Method for solving well deviation by using MDT test data

Abstract

The invention relates to the technical field of logging formation testing, in particular to a method for solving well deviation by using MDT test data. According to the method for solving the well deviation by using the MDT test data, data such as the density, the viscosity and the temperature of fluid existing in a target well are collected, the target well is subjected to well washing by using the fluid with the known density when necessary, then formation testing such as MDT testing, testing while drilling or oil testing is carried out once, the fluid liquid column pressure of a plurality of test points of a target well section is obtained through testing, and the well deviation is obtained. And finally, according to the corrected data, the hole drift angle and the vertical depth of the target well section are calculated. According to the method for solving the well deviation by using the MDT test data, the well deviation angle and the vertical depth of the target well section can be calculated according to the obtained pressure data after formation testing, it is ensured that determination of the underground environment and designation work of construction and a treatment scheme are conducted in time, the coincidence rate of oil and water recognition of a formation pressure profile is increased, and the method is suitable for popularization and application. And oilfield benefits are increased.

Description

Technical Field

[0001] The present invention relates to the technical field of logging formation testing, and particularly to a method for obtaining well inclination using MDT test data. Background Art

[0002] According to different designed trajectories, wellbores of drilling are divided into two categories: vertical wells and directional wells. However, due to the difficulty in controlling the trajectory, there is actually no absolutely vertical well. The real wellbore is an irregularly twisted space curve, and the bending shape of the wellbore is represented by parameters such as well inclination angle, azimuth angle, measured depth, and vertical depth. In the prior art, parameters such as well inclination angle and vertical depth of the target well section usually need to be obtained through special well inclination logging. However, when conducting preliminary discussions and formulating plans for downhole environment, construction, treatment plans, etc., due to the lack of key parameters, one can only wait for the completion of special well inclination logging data, resulting in untimely downhole analysis work, extended construction period, deviation in oil and water layer identification, and waste of construction resources. Therefore, in view of the above deficiencies, a method for obtaining well inclination using MDT test data is proposed. Summary of the Invention

[0003] (1) Technical Problems to be Solved

[0004] In view of the deficiencies of the prior art, the present invention provides a method for obtaining well inclination using MDT test data, which solves the problems of untimely downhole analysis work, extended construction period, deviation in oil and water layer identification, and waste of construction resources due to the lack of key parameters when conducting preliminary discussions and formulating plans for downhole environment, construction, treatment plans, etc.

[0005] (2) Technical Solutions

[0006] To solve the above problems, the present invention provides a method for obtaining well inclination using MDT test data, including:

[0007] Step 1: After the completion of drilling and before the start of formation testing, clean the debris in the well with a fluid of known density until the returned fluid meets the cleaning requirements;

[0008] Step 2: Conduct formation testing on the target well and record the test data;

[0009] Step 3: According to the data obtained in Step 2, set n test points in the target well section and calculate the static water column pressure at each test point;

[0010] Step 4: Calculate the ratio of the fluid column pressure in the well to the target static water column pressure;

[0011] Step 5: Correct the fluid column pressure in the well according to the ratio obtained in Step 4;

[0012] Step 6: Calculate the well deviation angle and vertical depth difference of the target well section according to the pressure conditions of the target well section in the wellbore.

[0013] Further, the fluid for well flushing is generally fresh water or fresh drilling fluid.

[0014] Further, in Step 2, the formation testing includes formation data obtained by formation testing and string testing methods.

[0015] Further, in Step 3, calculate the hydrostatic pressure using the measured depth of the target well section:

[0016] P 静液i = ρ × g × MD i i = 1, 2, …, n Formula 1

[0017] Where:

[0018] n — total number of test points;

[0019] P 静液i — Hydrostatic pressure at the i-th test point, kPa;

[0020] ρ — density of the fluid in the well;

[0021] g — gravitational coefficient, 9.8 m / s 2 ;

[0022] MD i — height of the test point.

[0023] Further, in Step 4, calculate the ratio of the fluid column pressure in the well to the static water column pressure at each test point. The formula is

[0024] β i = P 井内i / P 静液i i = 1, 2, ……, n Formula 2

[0025] Where:

[0026] β i — ratio of the fluid column pressure in the well to the hydrostatic pressure at the i-th test point;

[0027] P 井内i — fluid column pressure in the well at the i-th test point, kPa;

[0028] After calculation, for the ratio β of all test points i calculate the average value β 均 .

[0029] Further, the correction process in Step 5 is to use the β obtained in Step 4 均As the correction coefficient, respectively, and the static liquid column pressure P at each point in step 3 i Multiply to get the corrected hydrostatic column pressure P 校i , and its calculation formula is as follows:

[0030] P 校i =β 均 ×P i =β 均 ×ρ×g×MD i i=1,2,……,nFormula 3

[0031] Among them, P 校i ——The corrected fluid column pressure in the well at the i-th test point.

[0032] Furthermore, in step six, analysis is performed based on the pressure of the target well section to form a mechanical right triangle between the two measuring points, the hypotenuse of the triangle is the corrected static liquid column pressure difference between the two measuring points, and one right-angled side is the corrected static liquid column pressure difference between the two measuring points.

[0033] Furthermore, in the mechanical triangle, the well inclination angle is the angle between the hypotenuse and the third side, and the calculation formula of the well inclination angle is:

[0034]

[0035] in:

[0036] ——the inclination angle of the required well section;

[0037] p2-p1——corrected hydrostatic pressure difference between two adjacent points, MPa;

[0038] ρ——known fluid density in the wellbore, kg / m 3 ;

[0039] MD2-MD1——Measured depth difference between two adjacent points, m.

[0040] (III) Beneficial effects

[0041] The method for obtaining well inclination using MDT test data provided by the present invention can perform preliminary calculations on the well inclination angle and vertical depth of the target well section based on the obtained formation test data after a formation test, so that the determination of the downhole environment and the designation of construction and treatment plans can be carried out in a timely manner, saving working time, shortening the construction period, improving the compliance rate of oil and water layer interpretation and saving construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a flow chart of the method for obtaining well deviation using MDT test data in the present invention;

[0043] Figure 2 The top view of the wellhead of the implementation example of Well Zhao XX of the method for obtaining well inclination using MDT test data according to the present invention;

[0044] Figure 3 The wellbore spatial trajectory diagram of the implementation example of Well Zhao XX of the method for obtaining well inclination using MDT test data according to the present invention;

[0045] Figure 4 The vertical depth displacement diagram of the implementation example of Well Zhao XX of the method for obtaining well inclination using MDT test data according to the present invention;

[0046] Figure 5 The well inclination log data table of the implementation example of Well Zhao XX of the method for obtaining well inclination using MDT test data according to the present invention;

[0047] Figure 6 The result data table for calculating well inclination using pressure measurement data of the implementation example of Well Zhao XX of the method for obtaining well inclination using MDT test data according to the present invention. Specific implementation manners

[0048] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0049] In the description of the present invention, it is necessary to understand that the orientation or positional relationship indicated by "upper", "lower", "inner", "outer", "top", "bottom", etc. is all based on the orientation or positional relationship shown in the accompanying drawings. The purpose is only to facilitate the description of the present invention and simplify the description, and does not indicate or imply that the components referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0050] As Figure 1 shown, the present invention provides a method for obtaining well inclination using MDT test data, specifically including:

[0051] Step 1: After the well is drilled and before the formation test starts, wash the debris in the well with a fluid of known density until the returned fluid meets the cleaning requirements.

[0052] Among them, the fluid for well washing is generally fresh water or fresh drilling fluid. Under different construction environments and requirements, other fluids that can not only meet the on-site downhole safety construction but also have stable performance and significant differences from the regional formation fluids can also be used.

[0053] Step 2: Conduct a formation test on the target well and record the test data;

[0054] In Step 2, the formation testing includes testing methods such as formation testing and string testing. By using testing strings that can be raised and lowered, annulus pressure control testing tools, and expandable testing tools, formation data is collected.

[0055] Among them, the main principle of the above tools and testing methods is to lower the testing tools (including pressure and temperature gauges, packers, controllers, and samplers, etc.) into the testing interval through certain technical means. The packer separates the target formation, isolating other formations and drilling fluids from the testing interval. Through ground control and underbalanced blowout induction, the fluids in the testing interval flow into the string or the instrument sampling bucket through screens and testing valves, etc., and even PVT (Process Verification Test) samples can be obtained.

[0056] Step 3: Based on the data obtained in Step 2, set n testing points in the target well section and calculate the hydrostatic pressure at each testing point.

[0057] In Step 3, the hydrostatic pressure is calculated using the measured depth in the target well section. The formula is as follows:

[0058] P 静液i = ρ × g × MD i i = 1, 2,..., n Formula 1

[0059] Where:

[0060] n - Total number of testing points;

[0061] P 静液i — Hydrostatic pressure at the i-th testing point, kPa;

[0062] ρ — Density of the fluid in the well;

[0063] g — Gravity coefficient, 9.8 m / s 2 ;

[0064] MD i — Height of the testing point.

[0065] Among them, the number and distribution of the testing points should ensure that there is at least one testing point within each formation range in the target well section, and more testing points should be set appropriately in formations with larger thickness to ensure the accuracy of the calculation results.

[0066] Step 4: Calculate the ratio of the fluid column pressure in the well to the target hydrostatic pressure.

[0067] In Step 4, the fluid column pressure in the well is represented by P 井内i . Denote the ratio of the calculated fluid column pressure in the well to the target hydrostatic pressure as β i . Then the calculation formula is:

[0068] β i = P 井内i / P 静液i i = 1, 2, ……, n Formula 2

[0069] Wherein:

[0070] β i —— The ratio of the fluid column pressure in the well to the static fluid column pressure at the i-th test point;

[0071] P 井内i —— The fluid column pressure of the fluid in the well at the i-th test point, kPa.

[0072] After calculating β for each test point i and obtaining the results, the calculated results are summarized and the average value is denoted as β 均 , and the obtained β 均 is the finally determined correction coefficient.

[0073] Step Five: Correct the fluid column pressure in the well according to the ratio obtained in Step Four;

[0074] In Step Five, the correction process is to use β 均 obtained in Step Four as the correction coefficient, and multiply it with the static fluid column pressure P i at each point in Step Three to obtain the corrected static fluid column pressure P 校i . Its calculation formula is as follows:

[0075] P 校i = β 均 × P i = β 均 × ρ × g × MD i i = 1, 2, ……, n Formula 3

[0076] Wherein, P 校i —— The fluid column pressure of the fluid in the well at the i-th test point after correction.

[0077] Step Six: Calculate the well deviation angle and the vertical depth difference of the target well section according to the pressure situation of the target well section in the well.

[0078] In Step Six, according to the pressure of the target well section for analysis, a mechanical right triangle is formed between two measurement points. The hypotenuse of the triangle is the corrected static fluid column pressure difference between the two measurement points, and one right side is the corrected static fluid column pressure difference between the two measurement points.

[0079] Wherein, in the mechanical right triangle, the well deviation angle is the angle between the hypotenuse and the third side, so

[0080] It is derived that

[0081]

[0082] Wherein:

[0083] —— the well deviation angle of the section to be determined;

[0084] p2 - p1——the corrected hydrostatic pressure difference between two adjacent points, MPa;

[0085] ρ——the known fluid density in the wellbore, kg / m 3 ;

[0086] MD2 - MD1——the measured depth difference between two adjacent points, m.

[0087] Similar to Formula 4, it is derived that

[0088]

[0089] Substitute two adjacent test points P i into Formula 4 or Formula 5, and the well deviation angle can be obtained

[0090] Furthermore, substitute p2 - p1 and Z2 - Z1 into the existing static water head calculation formula, and the calculation formula for the vertical depth difference is

[0091]

[0092] Wherein, Z2 - Z1——the vertical depth difference between two adjacent points, m.

[0093] Example 2:

[0094] According to Figures 2 - 6 , taking Zhao XX's use of MDT test data to obtain the well deviation at the target interval of 1536 - 1571.2 m as an example, the specific operation process of this method is described in detail.

[0095] Step 1. After the well is drilled and before the formation test starts, clean the debris in the well with a fluid of known density, and the returned fluid meets the cleaning requirements. In this example, clean water is used as the well - washing liquid.

[0096] Step 2. As Figures 2 - 4 , collect and organize the density data of the fluid in the well during the test (such as drilling fluid, clean water, etc.) and the formation pressure and well - fluid column pressure at different target horizons (different measured depths) obtained through the test, and summarize them into a table as Figure 6 shown.

[0097] Step 3. Calculate the static water column pressure using the measured depth of the target interval:

[0098] P 静水i = ρ 水 ×g×MD i where i = 1, 2, …, n

[0099] In this embodiment, there are three test points, so n = 3. Among them, MD1 = 1536.53 m, MD2 = 1542.867 m, MD3 = 1571.2 m, ρ 水 = 1×10³ / m 3 , g = 9.8 m / s 2 , then

[0100] P 静水1 = ρ 水 ×g×MD1 = 1×10³×9.8×1536.53 = 15057.9548 kPa;

[0101] P 静水2 = ρ 水 ×g×MD2 = 1×10³×9.8×1542.87 = 15120.09333 kPa;

[0102] P 静水3 = ρ 水 ×g×MD3 = 1×10³×9.8×1571.2 = 15397.76 kPa.

[0103] Step Four: Calculate the ratio of the fluid column pressure in the well to the static water column pressure:

[0104] β i = P 井内i / P 静水i where i = 1, 2, ……, n

[0105] From Figure 6 it can be seen that at MD1 = 1536.53 m, P 井内1 = 20500.183 kPa, at MD2 = 1542.867 m, P 井内2 = 20495.50667 kPa,, at MD3 = 1571.2 m, P 井内3 = 21261.555 kPa. Substituting these values gives:

[0106] β1 = P 井内1 / P 静水1 = 20500.183 / 15057.9548 = 1.361419

[0107] β2 = P 井内2 / P 静水2 = 20495.5066 / 15120.09333 = 1.355515

[0108] β3 = P 井内3 / P 静水3 = 21261.555 / 15397.76 = 1.380821。

[0109] Then, calculate the mean value β of the ratio of the fluid column pressure in the well to the static water column pressure 均 :

[0110] β 均 = (β1 + β2 + β3) / 3 = (1.361419 + 1.355515 + 1.380821) / 3 = 1.365918。

[0111] Step Five: Correct the fluid column pressure in the well and calculate the corrected fluid column pressure in the well:

[0112] P 校i = β 均 × ρ 水 × g × MD i i = 1, 2, ……, n

[0113] P 校1 = β 均 × ρ 水 × g × MD1 = 1.361419 × 1 × 9.8 × 1536.526 = 20567.93 kPa;

[0114] P 校2 = β 均 × ρ 水 × g × MD2 = 1.355515 × 1 × 9.8 × 1542.866 = 20652.81 kPa;

[0115] P 校3 = β 均 × ρ 水 × g × MD3 = 1.380821 × 1 × 9.8 × 1571.2 = 21032.08 kPa。

[0116] Step Six: Select the P, MD, and ρ values at two pressure measurement points from the above data, substitute the data of points P 校 and P 校1 into p1 and p2 respectively, and apply Formula 4 or Formula 5 to calculate the well deviation angle. 校3

[0117] Obtain

[0118] At the same time, substitute the data of points P 校1 and P 校3 into p1 and p2, and apply Formula 6 to calculate and obtain

[0119] ​

[0120] Summarize the results obtained in the above step six into the table, as Figure 6 shown.

[0121] Figure 5 It is the well deviation logging data table of Well Zhao XX. Figure 6 The obtained data is compared with Figure 5 It can be obtained that the error between the two is extremely small. The well deviation angle and vertical depth difference of the target well section calculated by this method are highly reliable and can be used for the judgment and formulation of downhole environment, work and plans.

[0122] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for obtaining well inclination using MDT test data, characterized in that, Including: Step 1: After the well is drilled and before the formation test starts, collect data such as the density, viscosity, and temperature of fluids such as drilling fluid and fracturing fluid existing in the target well. If necessary, clean the debris in the well with a fluid of known density until the returned fluid meets the cleaning requirements; Step 2: Conduct a formation test on the target well and record the test data; Step 3: According to the data obtained in Step 2, set n test points in the target well section and calculate the static water column pressure at each test point; Step 4: Calculate the ratio of the fluid column pressure in the well to the target static water column pressure; Step 5: Correct the fluid column pressure in the well according to the ratio obtained in Step 4; Step 6: Calculate the well deviation angle and the vertical depth difference of the target well section according to the pressure situation of the downhole target well section.

2. The method for obtaining well inclination using MDT test data according to claim 1, characterized in that, The fluid for well washing is generally fresh water or fresh drilling fluid.

3. The method for obtaining well inclination using MDT test data according to claim 1, characterized in that, In Step 2, the formation test includes formation test, string test, MDT test, measurement-while-drilling test, and formation data obtained by well testing methods.

4. The method for obtaining well inclination using MDT test data according to claim 1, characterized in that, In Step 3, calculate the static liquid column pressure using the measured depth of the target well section. The calculation formula is as follows: P 静液i = ρ × g × MD i i = 1, 2, …, n Formula 1 Where: n - Total number of test points; P 静液i — Hydrostatic column pressure at the i-th test point, kPa; ρ - Density of the liquid in the well; g——Gravitational coefficient, 9.8 m / s 2 ; MD i ——Measurement point sounding.

5. The method for obtaining well inclination using MDT test data according to claim 1, characterized in that, In Step 4, calculate the ratio of the fluid column pressure in the well to the static liquid column pressure at each test point. The formula is β i = P 井内i / P 静液i where i = 1, 2, ……, n Equation 2 Where: β i —— Ratio of the in-well fluid column pressure to the static fluid column pressure at the i-th test point; P 井内i —— Fluid column pressure of the well at the i-th test point, kPa; After calculation, for the ratio β of all test points i Calculate the average value of β 均 .

6. The method for obtaining well inclination using MDT test data according to claim 1, characterized in that, In the calibration process of step five, β obtained in step four is 均 used as the calibration coefficient, and multiplied by the hydrostatic column pressure P of each point in step three respectively to obtain the calibrated hydrostatic column pressure P i . The calculation formula is as follows: 校i ​ P 校i = β 均 × P i = β 均 × ρ × g × MD i i = 1, 2, ……, n Equation 3 Among them, P 校i —— The hydrostatic pressure of the fluid in the well at the corrected i-th test point.

7. The method for obtaining well inclination using MDT test data according to claim 1, characterized in that, In Step 6, analyze according to the pressure of the target well section. A mechanical right triangle is formed between two measurement points. The hypotenuse of the triangle is the corrected static liquid column pressure difference between the two measurement points, and one right side is the corrected static water column pressure difference between the two measurement points.

8. The method for obtaining well inclination using MDT test data according to claim 7, characterized in that, In the mechanical triangle, the well deviation angle is the angle between the hypotenuse and the third side. The calculation formula for the well deviation angle is: Where: —— the well inclination angle of the section to be drilled p2 - p1 - Corrected static liquid column pressure difference between adjacent points, MPa; ρ——The known fluid density in the wellbore, kg / m 3 ; MD2 - MD1 - Measured depth difference between adjacent points, m.

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