Prediction method for early formation fluid properties after high-temperature and high-pressure deep well perforation

Abstract

The invention relates to the technical field of well test analysis, in particular to a method for predicting early formation fluid properties after perforation of a high-temperature and high-pressure deep well. The method comprises the following steps: establishing a fitting equation of the maximum value of the average density of a mixture in a well in the early stage of oil testing of a tested high-temperature and high-pressure deep well in a research area and the static pressure gradient at a perforation interval after normal trial production of the tested high-temperature and high-pressure deep well; establishing a corresponding relation table of the static pressure gradient T and the formation fluid property at the high-temperature and high-pressure deep well perforation section in the research area; and obtaining the predicted formation fluid property of the oil well to be evaluated according to the maximum value of the average density of the blowout downhole mixture in the early stage of oil testing of the oil well to be evaluated. The early-stage formation fluid property prediction method after high-temperature and high-pressure deep well perforation fills the technical blank of early-stage fluid property prediction after high-temperature and high-pressure deep well perforation, and has the characteristics of simplicity, convenience, high efficiency, low cost and high accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of well testing analysis and is a method for predicting early formation fluid properties after perforating a high-temperature and high-pressure deep well. Background Art

[0002] Domestic oil resource exploration and development has entered the deep well stage from shallow wells. The wells faced have the characteristics of high temperature, high pressure, and deep wells. At present, a large number of difficulties in medium and shallow oil test exploration and production technology have been overcome, but there are still many problems that need to be solved in high temperature and high pressure deep well oil test technology. In order to reduce the safety risk of oil testing, before perforating oil testing, it is necessary to carry out detailed design of oil testing schemes, pipe optimization and mechanical analysis, sand prediction, and production pressure difference control. In the process of design optimization, it is necessary to use formation fluid parameters. These fluid parameters are usually predicted based on recording and measurement data. However, due to the complex geological conditions in the deep layer, recording, measurement and other technical means cannot fully and accurately predict the fluid properties of the formation, which often leads to large deviations in oil testing schemes and high oil testing risks.

[0003] After perforating a high-temperature, high-pressure deep well, the formation fluid enters the tubing string and the wellhead pressure rises. At this time, it is urgent to determine the fluid properties to provide a basis for the next production pressure difference control, sand prevention, and casing anti-extrusion protection. The earlier and more accurate the fluid judgment, the more beneficial it is for the next production. At present, there is an urgent need for a method to predict the early fluid properties after perforating a high-temperature, high-pressure deep well, so as to determine the formation fluid properties as early as possible and achieve the purpose of optimizing the oil test plan as soon as possible. Summary of the invention

[0004] The present invention provides a method for predicting early formation fluid properties after high-temperature and high-pressure deep well perforation, which overcomes the shortcomings of the above-mentioned prior art and can effectively solve the problem of the blank of the existing technology for predicting early fluid properties after high-temperature and high-pressure deep well perforation.

[0005] The technical solution of the present invention is achieved by the following measures: A method for predicting the properties of early formation fluids after perforation in a high-temperature and high-pressure deep well is carried out according to the following steps:

[0006] The first step is to collect the relevant parameters of early blowout after oil test perforation of oil wells in the study area;

[0007] The second step is to establish the maximum value of the average density of the downhole mixture in the early stage of high temperature and high pressure deep well oil testing. Computational models;

[0008] The third step is to calculate the maximum average density of the downhole mixture in the early stage of the high-temperature and high-pressure deep wells tested in the study area. The static pressure gradient T at the perforation section of a high-temperature, high-pressure deep well that has been tested for oil production after normal production test is established. and the fitting equation of T;

[0009] The fourth step is to classify the properties of the actual produced formation fluid according to the static pressure gradient T at the perforation section of the high-temperature and high-pressure deep wells after normal production test, and establish a corresponding relationship table between the static pressure gradient T at the perforation section of the high-temperature and high-pressure deep wells in the study area and the properties of the formation fluid;

[0010] The fifth step is to determine the maximum value of the average density of the downhole mixture during the early blowout of the oil well to be evaluated. The estimated value of the static pressure gradient at the perforation section after normal production of the oil well to be evaluated is calculated, and the estimated formation fluid properties of the oil well to be evaluated are obtained by comparing the corresponding relationship table between the static pressure gradient T at the perforation section and the formation fluid properties in the study area.

[0011] The following are further optimizations and / or improvements to the above technical solutions:

[0012] In the first step above, the parameters related to early blowout after perforation for oil well testing in the study area include: the highest wellhead shut-in pressure P when shutting in after perforation; 井口 、The volume of the tubing string per meter in the well V 内容 , the density of the wellbore killing fluid during perforation ρ 压井液 , the volume of well-killing fluid produced when the well is opened for blowout V, the wellhead pressure P' when the wellhead produces the volume of well-killing fluid V 井口 , vertical depth of the middle part of the oil layer is h.

[0013] In the second step above, the maximum value of the average density of the downhole mixture in the early stage of high temperature and high pressure deep well oil testing is ρ 平均max Calculated according to the following formula 1:

[0014]

[0015]

[0016] Where V 内容 is the volume of the tubing string per meter in the well, V is the volume of the well-killing fluid produced when the well is opened and blown out, and P 井口 P′ is the highest shut-in pressure at the wellhead when shutting in the well after perforation. 井口 is the wellhead pressure when the wellhead produces a killing fluid volume V, ρ 压井液 It is the density of the wellbore pressure fluid during perforation.

[0017] In the third step above, The expressions of the fitting equations of and T are:

[0018] T=kρ 平均max -a Formula 3

[0019] Where k and a are coefficients.

[0020] In the fourth step above, when establishing the correspondence table between the static pressure gradient T and the formation fluid properties at the perforation section of the high-temperature and high-pressure deep well in the study area, the formation fluid properties are divided into five categories, namely, formation water, oil-water mixture, crude oil, natural gas + water or natural gas + oil mixture and natural gas. The values ​​of the static pressure gradient T at the perforation section corresponding to the five types of formation fluid properties decrease in sequence.

[0021] The present invention provides a method for predicting the properties of early-stage formation fluids after high-temperature and high-pressure deep well perforation, which fills the technical gap of predicting the properties of early-stage fluids after high-temperature and high-pressure deep well perforation and has the characteristics of simplicity, high efficiency, low cost and high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Attached Figure 1 The oil well tested in Example 6 of the present invention Correlation analysis diagram of T. DETAILED DESCRIPTION

[0023] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0024] The present invention will be further described below in conjunction with embodiments:

[0025] Example 1: The method for predicting the properties of early formation fluids after perforation in a high-temperature and high-pressure deep well is carried out according to the following steps:

[0026] The first step is to collect the relevant parameters of early blowout after oil test perforation of oil wells in the study area;

[0027] The second step is to establish the maximum value of the average density of the downhole mixture in the early stage of high temperature and high pressure deep well oil testing. Computational models;

[0028] The third step is to calculate the maximum average density of the downhole mixture in the early stage of the high-temperature and high-pressure deep wells tested in the study area. The static pressure gradient T at the perforation section of a high-temperature, high-pressure deep well that has been tested for oil production after normal production test is established. and the fitting equation of T;

[0029] The fourth step is to classify the properties of the actual produced formation fluid according to the static pressure gradient T at the perforation section of the high-temperature and high-pressure deep wells after normal production test, and establish a corresponding relationship table between the static pressure gradient T at the perforation section of the high-temperature and high-pressure deep wells in the study area and the properties of the formation fluid;

[0030] The fifth step is to determine the maximum value of the average density of the downhole mixture during the early blowout of the oil well to be evaluated. The estimated value of the static pressure gradient at the perforation section after normal production of the oil well to be evaluated is calculated, and the estimated formation fluid properties of the oil well to be evaluated are obtained by comparing the corresponding relationship table between the static pressure gradient T at the perforation section and the formation fluid properties in the study area.

[0031] Example 2: As an optimization of the above example, in the first step, the parameters related to early blowout after perforation of oil wells in the study area include: the highest wellhead shut-in pressure P when shutting in after perforation 井口 、The volume of the tubing string per meter in the well V 内容 , the density of the wellbore killing fluid during perforation ρ 压井液 , the volume of well-killing fluid produced when the well is opened for blowout V, the wellhead pressure P' when the wellhead produces the volume of well-killing fluid V 井口 , vertical depth of the middle part of the oil layer h;

[0032] Example 3: As an optimization of the above example, in the second step, the maximum value of the average density of the downhole mixture in the early stage of high temperature and high pressure deep well oil testing is Calculated according to the following formula 1:

[0033]

[0034]

[0035] Where V 内容 is the volume of the tubing string per meter in the well, V is the volume of the well-killing fluid produced when the well is opened and blown out, and P 井口 P′ is the highest shut-in pressure at the wellhead when shutting in the well after perforation. 井口 is the wellhead pressure when the wellhead produces a killing fluid volume V, ρ 压井液 It is the density of the wellbore pressure fluid during perforation.

[0036] The maximum value of average density of downhole mixture in early blowout of high temperature and high pressure deep well oil testing The derivation process of the calculation model is as follows:

[0037] When the wellhead produces volume V, the height of the downhole well-killing fluid + formation production mixture (i.e. the downhole mixture after high-temperature and high-pressure deep well perforation) in the tubing

[0038] P 地层压力 =ρ 压井液 gh+P 井口 ,

[0039] P 流压 =P′ 井口 +ρ 压井液 g(h-h1)+ρ 平均 gh1,

[0040] Formation output, production pressure difference ≥ 0, that is: ΔP = P地层压力 -P 流压 ≥0,

[0041] ρ 压井液 gh+P 井口 -[P′ 井口 +ρ 压井液 g(h-h1)+ρ 平均 gh1]≥0,

[0042] P 井口 -P′ 井口 +gh1(ρ 压井液 -ρ 平均 )≥0,

[0043]

[0044]

[0045] The maximum value of the average density of the underground mixture is

[0046] Embodiment 4: As an optimization of the above embodiment, in the third step, The expressions of the fitting equations of and T are:

[0047] T=kρ 平均max -a Formula 3

[0048] Where k and a are coefficients.

[0049] Example 5: As an optimization of the above example, in the fourth step, when establishing a correspondence table between the static pressure gradient T and the formation fluid properties at the perforation section of a high-temperature and high-pressure deep well in the study area, the formation fluid properties are divided into five categories, namely, formation water, oil-water mixture, crude oil, natural gas + water or natural gas + oil mixture and natural gas. The values ​​of the static pressure gradient T at the perforation section corresponding to the five types of formation fluid properties decrease successively.

[0050] Example 6: The method for predicting the early formation fluid properties after high-temperature and high-pressure deep well perforation is used to predict the formation fluid properties of the well GT1 to be predicted in the southern edge of the Junggar Basin in Xinjiang. The specific operations are as follows:

[0051] The static pressure gradient T (see Table 1) at the perforation section of 15 layers in the area, including LT1, TW1, and HT1, which have been tested in the oil field, was collected. Based on the relevant data of the perforation and blowout of the above oil layers, the static pressure gradient T of the tested wells was calculated according to Formula 1. For tested oil wells Correlation analysis was performed with T (see Figure 1 ), the relationship expression between the two is:

[0052] According to the static pressure gradient T at the perforation section of the tested oil well and the formation fluid properties of the tested oil layer in Table 1, a corresponding reference table between the two in the region is established, see Table 2.

[0053] The early data of the predicted well GT1 after perforation are as follows:

[0054] ① Known shut-in after perforation, the highest shut-in pressure at the wellhead, P 井口 =58.89MPa;

[0055] ②The volume of the oil pipe per meter in the well V 内容 =7L / m;

[0056] ③ Open the well and release the blowout, producing the killing fluid V=36.7m3;

[0057] ④ When the output volume V, the wellhead pressure P' 井口 =79.95MPa;

[0058] ⑤ During perforation, the fluid density of the entire wellbore pressure, ρ 压井液 =1.3g / cm3;

[0059] ⑥ The vertical depth of the middle oil layer is h=6771.5m.

[0060] According to formula 1, the maximum value of the average density of the GT1 downhole mixture (i.e., the well killing fluid and the formation production fluid) is:

[0061] Further, by The estimated static pressure gradient at the perforation section after the GT1 well oil test was normal production was 0.719MPa / 100m. Referring to Table 2, the formation fluid property of the GT1 well was expected to be crude oil, and the later oil test result of the well was an oil layer, which was an accurate prediction.

[0062] In summary, the present invention fills the gap in the technology of predicting early fluid properties after perforating in high-temperature and high-pressure deep wells. In the early stage of oil testing, the early fluid properties after perforating in high-temperature and high-pressure deep wells can be quickly and accurately identified, providing accurate guidance for controlling the production pressure difference, preventing sand production from the formation, and protecting the casing from extrusion deformation.

[0063] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

[0064] Table 1

[0065]

[0066] Table 2

[0067]

[0068]

Claims

1. A method for predicting early formation fluid properties after perforation in a high-temperature and high-pressure deep well, characterized in that Follow these steps: The first step is to collect the relevant parameters of early blowout after oil test perforation of oil wells in the study area; The second step is to establish the maximum value of the average density of the downhole mixture in the early stage of high temperature and high pressure deep well oil testing ρ 平均max Computational models; The third step is to calculate the maximum value of the average density of the downhole mixture during the early blowout of the high-temperature and high-pressure deep wells in the study area. 平均max The static pressure gradient T at the perforation section of a high-temperature and high-pressure deep well that has been tested for oil production after normal production test is established. 平均max and the fitting equation of T; The fourth step is to classify the properties of the actual produced formation fluid according to the static pressure gradient T at the perforation section of the high-temperature and high-pressure deep wells after normal production test, and establish a corresponding relationship table between the static pressure gradient T at the perforation section of the high-temperature and high-pressure deep wells in the study area and the properties of the formation fluid; The fifth step is to use the maximum value of the average density of the downhole mixture in the early stage of the oil test of the oil well to be evaluated, ρ 平均max The estimated value of the static pressure gradient at the perforation section after normal production of the oil well to be evaluated is calculated, and the estimated formation fluid properties of the oil well to be evaluated are obtained by comparing the corresponding relationship table between the static pressure gradient T at the perforation section and the formation fluid properties in the study area.

2. The method for predicting early formation fluid properties after high-temperature and high-pressure deep well perforation according to claim 1 is characterized in that In the first step, the parameters related to early blowout after perforation for oil wells in the study area include: the highest wellhead shut-in pressure P when shutting in after perforation; 井口 、The volume of the tubing string per meter in the well V 内容 , the density of the wellbore killing fluid during perforation ρ 压井液 , the volume of well-killing fluid produced when the well is opened for blowout V, the wellhead pressure P' when the wellhead produces the volume of well-killing fluid V 井口 , vertical depth of the middle part of the oil layer is h.

3. The method for predicting early formation fluid properties after high-temperature and high-pressure deep well perforation according to claim 1 or 2, characterized in that In the second step, the maximum value of the average density of the downhole mixture in the early stage of high temperature and high pressure deep well oil testing is ρ 平均max Calculated according to the following formula 1: Where V 内容 is the volume of the tubing string per meter in the well, V is the volume of the well-killing fluid produced when the well is opened and blown out, and P 井口 P′ is the highest wellhead shut-in pressure after perforation. 井口 is the wellhead pressure when the wellhead produces the killing fluid volume V, ρ 压井液 It is the density of the wellbore pressure fluid during perforation.

4. The method for predicting early formation fluid properties after high-temperature and high-pressure deep well perforation according to claim 1 or 2, characterized in that In the third step, ρ 平均max The expressions of the fitting equations of and T are: T = kρ 平均max - Equation 3 In the formula, k and a are coefficients.

5. The method for predicting early formation fluid properties after high-temperature and high-pressure deep well perforation according to claim 3 is characterized in that In the third step, ρ 平均max The expressions of the fitting equations of and T are: T = kρ 平均max - a Formula 3 In the formula, k and a are coefficients.

6. The method for predicting early formation fluid properties after high-temperature and high-pressure deep well perforation according to claim 5 is characterized in that In the fourth step, when establishing the correspondence table between the static pressure gradient T and the formation fluid properties at the perforation section of the high-temperature and high-pressure deep well in the study area, the formation fluid properties are divided into five categories, namely, formation water, oil-water mixture, crude oil, natural gas + water or natural gas + oil mixture and natural gas. The values ​​of the static pressure gradient T at the perforation section corresponding to the five types of formation fluid properties decrease in sequence.

7. The method for predicting early formation fluid properties after high-temperature and high-pressure deep well perforation according to claim 5 or 6, characterized in that In the fourth step, when establishing the correspondence table between the static pressure gradient T and the formation fluid properties at the perforation section of the high-temperature and high-pressure deep well in the study area, the formation fluid properties are divided into five categories, namely, formation water, oil-water mixture, crude oil, natural gas + water or natural gas + oil mixture and natural gas. The values ​​of the static pressure gradient T at the perforation section corresponding to the five types of formation fluid properties decrease in sequence.

8. The method for predicting early formation fluid properties after high-temperature and high-pressure deep well perforation according to claim 5 or 6, characterized in that In the fourth step, when establishing the correspondence table between the static pressure gradient T and the formation fluid properties at the perforation section of the high-temperature and high-pressure deep well in the study area, the formation fluid properties are divided into five categories, namely, formation water, oil-water mixture, crude oil, natural gas + water or natural gas + oil mixture and natural gas. The values ​​of the static pressure gradient T at the perforation section corresponding to the five types of formation fluid properties decrease in sequence.

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