A magnetic measurement method for radial horizontal well trajectory

Abstract

The present invention belongs to the field of oil and gas exploration and development, and specifically relates to a magnetic measurement method for radial horizontal well trajectories. Magnetic field parameter measurements and inertial measurements are performed with a deflector as the magnetic field source and a jet nozzle as the measuring point. The nozzle attitude quaternion or Euler angle at each moment is calculated based on the inertial measurement and data fusion principle. A fixed coordinate system in the wellbore and a nozzle body coordinate system are established with the deflector and the nozzle as the origins, respectively, and the transformation matrix between the two coordinate systems is calculated based on the nozzle attitude data. Combined with the artificial magnetic field gradient parameters, magnetic flux density, and magnetic field data measured at the nozzle, the coordinate points of the nozzle in the fixed coordinate system in the wellbore are calculated by inverse derivation. The radial horizontal well trajectory can be obtained by linking the nozzle coordinates at each moment.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas development, and in particular to a magnetic measurement method for radial horizontal well trajectories. Background Art

[0002] Controlling the actual drilling trajectory and accurately hitting the target are important requirements for oil and gas resource exploration and development. Measuring and mapping the actual drilling trajectory is an inevitable means to achieve these requirements.

[0003] Conventional trajectory measurement devices are currently inadequate for radial horizontal well trajectory mapping due to their small radius of curvature, large doglegs, and small borehole diameters. Therefore, there are currently only two technical solutions for mapping radial horizontal well trajectories. The first employs micro-electromechanical (MEMS) inertial devices to measure the jet nozzle attitude in radial horizontal wells and, combined with the coiled tubing lowering and raising speeds or lengths, cumulatively extrapolate the wellbore trajectory. However, due to device vibration and external environmental interference during the mapping process, errors in the measured data are present, which are gradually amplified during the cumulative extrapolation process, ultimately resulting in significant deviations from the actual wellbore trajectory. The second approach, based on the principle of potential measurement, uses the actual wellbore and another adjacent wellbore as electrodes to deliver a highly stable current into the formation to generate an initial formation electric field. Highly conductive fluid is then injected into the wellbore to induce changes in the initial formation electric field. The potential changes are then monitored using multiple ring-shaped observation points arranged on the surface, or a multi-layer, multi-directional array of observation points downhole, to infer the radial horizontal well trajectory.

[0004] There are at least the following problems in the existing technology: in the existing technology, due to external interference and measurement errors, the trajectory calculation based on the inertial principle is bound to lead to the accumulation of surveying and mapping errors, which ultimately leads to low accuracy of the calculated wellbore trajectory parameter data and low reliability of the drawn wellbore trajectory; in the existing technology, due to the limitation of the accuracy of the formation characteristics, and only multiple groups of annular measuring points are arranged on the ground, the changes in the measured potential can only reflect the drilling trend of the radial horizontal well in the horizontal projection, rather than the horizontal projection parameters of the actual trajectory, let alone the radial horizontal well trajectory within the spatial range; in the existing technology, the multi-layer and multi-directional observation point array in the well needs to be connected to the jet nozzle to measure the potential difference, which greatly changes the existing radial horizontal well equipment and process, the wiring is complex and easy to damage, and the system is complex and costly. Summary of the Invention

[0005] In response to the above problems, the present invention provides a magnetic measurement method for radial horizontal well trajectories, which uses a radial horizontal well diverter as a magnetic field source and a radial horizontal well nozzle as a measuring point. It combines magnetic field modeling, posture analysis, and the relative position between the three-axis magnetic flux density anti-diffraction flow nozzle and the window point to achieve the measurement of the radial horizontal well spatial trajectory.

[0006] The electrical measurement method of radial horizontal well trajectory of the present invention is implemented as follows:

[0007] During radial horizontal well drilling, the diverter is magnetized using technical means. Considering the impact of the casing metal environment, the selection of borehole locations for casing windowing and jet drilling in radial horizontal wells prioritizes construction along opposing azimuths and in an axisymmetric pattern. Similarly, to facilitate artificial magnetic field modeling, it is recommended to extend the diverter so that the diverter outlet (i.e., the casing windowing location) is located in the middle of the diverter. This allows the windowing hole to be located at the center of the magnetic field after magnetization. To avoid large-scale modifications to existing radial horizontal well technology, processes, and equipment systems, and to minimize complex algorithms to reduce the pressure on embedded systems in downhole equipment, magnetic field parameter measurements and inertial measurements are performed using the diverter as the magnetic field source and the jet nozzle as the measurement point. Quaternions or Euler angles of the nozzle attitude at each moment are calculated based on inertial measurements and data fusion principles. A fixed wellbore coordinate system and a nozzle body coordinate system are established with the diverter and nozzle as the origins, respectively. The transformation matrix between the two coordinate systems is calculated based on the nozzle attitude data. Combining the artificial magnetic field gradient parameters, magnetic flux density, and magnetic field data measured at the nozzle, the coordinates of the nozzle in a fixed coordinate system within the wellbore are calculated by inverse derivation. Linking the nozzle coordinates at each moment yields the radial horizontal well trajectory.

[0008] The beneficial effects of the present invention are:

[0009] It has the advantages of small changes in radial horizontal well equipment and processes, simple operation, low cost, and the ability to form spatial trajectories. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of the conventional radial horizontal well construction system and process;

[0011] Figure 2 Schematic diagram of the artificial field generated by the diverter as a fixed field source under the influence of the casing;

[0012] Figure 3 This is a schematic diagram of the arrangement of nozzle measurement point sensors;

[0013] Figure 4 This is the flow chart of the inverse derivation algorithm for magnetic measurement data;

[0014] Figure 5 Comparison cloud diagram of magnetic field intensity in xy plane and xz plane with the diverter and nozzle as the field source respectively;

[0015] Figure 6 The relationship diagram of the measurement point and the nearby artificial field parameters with the nozzle position when the diverter is used as the field source and the nozzle is used as the field source;

[0016] Figure 7 The diagram below shows the recommended sequence of window holes for radial horizontal wells.

[0017] Figure 8 The distribution of window holes for four typical radial horizontal wells;

[0018] Figure 9 Magnetic field cloud diagrams of four typical radial horizontal well window positions;

[0019] Figure 10 The magnetic flux density curves and local magnifications of four typical hole positions on the characteristic straight line are shown;

[0020] Figure 11 Schematic diagram of the principle of electrical measurement technology for existing radial horizontal well trajectories. DETAILED DESCRIPTION

[0021] The principles, features and methods of the present invention are described in detail below through examples.

[0022] Example 1:

[0023] The magnetic measurement method for radial horizontal well trajectories described in the present invention is essentially a positioning problem within an artificial field: that is, by forming a stable artificial field in the formation, combining the physical field characteristics to model the artificial field distribution, and obtaining a formula for the relationship between the relative position of the measuring point and the field source.

[0024]

[0025] However, during radial horizontal well construction, the jet nozzle has a dynamically changing inclination and orientation as it moves in the formation. The nozzle body coordinate system and the fixed point coordinate system in the wellbore are not simply translated, but a combination of translation and multi-axis rotation. Therefore, there is multi-dimensional motion between the measurement point and the source coordinate system, and the data relationship is as follows:

[0026]

[0027] Obviously, such methods require the use of a field source shielding attitude transformation matrix that is independent of the nozzle attitude.

[0028]

[0029] Or the alignment and fusion of measurement point data and independent nozzle posture data can be achieved through process and algorithm design.

[0030] The magnetic measurement method for radial horizontal well trajectories described in the present invention adopts the second approach.

[0031] Example 2:

[0032] like Figure 1As shown, in radial horizontal well construction operations, the conventional process is to use oil pipes to send the diverter into the designated operating layer and align the diverter outlet with the designated orientation, then use hydraulic anchors to fix the diverter outlet, and then use continuous oil pipes to send the jet operation string into the well for window opening and jet drilling operations. Relative to the nozzle, the diverter outlet depth D and azimuth AZI are known in radial horizontal well construction operations, and the relative nozzle position is fixed. Therefore, the magnetic measurement method for radial horizontal well trajectories described in the present invention selects the diverter as a fixed field source, magnetizes the diverter, and forms a stable artificial field in the formation such as Figure 2 .

[0033] A Cartesian coordinate system is established with the diverter outlet axis pointing to the formation direction and the wellbore axis pointing to the ground direction as the positive directions of the x and z axes. Figure 2 It can be seen that the artificial field exhibits good symmetry within the diverter coordinate system. Therefore, the magnetic field distribution at any point within the formation based on this coordinate system can be described by the aforementioned formula. Using the jet nozzle as the measuring point and the nozzle axis pointing in the direction of the formation as the y-axis, an arbitrary Cartesian coordinate system is established as the measuring point coordinate system. The data relationship between the measuring point and the field source can be described by the aforementioned formula.

[0034] The magnetic measurement method of radial horizontal well trajectory of the present invention takes the jet nozzle as the dynamic measurement point, and installs an inertial sensor and a magnetic sensor at the jet nozzle. Figure 3 , the sensor coordinate axes correspond to the axes of the nozzle measuring point coordinate system.

[0035] Generally speaking, inertial sensors are composed of accelerometers and gyroscopes. Based on inertial theory and fusion algorithm: Use gyroscope data to update attitude as shown in the formula

[0036]

[0037] Combine Kalman filtering, complementary filtering and other filtering algorithms to fuse acceleration data for attitude correction as shown in formula and formula

[0038]

[0039]

[0040] Substitute the formula to obtain the coordinate system transformation matrix C, and then substitute the formula to combine the field source parameters and the magnetic field measurement data to inversely derive the relative distance and coordinates between the measurement point and the field source.

[0041]

[0042] The radial horizontal well trajectory is obtained by sequentially linking the inverse derivative data points at each moment

[0043]

[0044]

[0045] Summarize its algorithm flow as follows Figure 4 .

[0046] Example 4:

[0047] Based on the concepts of this invention, those skilled in the art can, without inventive effort, propose a similar method for estimating radial horizontal well trajectories using a jet nozzle as the magnetic field source and fixed-point or array measurements within the wellbore. Based on electromagnetic principles and considering the influence of the casing metal environment, numerical simulations were performed using both the nozzle as the field source and the diverter as described in this invention. The magnetization intensity was set to 1 MA / m in both cases.

[0048] The simulation results are as follows Figure 5 As shown, it can be clearly seen that, affected by the metal environment of the casing and the size of the field source, the artificial magnetic field generated by the deflector as the field source in the present invention has a much higher range than the method using the nozzle as the field source under the same magnetization intensity.

[0049] Based on the steering coordinate system, the nozzle coordinates are (L / 2, 0, 0) and (L, 0, 0), respectively. The steering and nozzle are used as measuring points, and the magnetic flux density of the measuring point and its surrounding characteristic points is calculated as follows: Figure 6 . It can be clearly seen that, affected by the metal environment of the casing, the magnetic flux density of the artificial field with the jet nozzle as the field source at the measuring point and its adjacent range has only slight changes in the y-axis data, and the value and distribution of the three-axis magnetic flux density near the measuring point are almost independent of the movement of the nozzle (field source). In the magnetic measurement method for radial horizontal wells described in the present invention, when the deflector is used as the field source and the nozzle is used as the measuring point, the value and distribution of the magnetic flux density at the measuring point and its adjacent range vary greatly with the position of the nozzle (measuring point), and the recognition is higher.

[0050] Furthermore, because the measurement point data and nozzle posture data belong to two independent structures and are difficult to connect using cables, the method using the nozzle as the field source and the diverter as the measurement point requires the use of more complex algorithms to align and fuse the two sets of data. The method described in the present invention, using the diverter as the field source and the nozzle as the measurement point, can achieve data alignment directly at the sensor level during measurement, without the need for complex algorithms.

[0051] Therefore, the method of the present invention has the advantages of high recognition accuracy, low sensor accuracy requirement, simple algorithm, small amount of calculation, no need for cable connection, and high equipment reliability.

[0052] Example 5:

[0053] Based on electromagnetic theory, the metal environment has a significant impact on the magnetic field distribution in the medium. The casing window operation will inevitably affect the distribution of the artificial magnetic field downhole. Therefore, the magnetic measurement method of the radial horizontal well trajectory described in the present invention has strict requirements on the orientation and sequence of the radial horizontal well window operation.

[0054] Figure 7 The following is a window opening sequence and hole distribution recommended by the present invention. During the first construction, the window is opened and the drilling is completed according to the design plan. Figure 7 A. After that, the second hole is constructed in the opposite direction (180°) of the first hole. Figure 7 B. Then take the median of the first and second holes (i.e. 90°) to construct the third hole. Figure 7 C. Take the third hole opposite (270° direction) to construct the fourth hole. Figure 7 D. When performing hole densification, take the middle position of any two holes, such as the middle position of the second hole and the third hole (135° direction) to construct the fifth hole. Figure 7 E, take the fifth hole opposite (315° direction) to construct the sixth hole. Figure 7 F. Take the middle position of the first and third holes (45°) to construct the seventh hole. Figure 7 G, take the seventh hole opposite (225° direction) to construct the eighth hole. Figure 7 H.

[0055] Obviously, the magnetic measurement method of radial horizontal well trajectory described in the present invention and the strict requirements on the orientation and sequence of radial horizontal well window opening operations are essentially to require that when opening the casing window, it should be constructed in the opposite orientation and in an axially symmetrical form.

[0056] Therefore, those skilled in the art will appreciate that the construction orientation and sequence described in Example 4 is only a general form of the method of the present invention, and that different methods such as Figure 7 A(0°)→ Figure 7 B(180°)→ Figure 7 E(135°) or Figure 7 A(0°)→ Figure 7 B(180°)→20° azimuth→340° azimuth and similar forms.

[0057] Example 6:

[0058] As mentioned in Example 5, based on electromagnetic theory, the metal environment has a great influence on the magnetic field distribution in the medium, and the casing window operation will inevitably affect the distribution of the artificial magnetic field downhole. Figure 8 , perform hole opening along the direction of line ③ in the figure, and simulate the magnetic field distribution as shown below Figure 9 It is obvious that compared with Figure 9 A. Figure 9 B. Figure 9 C. Three symmetrical window openings. Figure 9 D shows obvious asymmetry in the window orientation.

[0059] Specifically, such as Figure 8 As shown in Figure 1, numerical simulation is performed on three characteristic measurement straight lines ①, ②, and ③ on the window opening and drilling azimuth lines. The simulation results are shown in Figure 1. Figure 10 shown.

[0060] Obviously, corresponding Figure 8 A. Figure 8 B. Figure 8 The three equally spaced characteristic curves of the three hole arrangement C show the characteristics of symmetry along the window opening and drilling azimuth line ( Figure 10 A. Figure 10 B. Figure 10 C), then the magnetic field is homogeneous along the gradient of each direction and can be expressed in a unified way; corresponding to Figure 8 D. The asymmetric hole arrangement has three equidistant characteristic curves showing an overall trend of being cheaper toward the asymmetric hole in the near-wellbore area. Its magnetic field distribution is uneven and asymmetric. The formula shows that the magnetic field is non-homogeneous along the gradient of each direction and cannot be expressed in a unified manner.

[0061]

[0062] Therefore, the magnetic measurement method of the radial horizontal well trajectory described in the present invention has strict requirements on the orientation and sequence of the radial horizontal well window opening operation. The essential requirement is that when opening the casing window, it is preferentially constructed along the opposite orientation and in an axially symmetrical form. The axially symmetrical arrangement of the radial horizontal well window holes is more conducive to the uniform and symmetrical distribution of the artificial magnetic field, which is conducive to reducing the difficulty of magnetic field modeling under the influence of the casing metal environment, and is conducive to improving the accuracy of the magnetic measurement method of the radial horizontal well trajectory.

[0063] Similarly, the relative position of the electrodes at the diverter and the casing window aperture has a certain degree of influence on the distribution of the artificial magnetic field. Therefore, to facilitate artificial magnetic field modeling, the present invention recommends using an extended diverter so that the diverter outlet (i.e., the casing window aperture) is located in the middle of the diverter. This allows the window aperture to be located at the center of the magnetic field after the diverter is magnetized.

[0064] Example 7:

[0065] Similar existing technologies include electrical measurement technology for radial horizontal well trajectory ( Figure 11 ) adopts the first type of thinking, by setting electrodes in the nozzle and the wellbore to form a stable electric field in the formation, based on the representation of the field intensity gradient change at the multi-layer multi-directional array measuring points, the data relationship between the measuring points is obtained by substituting into the above formula (where L, Lz is the structural parameter between sensor arrays. h is the distance between measuring points, V is the potential difference between measuring points, and k is the coefficient):

[0066]

[0067] Then, the least square solution of the nonlinear overdetermined equations is solved by mathematical iteration method to obtain the coordinates of the nozzle relative to the fixed measuring point coordinate system of the wellbore.

[0068] The magnetic measurement method for radial horizontal well trajectories of the present invention adopts the second approach. Compared with the first approach, although it adds additional calculation amount and increases the calculation complexity, since magnetic intensity measurement does not involve cable connection between measuring points, its device is simpler and relatively independent, and the changes to the existing radial horizontal well construction system and process are far less than those of the existing electrical measurement method.

[0069] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A magnetic measurement method for radial horizontal well trajectory, characterized in that: include: The radial horizontal well steering device is used as the magnetic field source and the radial horizontal well nozzle is used as the measuring point. The radial horizontal well spatial trajectory is measured by combining magnetic field modeling, posture analysis, and the relative position between the three-axis magnetic flux density anti-diffraction flow nozzle and the window point. Also includes: When selecting the hole location for casing windowing and jet drilling, the drilling should be carried out in opposite directions and in an axisymmetric manner; Use an extended steering gear so that the steering gear outlet is located in the middle of the steering gear and the window hole is located in the center of the magnetic field; An inertial sensor and a magnetic sensor are installed at the jet nozzle so that the sensor coordinate axes correspond to the axes of the nozzle measurement point coordinate system.

2. The magnetic measurement method for radial horizontal well trajectory according to claim 1, characterized in that: Also includes: The window opening sequence and hole distribution are as follows: During the first construction, after opening the window and completing the drilling according to the design plan, the second hole is constructed in the direction opposite to the first hole, and then the third hole is constructed at the midpoint of the orientation of the first and second holes, and the fourth hole is constructed in the direction opposite to the third hole.

3. The magnetic measurement method for radial horizontal well trajectory according to claim 2, characterized in that: Also includes: When carrying out hole encryption, take the middle position of the second and third holes to construct the fifth hole, take the sixth hole opposite the fifth hole to construct the sixth hole, take the middle position of the first and third holes to construct the seventh hole, take the eighth hole opposite the seventh hole to construct the eighth hole.

4. A magnetic measurement method for radial horizontal well trajectory according to any one of claims 1 to 3, characterized in that: include: Combining magnetic field modeling, posture analysis, and the relative position between the three-axis magnetic flux density anti-diffraction jet nozzle and the window point, the nozzle posture quaternion or Euler angle at each moment is calculated based on the inertial measurement and data fusion principles, and the transformation matrix between the fixed point coordinate system in the wellbore and the nozzle body coordinate system is calculated. Combined with the artificial magnetic field gradient, the relative distance between the nozzle and the window hole is calculated, and the nozzle coordinates in the fixed point coordinate system in the wellbore are obtained. The nozzle coordinates at each moment are linked in sequence to obtain the radial horizontal well trajectory parameters and curves.

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