BRPI1105272A2 - Method for azimuth measurements using a gyro unit, and azimuth measurement system - Google Patents

Abstract

Method for azimuth measurements using a gyro unit, and azimuth measurement system. Methods and systems for azimuth measurements using a gyro unit are disclosed. The method includes acquiring a ratio value between two orthogonal ground rate components together using the gyro unit at a measurement position; acquire three orthogonal gravity vector components from each other at the measurement position; and determining an azimuth with respect to a predetermined reference axis in the gyro unit based on the ratio value, the three gravity vector components, and a geodetic latitude of the measurement position.

Description

AZIMUTE MEASUREMENT METHOD USING A GYROSCOPE UNIT, AND AZIMUTE MEASUREMENT SYSTEM

FIELD OF THE INVENTION The present invention relates to azimuth measurement techniques using a well gyro unit, for example, for azimuth measurements during Drilling Measurement (MWD), Drilling Profiling (LWD) and cable profiling operations. of steel. More particularly, the invention relates to ground rate vector direction measurements for azimuth determination with at least one gyroscope and three accelerometers.

BACKGROUND OF THE INVENTION Well azimuth measurement technology is primarily categorized into magnetometer measurements and gyro measurements. The first uses triad magnetometers to measure the earth's magnetic field. However, magnetometers may only be used on site without any magnetic influence by magnetic materials such as a coating. The latter uses gyros to measure the direction of the ground rate vector for azimuth determination. Gyro measurements are hardly influenced by magnetic field. Therefore, the gyro can be used near or in such a coating of magnetic materials.

To determine azimuth using well ground rate, three ground rate components are usually measured with three gyros with orthogonal axes. All three components can determine the ground rate vector in the sensor coordinate system at any angle of attitude. If the two sensor axes are in the horizontal plane, a ratio of the two components can determine north and hence azimuth. North is a projection direction of the ground rate vector in the horizontal plane. If a single axis gyroscope rotates its input axis in the horizontal plane about the vertical axis, it can measure two orthogonal components. In this case, it is not even necessary to calibrate the scale factor if only the direction of the projection vector is measured. It is advantageous to use relatively low grade MEMS (Micro Electromechanical Systems) gyroscopes because of their low cost, small size and high environmental reliability. Today the performance of MEMS gyros is approaching that of conventional high-grade gyros, such as fiber optic gyros. However, MEMS gyros still show too low polarization stability to measure ground rate in a belt configuration. To counteract the bias error, the input axis direction must be reversed. If an inversion mechanism is also capable of pointing the input axis to various angular orientations, a single axis gyroscope can determine two orthogonal ground rate components as described in US Patent 7,712,223 issued May 11, 2010 and pending US patent application US 12 / 233,592 filed September 19, 2008. US patent 7,712,223 and US patent application US 12 / 240,943 are incorporated herein by reference in their entirety. The method using the inversion mechanism, however, requires a plane including two orthogonal axes to be kept horizontal. If the plane tilts, the relationship between the two measured ground rate components and the north becomes nontrivial. Therefore, three orthogonal components of the ground rate vector must be measured to allow the measurement system to tilt in any direction and any angles. Such a system needs a more complex mechanism to reverse the gyro to cancel polarization and / or point the input axis to various angular orientations to measure all three ground rate components. The mechanism makes the sensor package larger and less reliable despite the small size and high reliability of the MEMS gyro. The mechanism can also cause uncertain misalignment errors due to its mechanical tolerances. If only a single axis gyroscope is sufficient to determine azimuth, these disadvantages could be reduced and further applications would be expected. Therefore, it is beneficial if the restriction that the measurement plane must be kept horizontal is removed.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the present invention, a method for azimuth measurements using a gyro unit is provided. The method comprises acquiring a ratio value between two orthogonal ground rate components together using the gyro unit in a measuring position. acquire three orthogonal gravity vector components from each other at the measurement position; and determining an azimuth with respect to a predetermined reference axis in the gyro unit based on the ratio value, the three gravity vector components, and a geodetic latitude of the measurement position.

In aspects herein, determining azimuth with respect to the reference axis may comprise determining a horizontal, vertical plane at a determined gravity direction based on the three gravity vector components; determining a normalized ground rate projection vector in a measurement coordinate plane based on the ratio value, the measurement coordinate plane being defined by predetermined coordinate axes in the gyro unit; determining a vertical ground rate plane to the measurement coordinate plane such that a first line of intersection between the ground rate plane and the measurement coordinate plane is parallel to the ground rate projection vector; determine a north direction on the horizontal plane based on the ground rate plane and geodetic latitude; and determine azimuth by calculating an angle between the north direction and a projection vector of the reference axis projected on the horizontal plane.

In aspects disclosed herein, determining the north direction may comprise determining a vertical plane, vertical to the horizontal plane; determine a second intersection line between the vertical plane and the ground rate plane; determine a third intersection line between the vertical plane and the horizontal plane; and determining a direction along the third intersection line as the north direction where an angle between the second intersection line and the third intersection line is equal to the geodetic latitude.

In aspects here, azimuth can be determined using: where the X axis and Y axis of an orthogonal coordinate system are defined to measure the two ground rate components, the X axis is defined as the reference axis, δ represents an angle between the projection of the X axis in the horizontal plane and a fourth intersection line between the ground rate plane and the horizontal plane, ε represents an angle between the third intersection line and the fourth intersection line, σ represents the azimuth , Χ'χ and Ω'γ represent components along the X axis and Y axis of the normalized ground rate projection vector in an XY plane as the measurement coordinate plane, Gx, Gy and Gz represent the vector components. normalized gravity and λ represents the geodetic latitude having a positive value in the Northern Hemisphere and a negative value in the Southern Hemisphere. Further, azimuth be determined using one of the equations (30-1) to (30-8) in Table I , ç on the basis of conditions for selecting an azimuth formula with respect to a normal unit vector Pq of the ground rate plane, a unit gravity vector G, a unit vector L0_d of the fourth intersection line, and a unit vector X 'of the X axis projected in the horizontal plane. The two ground rate components can be measured by a single rotating gyroscope to align an input axis to each of the two orthogonal axes with each other. One of the two ground rate components can be measured by a first gyroscope with an input axis aligned to a first axis and the other ground rate component can be measured by a second gyroscope with an input axis aligned to a second axis. orthogonal to the first axis. The gyroscope may comprise one or two MEMS type gyros.

In yet another aspect of the present invention, the disclosure provides a system for azimuth measurements. The system comprises a housing; a gyro unit including one or two gyros; three orthogonal axis accelerometers; a data processing unit; and a power supply unit. The data processing unit comprises a computer having a processor and a memory. Memory stores a program having instructions for acquiring a ratio value between two orthogonal ground rate components together using the gyro unit in a measuring position; acquire three orthogonal gravity vector components from each other at the measurement position; and determining an azimuth with respect to a predetermined reference axis in the gyro unit, based on the ratio value, the three gravity vector components, and a geodetic latitude of the measurement position.

In understanding the scope of the present invention, the term "geodetic latitude" as used herein means an angle from the equatorial plane to the vertical direction of a line normal to the ellipsoid through a given point when assuming the earth as the shaped ellipsoid, as described in the Naval Surface Warfare Center report entitled "A Method for Calculating Exact Geodetic Latitude and Altitude" by Isaac Sofair, April 1985 (revised March 1993). This report is incorporated herein by reference in its entirety.

Additional advantages and novel features of the invention will be defined in the following description or may be learned by those skilled in the art by reading the materials herein or practicing the invention. The advantages of the invention may be achieved by means recited in the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings illustrate preferred embodiments of the present invention and are part of the specification. Together with the following description, the drawings demonstrate and explain the principles of the present invention. Fig. 1 is a flow chart of an exemplary method of measuring azimuth using a gyro unit according to the disclosure of this document. Fig. 2 is a flow chart of exemplary steps of determining azimuth with respect to a reference axis according to the disclosure of this document. Fig. 3 is a flow chart of exemplary steps of determining the north direction according to the disclosure of this document. Fig. 4 is an illustration showing a geometric configuration of azimuth measurements according to the disclosure of this document. Fig. 5 is an illustration showing a geometric configuration of determining the north direction by rotating the vertical plane according to the disclosure of this document. Fig. 6 is an illustration showing a rotation operation with an infinitesimal rotation angle ε according to the disclosure of this document. Fig. 7 is an illustration showing a modified rotation operation according to the disclosure of this document. Fig. 8 is a list of an exemplary simulation result of calculating azimuth error with respect to various yaw angles (Ψ) and swing angles (Θ) according to the disclosure herein. Fig. 9 is an illustration showing a definition of angles of rotation (Ψ, Θ, Φ) according to the disclosure herein. Fig. 10 illustrates an exemplary system including a single gyroscope and three orthogonal axis accelerometers according to the disclosure of this document. Fig. 11 shows a block diagram of the system electrical system according to the disclosure of this document. Fig. 12 illustrates another exemplary system including two orthogonal axis gyros and three orthogonal axis accelerometers according to the disclosure of this document; and Fig. 13 illustrates a well rental system in which the present invention may be employed in accordance with the disclosure herein.

In all drawings, identical reference numerals indicate similar, but not necessarily identical, elements. Although the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Instead, the invention will cover all modifications, equivalents and alternatives falling within the scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Illustrative embodiments and aspects of the present disclosure are described below. For the sake of clarity, not all features of an actual implementation are described in the descriptive report. It will certainly be appreciated that in the development of any such real modality, numerous specific implementation decisions must be made to achieve specific developer goals, such as compliance with system and enterprise restrictions, which will vary from implementation to implementation. In addition, it will be appreciated that such a development effort can be complex and time consuming, but would nevertheless be a routine undertaking for those skilled in the art having the benefit of disclosing this document.

In one of the exemplary applications of azimuth measurement methods and systems using a gyro unit as disclosed herein, it is possible for a single gyroscope to determine azimuth over a wide range of attitudes of a well system used in a wellbore. with respect to the direction of gravity. Azimuth measurements are based on the following fact that, in normal navigation systems, a moving object is supposed to move over a wide area where geodetic latitude may not be constant. In well applications, however, a well length may be several kilometers only. Although almost part of the well trajectory is horizontal, the geodetic lalitude change will be approximately ± 0.02 degrees maximum and can be considered constant. Constraint, a constant geodetic latitude, allows you to determine the ground rate vector direction with two orthogonal ground rate components on a slope piano. Fig. 1 illustrates one embodiment of an azimuth measurement method for wellbore lifting using an inertial sensing apparatus, such as a gyro unit, and accelerometers included in a well system as disclosed herein. Method 1000 begins by acquiring a ratio value between two orthogonal ground rate components together using the gyroscope unit in a borehole or ground measuring position apparatus as defined in box 1100. Two ground rate components are measured by a single rotating gyro to align an input axis to each of the two orthogonal axes with each other. In other embodiments, one of the ground rate components may be measured by a first gyroscope with an input axis aligned to a first axis and the other ground rate component may be measured by a second gyroscope with an input axis aligned to a first axis. a second axis orthogonal to the first axis. One or two MEMS-type gyros (microelectromechanical systems) can be used on the gyro unit. Method 1000 continues, as set out in box 1200, by acquiring three components of the orthogonal gravity vector together at the measuring position. The three components of the gravity vector can be calculated using three orthogonal axis accelerometers. Then, as provided in box 1300, method 1000 concludes, in this particular embodiment, by determining an azimuth with respect to a predetermined reference axis in the gyro unit, based on the ratio value, the three components of the gravity vector and a geodetic latitude (λ) of the measuring position. The reference axis can be defined in a system including the gyro unit and the three orthogonal axis accelerometers. Fig. 2 is a flow chart of exemplary azimuth steps with respect to a reference axis set in box 1300 of Fig. 1. Azimuth step 1300 begins by determining a horizontal plane, vertical to a determined gravity direction. based on the three gravity vector components as defined in box 1310. Step 1300 continues, as set out in box 1320, determining a normalized ground rate projection vector Ω 'in a value-based measurement coordinate plane of reason. The measurement coordinate plane is defined by predetermined coordinate axes in the gyro unit, such as an X-Y plane of a predetermined orthogonal X, Y, Z coordinate system in the system within the well. Step 1300 continues, as set out in box 1330, determining a ground rate plane (plane Ω) vertical to the measurement coordinate plane, such that a first line of intersection between the ground rate plane and the coordinate plane is parallel to the ground rate projection vector (Ω '). Then, step 1300 continues, as determined in boxes 1340 and 1350, determining a north (N) direction in the horizontal plane, based on the ground rate plane (Ω plane) and geodetic latitude (λ) and determining azimuth calculating an angle between the north direction and a projection vector of the reference axis projected in the horizontal plane. Fig. 3 is a flowchart of exemplary north direction determining steps set out in box 1340 of Fig. 2. The north direction step 1340 begins by determining a vertical plane, vertical to the horizontal plane as defined in box 1341. Step 1340 continues, as set forth in boxes 1342 and 1343, determining a second intersection line between the vertical plane and the ground rate plane (plane Ω) and determining a third intersection line between the vertical plane and the horizontal plane. . Then, as defined in box 1344, step 1340 concludes by determining a direction along the third intersection line as the north direction where an angle between the second intersection line and the third intersection line is equal to geodetic latitude (λ) .

In one embodiment of azimuth measurement methods and systems as disclosed herein, it is assumed that a well tool carries a single axis gyroscope with an input axis parallel to the XY plane, which is one of the coordinate planes of a XYZ orthogonal coordinate system predetermined on the tool inside the well. The input axis is rotatable in the X-Y plane around the Z axis as the aforementioned measurement coordinate plane for measuring ground rate components (Ω) in various angular orientations. The Z axis can be set to be the longitudinal axis of the tool within the well. By fitting a sinusoidal curve to the data measured on the ground rate component plot against angular orientations, a ground rate vector projection Ω 'η the X-Y plane can be determined. The ground rate vector projection Ω 'is a ground rate vector projected on the X-Y plane. In this embodiment, the gyro sensor scale factor may not be well calibrated just to determine the direction of the ground rate vector. However, the present method according to the disclosure of this document is applicable to any type of gyroscope that can measure two orthogonal ground rate components. The direction of the ground rate vector projection plano'ηο the X-Y plane is determined using data from a ratio of two ground rate components along the X axis and Y axis measured with a gyro unit at a measurement position. The inclination angle of the X-Y plane is measured with orthogonal three-axis accelerometers. The geodetic latitude (λ) at the measuring position is known. Azimuth is determined with this information from the ratio data, the inclination angle of the X-Y plane and the geodetic latitude (λ) of the measurement position. Azimuth is defined as an angle between the north direction and an X-axis projection in a horizontal plane, vertical to the gravity direction in applications. The X axis is a reference axis for azimuth measurements that is predetermined in the tool's XYZ coordinate system within the well. Fig. 4 shows a geometric configuration of a model to derive an algorithm and formula for calculating azimuth values. Knowing a ground rate projection vector Ω ', we can make a plane Ω (ground rate plane) 920 vertical to the XY 900 plane. Intersection line ab, like the first intersection line, is parallel to the projection vector of land rate Ω '. The plan Ω must contain the land rate vector Ω in it. Plane Ω intersects horizontal plane 910 at intersection line c-d as the fourth intersection line. The e-f line is the intersection between the X-Y 900 plane and the horizontal plane 910.

To determine a north direction in the model, a vertical plane 930 rotating around the vertical line Ov is defined as shown in Fig. 5. The vertical plane 930 intersects the 20 (ground rate plane) plane 920 on a second intersecting line. of Og and the horizontal plane 910 on a third intersection line Oh. The angle between the second intersection line O-g and the third intersection line O-h is denoted by a. Determining a north direction is to look for a direction from the third intersection line O-h, where α = λ, by rotating the vertical plane 930 around the vertical line O-v. The angle of λ can be determined from the geodetic latitude of the measuring position.

In this model, azimuth is defined as the angle σ between the north direction N and the X-axis (reference axis) projection vector in the horizontal plane 910. The algorithm and formula are derived assuming that the measurement position is located at the Northern Hemisphere of the Earth and then the developed algorithm and formula are adopted for the Southern Hemisphere.

In the present model, the algorithm and formula for calculating azimuth values are derived with the following mathematics using three-dimensional vector algebra. A plane is denoted as a normal vector of the plane and a line is denoted as a direction vector. Only line and plane directions are considered and vector magnitudes have no meaning in the derivation of algorithm and formula. All vectors are normalized to eventually be unit vectors. The horizontal plane 910 is expressed as a normal unit vector Ph as follows: Ph = G, (1) where G is the normalized gravity vector. The plane XY (measurement coordinate plane) 900 is expressed with a normal unit vector Ρχ-y, as follows: Px-r “2, (2) where Z is the parallel unit vector of the Z axis. The plane Ω (plane 920 is expressed with a normal unit vector Pq as follows: where x represents the external product. The fourth intersection line cd denoted by L0_d between the horizontal plane 910 and the plane 920 is expressed as follows: Making a vertical plane 930 parallel to the fourth intersection line cd (see Fig. 5), the vertical plane 930 is expressed with a normal unit vector Pv as follows: By rotating the vertical plane 930 around the vertical line Ov, the third intersection line between the vertical plane 930 and the horizontal plane 910 rotates in the vertical plane 930. The line of rotation, i.e. , the third intersection line is denoted by L0-h as follows: where R is a rotation operator that rotates a vector around vector G.

Therefore, the third intersecting line, L0_h is expressed as follows: The normal unit vector of the vertical plane of rotation, Pv ', is calculated by multiplying G to the right side of formula (7) as follows: The vertical plane of rotation intersects the Ω 920 plane on the second intersection line Og, denoted by L0_g. The second intersection line L0 g is expressed as follows: Note that if the vertical plane 930 does not rotate, the second intersection line L0 g must be parallel to the fourth intersection line L0_d. In fact, the angle ε between the third intersection line 0-h and the second intersection line 0-g is calculated from the internal product of the vectors of these lines. The internal product of formulas (4) and (6) is expressed as follows: To determine the angle ε satisfying λ = α, it is necessary to solve equation (11) for ε. It is possible to facilitate the solution by rewriting equation (11) in terms of the ground rate and gravity unit vector components. Each term of equation (11) is as follows: The rotation operation is usually expressed in terms of Euler angles. However, it leads to very complicated expressions. Vector algebra is very convenient and used here.

If the rotation angle, ε, is infinitesimal, the rotation operator, a rotated vector Z ', would be calculated with a rotation vector R, as follows: However, the rotation angle, ε in this case is usually finite. Thus, equation (14) has to be modified. In fact, dZ is not RxZ in Fig. 6.

Using two vectors of RxZ sin (e) and - (1-cos (ε)) (Z- (R'Z) R) instead of dZ, as shown in Fig. 7, equation (14) is modified as To calculate the internal product of the third intersection line L0-h and the second intersection line L0-g, each term in equations (9) and (11) needs to be rewritten in terms of the measurement coordinate system orthogonal coordinates XYZ) under the following conditions: Using the rewritten equations, the third intersection line L0-h and the second intersection line L0 ~ g can be calculated as follows: Then the internal product of L0-h and Lo q is expressed as follows: Norm of L0-h · L0-g is Therefore, the equation to solve for ε where α = λ is expressed as follows: Note that if ε = 0, the intersecting lines La_ ή and L0 ~ g should be parallel to each other and angle a would be zero.

Actually Dai, the - 0.

Squaring both sides of equation (27) to solve for ε is it is expressed as follows: Solving the equation for ε, two solutions are obtained as follows: Then, the angle ε expressed with equation ( 29) can be positive or negative here because the cosine arc function does not discriminate the signal. In the present applications it is necessary to decide the signal considering something else such as the inclination of the plane plano independently.

To determine the azimuth defined as the angle σ between an X-axis projection and a horizontal plane ground rate vector projection 910, it is necessary to know the angle between the X-axis projection and the second intersection line between the Ω plane. 920 and the horizontal plane 910. The projection on the X axis to the horizontal plane is denoted by X 'as follows: x' = x - (xg) g. The angle between the x-axis projection, X ', and the fourth intersection line L0d is expressed as follows: X-axis projection.

Consequently azimuth is expressed as follows: under the conditions expressed in the following equations: if Gz> 0 f Ά Table I shows a list of azimuth formulas under the above conditional equation to select an azimuth formula with respect to a normal unit vector Pn of the ground rate plane, a unitary gravity vector G, a unitary vector L0_d of the fourth intersection line, and a unitary vector X 'of the X axis projected on the horizontal plane. Azimuth can be determined using one of equations (30-1) to (30-8) listed in Table I, based on the conditional equations.

Table I Figure 8 shows a list of an exemplary simulation result of calculating azimuth error with respect to the entire Yaw (Ψ) and Swing (Θ) and Rolling (Φ) = 0 ° and λ = 35 ° angle ranges. Azimuth error is calculated as "Azimuth - True Azimuth". Azimuth is calculated using the azimuth formula (30) and the conditional equations. Yaw (Ψ), Balance (Θ), and Rolling (Φ) angles are defined as shown in Fig. 9. True azimuth can be calculated using the ground rate vector Ω and the X, X axis projection vector. ', in the horizontal plane as follows: The dashed areas in Fig. 8 show the non-zero error data and the other data in the non-dashed area represent no error, 0. The data indicated in box 801 is computed under the condition at that the axis minus Z is gravity oriented at Θ = 90 °. The tool inside the well can be tilted within ± 50 ° and turned upside down although this is not expected. The error ranges in the dashed areas surrounded by solid lines correspond to the range in which a more conditional parameter "LDd. Ω" is not specified in this simulation. The L0 d ■ sinal signal can eliminate the nonzero error range, but it is impossible to use the condition "L0 d. Ω" because Ω is the target to be measured and an unknown value until azimuth is determined. Note also that error ranges are caused by a combination of signals from two angles of δ and ε, not their values, which are calculated correctly.

The conditional equations used for this simulation are determined only Scroll Θ = 0o and geodetic latitude λ = 35 ° indicating a location in the Northern Hemisphere. In the Southern Hemisphere, the same algorithm can be used with a negative geodetic latitude value. Fig. 10 illustrates an exemplary system including a single gyroscope and three orthogonal axis accelerometers according to the disclosure herein. 11 Fig. 11 shows a block diagram of the sensor system electrical system. Sensor system 30 includes a housing 300, a gyro unit 310 including a single gyro 312, an accelerometer module 350 including three orthogonal axis accelerometers 352 X, 352Y, 352Z, a drive mechanism 400 for gyro 312 for inverting and / or rotate a gyro input shaft 312. Drive mechanism 400 reverses and / or rotates gyro 312 using a single 401 motor (preferably a stepper motor) and gears to carry the rotational force to a rotating axis. of the gyro. By inverting and / or rotating gyro 312, the gyro 312 input axis can be aligned to an X axis and a Y axis of orthogonal XYZ coordinate system (measurement coordinate system). The X axis can be established as a reference axis for calculating an azimuth using the above mentioned algorithm and formula. Gyro 312 measures two orthogonal ground rate components against each other with respect to the X axis and Y axis. The two ground rate components are sent from the gyro unit 310 to the data processing unit 600 and used to calculate data from a ratio between the two ground rate components. The reason data can be sent directly from the gyro unit 310 to the data processing unit 600. sensor system 30 also includes a controller 500 for the drive mechanism, a data processing unit 600 and a power supply unit. 700. Data processing unit 600 includes a computer having a processor 6 processador1 and memory 602. Memory 602 stores a program having instructions for azimuth measurements described above. Gyro 312, accelerators 352X, 352Y, 352Z, drive mechanism 400, controller 500 for drive mechanism 400, data processing unit 600, and power supply unit 700 are installed in housing 300. IJm Angle position sensor 402 may preferably be provided to detect the position of a rotational angle of a rotational axis of motor 401 or gyro. Using the detected rotational angle position, the angular orientation of the gyro input shaft 312 can be identified. Angle position sensor 402 can be used to monitor an angular rotation position of the motor shaft. This angular rotation position monitoring allows the sensor system 30 to return gyro 312 to a home position and adjust the gyro input shaft 312 parallel to a predetermined initial angular orientation (original angular orientation) whenever system power is on. In addition, it is important to monitor the angular rotation position during azimuth measurement for sensor system reliability.

In another embodiment of the present system, it is possible to use a gyro unit including two 312X, 312Y orthogonal axis gyros, as shown in Fig. 12. One of the two orthogonal ground rate components is measured by the 312X gyroscope with the input axis. X-axis aligned and other ground rate components are measured by the gyroscope 312Y with the input axis aligned with the Y axis. In this embodiment, the drive mechanism 401 in Fig. 11 may be omitted in the sensor system 30.

There are many different types of gyro sensors used for azimule measurements including a MEMS gyroscope. Among the varied types of gyro sensors, a ring oscillating lipo MEMS gyroscope can be used preferably in terms of accuracy, robustness of measurement under ambient vibration conditions. The three 352X, 352Y, 352Z accelerometers can be either conventional Q-flex or MEMS accelerometers. Fig. 13 illustrates a well rental system in which the present invention may be employed. The well lease can be on land or at sea. In this exemplary system, a well 11 is formed into subsurface formations by rotary drilling in a manner that is well known. Embodiments of the invention may also use directional drilling, as will be described below.

A drill string 12 is suspended within well 11 and has a bottom composition 100 that includes a drill bit 105 at its lower end. The surface system includes platform and tower assembly 10 positioned over well 11, assembly 10 including a rotary table 16, kelly 17, hook 18 and rotary swivel 19. Drilling column 12 is rotated by rotary table 16, powered by means not shown, which engages kelly 17 at an upper end of the drill string. The drill string 12 is suspended from a hook 18, fixed to a catarina (also not shown) by means of kelly 17, and a rotatable swivel 19 which allows rotation of the drill column relative to the hook. As is well known, an alternatively top drive system could be used.

In the example of this embodiment, the surface system further includes drilling fluid or mud 26 stored in a sump 27 formed at the well location. A pump 29 releases drilling fluid 26 into the drilling column 12 through an opening in swivel 19, causing the drilling fluid to flow downwardly through the drilling column 12, as indicated by the directional arrow 8. The fluid The drill bit exits the drill string 12 through the openings in the drill bit 105 and then circulates upwardly through the annular region between the exterior of the drill string and the well wall, as indicated by the directional arrows 9. In this manner As known, the drilling fluid lubricates drill bit 105 and conveys debris and gravel to the surface when it is returned to reservoir 27 for recirculation. Background composition 100 of the illustrated embodiment includes a drill-in profiling module (LWD) 120, a drill-in measurement module (MWD) 130, a rotor-steerable system and motor, and drill bit 105. The LWD module 120 is housed in a special type of drill collar, as is known in the art, and may contain one or a plurality of known types of profiling tools. It will also be understood that more than one LWD and / or MWD module may be employed, for example, as depicted in 120A. (References throughout the report to a module at position 120 may alternatively mean a module at position 120A as well.) The LWD module includes capabilities for measuring, processing, and storing information as well as for communicating with surface equipment. In the present embodiment, the LWD module includes a pressure measuring device. MWD module 130 is also housed in a special type of drill collar, as is known in the art, and may contain one or more devices for measuring drill string and drill bit characteristics. The MWD tool even includes a device (not shown) to generate electrical power for the system within the well. Typically, this may include a mud turbine generator powered by the drilling fluid flow, it being understood that other power and / or battery systems may be employed. In the present embodiment, the MWD module includes one or more of the following types of measuring devices: a drill weight measuring device, a torque measuring device, a vibration measuring device, a shock measuring device, a driving wedge measuring device, a steering measuring device and a tilt measuring device.

A particularly advantageous use of the system of this document is in conjunction with controlled orientation drilling or "directional drilling". In this embodiment, a rotatable swivel subsystem 150 is provided. Directional drilling is the intentional deviation of the wellbore from the path it would naturally take. In other words, directional drilling is the orientation of the drilling column. so that it moves in a desired direction. Directional drilling is, for example, advantageous in offshore drilling because it allows many wells to be drilled from a single platform. Directional drilling also allows horizontal drilling through a reservoir. Horizontal drilling allows a longer length of wellbore to pass through the reservoir, which increases the well production rate. A directional drilling system can also be used in vertical drilling operation. Often the drill will deviate from a planned drill path because of the unpredictable nature of the formations being penetrated or the varying forces that the drill drill experiences. When such deviation occurs, a directional drilling system may be used to return the drill bit back to the stroke. A known method of directional drilling includes the use of a rotatable swivel system ("RSS"). In an RSS, the drill string is rotated from the surface and devices inside the well cause the drill to drill in the desired direction. Rotation of the drill string greatly reduces occurrences of the drill string from hanging or gripping during drilling. Rotatable swivel drilling systems for drilling diverted wells in the ground can generally be classified as either point the bit or push the bit systems. In the point the bit system, the rotary axis of the drill bit is offset from the local axis of the bottom composition in the general direction of the new hole. The hole is propagated according to the usual three-point geometry defined by upper and lower stabilizer contact points and the drill bit. The angle of deviation of the drill bit shaft coupled to a finite distance between the drill bit and the lower stabilizer results in the non-collinear condition required for a curve to be generated. There are many ways in which this can be achieved by including a fixed curve at a point in the bottom composition near the bottom stabilizer or a bending of the drill bit drive shaft distributed between the top and bottom stabilizer. In its ideal form, the drill bit is not required to cut sideways, because the drill shaft is continuously rotated in the direction of the bent hole. Examples of point-the-bit rotatable steerable systems, and how they operate, are described in US Patent Publications US 2002/0011359; 2001/0052428 and US Patents 6,394,193; 6,364,034; 6,244,361; 6,158,529; 6,092,610 and 5,113,953 all incorporated herein by reference. In the push-the-bit rotary swivel system there is usually no mechanism identified to divert the drill axis from the local background composition axis; instead, the required non-collinear condition is achieved by causing each or both of the upper or lower stabilizers to apply an eccentric force or displacement in a direction that is preferably oriented with respect to the direction of hole propagation. Again, there are many ways in which this can be achieved, including non-rotating (borehole) eccentric stabilizers (displacement approaches) and eccentric actuators that apply force to the drill bit in the desired orientation direction. Again, orientation is obtained by creating non-collinearity between the drill bit and at least two other contact points. In its idealized form the drill is required to cut sideways to generate a bent hole. Examples of push-the-bit rotary steerable systems, and how they operate, are described in US Patents 5,265,682; 5,553,678; 5,803,185; 6,089,332; 5,695,015; 5,685,379; 5,706,905; 5,553,679; 5,673,763; 5,520,255; 5,603,385; 5,582,259; 5,778,992; 5,971,085 all incorporated herein by reference. The foregoing description has been given only to illustrate and describe certain embodiments. It is not intended to be exhaustive or to limit the invention to any precise form disclosed. Many modifications and variations are possible in light of the above teachings.

Modalities and aspects have been chosen and described in order to further explain the principles of the invention and their practical applications. The foregoing description is intended to enable others skilled in the art to better utilize the principles in various embodiments and aspects and with various modifications as are appropriate for the particular use contemplated. It is intended that the scope of the invention be defined by the following claims. - CLAIMS -

Claims (16)

Method for azimuth measurements using a gyroscope unit, comprising: acquiring a ratio value between two orthogonal ground rate components together using the gyroscope unit in a measuring position; acquire three orthogonal gravity vector components from each other at the measurement position; and determining an azimuth with respect to a predetermined reference axis in the gyro unit based on the ratio value, the three gravity vector components, and a geodetic latitude of the measurement position. Method according to claim 1, characterized in that the azimuth determination with respect to the reference axis comprises: determining a vertical horizontal plane at a gravity direction determined based on the three gravity vector components; determining a normalized ground rate projection vector in a measurement coordinate plane based on the ratio value, the measurement coordinate plane being defined by predetermined coordinate axes in the gyro unit; determining a vertical ground rate plane to the measurement coordinate plane such that a first line of intersection between the ground rate plane and the measurement coordinate plane is parallel to the ground rate projection vector; determine a north direction on the horizontal plane based on the ground rate plane and geodetic latitude; and determine the azimuth by calculating an angle between the north direction and a reference axis projection vector ________ projected over the horizontal plane. Method according to claim 2, characterized in that the determination of the north direction comprises: determining a vertical plane, vertical to the horizontal plane; determine a second intersection line between the vertical plane and the ground rate plane; determine a third intersection line between the vertical plane and the horizontal plane; and determining a direction along the third intersection line as the north direction, where an angle between the second intersection line and the third intersection line is equal to the geodetic latitude. Method according to claim 3, characterized in that the azimuth is determined using: where the X axis and Y axis of an orthogonal coordinate system are defined to measure the two ground rate components, the X axis is defined. as the reference axis, δ represents an angle between the X-axis projection in the horizontal plane and a fourth intersection line between the ground rate plane and the horizontal plane, ε represents an angle between the third intersection line and the fourth plane. intersecting line, σ represents azimuth, Ω'χ and Ω'γ represent components along the X axis and Y axis of the normalized ground rate projection vector in an XY plane as the measurement coordinate plane, Gx, Gy and Gz represent the normalized gravity vector components and λ represents the geodetic latitude having a positive value in the Northern Hemisphere and a negative value in the Southern Hemisphere. Method according to claim 4, characterized in that the azimuth is determined using one of the equations (1-1) to (1-8) in Table I, based on conditions for selecting an azimuth formula with respect to a normal unit vector Pq of the ground rate plane, a unit gravity vector G, a unit vector L0_d of the fourth intersection line, and a unit X vector of the X axis projected on the horizontal plane. Method according to claim 1, characterized in that the two ground rate components are measured by a single rotating gyroscope to align an input axis to each of the two orthogonal axes with each other. Method according to claim 1, characterized in that one of the two ground rate components is measured by a first gyroscope with an input axis aligned with a first axis and the other ground rate component is measured by a second one. gyroscope with an input axis aligned with a second axis orthogonal to the first axis. Method according to claim 1, characterized in that the gyro unit comprises one or two MEMS-like gyros. 9. AZIMUTE MEASURING SYSTEM, characterized in that it comprises: a housing; a gyro unit including one or two gyros; three orthogonal axis accelerometers; a data processing unit; and a power supply unit, wherein the processing unit comprises a computer having a processor and a memory; and where the memory stores a program. Reading instructions for: acquiring a ratio value between two orthogonal ground rate components with each other using the gyro unit in a measuring position; acquire three orthogonal gravity vector components from each other at the measurement position; and determining an azimuth with respect to a predetermined reference axis in the gyro unit, based on the ratio value, the three gravity vector components, and a geodetic latitude of the measurement position. System according to claim 9, characterized in that the instructions for determining azimuth with respect to the reference axis comprise instructions for: determining a horizontal, vertical plane at a direction of gravity determined on the basis of the three gravity vector components. ; determining a normalized ground rate projection vector in a measurement coordinate plane based on the ratio value, the measurement coordinate plane being defined by predetermined coordinate axes in the gyro unit; determining a vertical ground rate plane to the measurement coordinate plane such that a first line of intersection between the ground rate plane and the measurement coordinate plane is parallel to the ground rate projection vector; determine the north direction in the horizontal plane based on the ground rate plane and geodetic latitude; and determine the azimuth by calculating an angle between the north direction and a projection vector of the reference axis projected on the horizontal plane. System according to Claim 10, characterized in that the instructions for determining the north direction comprise instructions for: determining a vertical plane, vertical to the horizontal plane; determine a second intersection line between the vertical plane and the ground rate plane; determine a third intersection line between the vertical plane and the horizontal plane; and determining a direction along the third intersection line as the north direction where an angle between the second intersection line and the third intersection line is equal to the geodetic latitude. System according to Claim 11, characterized in that the azimuth is determined using: where the X axis and Y axis of an orthogonal coordinate system are defined to measure the two ground rate components, the X axis is defined. as the reference axis, δ represents an angle between the horizontal axis projection of the X axis and a fourth intersection line between the ground rate plane and the horizontal plane, ε represents an angle between the third intersection line and the fourth line. intersection, σ represents azimuth, Ω'χ and Ω'γ represent components along the X axis and Y axis of the normalized ground rate projection vector in a plan XY as the measurement coordinate plane, Gx, Gy and Gz represent the normalized gravity vector components and λ represents the geodetic latitude having a positive value in the Northern Hemisphere and a negative value in the Southern Hemisphere. System according to claim 12, characterized in that the azimuth is determined using one of the equations (30-1) to (30-8) in Table I, based on conditions for selecting an azimuth formula with respect to a normal unit vector Pq of the ground rate plane, a unit gravity vector Gr a unit vector L0_d of the fourth intersection line and a unit vector X 'of the X axis projected on the horizontal plane. System according to claim 9, characterized in that the gyro unit comprises a single rotating gyroscope for aligning an input axis to each of the two orthogonal axes with each other. System according to claim 9, characterized in that the gyro unit comprises a first gyroscope with an input axis aligned with the first axis and a second gyroscope with an input axis aligned with a second axis orthogonal to the first axis. System according to claim 9, characterized in that the gyro unit comprises one or two MEMS-like gyros.