Easy-to-clean visual graMethod for remotely shutting down downhole unit of rotary steering system from groundin monitoring device

Abstract

A method for remotely shutting down a downhole unit of a rotary steering system from ground includes steps of: a: calculating a pressure difference P.sub.1 between a front end and a rear end of the drill water hole; b: calculating an extension loss ΔP; c: calculating a pressure P.sub.2 at the riser after turning on the downlink device; d: calculating an opening area S.sub.1 of the throttle valve of the downlink device; and e: adjusting the throttle valve to a calculated opening degree; automatically targeting the function block that needs to be cut off according to a flow change detected downhole, and shutting down the downhole unit. The method can realize self-protection and continuous operation of the entire rotary steering system, reduce frequency of inspection that needs to pull back the drill when the rotary steering system is abnormal, improve drilling efficiency, and reduce costs.

Claims

1-5. (canceled)

6. A method for remotely shutting down a downhole unit of a rotary steering system from ground, comprising steps of: a: setting a diversion ratio of a downlink device as k, an equivalent area of a drill water hole as s, a total displacement of a mud pump as Q, and a pressure of a riser before the downlink device is turned on as P; calculating a pressure difference P.sub.1 between a front end and a rear end of the drill water hole by a formula 1;
P.sub.1=Q2ρ/2μ2s2   formula 1; wherein Q is the total displacement of the mud pump, m.sup.2/s; μ is a flow coefficient and μ=0.63; s is the equivalent area of the drill water hole, m.sup.2; P.sub.1 is the pressure difference between the front end and the rear end of the drill water hole, Pa; and ρ is fluid density, Kg/m.sup.3; b: calculating an extension loss ΔP by a formula 2;
ΔP=P−P.sub.1   formula 2; c: calculating a pressure P.sub.2 at the riser after turning on the downlink device by a formula 3;
P.sub.2=ΔP+ρ(1−k).sup.2Q.sup.2/2μ.sup.2s.sup.2   formula 3; d: since a pressure drop of a throttle valve of the downlink device is also P.sub.2 according to a pressure balance relationship, calculating an opening area S.sub.1 of the throttle valve of the downlink device by a formula 4; $\begin{array}{cc}{S}_1=\mathrm{kQ}/\sqrt[\mu ]{2P_2/\rho };& \mathrm{formula}4\end{array}$ and e: adjusting the throttle valve to a calculated opening degree according to a relationship between the opening degree and the opening area S.sub.1 of the throttle valve, so that a diverting flow automatically reaches the set diversion ratio; providing a cut-off circuit to each function block of the rotary steering system; numbering each function block, and forming a preset corresponding relationship between the function block and the diverting flow of the downlink device, which is solidified in a rotary steering tool control software; if any function block is abnormal, adjusting the diverting flow of the downlink device according to the preset corresponding relationship between the function block and the diverting flow; automatically targeting the function block that needs to be cut off according to a flow change detected downhole, and shutting down the downhole unit.

7. The method for remotely shutting down the downhole unit of the rotary steering system from the ground, as recited in claim 6, wherein in the step e, adjusting the throttle valve to the calculated opening degree comprises specific steps of: calibrating indoors to form a relationship curve between the opening degree and the opening area; and obtaining a required opening degree based on the relationship curve between the opening degree and the opening area, as well as a required opening area of the throttle valve area corresponding to the diversion ratio set in the previous step.

8. The method for remotely shutting down the downhole unit of the rotary steering system from the ground, as recited in claim 6, wherein in the step e, the diverting flow automatically reaches the set diversion ratio through specific steps of: after the downlink device receives the set diversion ratio, calculating a required opening area of the throttle valve of the downlink device according to a calculation formula, and then obtaining a required opening degree of the throttle valve according to the relationship between the opening degree and the opening area S.sub.1 of the throttle valve; according to a corresponding relationship between the required opening degree of the throttle valve and an analog electrical signal, outputting a current signal, so as to reach the set diversion ratio through automatic adjustment of the throttle valve of the downlink device.

9. The method for remotely shutting down the downhole unit of the rotary steering system from the ground, as recited in claim 7, wherein in the step e, the diverting flow automatically reaches the set diversion ratio through specific steps of: after the downlink device receives the set diversion ratio, calculating a required opening area of the throttle valve of the downlink device according to a calculation formula, and then obtaining a required opening degree of the throttle valve according to the relationship between the opening degree and the opening area S.sub.1 of the throttle valve; according to a corresponding relationship between the required opening degree of the throttle valve and an analog electrical signal, outputting a current signal, so as to reach the set diversion ratio through automatic adjustment of the throttle valve of the downlink device.

10. The method for remotely shutting down the downhole unit of the rotary steering system from the ground, as recited in claim 6, wherein in the step e, forming the preset corresponding relationship between the function block and the diverting flow comprises specific steps of: presetting 9 function blocks, and installing a controllable diode on each of the 9 function blocks; using three flows of 10%, 15% and 20% with different durations to represent the 9 function blocks; wherein the 10% diverting flow lasting for 2 s means to shut down a 1# function block; the 10% diverting flow lasting for 4 s means to shut down a 2# function block; the 10% diverting flow lasting for 6 s means to shut down a 3# function block; the 15% diverting flow lasting for 2 s means to shut down a 4# function block; the 15% diverting flow lasting for 4 s means to shut down a 5# function block; the 15% diverting flow lasting for 6 s means to shut down a 6# function block; the 20% diverting flow lasting for 2 s means to shut down a 7# function block; the 20% diverting flow lasting for 4 s means to shut down a 8# function block; and the 20% diverting flow lasting for 6 s means to shut down a 9# function block.

11. The method for remotely shutting down the downhole unit of the rotary steering system from the ground, as recited in claim 7, wherein in the step e, forming the preset corresponding relationship between the function block and the diverting flow comprises specific steps of: presetting 9 function blocks, and installing a controllable diode on each of the 9 function blocks; using three flows of 10%, 15% and 20% with different durations to represent the 9 function blocks; wherein the 10% diverting flow lasting for 2 s means to shut down a 1# function block; the 10% diverting flow lasting for 4 s means to shut down a 2# function block; the 10% diverting flow lasting for 6 s means to shut down a 3# function block; the 15% diverting flow lasting for 2 s means to shut down a 4# function block; the 15% diverting flow lasting for 4 s means to shut down a 5# function block; the 15% diverting flow lasting for 6 s means to shut down a 6# function block; the 20% diverting flow lasting for 2 s means to shut down a 7# function block; the 20% diverting flow lasting for 4 s means to shut down a 8# function block; and the 20% diverting flow lasting for 6 s means to shut down a 9# function block.

12. The method for remotely shutting down the downhole unit of the rotary steering system from the ground, as recited in claim 8, wherein in the step e, forming the preset corresponding relationship between the function block and the diverting flow comprises specific steps of: presetting 9 function blocks, and installing a controllable diode on each of the 9 function blocks; using three flows of 10%, 15% and 20% with different durations to represent the 9 function blocks; wherein the 10% diverting flow lasting for 2 s means to shut down a 1# function block; the 10% diverting flow lasting for 4 s means to shut down a 2# function block; the 10% diverting flow lasting for 6 s means to shut down a 3# function block; the 15% diverting flow lasting for 2 s means to shut down a 4# function block; the 15% diverting flow lasting for 4 s means to shut down a 5# function block; the 15% diverting flow lasting for 6 s means to shut down a 6# function block; the 20% diverting flow lasting for 2 s means to shut down a 7# function block; the 20% diverting flow lasting for 4 s means to shut down a 8# function block; and the 20% diverting flow lasting for 6 s means to shut down a 9# function block.

13. The method for remotely shutting down the downhole unit of the rotary steering system from the ground, as recited in claim 9, wherein in the step e, forming the preset corresponding relationship between the function block and the diverting flow comprises specific steps of: presetting 9 function blocks, and installing a controllable diode on each of the 9 function blocks; using three flows of 10%, 15% and 20% with different durations to represent the 9 function blocks; wherein the 10% diverting flow lasting for 2 s means to shut down a 1# function block; the 10% diverting flow lasting for 4 s means to shut down a 2# function block; the 10% diverting flow lasting for 6 s means to shut down a 3# function block; the 15% diverting flow lasting for 2 s means to shut down a 4# function block; the 15% diverting flow lasting for 4 s means to shut down a 5# function block; the 15% diverting flow lasting for 6 s means to shut down a 6# function block; the 20% diverting flow lasting for 2 s means to shut down a 7# function block; the 20% diverting flow lasting for 4 s means to shut down a 8# function block; and the 20% diverting flow lasting for 6 s means to shut down a 9# function block.

14. The method for remotely shutting down the downhole unit of the rotary steering system from the ground, as recited in claim 6, wherein in the step e, shutting down the downhole unit comprises specific steps of: since the rotary steering system comprises a downhole mud turbine generator and a voltage frequency changes accordingly when a mud flow through the downhole mud turbine generator changes, detecting a voltage frequency change by a rotary steering control module, so as to obtain a mud flow change; detecting a size of the diverting flow downhole and combining with an inherent coding method to complete identification of a downlink command; after receiving a shutdown command, setting a controllable diode of a corresponding function block to a cut-off state.

15. The method for remotely shutting down the downhole unit of the rotary steering system from the ground, as recited in claim 7, wherein in the step e, shutting down the downhole unit comprises specific steps of: since the rotary steering system comprises a downhole mud turbine generator and a voltage frequency changes accordingly when a mud flow through the downhole mud turbine generator changes, detecting a voltage frequency change by a rotary steering control module, so as to obtain a mud flow change; detecting a size of the diverting flow downhole and combining with an inherent coding method to complete identification of a downlink command; after receiving a shutdown command, setting a controllable diode of a corresponding function block to a cut-off state.

16. The method for remotely shutting down the downhole unit of the rotary steering system from the ground, as recited in claim 8, wherein in the step e, shutting down the downhole unit comprises specific steps of: since the rotary steering system comprises a downhole mud turbine generator and a voltage frequency changes accordingly when a mud flow through the downhole mud turbine generator changes, detecting a voltage frequency change by a rotary steering control module, so as to obtain a mud flow change; detecting a size of the diverting flow downhole and combining with an inherent coding method to complete identification of a downlink command; after receiving a shutdown command, setting a controllable diode of a corresponding function block to a cut-off state.

17. The method for remotely shutting down the downhole unit of the rotary steering system from the ground, as recited in claim 9, wherein in the step e, shutting down the downhole unit comprises specific steps of: since the rotary steering system comprises a downhole mud turbine generator and a voltage frequency changes accordingly when a mud flow through the downhole mud turbine generator changes, detecting a voltage frequency change by a rotary steering control module, so as to obtain a mud flow change; detecting a size of the diverting flow downhole and combining with an inherent coding method to complete identification of a downlink command; after receiving a shutdown command, setting a controllable diode of a corresponding function block to a cut-off state.

18. The method for remotely shutting down the downhole unit of the rotary steering system from the ground, as recited in claim 6, wherein the total displacement of the mud pump is constant during a drilling process of one layer section.

19. The method for remotely shutting down the downhole unit of the rotary steering system from the ground, as recited in claim 6, wherein the mud flow change reflects the diverting flow of the downlink device.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0025] Embodiment 1

[0026] A method for remotely shutting down a downhole unit of a rotary steering system from ground is provided, comprising steps of: [0027] a: setting a diversion ratio of a downlink device as k, an equivalent area of a drill water hole as s, a total displacement of a mud pump as Q, and a pressure of a riser before the downlink device is turned on as P; calculating a pressure difference P.sub.1 between a front end and a rear end of the drill water hole by a formula 1;

P.sub.1=Q2ρ/2μ2s2   formula 1; [0028] wherein Q is the total displacement of the mud pump, m.sup.2/s; μ is a flow coefficient and μ=0.63; s is the equivalent area of the drill water hole, m.sup.2; P.sub.1 is the pressure difference between the front end and the rear end of the drill water hole, Pa; and ρ is fluid density, Kg/m.sup.2; [0029] b: calculating an extension loss ΔP by a formula 2;

ΔP=P−P.sub.1   formula 2; [0030] c: calculating a pressure P.sub.2 at the riser after turning on the downlink device by a formula 3;

P.sub.2=ΔP+ρ(1−k).sup.2Q.sup.2/2μ.sup.2s.sup.2   formula 3; [0031] d: since a pressure drop of a throttle valve of the downlink device is also P.sub.2 according to a pressure balance relationship, calculating an opening area S.sub.1 of the throttle valve of the downlink device by a formula 4;

[00002]$\begin{array}{cc}{S}_1=\mathrm{kQ}/\sqrt[\mu ]{2P_2/\rho };& \mathrm{formula}4\end{array}$

and [0032] e: adjusting the throttle valve to a calculated opening degree according to a relationship between the opening degree and the opening area S.sub.1 of the throttle valve, so that a diverting flow automatically reaches the set diversion ratio; providing a cut-off circuit to each function block of the rotary steering system; numbering each function block, and forming a preset corresponding relationship between the function block and the diverting flow of the downlink device, which is solidified in a rotary steering tool control software; if any function block is abnormal, adjusting the diverting flow of the downlink device according to the preset corresponding relationship between the function block and the diverting flow; automatically targeting the function block that needs to be cut off according to a flow change detected downhole, and shutting down the downhole unit.

[0033] Since the front end of the throttle valve and the riser are the same pressure system, the pressures of the two are the same. Based on the pressure balance and the relationship between flow and pressure, it can be assumed that the diversion ratio of the downlink device is k, the equivalent area of the drill water hole is s, the total discharge of the mud pump is Q, and the pressure of the riser before the downlink device is turned on is P. The pressure difference P.sub.1 between the front end and the rear end of the drill water hole, the extension loss ΔP, the pressure P.sub.2 at the riser after turning on the downlink device, and the opening area S.sub.1 of the throttle valve of the downlink device are calculated to obtain an accurate diversion algorithm of the downlink device. Compared with the prior art, if any function block is abnormal, the diverting flow of the downlink device can be adjusted according to the preset corresponding relationship between the function block and the diverting flow, thereby automatically targeting the function block that needs to be cut off according to a flow change detected downhole, so as to realize self-protection and continuous operation of the entire rotary steering system, reduce frequency of inspection that needs to pull back the drill when the rotary steering system is abnormal, improve drilling efficiency, and reduce costs.

[0034] Embodiment 2

[0035] A method for remotely shutting down a downhole unit of a rotary steering system from ground is provided, comprising steps of: [0036] a: setting a diversion ratio of a downlink device as k, an equivalent area of a drill water hole as s, a total displacement of a mud pump as Q, and a pressure of a riser before the downlink device is turned on as P; calculating a pressure difference P.sub.1 between a front end and a rear end of the drill water hole by a formula 1;

P.sub.1=Q2ρ/2μ2s2   formula 1;

wherein Q is the total displacement of the mud pump, m.sup.2/s; μ is a flow coefficient and μ=0.63; s is the equivalent area of the drill water hole, m.sup.2; P.sub.1 is the pressure difference between the front end and the rear end of the drill water hole, Pa; and ρ is fluid density, Kg/m.sup.3; [0037] b: calculating an extension loss ΔP by a formula 2;

ΔP=P−P.sub.1   formula 2; [0038] c: calculating a pressure P.sub.2 at the riser after turning on the downlink device by a formula 3;

P.sub.2=ΔP+ρ(1−k).sup.2Q.sup.2/2μ.sup.2s.sup.2   formula 3; [0039] d: since a pressure drop of a throttle valve of the downlink device is also P.sub.2 according to a pressure balance relationship, calculating an opening area S.sub.1 of the throttle valve of the downlink device by a formula 4;

[00003]$\begin{array}{cc}{S}_1=\mathrm{kQ}/\sqrt[\mu ]{2P_2/\rho };& \mathrm{formula}4\end{array}$

and [0040] e: adjusting the throttle valve to a calculated opening degree according to a relationship between the opening degree and the opening area S.sub.1 of the throttle valve, so that a diverting flow automatically reaches the set diversion ratio; providing a cut-off circuit to each function block of the rotary steering system; numbering each function block, and forming a preset corresponding relationship between the function block and the diverting flow of the downlink device, which is solidified in a rotary steering tool control software; if any function block is abnormal, adjusting the diverting flow of the downlink device according to the preset corresponding relationship between the function block and the diverting flow; automatically targeting the function block that needs to be cut off according to a flow change detected downhole, and shutting down the downhole unit.

[0041] In the step e, adjusting the throttle valve to the calculated opening degree comprises specific steps of: calibrating indoors to form a relationship curve between the opening degree and the opening area; and obtaining a required opening degree based on the relationship curve between the opening degree and the opening area, as well as a required opening area of the throttle valve area corresponding to the diversion ratio set in the previous step.

[0042] Embodiment 3

[0043] A method for remotely shutting down a downhole unit of a rotary steering system from ground is provided, comprising steps of: [0044] a: setting a diversion ratio of a downlink device as k, an equivalent area of a drill water hole as s, a total displacement of a mud pump as Q, and a pressure of a riser before the downlink device is turned on as P; calculating a pressure difference P.sub.1 between a front end and a rear end of the drill water hole by a formula 1;

P.sub.1=Q2ρ/2μ2s2   formula 1; [0045] wherein Q is the total displacement of the mud pump, m.sup.2/s; μ is a flow coefficient and μ=0.63; s is the equivalent area of the drill water hole, m.sup.2; P.sub.1 is the pressure difference between the front end and the rear end of the drill water hole, Pa; and ρ is fluid density, Kg/m.sup.2; [0046] b: calculating an extension loss ΔP by a formula 2;

ΔP=P−P.sub.1   formula 2; [0047] c: calculating a pressure P.sub.2 at the riser after turning on the downlink device by a formula 3;

P.sub.2=ΔP+ρ(1−k).sup.2Q.sup.2/2μ.sup.2s.sup.2   formula 3; [0048] d: since a pressure drop of a throttle valve of the downlink device is also P.sub.2 according to a pressure balance relationship, calculating an opening area S.sub.1 of the throttle valve of the downlink device by a formula 4;

[00004]$\begin{array}{cc}{S}_1=\mathrm{kQ}/\sqrt[\mu ]{2P_2/\rho };& \mathrm{formula}4\end{array}$

and [0049] e: adjusting the throttle valve to a calculated opening degree according to a relationship between the opening degree and the opening area S.sub.1 of the throttle valve, so that a diverting flow automatically reaches the set diversion ratio; providing a cut-off circuit to each function block of the rotary steering system; numbering each function block, and forming a preset corresponding relationship between the function block and the diverting flow of the downlink device, which is solidified in a rotary steering tool control software; if any function block is abnormal, adjusting the diverting flow of the downlink device according to the preset corresponding relationship between the function block and the diverting flow; automatically targeting the function block that needs to be cut off according to a flow change detected downhole, and shutting down the downhole unit.

[0050] In the step e, adjusting the throttle valve to the calculated opening degree comprises specific steps of: calibrating indoors to form a relationship curve between the opening degree and the opening area; and obtaining a required opening degree based on the relationship curve between the opening degree and the opening area, as well as a required opening area of the throttle valve area corresponding to the diversion ratio set in the previous step.

[0051] In the step e, the diverting flow automatically reaches the set diversion ratio through specific steps of: after the downlink device receives the set diversion ratio, calculating a required opening area of the throttle valve of the downlink device according to a calculation formula, and then obtaining a required opening degree of the throttle valve according to the relationship between the opening degree and the opening area S.sub.1 of the throttle valve; according to a corresponding relationship between the required opening degree of the throttle valve and an analog electrical signal, outputting a current signal, so as to reach the set diversion ratio through automatic adjustment of the throttle valve of the downlink device.

[0052] Since it is possible to adjust the diverting flow of the downlink device through the preset corresponding relationship between the function block and the diverting flow, when error occurs in a certain function block, that function block can be automatically targeted, and a command to shut down that function block will be issued through the downlink device, thereby avoiding affecting the operation of the whole system due to the error of the certain function block. The pertinence is strong.

[0053] Embodiment 4

[0054] A method for remotely shutting down a downhole unit of a rotary steering system from ground is provided, comprising steps of: [0055] a: setting a diversion ratio of a downlink device as k, an equivalent area of a drill water hole as s, a total displacement of a mud pump as Q, and a pressure of a riser before the downlink device is turned on as P; calculating a pressure difference P.sub.1 between a front end and a rear end of the drill water hole by a formula 1;

P.sub.1=Q2ρ/2μ2s2   formula 1; [0056] wherein Q is the total displacement of the mud pump, m.sup.2/s; μ is a flow coefficient and μ=0.63; s is the equivalent area of the drill water hole, m.sup.2; P.sub.1 is the pressure difference between the front end and the rear end of the drill water hole, Pa; and ρ is fluid density, Kg/m.sup.3; [0057] b: calculating an extension loss ΔP by a formula 2;

ΔP=P−P.sub.1   formula 2; [0058] c: calculating a pressure P.sub.2 at the riser after turning on the downlink device by a formula 3;

P.sub.2=ΔP+ρ(1−k).sup.2Q.sup.2/2μ.sup.2s.sup.2   formula 3; [0059] d: since a pressure drop of a throttle valve of the downlink device is also P.sub.2 according to a pressure balance relationship, calculating an opening area S.sub.1 of the throttle valve of the downlink device by a formula 4;

[00005]$\begin{array}{cc}{S}_1=\mathrm{kQ}/\sqrt[\mu ]{2P_2/\rho };& \mathrm{formula}4\end{array}$

and [0060] e: adjusting the throttle valve to a calculated opening degree according to a relationship between the opening degree and the opening area S.sub.1 of the throttle valve, so that a diverting flow automatically reaches the set diversion ratio; providing a cut-off circuit to each function block of the rotary steering system; numbering each function block, and forming a preset corresponding relationship between the function block and the diverting flow of the downlink device, which is solidified in a rotary steering tool control software; if any function block is abnormal, adjusting the diverting flow of the downlink device according to the preset corresponding relationship between the function block and the diverting flow; automatically targeting the function block that needs to be cut off according to a flow change detected downhole, and shutting down the downhole unit.

[0061] In the step e, adjusting the throttle valve to the calculated opening degree comprises specific steps of: calibrating indoors to form a relationship curve between the opening degree and the opening area; and obtaining a required opening degree based on the relationship curve between the opening degree and the opening area, as well as a required opening area of the throttle valve area corresponding to the diversion ratio set in the previous step.

[0062] In the step e, the diverting flow automatically reaches the set diversion ratio through specific steps of: after the downlink device receives the set diversion ratio, calculating a required opening area of the throttle valve of the downlink device according to a calculation formula, and then obtaining a required opening degree of the throttle valve according to the relationship between the opening degree and the opening area S.sub.1 of the throttle valve; according to a corresponding relationship between the required opening degree of the throttle valve and an analog electrical signal, outputting a current signal, so as to reach the set diversion ratio through automatic adjustment of the throttle valve of the downlink device.

[0063] In the step e, forming the preset corresponding relationship between the function block and the diverting flow comprises specific steps of: presetting 9 function blocks, and installing a controllable diode on each of the 9 function blocks; using three flows of 10%, 15% and 20% with different durations to represent the 9 function blocks; wherein the 10% diverting flow lasting for 2 s means to shut down a 1# function block; the 10% diverting flow lasting for 4 s means to shut down a 2# function block; the 10% diverting flow lasting for 6 s means to shut down a 3# function block; the 15% diverting flow lasting for 2 s means to shut down a 4# function block; the 15% diverting flow lasting for 4 s means to shut down a 5# function block; the 15% diverting flow lasting for 6 s means to shut down a 6# function block; the 20% diverting flow lasting for 2 s means to shut down a 7# function block; the 20% diverting flow lasting for 4 s means to shut down a 8# function block; and the 20% diverting flow lasting for 6 s means to shut down a 9# function block.

[0064] Embodiment 4

[0065] A method for remotely shutting down a downhole unit of a rotary steering system from ground is provided, comprising steps of: [0066] a: setting a diversion ratio of a downlink device as k, an equivalent area of a drill water hole as s, a total displacement of a mud pump as Q, and a pressure of a riser before the downlink device is turned on as P; calculating a pressure difference P.sub.1 between a front end and a rear end of the drill water hole by a formula 1;

P.sub.1=Q2ρ/2μ2s2   formula 1; [0067] wherein Q is the total displacement of the mud pump, m.sup.2/s; μ is a flow coefficient and μ=0.63; s is the equivalent area of the drill water hole, m.sup.2; P.sub.1 is the pressure difference between the front end and the rear end of the drill water hole, Pa; and ρ is fluid density, Kg/m.sup.3; [0068] b: calculating an extension loss ΔP by a formula 2;

ΔP=P−P.sub.1   formula 2; [0069] c: calculating a pressure P.sub.2 at the riser after turning on the downlink device by a formula 3;

P.sub.2=ΔP+ρ(1−k).sup.2Q.sup.2/2μ.sup.2s.sup.2   formula 3; [0070] d: since a pressure drop of a throttle valve of the downlink device is also P.sub.2 according to a pressure balance relationship, calculating an opening area S.sub.1 of the throttle valve of the downlink device by a formula 4;

[00006]$\begin{array}{cc}{S}_1=\mathrm{kQ}/\sqrt[\mu ]{2P_2/\rho };& \mathrm{formula}4\end{array}$

and [0071] e: adjusting the throttle valve to a calculated opening degree according to a relationship between the opening degree and the opening area S.sub.1 of the throttle valve, so that a diverting flow automatically reaches the set diversion ratio; providing a cut-off circuit to each function block of the rotary steering system; numbering each function block, and forming a preset corresponding relationship between the function block and the diverting flow of the downlink device, which is solidified in a rotary steering tool control software; if any function block is abnormal, adjusting the diverting flow of the downlink device according to the preset corresponding relationship between the function block and the diverting flow; automatically targeting the function block that needs to be cut off according to a flow change detected downhole, and shutting down the downhole unit.

[0072] In the step e, adjusting the throttle valve to the calculated opening degree comprises specific steps of: calibrating indoors to form a relationship curve between the opening degree and the opening area; and obtaining a required opening degree based on the relationship curve between the opening degree and the opening area, as well as a required opening area of the throttle valve area corresponding to the diversion ratio set in the previous step.

[0073] In the step e, the diverting flow automatically reaches the set diversion ratio through specific steps of: after the downlink device receives the set diversion ratio, calculating a required opening area of the throttle valve of the downlink device according to a calculation formula, and then obtaining a required opening degree of the throttle valve according to the relationship between the opening degree and the opening area S.sub.1 of the throttle valve; according to a corresponding relationship between the required opening degree of the throttle valve and an analog electrical signal, outputting a current signal, so as to reach the set diversion ratio through automatic adjustment of the throttle valve of the downlink device.

[0074] In the step e, forming the preset corresponding relationship between the function block and the diverting flow comprises specific steps of: presetting 9 function blocks, and installing a controllable diode on each of the 9 function blocks; using three flows of 10%, 15% and 20% with different durations to represent the 9 function blocks; wherein the 10% diverting flow lasting for 2 s means to shut down a 1# function block; the 10% diverting flow lasting for 4 s means to shut down a 2# function block; the 10% diverting flow lasting for 6 s means to shut down a 3# function block; the 15% diverting flow lasting for 2 s means to shut down a 4# function block; the 15% diverting flow lasting for 4 s means to shut down a 5# function block; the 15% diverting flow lasting for 6 s means to shut down a 6# function block; the 20% diverting flow lasting for 2 s means to shut down a 7# function block; the 20% diverting flow lasting for 4 s means to shut down a 8# function block; and the 20% diverting flow lasting for 6 s means to shut down a 9# function block.

[0075] In the step e, shutting down the downhole unit comprises specific steps of: since the rotary steering system comprises a downhole mud turbine generator and a voltage frequency changes accordingly when a mud flow through the downhole mud turbine generator changes, detecting a voltage frequency change by a rotary steering control module, so as to obtain a mud flow change; detecting a size of the diverting flow downhole and combining with an inherent coding method to complete identification of a downlink command; after receiving a shutdown command, setting a controllable diode of a corresponding function block to a cut-off state.

[0076] Since the total mud displacement of the mud pump is constant during the drilling process of one layer section, the change of the mud flow reflects the diverting flow of the downlink device. Therefore, it is possible to represent different commands by the size and duration of the diverting flow, which forms the inherent coding method. The rotary steering system detects the size of the diverting flow downhole, and combines with the inherent coding method to complete the identification of the downlink command, which is easy to operate.