924926 A CN110924926 A CN 110924926A CN 201811024530 A CN201811024530 A CN 201811024530A CN 110924926 A CN110924926 A CN 110924926A
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concentration value
value
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CN110924926B (en
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刘己全
潘昭才
孟祥娟
刘举
王茜
李科
孙涛
钟诚
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Petrochina Co Ltd
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Abstract

The invention provides a method and a device for determining ion concentration based on a shaft, wherein the method comprises the following steps: repeating all of the following steps until a concentration value of the first ion is determined for having scale in the wellbore: determining the ion intensity according to a preset first concentration value of a first ion, wherein the first ion is a bicarbonate ion; determining a second concentration value of the first ion according to the ion intensity and a preset saturation index, wherein the value of the saturation index represents the fouling state of the wellbore; calculating a difference between the first concentration value and the second concentration value; if the difference value is smaller than or equal to a preset value, determining that the second concentration value is the concentration value of the first ions when scales exist in the shaft; and if the difference value is larger than the preset value, determining the average value of the first concentration value and the second concentration value as a new first concentration value. The method and the device can predict the concentration of ions generating scaling phenomena in the shaft, and solve the problem that scaling of the shaft can block a pipeline.

Description

Method and apparatus for wellbore-based ion concentration determination
Technical Field
The invention relates to the technical field of oil and gas field development, in particular to a method and a device for determining ion concentration based on a shaft.
Background
In the process of oil field exploitation, especially in the high water content oil extraction period, part of a well bore can be scaled, the well bore can be scaled to block a pipeline, the yield is reduced, and the well bore scaling becomes one of important factors troubling the oil field production, wherein calcium carbonate scale (CaCO)3) Is the common scale in oil field production.
In the prior art, whether the scaling phenomenon occurs currently can be determined by detecting the ion concentration in the shaft water.
However, in the prior art, whether a scaling phenomenon occurs in a shaft can only be detected in real time, whether the scaling phenomenon occurs in the shaft can not be predicted, the concentration of ions causing the scaling phenomenon in the shaft can not be predicted, and then the scaling in the shaft can only be cleaned when the scaling phenomenon occurs in the shaft, and the problem that the pipeline is blocked by the scaling in the shaft can still be caused.
Disclosure of Invention
The invention provides a method and a device for determining ion concentration based on a shaft, which can predict the ion concentration of the shaft with scaling phenomenon and solve the problem that the scaling of the shaft can block a pipeline.
In one aspect, the present invention provides a wellbore-based ion concentration determination method, comprising:
repeating all of the following steps until a concentration value of the first ion is determined for having scale in the wellbore:
determining the ion intensity according to a preset first concentration value of the first ions, wherein the first ions are bicarbonate ions;
determining a second concentration value of the first ion based on the ion intensity and a preset saturation index, wherein a value of the saturation index represents a fouling state of the wellbore;
calculating a difference between the first concentration value and the second concentration value;
if the difference value is smaller than or equal to a preset value, determining that the second concentration value is the concentration value of the first ions when scales exist in the shaft;
and if the difference value is larger than a preset value, determining the average value of the first concentration value and the second concentration value as a new first concentration value.
Further, when there is gas phase production in the wellbore, the determining a second concentration value of the first ions according to the ion intensity and a preset saturation index includes:
obtaining a first content value of carbon dioxide gas in the gas phase under the conditions of preset temperature and pressure
Figure BDA0001788161040000021
And obtaining the fugacity coefficient of carbon dioxide gas in the mixed gas of methane gas and carbon dioxide gas
Figure BDA0001788161040000022
The first content value is measured
Figure BDA0001788161040000023
The fugacity coefficient
Figure BDA0001788161040000024
Substituting the ion intensity into a saturation index to obtain a second concentration value; wherein the saturation index is
Figure BDA0001788161040000025
Figure BDA0001788161040000026
Figure BDA0001788161040000027
Wherein, [ Ca ]2+]Is the concentration value of calcium ions in the water of the wellbore,
Figure BDA0001788161040000028
and P is the second concentration value, P is absolute pressure, t is wellhead temperature of the wellbore, and u is the ionic strength.
Further, when no gas phase is produced in the wellbore, the determining a second concentration value of the first ion according to the ion intensity and a preset saturation index includes:
obtaining a second content value of carbon dioxide gas in daily production fluid of the wellbore
Figure BDA0001788161040000029
The second content value
Figure BDA00017881610400000210
Substituting the ionic strength into the saturation index to obtain a second concentration value; wherein the saturation index is
Figure BDA00017881610400000211
Figure BDA0001788161040000031
Figure BDA0001788161040000032
Wherein, [ Ca ]2+]Is the concentration value of calcium ions in the water of the wellbore,
Figure BDA0001788161040000033
is the second concentration value, P is the absolute pressure,t is the wellhead temperature of the wellbore, and u is the ionic strength.
Further, the ionic strength is
Figure BDA0001788161040000034
Wherein, ciIs the concentration value of the i-th ion, ziIs the valence of the i-th ion, wherein c1Is a first concentration value, z, of said first ion1Is the valence of the first ion.
Further, after determining the concentration value of the first ion when the scale is in the wellbore, the method further comprises:
obtaining an actual concentration value of the first ion in the wellbore;
and if the actual concentration value is greater than or equal to the second concentration value, determining to perform scale removal treatment on the shaft.
In another aspect, the present invention provides a wellbore-based ion concentration determination apparatus, comprising:
a first determining unit, configured to determine an ion intensity according to a preset first concentration value of the first ion, where the first ion is a bicarbonate ion;
a second determination unit, configured to determine a second concentration value of the first ion according to the ion intensity and a preset saturation index, where a value of the saturation index represents a fouling state of the wellbore;
a calculation unit for calculating a difference between the first concentration value and the second concentration value;
a third determining unit, configured to determine, if the difference is smaller than or equal to a preset value, that the second concentration value is a concentration value of the first ion when there is scale in the wellbore;
and the fourth determining unit is used for determining an average value of the first concentration value and the second concentration value as a new first concentration value if the difference value is larger than a preset value, and triggering the first determining unit until the concentration value of the first ions is determined to be scaling in the shaft.
Further, the method can be used for preparing a novel materialWhen gas phase is produced in the well bore, the second determination unit is used for acquiring a first content value of carbon dioxide gas in the gas phase under preset temperature and pressure conditions
Figure BDA0001788161040000037
And obtaining the fugacity coefficient of carbon dioxide gas in the mixed gas of methane gas and carbon dioxide gas
Figure BDA0001788161040000038
The first content value is measured
Figure BDA0001788161040000035
The fugacity coefficient
Figure BDA0001788161040000036
Substituting the ion intensity into a saturation index to obtain a second concentration value; wherein the saturation index is
Figure BDA0001788161040000041
Figure BDA0001788161040000042
Figure BDA0001788161040000043
Wherein, [ Ca ]2+]Is the concentration value of calcium ions in the water of the wellbore,
Figure BDA0001788161040000044
and P is the second concentration value, P is absolute pressure, t is wellhead temperature of the wellbore, and u is the ionic strength.
Further, when no gas phase is produced in the wellbore, the second determination unit is used for obtaining a second content value of carbon dioxide gas in daily produced liquid of the wellbore
Figure BDA00017881610400000410
The second content value
Figure BDA00017881610400000411
Substituting the ionic strength into the saturation index to obtain a second concentration value; wherein the saturation index is
Figure BDA0001788161040000045
Figure BDA0001788161040000046
Figure BDA0001788161040000047
Wherein, [ Ca ]2+]Is the concentration value of calcium ions in the water of the wellbore,
Figure BDA0001788161040000048
and P is the second concentration value, P is absolute pressure, t is wellhead temperature of the wellbore, and u is the ionic strength.
Further, the ionic strength is
Figure BDA0001788161040000049
Wherein, ciIs the concentration value of the i-th ion, ziIs the valence of the i-th ion, wherein c1Is a first concentration value, z, of said first ion1Is the valence of the first ion.
Further, the apparatus further comprises:
a fifth determining unit, configured to obtain an actual concentration value of a first ion in a wellbore after determining the concentration value of the first ion when the wellbore has scale; and if the actual concentration value is greater than or equal to the second concentration value, determining to perform scale removal treatment on the shaft.
The invention provides a method and a device for determining ion concentration based on a shaft, which are characterized in that firstly, the ion strength is determined according to a preset first concentration value of a first ion, wherein the first ion is bicarbonate ion, then the determined ion strength is substituted into a saturation index, the value of the saturation index is zero, which indicates that the shaft is in a scaling critical state, the saturation index is made equal to zero to determine a second concentration value of the first ion, then, the difference value between the first concentration value and the second concentration value is calculated, when the difference value is larger than the preset value, the first concentration value needs to be updated, the second concentration value is recalculated until the difference value is smaller than or equal to the preset value, the second concentration value is determined to be the concentration value of the first ion when the shaft is scaled, namely, the concentration of the ion with the scaling phenomenon occurring in the shaft is predicted, so that the shaft which is not scaled can be prevented according to the concentration value, and then solved and can only clear up the problem of the scale deposit of pit shaft when the pit shaft takes place the scale deposit phenomenon, avoided the scale deposit of pit shaft to block up the problem of pipeline.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure.
FIG. 1 is a flow chart of a method for determining a wellbore-based ion concentration according to an embodiment of the invention;
FIG. 2 is a flow chart of a method for determining a wellbore-based ion concentration in a gas phase produced according to a second embodiment of the present invention;
FIG. 3 is a flow chart of a method for determining a wellbore-based ion concentration during gas-free phase production according to a third embodiment of the present invention;
fig. 4 is a schematic structural diagram of a wellbore-based ion concentration determination apparatus according to a fourth embodiment of the present invention;
fig. 5 is a schematic structural diagram of a wellbore-based ion concentration determination apparatus according to a fifth embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 is a flowchart of a method for determining a concentration of ions in a wellbore according to an embodiment of the present invention, as shown in fig. 1, the method including:
repeating all of the following steps until a concentration value of the first ion is determined for having scale in the wellbore:
step 101: and determining the ion intensity according to a preset first concentration value of the first ions, wherein the first ions are bicarbonate ions.
In this embodiment, a first concentration value of 0.01 millimole/liter (mmol/L) of bicarbonate ion is preset initially, then the ion intensity is determined according to 0.01mmol/L, and if the 0.01mmol/L is updated later, for example, to 0.12mmol/L, then a new ion intensity is determined again according to 0.12mmol/L, and the subsequent operations are performed.
Step 102: determining a second concentration value of the first ion based on the ion intensity and a preset saturation index, wherein a value of the saturation index is indicative of a fouling state of the wellbore.
In this embodiment, there is gas phase production and no gas phase production in the wellbore corresponding to different saturation indexes, wherein, no matter which saturation index is used, when the saturation index is greater than 0, it indicates that the wellbore has scale, when the saturation index is equal to 0, it indicates that the wellbore is in a critical state, and when the saturation index is less than 0, it indicates that the wellbore has no scale. Substituting the ion intensity calculated in the above step 101 into the saturation index, and making the saturation index equal to 0, the concentration of only bicarbonate ions in the saturation index is unknown, thereby determining a second concentration value of bicarbonate ions.
Step 103: calculating a difference value between the first concentration value and the second concentration value, if the difference value is less than or equal to a preset value, executing step 104, and if the difference value is greater than the preset value, executing step 105.
In this embodiment, the preset value may be set according to an actual requirement, for example, the preset value is 0.01mmol/L, if a difference between the first concentration value of bicarbonate ions used in the step 101 and the second concentration value of bicarbonate ions determined in the step 102 is less than or equal to 0.01mmol/L, step 104 is executed, all steps are not executed again, and if the difference is greater than 0.01mmol/L, step 105 needs to be executed, and the first concentration value in the step 101 is updated.
Step 104: determining the second concentration value to be a concentration value of the first ion when there is scale in the wellbore.
Step 105: determining an average value of the first concentration value and the second concentration value as a new first concentration value.
The embodiment of the invention provides a method for determining ion concentration based on a shaft, which comprises the steps of firstly determining ion strength according to a preset first concentration value of a first ion, wherein the first ion is bicarbonate ion, then substituting the determined ion strength into a saturation index, enabling the shaft to be in a scaling critical state when the value of the saturation index is zero, enabling the saturation index to be equal to zero to determine a second concentration value of the first ion, then calculating a difference value between the first concentration value and the second concentration value, updating the first concentration value when the difference value is larger than the preset value, recalculating the second concentration value until the difference value is smaller than or equal to the preset value, determining the second concentration value to be the concentration value of the first ion when the shaft is scaled, namely predicting the concentration of ions generating a scaling phenomenon in the shaft, and preventing the shaft which is not scaled according to the concentration value, and then solved and can only clear up the problem of the scale deposit of pit shaft when the pit shaft takes place the scale deposit phenomenon, avoided the scale deposit of pit shaft to block up the problem of pipeline.
Fig. 2 is a flowchart of a method for determining a wellbore-based ion concentration in a gas phase production according to a second embodiment of the present invention, as shown in fig. 2, the method may include:
step 201: and determining the ion intensity according to a preset first concentration value of the first ions, wherein the first ions are bicarbonate ions.
In the embodiment, the wellhead temperature and pressure values of the shaft are firstly recorded, and the temperature and pressure conditions in the shaft can be restored through related software; secondly, recording the daily produced gas amount (which needs to be changed to the standard temperature and pressure condition and has the unit of m3) Daily oil production (in m)3) And the daily gas production (in m)3) (ii) a Taking implementation of carbon dioxide gas flooding as an example, then taking a water sample, generally an oil-gas-water separator water sample, at a wellhead of an oil-gas well for implementing carbon dioxide gas flooding (if the carbon dioxide section is subjected to race flooding, the wellhead of the oil-gas well for carbon dioxide section race flooding); then detecting the hydrogen ion concentration index (PH for short), each ion type and concentration value of the taken water sample; then, whether CaCO exists or not is detected by means of the Oddo-Tomson saturation index theory3And (3) scale formation, if the scale formation exists, performing scale prevention by adopting a physical method or screening a targeted scale removal and prevention agent for removing and preventing scale, and if the scale formation does not exist, determining the ionic strength according to a preset first concentration value of bicarbonate ions, wherein the ionic strength is 0.01mmol/L, for example
Figure BDA0001788161040000081
Wherein, ciIs the concentration value of the i-th ion, ziIs the valence of the i-th ion, wherein c1Is a first concentration value of a first ion, z1The valence of the first ion, that is, 0.01mmol/L, the concentration values of other ions that have been detected, and the valence of each ion are substituted into u, whereby the ion strength is determined.
It should be noted that, when the correction coefficient is used, the correction coefficient K can be obtained by looking up the relationship between the ionic strength u and the correction coefficient K at different temperatures.
Step 202: acquiring a first content value of carbon dioxide gas in a gas phase under preset temperature and pressure conditions, and acquiring a fugacity coefficient of the carbon dioxide gas in a mixed gas of methane gas and the carbon dioxide gas.
In this example, the fugacity coefficient of carbon dioxide gas in the mixed gas of methane gas and carbon dioxide gas
Figure BDA0001788161040000082
Can be calculated by formula (1), wherein formula (1) is:
Figure BDA0001788161040000083
wherein, P is absolute pressure, and t is wellhead temperature of a shaft.
A first content value of carbon dioxide gas in gas phase under preset temperature and pressure conditions
Figure BDA0001788161040000084
May be expressed in percent; can be calculated by formula (2), wherein formula (2) is:
Figure BDA0001788161040000085
wherein the content of the first and second substances,
Figure BDA0001788161040000086
the third content value of the carbon dioxide gas in the oil, gas and water mixed system under the ground condition; p is absolute pressure in megapascals (MPa); t is the wellhead temperature of the shaft, and the unit is centigrade (DEG C);
Figure BDA0001788161040000087
is the fugacity coefficient of carbon dioxide gas in the mixed gas of methane gas and carbon dioxide gas; qgIs the total amount of gas produced per day from the wellbore under standard temperature and pressure conditions, in m3；QWIs the amount of water produced from the wellbore on a daily basis, in m3；QoIs the daily amount of oil recovered from the wellbore in m3。
Step 203: and substituting the first content value, the fugacity coefficient and the ionic strength into the saturation index to obtain a second concentration value.
In this embodiment, when the wellbore has gas phase production, the saturation index is
Figure BDA0001788161040000091
Figure BDA0001788161040000092
Figure BDA0001788161040000093
Wherein, [ Ca ]2+]Is the concentration value of calcium ions in water of a well bore, and has the unit of mol per liter (mol/L),
Figure BDA0001788161040000094
is a second concentration value, P is absolute pressure, t is wellhead temperature of the wellbore, and u is ionic strength;
Figure BDA0001788161040000095
a third content value of carbon dioxide gas in the oil, gas and water mixed system under the ground condition, which is expressed by percentage;
Figure BDA0001788161040000096
is the fugacity coefficient of carbon dioxide gas in the mixed gas of methane gas and carbon dioxide gas.
The first content value in the above steps
Figure BDA0001788161040000097
Coefficient of fugacity
Figure BDA0001788161040000098
Substituting the ion intensity into the saturation index, making the saturation index equal to 0, and obtaining the unique unknown number
Figure BDA0001788161040000099
I.e. a second concentration value of bicarbonate ions.
Specifically, it can be calculated by MATLAB program language
Figure BDA00017881610400000910
Solving with solve function in MATLAB
Figure BDA00017881610400000911
{ > syms x; % defines a variable x of
Figure BDA00017881610400000912
＞＞x＝solve(‘
Figure BDA00017881610400000918
Figure BDA00017881610400000914
Figure BDA00017881610400000915
', ' x '); % defines a 1X 1 array, stores x
＞＞x}
X in the MATLAB program is
Figure BDA00017881610400000916
Known parameters are substituted to directly obtain
Figure BDA00017881610400000917
I.e. a second concentration value of bicarbonate ions.
Step 204: calculating a difference value between the first concentration value and the second concentration value, if the difference value is less than or equal to a preset value, executing step 205, and if the difference value is greater than the preset value, executing step 206.
In this embodiment, a difference is calculated between the first concentration value of bicarbonate ions in step 201 and the second concentration value of bicarbonate ions determined in step 203, where the difference may be an absolute value of a subtraction between the two, and if the absolute value is less than or equal to a predetermined value, for example, the predetermined value is 0.01 mmol/L.
Step 205: the second concentration value is determined to be the concentration value of the first ion with scale in the wellbore and step 207 is performed.
Step 206: an average value of the first density value and the second density value is determined as a new first density value, and step 201 is performed.
And when the determined second concentration value is not the concentration value when the shaft is scaled, updating the first concentration value in the step 201 again, and returning to execute the steps 201 to 204 again until the concentration value when the shaft is scaled is determined.
Step 207: an actual concentration value of the first ion in the wellbore is obtained.
Step 208: and if the actual concentration value is greater than or equal to the second concentration value, determining to perform scale removal treatment on the shaft.
In the embodiment of the invention, the actual concentration value of the wellhead water sample of the shaft is compared with the determined second concentration value, if the actual concentration value is greater than or equal to the second concentration value, experimental verification is carried out, and corresponding scale cleaning measures are taken, so that a theoretical basis is provided for prevention and treatment of calcium carbonate scale in the non-scale shaft containing scale forming ions, namely bicarbonate ions, and the scale forming trends of the shaft of the oil and gas well containing carbon dioxide in the stratum can be predicted.
Fig. 3 is a flowchart of a method for determining an ion concentration based on a wellbore during gas-free phase production according to a third embodiment of the present invention, as shown in fig. 3, the method may include:
step 301: and determining the ion intensity according to a preset first concentration value of the first ions, wherein the first ions are bicarbonate ions.
In this embodiment, when performing this step, reference may be made to the explanation at step 201 in the second embodiment, and details are not described here.
Step 302: a second content value of carbon dioxide gas in the daily production fluid of the wellbore is obtained.
In this example, the oxidation of dioxide in the daily production fluid of the wellboreSecond content value of carbon gas
Figure BDA0001788161040000101
Can be calculated by formula (3), wherein formula (3) is:
Figure BDA0001788161040000111
wherein the content of the first and second substances,
Figure BDA0001788161040000115
a fourth content value that is a daily production of carbon dioxide gas from the wellbore under standard temperature and pressure conditions; qwIs the amount of water produced daily from the wellbore; qoIs the daily amount of oil produced from the wellbore.
Wherein the fourth content value
Figure BDA0001788161040000116
Can be calculated by formula (4), wherein formula (4) is:
Figure BDA0001788161040000112
wherein the content of the first and second substances,
Figure BDA0001788161040000117
the fifth content value of the carbon dioxide gas in the oil, gas and water mixed system under the ground condition; qgIs the total amount of gas produced per day from the wellbore under standard temperature and pressure conditions.
Step 303: and substituting the second content value and the ionic strength into the saturation index to obtain a second concentration value.
In this example, when the wellbore is producing no gas phase, the saturation index is
Figure BDA0001788161040000118
Figure BDA0001788161040000119
Figure BDA00017881610400001110
Wherein, [ Ca ]2+]Is the concentration value of calcium ions in the water in the wellbore,
Figure BDA00017881610400001111
and P is the absolute pressure, t is the wellhead temperature of the wellbore, and u is the ionic strength.
The second content value in the above step
Figure BDA00017881610400001112
And ion intensity, substituting into the saturation index, making the saturation index equal to 0, and calculating unique unknown number
Figure BDA00017881610400001113
I.e. a second concentration value of bicarbonate ions.
Specifically, calculated by MATLAB programming language
Figure BDA00017881610400001114
Solving with solve function in MATLAB
Figure BDA00017881610400001115
{ > syms x; % defines a variable x of
Figure BDA00017881610400001116
＞＞x＝solve(‘
Figure BDA0001788161040000113
Figure BDA0001788161040000114
', ' x '); % defines a 1X 1 array, stores x
＞＞x}
X in the MATLAB program is
Figure BDA0001788161040000121
Concentration, by introducing known parameters, can be directly obtained
Figure BDA0001788161040000122
I.e. a second concentration value of bicarbonate ions.
Step 304: calculating a difference value between the first concentration value and the second concentration value, if the difference value is less than or equal to a preset value, executing step 305, and if the difference value is greater than the preset value, executing step 306.
Step 305: the second concentration value is determined to be the concentration value of the first ion with scale in the wellbore and step 307 is performed.
Step 306: an average value of the first density value and the second density value is determined as a new first density value, and step 301 is performed.
Step 307: an actual concentration value of the first ion in the wellbore is obtained.
Step 308: and if the actual concentration value is greater than or equal to the second concentration value, determining to perform scale removal treatment on the shaft.
In the embodiment of the invention, the actual concentration value of the wellhead water sample of the shaft is compared with the determined second concentration value, if the actual concentration value is greater than or equal to the second concentration value, experimental verification is carried out, and corresponding scale cleaning measures are taken, so that a theoretical basis is provided for prevention and treatment of calcium carbonate scale in the non-scale shaft containing scale forming ions, namely bicarbonate ions, and the scale forming trends of the shaft of the oil and gas well containing carbon dioxide in the stratum can be predicted.
Fig. 4 is a schematic structural diagram of a wellbore-based ion concentration determination apparatus according to a fourth embodiment of the present invention, including:
a first determining unit 401, configured to determine an ion intensity according to a preset first concentration value of the first ion, where the first ion is a bicarbonate ion;
a second determining unit 402, configured to determine a second concentration value of the first ion according to the ion intensity and a preset saturation index, wherein a value of the saturation index indicates a fouling state of the wellbore;
a calculation unit 403 for calculating a difference between the first and second concentration values;
a third determining unit 404, configured to determine the second concentration value as the concentration value of the first ion when there is scale in the wellbore if the difference value is smaller than or equal to a preset value;
a fourth determining unit 405, configured to determine, if the difference is greater than a preset value, an average value of the first concentration value and the second concentration value as a new first concentration value, and trigger the first determining unit until the concentration value of the first ion is determined when there is a scale in the wellbore.
In this embodiment, the device for determining ion concentration based on a wellbore of this embodiment can perform the method for determining ion concentration based on a wellbore provided in the first embodiment of the present invention, and the implementation principles are similar, and are not described herein again.
The embodiment of the invention firstly determines the ion intensity according to a preset first concentration value of a first ion, wherein the first ion is bicarbonate ion, then the determined ion intensity is substituted into a saturation index, when the saturation index is zero, the shaft is in a scaling critical state, the saturation index is enabled to be equal to zero to determine a second concentration value of the first ion, then a difference value between the first concentration value and the second concentration value is calculated, when the difference value is larger than the preset value, the first concentration value needs to be updated, the second concentration value is recalculated, until when the difference value is smaller than or equal to the preset value, the second concentration value is determined to be the concentration value of the first ion when the shaft is scaled, namely the concentration of the ion with the scaling phenomenon in the shaft is predicted, so that the shaft which is not scaled can be prevented according to the concentration value, and the problem that the shaft can only be cleaned when the shaft is scaled is solved, the problem that the scaling of the shaft can block the pipeline is avoided.
Fig. 5 is a schematic structural diagram of an ion concentration determination apparatus based on a wellbore according to a fourth embodiment of the present invention, and based on the third embodiment, as shown in fig. 5,
when there is gas phase production in the wellbore, the second determining unit 402 is configured to obtain a first content value of carbon dioxide gas in the gas phase under preset temperature and pressure conditions
Figure BDA0001788161040000131
And obtaining the fugacity coefficient of carbon dioxide gas in the mixed gas of methane gas and carbon dioxide gas
Figure BDA0001788161040000132
The first content value is measured
Figure BDA0001788161040000133
The fugacity coefficient
Figure BDA0001788161040000134
Substituting the ion intensity into a saturation index to obtain a second concentration value; wherein the saturation index is
Figure BDA0001788161040000141
Figure BDA0001788161040000142
Figure BDA0001788161040000143
Wherein, [ Ca ]2+]Is the concentration value of calcium ions in the water of the wellbore,
Figure BDA0001788161040000144
and P is the second concentration value, P is absolute pressure, t is wellhead temperature of the wellbore, and u is the ionic strength.
The second determining unit 402 is configured to obtain the produced gas when no gas phase is produced in the wellboreA second content value of carbon dioxide gas in daily production fluid of the wellbore
Figure BDA00017881610400001410
The second content value
Figure BDA00017881610400001411
Substituting the ionic strength into the saturation index to obtain a second concentration value; wherein the saturation index is
Figure BDA0001788161040000145
Figure BDA0001788161040000146
Figure BDA0001788161040000147
Wherein, [ Ca ]2+]Is the concentration value of calcium ions in the water of the wellbore,
Figure BDA0001788161040000148
and P is the second concentration value, P is absolute pressure, t is wellhead temperature of the wellbore, and u is the ionic strength.
Further, the ionic strength is
Figure BDA0001788161040000149
Wherein, ciIs the concentration value of the i-th ion, ziIs the valence of the i-th ion, wherein c1Is a first concentration value, z, of said first ion1Is the valence of the first ion.
The device, still include:
a fifth determining unit 501, configured to obtain an actual concentration value of a first ion in a wellbore after determining the concentration value of the first ion when the wellbore has scale; and if the actual concentration value is greater than or equal to the second concentration value, determining to perform scale removal treatment on the shaft.
In this embodiment, the device for determining ion concentration based on a wellbore of this embodiment can perform the methods for determining ion concentration based on a wellbore provided in the second embodiment of the present invention and the third embodiment of the present invention, and the implementation principles thereof are similar, and are not described herein again.
In the embodiment of the invention, the actual concentration value of the wellhead water sample of the shaft is compared with the determined second concentration value, if the actual concentration value is greater than or equal to the second concentration value, experimental verification is carried out, and corresponding scale cleaning measures are taken, so that a theoretical basis is provided for prevention and treatment of calcium carbonate scale in the non-scale shaft containing scale forming ions, namely bicarbonate ions, and the scale forming trends of the shaft of the oil and gas well containing carbon dioxide in the stratum can be predicted.
Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.
It will be understood that the present disclosure is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims (10)

1. A wellbore-based ion concentration determination method, comprising:
repeating all of the following steps until a concentration value of the first ion is determined for having scale in the wellbore:
determining the ion intensity according to a preset first concentration value of the first ions, wherein the first ions are bicarbonate ions;
determining a second concentration value of the first ion based on the ion intensity and a preset saturation index, wherein a value of the saturation index represents a fouling state of the wellbore;
calculating a difference between the first concentration value and the second concentration value;
if the difference value is smaller than or equal to a preset value, determining that the second concentration value is the concentration value of the first ions when scales exist in the shaft;
and if the difference value is larger than a preset value, determining the average value of the first concentration value and the second concentration value as a new first concentration value.
2. The method of claim 1, wherein determining the second concentration value of the first ions based on the ion intensity and a preset saturation index when gas phase production is in the wellbore comprises:
obtaining a first content value of carbon dioxide gas in the gas phase under the conditions of preset temperature and pressure
Figure FDA0001788161030000011
And obtaining the fugacity coefficient of carbon dioxide gas in the mixed gas of methane gas and carbon dioxide gas
Figure FDA0001788161030000012
The first content value is measured
Figure FDA0001788161030000013
The fugacity coefficient
Figure FDA0001788161030000014
Substituting the ion intensity into a saturation index to obtain a second concentration value; wherein the content of the first and second substances,the saturation index is
Figure FDA0001788161030000015
Figure FDA0001788161030000016
Figure FDA0001788161030000017
Wherein, [ Ca ]2+]Is the concentration value of calcium ions in the water of the wellbore,
Figure FDA0001788161030000018
and P is the second concentration value, P is absolute pressure, t is wellhead temperature of the wellbore, and u is the ionic strength.
3. The method of claim 1, wherein determining the second concentration value of the first ion based on the ion intensity and a preset saturation index when no gas phase is produced in the wellbore comprises:
obtaining a second content value of carbon dioxide gas in daily production fluid of the wellbore
Figure FDA0001788161030000021
The second content value
Figure FDA0001788161030000022
Substituting the ionic strength into the saturation index to obtain a second concentration value; wherein the saturation index is
Figure FDA0001788161030000023
Figure FDA0001788161030000024
Figure FDA0001788161030000025
Wherein the content of the first and second substances,
Figure FDA0001788161030000026
is the concentration value of calcium ions in the water of the wellbore,
Figure FDA0001788161030000027
and P is the second concentration value, P is absolute pressure, t is wellhead temperature of the wellbore, and u is the ionic strength.
4. The method of claim 1, wherein the ionic strength isWherein, ciIs the concentration value of the i-th ion, ziIs the valence of the i-th ion, wherein c1Is a first concentration value, z, of said first ion1Is the valence of the first ion.
5. The method of any of claims 1-4, further comprising, after the determining the concentration value of the first ion at the time of the scale in the wellbore:
obtaining an actual concentration value of the first ion in the wellbore;
and if the actual concentration value is greater than or equal to the second concentration value, determining to perform scale removal treatment on the shaft.
6. A wellbore-based ion concentration determination apparatus, comprising:
a first determining unit, configured to determine an ion intensity according to a preset first concentration value of the first ion, where the first ion is a bicarbonate ion;
a second determination unit, configured to determine a second concentration value of the first ion according to the ion intensity and a preset saturation index, where a value of the saturation index represents a fouling state of the wellbore;
a calculation unit for calculating a difference between the first concentration value and the second concentration value;
a third determining unit, configured to determine, if the difference is smaller than or equal to a preset value, that the second concentration value is a concentration value of the first ion when there is scale in the wellbore;
and the fourth determining unit is used for determining an average value of the first concentration value and the second concentration value as a new first concentration value if the difference value is larger than a preset value, and triggering the first determining unit until the concentration value of the first ions is determined to be scaling in the shaft.
7. The apparatus of claim 6, wherein the second determining unit is configured to obtain a first content value of carbon dioxide gas in the gas phase under preset temperature and pressure conditions when the gas phase is produced in the wellbore
Figure FDA0001788161030000031
And obtaining the fugacity coefficient of carbon dioxide gas in the mixed gas of methane gas and carbon dioxide gas
Figure FDA0001788161030000032
The first content value is measured
Figure FDA0001788161030000033
The fugacity coefficient
Figure FDA0001788161030000034
Substituting the ion intensity into a saturation index to obtain a second concentration value; wherein the saturation index is
Figure FDA0001788161030000035
Figure FDA0001788161030000036
Figure FDA0001788161030000037
Wherein the content of the first and second substances,
Figure FDA0001788161030000038
is the concentration value of calcium ions in the water of the wellbore,
Figure FDA0001788161030000039
and P is the second concentration value, P is absolute pressure, t is wellhead temperature of the wellbore, and u is the ionic strength.
8. The apparatus of claim 6, wherein the second determination unit is configured to obtain a second content value of carbon dioxide gas in a daily production fluid of the wellbore when no gas phase is produced in the wellbore
Figure FDA00017881610300000310
The second content value
Figure FDA00017881610300000311
Substituting the ionic strength into the saturation index to obtain a second concentration value; wherein the saturation index is
Figure FDA00017881610300000312
Figure FDA00017881610300000313
Figure FDA00017881610300000314
Wherein the content of the first and second substances,
Figure FDA00017881610300000315
is the concentration value of calcium ions in the water of the wellbore,
Figure FDA00017881610300000316
and P is the second concentration value, P is absolute pressure, t is wellhead temperature of the wellbore, and u is the ionic strength.
9. The apparatus of claim 6, wherein the ionic strength is
Figure FDA00017881610300000317
Wherein, ciIs the concentration value of the i-th ion, ziIs the valence of the i-th ion, wherein c1Is a first concentration value, z, of said first ion1Is the valence of the first ion.
10. The apparatus of any of claims 6-9, further comprising:
a fifth determining unit, configured to obtain an actual concentration value of a first ion in a wellbore after determining the concentration value of the first ion when the wellbore has scale; and if the actual concentration value is greater than or equal to the second concentration value, determining to perform scale removal treatment on the shaft.
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