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Method for evaluating influence of carbon dioxide flooding salt deposit precipitation on recovery efficiency

A carbon dioxide and oil recovery technology, applied in the fields of mining fluid, earthwork drilling, design optimization/simulation, etc., can solve problems such as plugging pore throats, reducing reservoir permeability, lack of calculation methods for salt scale precipitation, etc., to achieve convenient Prediction, the effect of improving accuracy

Active Publication Date: 2021-01-15
PETROCHINA CO LTD
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Problems solved by technology

[0003] If the formation water itself contains high concentrations of calcium ions, magnesium ions and other scaling ions, along with CO 2 The concentration of carbonate and bicarbonate ions in the formation water increases, and the carbonate and bicarbonate ions react with calcium ions and magnesium ions to form calcium carbonate and magnesium carbonate solid phase deposition, which block the pore throats and reduce the reservoir permeability. , which in turn affects the oil displacement effect of carbon dioxide, but there is currently a lack of calculation methods for the impact of salt scale precipitation on oil recovery

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  • Method for evaluating influence of carbon dioxide flooding salt deposit precipitation on recovery efficiency
  • Method for evaluating influence of carbon dioxide flooding salt deposit precipitation on recovery efficiency

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Embodiment 1

[0045]This embodiment provides a method for evaluating the impact of carbon dioxide flooding salt scale precipitation on recovery, including the following steps:

[0046] Step 1) Collect water samples from multiple oil wells in the formation of the target oil reservoir, analyze and obtain the scale-forming ion species and scale-forming ion content M;

[0047] Step 2) Under different temperatures and different pressure differences, carry out the interaction reaction experiment between carbon dioxide and formation water, obtain the amount of salt scale precipitation generated by carbon dioxide and formation water, and establish the temperature T, pressure difference ΔP, scale-forming ion content M and salt The relational formula of scale deposition amount;

[0048] Step 3) According to the temperature T, the pressure difference ΔP, and the relational expression between the scale-forming ion content M and the salt scale precipitation amount, the salt scale precipitation amount co...

Embodiment 2

[0059] On the basis of Example 1, this example provides a method for evaluating the influence of carbon dioxide flooding salt scale precipitation on recovery factor. In step 2), temperature T, pressure difference ΔP, scale-forming ion content M and salt scale precipitation amount The relationship is as follows:

[0060] y=ae (bT+cΔp+dM)

[0061] In the formula, a, b, c and d are constants; T is temperature, °C; ΔP is pressure difference, MPa; M is the scale-forming ion content, mg / L.

[0062] In this embodiment, an expression for calculating the amount of salt scale precipitation after the interaction between carbon dioxide and formation water is established based on the experimental data. The amount of salt scale deposition has an exponential relationship with temperature, pressure difference, and scale-forming ion content. By substituting four sets of data in the formula, four constant values ​​of a, b, c and d can be obtained.

Embodiment 3

[0064] On the basis of Example 1, this example provides a method for evaluating the influence of carbon dioxide flooding salt scale precipitation on recovery factor. In step 4), Eclipse software is used to establish a one-dimensional numerical model of the physical properties of the target reservoir and the properties of formation fluids. The process is as follows:

[0065] Input the average porosity, permeability, original oil saturation, original pressure, and formation temperature of the target reservoir into the Eclipse software to generate a one-dimensional numerical model.

[0066] The parameters are shown in Table 3, and the one-dimensional numerical model is automatically generated after inputting the parameters with the help of Eclipse software.

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Abstract

The invention belongs to the technical field of oil and gas field development, and provides a method for evaluating the influence of carbon dioxide flooding salt deposit precipitation on recovery efficiency. On the basis of theoretical analysis and experimental research on salt deposit precipitation caused by CO2 flooding, a one-dimensional numerical model is established by using numerical simulation software, and a core CO2 flooding experiment is simulated. By using a chemical reaction model, the influence of salt deposit precipitation on the core in the CO2 flooding process is considered. Parameters are continuously adjusted in the numerical model, and correction is carried out by using a physical model experiment result. A one-dimensional model of salt deposit precipitation in the CO2 flooding process suitable for a research sample is established, and the influence of salt deposit precipitation on the final recovery efficiency is analyzed. Therefore, whether the influence of salt deposit precipitation needs to be considered in subsequent recovery efficiency prediction can be determined, recovery efficiency prediction is facilitated, and the accuracy of prediction is improved.

Description

technical field [0001] The invention belongs to the technical field of oil and gas field development, and in particular relates to a method for evaluating the influence of carbon dioxide driving salt scale precipitation on recovery factor. Background technique [0002] in CO 2 During the flooding process, the injection of CO 2 Meet the formation water in the formation, a small part of CO 2 Reacts with water to form carbonic acid, but most of the CO 2 CO in water 2 Molecular form exists, CO 2 Dissolved in formation water to generate carbonic acid. CO 2 Water dissolves much faster in water than in oil, but CO 2 The solubility in crude oil is 4-10 times that in water, so the CO dissolved in water 2 It can be dissolved in oil. CO 2 The solubility in water decreases with the increase of temperature and increases with the increase of pressure. At the same time, the salinity in water has an effect on CO 2 Solubility will also be affected, the higher the salt content, th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B43/16E21B49/00G06F30/20
CPCE21B43/164E21B49/00G06F30/20Y02P90/70
Inventor 上官阳南王永宏张永强熊维亮杨金龙郑自刚余光明雷欣慧
Owner PETROCHINA CO LTD
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