H in oil field gathering and transportation pipeline2S and CO2Method for obtaining partial pressure
阅读说明：本技术 一种油田集输管道内h2s和co2分压的获取方法 (H in oil field gathering and transportation pipeline2S and CO2Method for obtaining partial pressure ) 是由 唐德志 谷坛 陈宏健 于 2020-05-08 设计创作，主要内容包括：本发明公开了一种油田集输管道内H-(2)S和CO-(2)分压的获取方法,属于管道防腐领域。方法包括：获取油田集输管道内部的管道压力和管道温度；从油田集输管道的取样口处取样品,获取样品中包含的气体样品的体积和液体样品的体积；测量气体样品中的H-(2)S气体含量和CO-(2)气体含量,同时获取进行测量的环境的环境压力和环境温度；基于以上参数,分别获取得到油田集输管道内H-(2)S的分压和CO-(2)的分压。该方法可以获得油田集输管道内H-(2)S和CO-(2)在带温带压状态下的准确分压。(The invention discloses an H in an oil field gathering and transportation pipeline 2 S and CO 2 A partial pressure obtaining method belongs to the field of pipeline corrosion prevention. The method comprises the following steps: acquiring the pipeline pressure and the pipeline temperature inside an oil field gathering and transportation pipeline; sampling a sample from a sampling port of an oil field gathering and transportation pipeline, and acquiring the volume of a gas sample and the volume of a liquid sample contained in the sample; measuring H in a gas sample 2 S gas content and CO 2 Gas content, and simultaneously acquiring the environmental pressure and the environmental temperature of the environment for measurement; based on the parameters, H in the oil field gathering and transportation pipeline is obtained respectively 2 Partial pressure of S and CO 2 Partial pressure of (c). The method can obtain the oil field gathering and transportation pipelineInner H 2 S and CO 2 Accurate partial pressure under the condition of temperature and pressure.)
1. H in oil field gathering and transportation pipeline2S and CO2The partial pressure acquisition method is characterized by comprising the following steps:
acquiring the pipeline pressure and the pipeline temperature inside the oilfield gathering and transportation pipeline;
sampling a sample from a sampling port of the oilfield gathering and transportation pipeline, and acquiring the volume of a gas sample and the volume of a liquid sample contained in the sample;
measuring H in the gas sample2S gas content and CO2Gas content, simultaneously obtaining the ambient pressure and ambient temperature of the environment in which the measurements are made;
based on the parameters, respectively obtaining H in the oil field gathering and transportation pipeline through the following formula2Partial pressure of S and CO2Partial pressure of (a);
wherein, PCO2(T1)For CO inside the gathering and transportation pipeline of the oil field2Partial pressure;
PH2S(T1)for H inside gathering and transportation pipeline of oil field2S, partial pressure;
Vgis the volume of the gas sample;
VLis the volume of the liquid sample;
T0is ambient temperature, P0Is at ambient pressure;
T1is the temperature of the pipeline, P1Is the pipeline pressure;
at a temperature of T0Pressure of P0The gas fugacity coefficient below;
at a temperature of T1Pressure of P1The gas fugacity coefficient below;
KCO2(T0)at a temperature of T0CO of2The solution equilibrium constant of the gas;
KCO2(T1)at a temperature of T1CO of2The solution equilibrium constant of the gas;
KH2S(T0)at a temperature of T0H2S gas dissolution equilibrium constant;
KH2S(T1)at a temperature of T1H2S gas dissolution equilibrium constant;
xH2Sas H in gas samples2S content, mol%;
xCO2as CO in gas samples2Content, mol%.
2. The oilfield gathering and transportation pipeline internal H of claim 12S and CO2A method for obtaining a partial pressure, wherein the obtaining of a volume of a gas sample and a volume of a liquid sample contained in the sample comprises:
putting the sample obtained from the sampling port into a transparent sampling bottle with scales, sealing and standing;
standing for a set time until gas and liquid in the sample are layered;
the volume of the gas sample and the volume of the liquid sample are read separately.
3. The oilfield gathering and transportation pipeline internal H of claim 12S and CO2Obtaining of partial pressureThe method is characterized in that H in the gas sample is respectively measured by adopting a gas chromatography or a colorimetric tube method2S gas content and CO2Gas content.
4. The oilfield gathering and transportation pipeline internal H of claim 12S and CO2Method for obtaining partial pressure, characterized in thatObtained by the following formula:
5. the oilfield gathering and transportation pipeline internal H of claim 12S and CO2Method for obtaining partial pressure, characterized in thatObtained by the following formula:
6. the oilfield gathering and transportation pipeline internal H of claim 12S and CO2Method for obtaining partial pressure, characterized in that said K isCO2(T0)And said KCO2(T1)Are obtained by the following formula:
wherein I is the ionic strength in the liquid sample;
t is T0Or T1。
7. The oilfield gathering and transportation pipeline internal H of claim 62S and CO2The method for obtaining partial pressure is characterized in that the ionic strength I in the liquid sample is obtained by the following formula:
wherein m isiIs the ion concentration of the i ion in the liquid sample;
ziis the valence state of i ion in the liquid sample;
the i ions include: mg (magnesium)2+、Ca2+、K+、Na+、Cl-、CO3 2-、HCO3 -And SO4 2-Ions.
8. The oilfield gathering and transportation pipeline internal H of claim 72S and CO2A method for obtaining a partial pressure, characterized in that an ion concentration of i ions in the liquid sample is measured by a spectrophotometer.
9. The oilfield gathering and transportation pipeline internal H of claim 12S and CO2Method for obtaining partial pressure, characterized in that said K isH2S(T0)And said KH2S(T1)Are obtained by the following formula:
wherein I is the ionic strength in the liquid sample;
t is T0Or T1。
10. The oilfield gathering and transportation pipeline internal H of claim 12S and CO2The method for obtaining partial pressure is characterized in thatAnd respectively acquiring the pipeline pressure and the pipeline temperature through a pressure gauge and a thermometer assembled on the oilfield gathering and transportation pipeline.
Technical Field
The invention relates to the field of pipeline corrosion prevention, in particular to an H in an oil field gathering and transportation pipeline2S and CO2And a partial pressure obtaining method.
Background
At present, contains H2S、CO2More and more oil fields, H2S、CO2Under the coexistence condition, the corrosion in the oil field gathering and transportation pipeline is easy to cause. Research shows that H is in the gathering and transportation pipeline of the oil field2S、CO2Partial pressure is a key factor in determining the degree of corrosion in the pipeline, so obtaining H in the pipeline2S and CO2The partial pressure of (c) is necessary.
In the prior art, H in gas phase after temperature reduction and pressure reduction is carried out on the sampling port of an oil field gathering and transportation pipeline on the site of an oil field2S and CO2The partial pressure of the pressure is used as H in the pipeline under the state of temperature and pressure2S and CO2Partial pressure.
In the process of implementing the invention, the inventor finds that the prior art has at least the following technical problems:
due to the influence of temperature and pressure, H in the gas phase is reduced in temperature and pressure2S and CO2The partial pressures are significantly different from their actual partial pressures in the pipeline, which can cause H pairs2S and CO2The difference of the understanding of corrosion in the gathering and transportation pipeline of the oil field under the coexistence condition can even cause misjudgment, thus leading to the corrosion perforation of the pipeline.
Disclosure of Invention
In view of the above, the present invention provides an H in an oil field gathering and transportation pipeline2S and CO2The partial pressure obtaining method can obtain H in the oil field gathering and transportation pipeline under the condition of temperature and pressure2S and CO2The exact partial pressure of (a).
Specifically, the method comprises the following technical scheme:
h in oil field gathering and transportation pipeline2S and CO2A method of obtaining partial pressure, the method comprising:
acquiring the pipeline pressure and the pipeline temperature inside the oilfield gathering and transportation pipeline;
sampling a sample from a sampling port of the oilfield gathering and transportation pipeline, and acquiring the volume of a gas sample and the volume of a liquid sample contained in the sample;
measuring H in the gas sample2S gas content and CO2Gas content, simultaneously obtaining the ring in which the measurement is madeAmbient pressure and ambient temperature;
based on the parameters, respectively obtaining H in the oil field gathering and transportation pipeline through the following formula2Partial pressure of S and CO2Partial pressure of (a);
wherein, PCO2(T1)For CO inside the gathering and transportation pipeline of the oil field2Partial pressure;
PH2S(T1)for H inside gathering and transportation pipeline of oil field2S, partial pressure;
Vgis the volume of the gas sample;
VLis the volume of the liquid sample;
T0is ambient temperature, P0Is at ambient pressure;
T1is the temperature of the pipeline, P1Is the pipeline pressure;
at a temperature of T0Pressure of P0The gas fugacity coefficient below;
at a temperature of T1Pressure of P1The gas fugacity coefficient below;
KCO2(T0)at a temperature of T0CO of2The solution equilibrium constant of the gas;
KCO2(T1)at a temperature of T1CO of2The solution equilibrium constant of the gas;
KH2S(T0)at a temperature of T0H2S gas dissolution equilibrium constant;
KH2S(T1)at a temperature of T1H2S gas dissolution equilibrium constant;
xH2Sas H in gas samples2S content, mol%;
xCO2as CO in gas samples2Content, mol%.
In one possible implementation, the obtaining a volume of the gas sample and a volume of the liquid sample contained in the sample includes:
putting the sample obtained from the sampling port into a transparent sampling bottle with scales, sealing and standing;
standing for a set time until gas and liquid in the sample are layered;
the volume of the gas sample and the volume of the liquid sample are read separately.
In one possible implementation, the H in the gas sample is measured by using gas chromatography or a cuvette method, respectively2S gas content and CO2Gas content.
In one possible implementation, the method comprisesObtained by the following formula:
in one possible implementation, the method comprisesObtained by the following formula:
in one possible implementation, the KCO2(T0)And said KCO2(T1)Are obtained by the following formula:
wherein I is the ionic strength in the liquid sample;
t is T0Or T1。
In one possible implementation, the ionic strength I in the liquid sample is obtained by the following formula:
wherein m isiIs the ion concentration of the i ion in the liquid sample;
ziis the valence state of i ion in the liquid sample;
the i ions include: mg (magnesium)2+、Ca2+、K+、Na+、Cl-、CO3 2-、HCO3 -And SO4 2-Ions.
In one possible implementation, the ion concentration of i ions in the liquid sample is measured by a spectrophotometer.
In one possible implementation, the KH2S(T0)And said KH2S(T1)Are obtained by the following formula:
wherein I is the ionic strength in the liquid sample;
t is T0Or T1。
In one possible implementation, the pipeline pressure and the pipeline temperature are obtained by a pressure gauge and a temperature gauge assembled on the oilfield gathering and transportation pipeline, respectively.
The technical scheme provided by the embodiment of the invention has the beneficial effects that at least:
the method provided by the embodiment of the invention is based on a gas state equation and a substance quantity conservation principle, combines gas dissolution balance, and utilizes the following parameters obtained by measurement: pipeline pressure and pipeline temperature inside oilfield gathering and transportation pipeline, environmental pressure and environmental temperature of temperature-reducing and pressure-reducing measurement environment, volume of gas sample and volume of liquid sample contained in sample, and H in gas sample2S gas content and CO2Gas content, calculating the gas fugacity coefficient and H2S gas and CO2Respectively calculating the dissolved equilibrium constant of the gas by using a formula (1) and a formula (2) to obtain H in the oil field gathering and transportation pipeline2Partial pressure of S and CO2Partial pressure of (c). The embodiment of the invention provides a method for acquiring H in an oil field gathering and transportation pipeline2Partial pressure of S and CO2The partial pressure method of (1) is to measure H in the gathering and transportation pipeline sample after temperature and pressure reduction2S partial pressure and CO2Partial pressure reduction is carried out to obtain in-situ H in the state of temperature and pressure in the pipeline2S partial pressure and CO2Partial pressure, can obtain H in the oil field gathering and transportation pipeline in the in-situ state with high precision2S gas and CO2Partial pressure of gas, favouring H2S and CO2Under the coexistence condition, the corrosion in the oil field gathering and transportation pipeline can be accurately known and judged, and the method has important significance for effectively controlling the corrosion of the pipeline.
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 will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 shows an embodiment of the present invention, which provides an H-channel in an oilfield gathering and transportation pipeline2S and CO2A flow chart of a method for obtaining the partial pressure.
Detailed Description
In order to make the technical solutions and advantages of the present invention clearer, the following will describe embodiments of the present invention in further detail with reference to the accompanying drawings.
The embodiment of the invention provides an H in an oil field gathering and transportation pipeline2S and CO2The method for obtaining the partial pressure is shown in the attached figure 1, and comprises the following steps:
step S1: acquiring pipeline pressure P inside oil field gathering and transportation pipeline1And temperature T of the pipe1。
Step S2: sampling from the sampling port of the oil field gathering and transportation pipeline to obtain the volume V of the gas sample contained in the samplegAnd volume V of the liquid sampleL。
Step S3: measuring H in a gas sample2S gas content xH2SAnd CO2Gas content xCO2Simultaneously acquiring the ambient pressure P of the environment in which the measurement is to be made0And the ambient temperature T0。
Step S4: based on the parameters, the H in the oil field gathering and transportation pipeline is respectively obtained through the following formula (1) and formula (2)2Partial pressure of S and CO2Partial pressure of (a);
wherein, PCO2(T1)For CO inside oil field gathering and transportation pipeline2Partial pressure in Pa;
PH2S(T1)for H inside gathering and transportation pipeline of oil field2S partial pressure with the unit of Pa;
Vgvolume of the gas sample in m3；
VLIs the volume of the liquid sample in m3；
T0Is the ambient temperature in units of K, P0Is ambient pressure in Pa；
T1Is the temperature of the pipeline in units of K, P1Is the pipeline pressure in Pa;
at a temperature of T0Pressure of P0The gas fugacity coefficient below;
at a temperature of T1Pressure of P1The gas fugacity coefficient below;
KCO2(T0)at a temperature of T0CO of2The solution equilibrium constant of the gas;
KCO2(T1)at a temperature of T1CO of2The solution equilibrium constant of the gas;
KH2S(T0)at a temperature of T0H2S gas dissolution equilibrium constant;
KH2S(T1)at a temperature of T1H2S gas dissolution equilibrium constant;
xH2Sas H in gas samples2S content, mol%;
xCO2as CO in gas samples2Content, mol%;
r is an ideal gas constant and has a value of 8.314 J.mol-1·K-1。
The method provided by the embodiment of the invention is based on a gas state equation and a substance quantity conservation principle, combines gas dissolution balance, and utilizes the following parameters obtained by measurement: pipeline pressure and pipeline temperature inside oilfield gathering and transportation pipeline, environmental pressure and environmental temperature of temperature-reducing and pressure-reducing measurement environment, volume of gas sample and volume of liquid sample contained in sample, and H in gas sample2S gas content and CO2Gas content, calculating the gas fugacity coefficient and H2S gas and CO2The dissolved equilibrium constant of the gas is determined byRespectively calculating the formula (1) and the formula (2) to obtain H in the oil field gathering and transportation pipeline2Partial pressure of S and CO2Partial pressure of (c). The embodiment of the invention provides a method for acquiring H in an oil field gathering and transportation pipeline2Partial pressure of S and CO2The partial pressure method of (1) is to measure H in the gathering and transportation pipeline sample after temperature and pressure reduction2S partial pressure and CO2Partial pressure reduction is carried out to obtain in-situ H in the state of temperature and pressure in the pipeline2S partial pressure and CO2Partial pressure, can obtain H in the oil field gathering and transportation pipeline in the in-situ state with high precision2S gas and CO2Partial pressure of gas, favouring H2S and CO2Under the coexistence condition, the corrosion in the oil field gathering and transportation pipeline can be accurately known and judged, and the method has important significance for effectively controlling the corrosion of the pipeline.
For step S1, the oilfield gathering and transportation pipeline is equipped with a pressure gauge and a thermometer, and the embodiment of the present invention can obtain the accurate pipeline pressure P by reading the readings of the pressure gauge and the thermometer on the oilfield gathering and transportation pipeline1And temperature T of the pipe1. The pressure P of the pipeline1And temperature T of the pipe1The pressure and the temperature in the oil field gathering and transportation pipeline can be accurately reflected.
Ambient pressure P for the environment in which the measurement is being made0And the ambient temperature T0Generally speaking, the two are outdoor atmospheric pressure and outdoor atmospheric temperature, respectively.
For step 2, after a sample is taken from the sampling port of the oilfield gathering and transportation pipeline, the volume of the gas sample and the volume of the liquid sample contained in the sample are obtained so as to facilitate the subsequent H pair2S gas content and CO2And (4) calculating the gas content.
Wherein the following method may be employed to obtain the volume of the gas sample and the volume of the liquid sample contained in the sample:
and (3) placing the sample obtained from the sampling port of the oil field gathering and transportation pipeline into a transparent sampling bottle with scales, sealing and standing, layering gas and liquid in the sample after standing for a set time, and reading the volume of the gas sample and the volume of the liquid sample respectively.
The method comprises the steps that a transparent sampling bottle with a known volume is filled with a sample, after a gas sample and a liquid sample are formed by gas-liquid layering, the volume of the liquid sample is directly read by using scales, and the volume of the liquid sample is subtracted from the volume of the sampling bottle, so that the volume of the gas sample can be obtained.
It is understood that the gases in the gas sample include, but are not limited to: h2S gas and CO2A gas; the liquid sample is essentially an oilfield produced fluid.
In step 3, for H contained in the gas sample2S gas and CO2The content of gas can be measured by gas chromatography or colorimetric tube method (colorimetric method for short) to obtain H in gas sample2S gas content and CO2Gas content, i.e. H2S gas in mol% of the gas sample, and, CO2The gas represents mol% of the gas sample.
For gas chromatography, a gas chromatograph is used to operate, and a gas sample is introduced via injection or automatically, and is carried by a carrier gas through a separation column to a detector for detection. Due to H2S gas and CO2The time of gas passing through the separation column is different, and the concentration is proportional to the detection signal, so that the H in the gas sample can be accurately obtained2S gas content and CO2Gas content.
For the colorimetric cylinder method, gas samples are directly and respectively sucked from a sampling bottle twice, the sucked gas samples are respectively led into a colorimetric cylinder containing a specific chemical reagent, and H2S gas and CO2The gas respectively presents different colors after reacting with specific chemical reagent, and H can be obtained according to the presented color because the presented color has a proportional relation with the concentration2S gas content and CO2Gas content.
The manner in which the gas fugacity coefficient and the solution equilibrium constant are obtained is described below:
for a temperature of T0Pressure of P0Coefficient of gas fugacityCan be obtained by the following formula (3):
for a temperature of T1Pressure of P1Coefficient of gas fugacityCan be obtained by the following formula (4):
for CO2Gas at a temperature T0And a temperature T1Solution equilibrium constant K ofCO2(T0)And KCO2(T1)Both are obtained by the following formula (5):
wherein I is the ionic strength in the liquid sample; t is T0Or T1。
T is T0Then, K is calculatedCO2(T)Is KCO2(T0)；
T is T1Then, K is calculatedCO2(T)Is KCO2(T1)。
For the ionic strength I in the liquid sample referred to above, it can be obtained by the following formula (6):
wherein m isiIs the ion concentration of the i ion in the liquid sample;
ziis the valence state of i ion in the liquid sample;
the i ions include: mg (magnesium)2+、Ca2+、K+、Na+、Cl-、CO3 2-、HCO3 -And SO4 2-Ions.
The method provided by the embodiment of the invention fully considers common ions such as Mg in the gathering and transportation pipeline of the oil field2+、Ca2+、K+、Na+、Cl-、CO3 2-、HCO3 -And SO4 2-Influence of ions, calculating CO from the ionic strength of the above ions in the liquid sample2The solution equilibrium constant of the gas can be obviously improved in such a way that the H in the oil field gathering and transportation pipeline in an in-situ state can be obviously improved2S partial pressure and CO2The calculation accuracy of the partial pressure.
Wherein the ion concentration m of i ions in the liquid sampleiCan be measured by a spectrophotometer.
For H2S gas at a temperature of T0And a temperature T1Solution equilibrium constant K ofH2S(T0)And KH2S(T1)Both are obtained by the following formula (7):
wherein T is T0Or T1。
T is T0Then, K is calculatedH2S(T)Is KH2S(T0)；
T is T1Then, K is calculatedH2S(T)Is KH2S(T1)。
The invention will be further described by the following specific examples:
step 1, researching a gathering and transportation pipeline of an oil field, and respectively acquiring the pipeline temperature T in the pipeline by using a thermometer and a pressure gauge on the gathering and transportation pipeline of the oil field1At 50 ℃ and a pipeline pressure P1Is 10 MPa.
Step 2, utilizing one belt to carveAnd a transparent sampling bottle for taking a sample from the sampling port of the oilfield gathering and transportation pipeline. After the sample is taken back to the laboratory and kept stand for 24 hours, the volume V of the gas sample is respectively read through the scale marks on the wall of the sampling bottleg200ml, volume V of liquid sampleLIs 300 ml.
Step 3, respectively measuring H in the gas sample by adopting gas chromatography2S gas content xH2SAnd CO2Gas content xCO22.5 mol% and 5 mol%, respectively, and simultaneously, a thermometer and a pressure gauge are used for respectively reading the indoor environment temperature T0At 25 ℃ and an ambient pressure P0Is 1.1 MPa.
Step 4, measuring the ion concentration m of various ions in the liquid sample by using a spectrophotometeriRespectively as follows: mg (magnesium)2+800mol/L，Ca2+550mol/L，K+400mol/L，Na+300mol/L，Cl-500mol/L，CO3 2-250mol/L，HCO3 -300mol/L and SO4 2-350mol/L。
From the above ion concentrations, the ion intensity i was calculated to be 2700mol/L by the following formula (6).
Step 5, converting the units of the parameters into standard units, for example, converting the temperature from the DEG C to the K, and then obtaining the H in the oil field gathering and transportation pipeline according to the parameters of the standard units through the following formula (1) and formula (2) respectively2Partial pressure of S and CO2Partial pressure of (c):
wherein the temperature is T0Pressure and pressureForce P0Coefficient of gas fugacityCan be obtained by the following formula (3):
temperature of T1Pressure of P1Coefficient of gas fugacityCan be obtained by the following formula (4):
CO2gas at a temperature T0And a temperature T1Solution equilibrium constant K ofCO2(T0)And KCO2(T1)Both are obtained by the following formula (5):
H2s gas at a temperature of T0And a temperature T1Solution equilibrium constant K ofH2S(T0)And KH2S(T1)Both are obtained by the following formula (7):
the calculation result is as follows: in the oil field gathering and transportation pipeline, H is in an in-situ state (with temperature and pressure)2Partial pressure P of SH2S(T1)0.11MPa, CO2Partial pressure P ofCO2(T1)It was 0.055 MPa.
The above description is only for facilitating the understanding of the technical solutions of the present invention by those skilled in the art, and is not intended to limit the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.