US20160040526A1

US20160040526A1 - System and method for communicating complex downhole information

Info

Publication number: US20160040526A1
Application number: US14/451,630
Authority: US
Inventors: Robert Eugene Mebane, III; Michael Gaines
Original assignee: National Oilwell Varco LP
Current assignee: National Oilwell Varco LP
Priority date: 2014-08-05
Filing date: 2014-08-05
Publication date: 2016-02-11

Abstract

A system and method for communicating downhole information through a wellbore to a surface location includes a drill string with a downhole tool, a pump for flowing drilling mud through the drill string and wellbore, a valve for flow restriction of the drilling mud, a sensing module for measuring downhole conditions in first and second orientations of the downhole tool, an actuator between two static positions, and a detector for measurement values at the surface location correlative to time between changes of pressure of the drilling mud. The time between pressure changes, as the actuator moves between static positions, conveys encoded data to the detector. The encoded data is compiled from downhole conditions measured by the sensing module, in addition to orientation of the downhole tool. Complex downhole conditions dependent on knowing the multiple orientations of the sensing module can now be communicated by a pressure releasing encoding system.

Description

RELATED U.S. APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO MICROFICHE APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a system and method for transmitting downhole information to a surface location. More particularly, the present invention relates to a system and method for communicating downhole information from multiple orientations of a downhole tool through pressure release encoding. The present invention also relates to a system and method with a means to detect vertical and lateral orientation of a downhole tool. More particularly, the present invention relates to adjusting interpretation of data from the sensors measuring downhole conditions, according to the detected orientation of the downhole tool.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
Natural resources, such as ground water, natural gas, and petroleum, are deposited underground. Drilling is part of a process for extracting those resources from their remote location. A well or borehole can be created by use of a drilling rig to rotate a drill string, which has a drill bit attached at its end in order to bore into the ground to a desired depth. Drill collars and drill pipe sections add length, weight and support along the drill string as the borehole deepens, and different types of drill bits cut into all types of rock formations and soil combinations. In rotary drilling, the drill bit is rotated by rotating the drill string at the surface. Rotary drilling can be efficient for boring vertically into the ground, because there is only one direction of the drill bit. In directional drilling, the drill bit can be rotated by a downhole mud motor or other device, including types of rotary assemblies, coupled to the drill bit. The drill bit can deviate from vertical, so as to slant the borehole or even angle the borehole towards horizontal. In a steerable drill string, the mud motor is bent at a slight angle to the centerline of the drill bit so as to create a side force that directs the path of the drill bit away from a straight line.
Drilling fluid or drilling mud pumps through the inside of the drill string, out of the drill bit by nozzles or jets, and up the annulus to the surface, in order to create the proper physical and hydrostatic conditions to safely drill the well. Additionally, the rock cuttings are removed from the borehole in the drilling mud circulation flowing to the surface.
The distal end of a drill string is the bottom hole assembly (BHA), which includes the drill bit, the drilling sub and drill collars. In “measurement while drilling” (MWD) or “logging while drilling” (LWD) applications, sensing modules in the BHA, or other downhole tools, provide information concerning the downhole conditions, such as direction of the drilling. The actual sensors may include devices to measure angle of inclination, azimuth and toolface direction, including magnetometers and accelerometers. This information can be used, for example, to control the direction in which the drill bit should adjust, during directional drilling or as steerable drilling.
Sensing modules can also provide useful downhole information in real-time with regard to other aspects of the drilling operation. For example, ultrasonic transducers monitor resistivity of high frequency wavelength signals bounced back from the rock formation downhole so that characteristics of the formation can be determined. Water or hydrocarbons or rock at the downhole depth can be mapped in real time. Other sensing modules can include magnetic resonance imaging (MRI), gamma scintillators, and nuclear detectors. Radioactivity, porosity, and density can be other downhole conditions detected by some of these other sensing modules.
The downhole information collected by the sensing modules is transmitted to the surface for analysis. Mud pulse telemetry receives data from the sensing modules, digitally encodes the data, and actuates a pulser to send pressure pulses within the flow of drilling mud. A receiver at the surface interprets the pressure pulses to collect the encoded data. Conventional mud pulsers require a large amount of power to actuate the valve and modulate the drilling mud sufficient for detection at the surface. Oscillating drilling mud for a pressure transducer to detect at the surface is difficult to power and control. More recent developments in mud pulse telemetry include a pressure release encoding system to reduce the power requirements and to increase efficiency for generating pulses through the drilling mud. In particular, only a small amount of power is needed because the mud pump becomes the primary energy source of the pressure release encoding system. A valve means restricts mud flow, and a brake means progressively releases the valve means to create the pressure drop. The pressure drop is generated by setting an equilibrium pressure gradient across the valve means based on the mud pump energy, releasing the brake means to a second position, and resetting the equilibrium pressure gradient across the valve means based on the mud pump energy again. No additional modulation or actuation of the drilling mud is required by this pressure release encoding system. There is no additional manipulation of the originating mud pump delivering the drilling mud to the borehole at a set rate and pressure.
For pressure release encoding systems, additional information must be encoded when the downhole tool, such as a BHA, changes orientation. The actual sensors of a sensing module measure the same properties in any orientation. However, a change in orientation of the downhole tool affects how these measured properties relate to downhole conditions. For example, an accelerometer measures inclination angle. The deviation from vertical is detected so that the slant of the borehole can be monitored for directional drilling. If the orientation changes toward lateral or horizontal, then the accelerometer can no longer measure deviation from vertical. Some inclination sensors have a range of 0 to 20 degrees, such that more than 20 degrees of slant exceeds the range of the inclinations sensor. There is no more useful information from the inclinations sensor past 20 degrees from vertical. Measurements past 20 degrees of slant would show no changes, but that lack of change does not mean that the downhole condition is vertical anymore.
In another example, a magnetometer measures azimuth. The direction of slant from vertical is detected, not just the slant itself, can be monitored for directional drilling. When the orientation changes toward lateral or horizontal, then the magnetometer measures direction from horizontal, not vertical. The directional data is no longer direction of slant, but rather direction of the toolface. The tool face can be moving up, down or side to side through the formation, not just deviating from vertical. The same measurements and readings are being produced from the magnetometer, but the downhole condition has changed from direction of slant from vertical to direction of the toolface.
It is an object of the present invention to provide an embodiment of a system and method for communicating downhole information through pressure release encoding to the surface.
It is an object of the present invention to provide an embodiment of a system and method for communicating downhole information collected from a sensing module on a downhole tool, such as a BHA, in different orientations.
It is another object of the present invention to provide an embodiment of a system and method for communicating downhole information collected from a sensing module in vertical and lateral orientations.
It is still another object of the present invention to provide an embodiment of a system and method for communicating downhole information collected from a sensing module measuring properties in vertical and lateral orientations.
It is an object of the present invention to provide an embodiment of a system and method for communicating downhole information with a means to detect vertical and lateral orientation of a downhole tool.
It is another object of the present invention to provide an embodiment of a system and method for communicating downhole information, according to detected orientation of the downhole tool.
It is still another object of the present invention to provide an embodiment of a system and method for communicating downhole information according to detected orientation of the downhole tool through pressure release encoding.
It is an object of the present invention to provide an embodiment of a system and method for communicating downhole information from a complex sensing module through pressure release encoding to the surface.
These and other objectives and advantages of the present invention will become apparent from a reading of the attached specifications and appended claims.

SUMMARY OF THE INVENTION

Embodiments of the system for communicating downhole information through a wellbore to a surface location include communicating complex downhole information dependent upon orientation. Prior art systems convey simple downhole information easily, such as the angle of inclination of the drilling sub in a wellbore. However, the same sensors for angle of inclination no longer measure that same downhole information, when the orientation of the downhole tool changes too much. The direction can be changed, such that the sensor no longer functions or the calibration no longer corresponds to the new orientation. For directional drilling beyond straight vertical drilling, the orientation of the downhole changes frequently. Embodiments of the system and method of the present invention accommodate the changes in orientation and communication of this more complex downhole information through a pressure releasing encoding system.
The system of the present invention includes a drill string with a downhole tool at an end thereof, a pumping means for pumping drilling mud through the wellbore, the drill string, and the downhole tool, a valve means for providing a flow restriction to the drilling mud passing through the downhole tool, a sensing module positioned in the downhole tool, an actuator means cooperative with the valve means, and a detector means at the surface location. The drilling mud is fluid and circulates through the wellbore, drill string, and downhole tool to the surface location. The wellbore, drill string, and downhole tool are in fluid connection. The pump means can be located at the surface location. The valve means controls flow of the drilling mud through the downhole tool. The actuator means fixes the valve means in at least two static positions. The actuator means can be a hydraulic brake that releases the valve to move between the static positions. The time between pressure changes at the static positions relate to downhole information from the sensing module. The detector means is cooperative with the drilling mud passing through the downhole tool, such that the time between pressure changes at the downhole tool can be measured at the surface location. The measurement value of the detector means at the surface location is the communication of downhole information to the surface location. The changes of pressure of the drilling mud convey the downhole conditions measured by the sensing module.
The downhole tool has a first orientation and a second orientation. The downhole tool can be a drilling sub, drilling collar, stabilizer or other attachment to the drill string. The first orientation is different from the second orientation. The first orientation can be vertical, while the second orientation is lateral. Alternatively, the first orientation can be vertical, while the second orientation is more than twenty degrees from vertical. As long as the first and second orientations are different, the sensing module on the downhole tool measures different downhole conditions with the same sensors. The more complex downhole conditions can be encoded for communication to the surface location, instead of the only simple downhole conditions.
Embodiments of the sensing module include a first sensor means for measuring a first downhole condition in the first orientation, and a second sensor means for measuring a second downhole condition in the second orientation. The sensor means and the orientation determines the downhole condition, such that the downhole condition is now more complex. When the first orientation is generally vertical and the second orientation is generally lateral, the first sensor means can be an inclination sensor and the second sensor means can be an inclination sensor. Thus, the first downhole condition is angle of inclination, while the sensing module and downhole tool are in the vertical orientation. The second downhole condition is toolface inclination, while the sensing module and downhole tool are in the lateral orientation.
Embodiments of the sensing module also include a sensor means for measuring a first downhole condition in the first orientation and for measuring a second downhole condition in the second orientation. The same sensor measures the same property in different orientations, such that the data relates to different downhole conditions. Measurements in one orientation relate to a different downhole condition in another orientation. The sensor means and the orientation determines the downhole condition, such that the downhole condition remains complex. When the sensor means is comprised of an azimuth sensor, such as a magnetometer, the first downhole condition is the direction of slant from vertical, and the second downhole condition is direction of toolface. The directional measurement of the azimuth is the same, but the added information of orientation makes the downhole condition information more complex. This additional information can also be communicated to the surface location with the changes in pressure according to the actuator means. Other sensors, including an azimuth sensor, a magnetometer, a transducer, a gamma scintillator, nuclear detectors, an accelerometer, and a magnetic resonance imaging device can incorporate the orientation information for more complex downhole conditions too.
A switch and logic means can be incorporated in some embodiments to encode the downhole condition with the complexity of orientation data. The switch can activate either the first sensor means or second sensor means, according to position of the downhole tool. For example, if both the first sensor means and the second sensor means are inclination sensors, the system can alternate between sensing the slant of vertical drilling and the direction of the toolface for lateral drilling. Alternatively, if the inclination sensor is an accelerometer with a range of twenty degrees from vertical in the first orientation, the switch deactivates the inclination sensor above twenty degrees from vertical, while activating another inclination sensor to cover the range remaining above twenty degrees from vertical.
There is a drilling mud circulation system, defined by the drilling mud flowing through the drill string, the downhole tool, and the wellbore. Embodiments of the method for communicating the complex downhole information through the wellbore to the surface location include positioning the valve means in a fluid passageway of the downhole tool, positioning the actuator means cooperative with the valve means for fixing the valve means in at least two static positions, and forming a flow restriction within the circulation system at the downhole tool, the flow restriction being comprised of the valve means and the actuator means. A quantified pressure of drilling mud in the circulation system is applied against the flow restriction for a stable pressure powered by the originating mud pump.
Next, the first downhole condition in the first orientation is measured. A first percentage of pressure within the flow restriction is released at a first time, and the valve means moves to another static position. A pressure drop in the drilling mud is created. A second percentage of pressure within the flow restriction is released at a second time, and the valve means moves to another status position. Another pressure drop in the drilling mud is created. The time between the first pressure drop at the first time and the second pressure drop at the second time is correlative to the first downhole condition in the first orientation. The method further includes determining the first downhole condition at a surface location by sensing the time between the first pressure drop at the first time and the second pressure drop at the second time, according to orientation of the downhole tool. Repeating releases of percentages of pressure, within the flow restriction at additional times, communicates additional downhole conditions, such as the second downhole condition in the second orientation.
In other embodiments of the method, a single sensor can measure the first downhole condition in the first orientation and the second downhole condition in the second orientation. These sensors do not deactivate or require re-calibration to take measurements again, such as inclination sensors. These sensors can be an azimuth sensor, a magnetometer, a transducer, a gamma scintillator, nuclear detectors, or a magnetic resonance imaging device. The method of the present invention detects orientation of the downhole tool, and correlating a sensed time between controlled static pressure drops across the valve means to first and second downhole conditions, according to orientation of the downhole tool. Complex downhole conditions, including orientation data, are conveyed to the surface location by a pressure release encoding system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating the system of the present invention in association with components of a conventional drilling rig, showing vertical orientation of the downhole tool.

FIG. 2 is a partial exploded sectional view, showing a downhole tool of the present invention as a drilling sub attached to the drill string.

FIG. 3 is a schematic view illustrating the system of the present invention in association with components of a conventional drilling rig, showing another orientation of the downhole tool, deviating from vertical.

FIG. 4 is a schematic view illustrating the system of the present invention in association with components of a conventional drilling rig, showing still another orientation of the downhole tool, being generally lateral.

FIG. 5 is a cross-sectional view of a downhole tool with a sensing module, according to the system of the present invention.

FIG. 6 is a block diagram of a microprocessor-based electronics section of the downhole tool of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIGS. 1-6, there are embodiments of the system 10 for communicating downhole information through a wellbore 12 to a surface location 14. FIGS. 1, 3 and 4 show a drilling rig 30 located at a site above the wellbore 12. The drill string 16 is supported by the derrick 18 and has drill collars 20 and a drill bit 22. A drill sub 24 is also shown. The drill collars 20, drill bit 22, and drill sub 24 may be considered downhole tools 28 for purposes of the present application. Other downhole tools 28, such as stabilizers on the drill string 16, can also have sensors. Embodiments of the present invention include any downhole tool 28 with a sensing module 32, valve means 34 and actuator means 36.
The present invention is a system 10 for communicating complex downhole information dependent upon orientation of the downhole tool 28. FIG. 1 shows one orientation of at least one downhole tool 28 as vertical; the drill sub 24, in particular, can be considered the downhole tool 28 for an embodiment of the present invention. FIG. 3 shows another orientation of the downhole tool 28 deviated from vertical; and FIG. 4 shows still another orientation of the downhole tool 28 as generally lateral. Simple downhole information can be conveyed to the surface location 14 easily, such as the angle of inclination of the drilling sub 24 in a wellbore 12. However, the same sensing module 32 for angle of inclination no longer measure angle of inclination, when the orientation of the downhole tool 28 changes too much. FIGS. 1 and 3 show the drill sub 24 measuring angle of inclination so that the deviation from vertical can be measured. FIG. 4 shows a different orientation so that the sensing module 32 in the drill sub 24 is no longer aligned to measure angle of inclination for deviation from vertical. The calibration of the sensing module 32 also may no longer correspond to the new orientation. For directional drilling beyond straight vertical drilling, the orientation of the downhole tool 28 changes frequently. Embodiments of the system 10 and method of the present invention accommodate the changes in orientation and communication of this more complex downhole information through a pressure releasing encoding system.
FIGS. 1, 3 and 4 also show the circulation system for drilling mud through the system 10. There is a pumping means 40 connected through stand pipes and mud hoses to the drill string 16. Drilling mud flows from the pumping means 40, down through the drill string 16, passing through the downhole tools 28, exiting from the drill bit 22, up the wellbore 12, and back to the surface location 14. FIGS. 1, 3 and 4 show the drilling mud in a mud pit 38 at the surface location 14.
Embodiments of the system 10 of the present invention include a drill string 16 with a downhole tool 28 at an end thereof, a pumping means 40 for pumping drilling mud through the wellbore 12, the drill string 16, and the downhole tool 28, a valve means 34 for providing a flow restriction to the drilling mud passing through the downhole tool 28, a sensing module 32 positioned in the downhole tool 28, an actuator means 36 cooperative with the valve means 34, and a detector means 42 at the surface location 14. FIGS. 1, 3 and 4 show the wellbore 12, drill string 16, and downhole tool 28 in fluid connection.
FIGS. 2 and 5 show embodiments of the downhole tool 28 of the present invention. FIG. 2 shows a partial cut-away view with the downhole tool 28 having an interior passageway 44 extending axially longitudinally therethrough. The drilling mud flows through this passageway 44. A valve means 34, such as any float valve, is positioned to one end of the downhole tool 28 within passageway 44. The valve means 34 controls flow of the drilling mud through the downhole tool 28. FIG. 5 shows a valve means 34 as a float valve with a housing, shaft and float. FIG. 2 also shows the actuator means 36 placed in the passageway 44 to engage the valve means 34 in at least two static positions. The actuator means 36 can be a hydraulic brake that releases the valve means 34 to move between the static positions. The time between pressure changes at the static positions relate to downhole information from the sensing module 32. FIG. 5 shows the actuator means 36 as a hydraulic brake. The hydraulic brake section includes the hydraulic actuator piston fixed to a piston rod extended outwardly of a brake housing. The piston rod has end suitable for abutting the piston stem of the float valve of the valve means 34. FIG. 5 also shows the sensing module 32 in the downhole tool 28. The placement is fixed in the downhole tool 28, such that changing orientation of the downhole tool 28 changes orientation of the sensing module 32.
At the surface location 14, embodiments of the present invention have the detector means 42 cooperative with the drilling mud passing through the downhole tool 28, such that the time between pressure changes at the downhole tool 28 can be measured at the surface location 14.
FIGS. 1, 3 and 4 shows the detector means 42 comprised of a computer 46 with a processor and logic means 48 to interpret encoded data from the drilling mud.
The measurement value of the detector means 42 at the surface location is the communication of downhole information to the surface location 14. The changes of pressure of the drilling mud convey the downhole conditions measured by the sensing module 32.
Embodiments of the system 10 of the present invention show the downhole tool 28 having a first orientation and a second orientation. The first orientation is different from the second orientation. The first orientation can be vertical as shown in FIGS. 1 and 3, while the second orientation is lateral as shown in FIG. 4. Alternatively, the first orientation can be vertical as in FIGS. 1 and 3, while the second orientation is defined as more than twenty degrees from vertical as in FIG. 4. The “more than twenty degrees from vertical” embodiment is relevant to current inclination sensors, which are calibrated to measure deviations from vertical from zero to twenty degrees. Once past twenty degrees, these inclination sensors no longer function as calibrated. The information gathered from these inclination sensors no longer provides useful data. A second sensor must be calibrated to measure beyond twenty degrees from vertical, and the system must recognize that data from that inclination sensor is no longer relevant. As long as the first and second orientations are different, the sensing module 32 on the downhole tool 28 may be measuring different downhole conditions with the same sensors. The data collected must be interpreted and coded differently than a system with just one orientation. With the present invention, the more complex downhole conditions can be encoded for communication to the surface location 14, instead of the only simple downhole conditions.
FIG. 6 shows a block diagram of embodiments of the sensing module 32 in the downhole tool 28 of FIG. 5. The sensing module 32 can include a first sensor means 50 for measuring a first downhole condition in the first orientation, and a second sensor means 52 for measuring a second downhole condition in the second orientation. The sensor means 50, 52 and the orientation determines the downhole condition, such that the data collected for the downhole condition is now more complex. When the first orientation is generally vertical and the second orientation is generally lateral, as in FIGS. 1 and 3 to FIG. 4, the first sensor means 50 can be an inclination sensor and the second sensor means 52 can be an inclination sensor. In that embodiment, the first downhole condition is angle of inclination. The deviation from vertical can be determined for guiding a slanted wellbore 12. Certain formations underground can be avoided. FIGS. 1 and 3 show this first orientation with the sensing module 32 and downhole tool 28 being in a generally vertical orientation. In the same embodiment, the second downhole condition is toolface inclination because the sensing module 32 and downhole tool 28 are now in the lateral orientation, as in FIG. 4. In the second sensor means 52 is an inclination sensor calibrated for the lateral orientation. The measurements no longer detect deviation from vertical, but rather toolface inclination, that is, whether the toolface is moving up, down or side-to-side. The sensing module 32 recognizes that the orientation changed so that the first sensor means 50 is no longer providing useful data for deviation from vertical. The sensing module 32 also recognizes that the second sensor means 52 is now active and providing useful information for the inclination of the toolface. The present invention can now communicate this complex downhole condition to the surface location 14.
The embodiments of FIG. 6 show the system 10 with the microprocessor 100 to coordinate all data to be communicated to the surface. There is a clock 102, a serial port 104 for connecting to other downhole tools on the drill string 16, and inputs from the pressure sensor 106 and valve control 108 of the actuator means 36. The sensing module 32 data can be compiled for the complex downhole information conveyed through the drilling mud.
FIG. 6 also shows a third sensor means 54. This third sensor means 54 can be an azimuth sensor, a magnetometer, a transducer, a gamma scintillator, nuclear detectors, an accelerometer, a magnetic resonance imaging device or other measurement device. The third sensor means 54 measures a third downhole condition to contribute further to the encoded data communicated through the drilling mud to the surface location 14. For example, a third sensor means 54 as an azimuth sensor gives directional information. When combined with the first sensor means 50 in the first orientation, the complex downhole condition is the deviation from vertical and the direction of the deviation. The encoded data reveals that the wellbore is slanted and the direction of the slant. This encoded data is more useful for guiding directional drilling. When combined in the system 10 with the second sensor means 52 in the second orientation, the complex downhole condition is the toolface inclination and direction of the deviation. The encoded data reveals that the toolface of the downhole tool 28 is moving at an angle and the direction of that angle, such as moving to the left or right and how much to the left or right. This encoded data is more useful for steering around formations and deposits in directional drilling also.
The system 10 further includes a switch means to deactivate the first sensor means 50, when the orientation changes. For example, when the orientation passes twenty degrees from vertical, the inclination sensor of the first sensor means 50 can be deactivated because no more useful information is being measured. The system 10 will now active the second sensor means 52 to begin collecting data, since the orientation is now in the second orientation of the downhole tool 28. The switch means moves back and forth, as the downhole tool 28 can move in all directions. The downhole tool 28 may return to a generally vertical orientation, returning to the first orientation, so that the first sensor means 50 can collect relevant deviation from vertical data again.
Embodiments of the system 10 include the computer 46 with the logic means and display means for the encoded data from the drilling mud. The complex downhole conditions are interpreted from the encoded data, including the detected orientation of the downhole tool. Any means to detect the orientation of the downhole tool contributes to the encoded data from the sensing module 32. The means for detecting may be compass or bubble devices on inclination sensors as either the first or second sensor means 50, 52 or a device separate from the first and second sensor means 50, 52.
An alternate embodiment of the sensing module 32′ is shown in FIG. 6. This embodiment of the sensing module 32′ has a single sensor means 56 for measuring a first downhole condition in the first orientation and for measuring a second downhole condition in the second orientation. The same sensor means 56 measures the same property in different orientations, such that the data relates to different downhole conditions. For example, the single sensor means 56 can be a magnetometer, which is an azimuth sensor for direction. In the first orientation, the azimuth sensor measures the direction of the slant of the downhole tool 28 (but not the amount of slant, which would come from a different sensor). The direction of the slant is the first downhole condition. In the second orientation, the azimuth sensor measures the direction of the toolface inclination, which is still directional information. The amount of inclination of the toolface may be provided by another sensor. In this alternative embodiment, there is no need for a second sensor means in the second orientation. The same sensor can be used in the second orientation, but the significance of the data collected is now different. The system 10 of the present invention still accounts for this increased complexity of the data. It is not enough to collect the directional data because the orientation information must also be considered for the directional data to be properly interpreted. The present invention communicates this level of complex downhole information. Measurements in one orientation relate to a different downhole condition in another orientation. The sensor means and the orientation determines the downhole condition, such that the downhole condition remains complex. Other sensors, including a transducer, a gamma scintillator, nuclear detectors, an accelerometer, and a magnetic resonance imaging device can incorporate the first and second orientation information for more complex downhole conditions too. The same detector means 42 with computer 46 and microprocessor 100 of FIG. 6 can be applied to an embodiment with a single sensor in the sensing module 32′. The orientation information can be applied to this alternative embodiment.
The present invention also includes the method for communicating the complex downhole information through a pressure releasing encoding system. With the drilling mud circulation, defined by the drilling mud flowing through the drill string 16, the downhole tool 28, and the wellbore 12, embodiments of the method for communicating the complex downhole information through the wellbore 12 to the surface location 14 include positioning the valve means 34 in a fluid passageway 44 of the downhole tool 28, positioning the actuator means 36 cooperative with the valve means 34 for fixing the valve means 34 in at least two static positions, and forming a flow restriction within the circulation system at the downhole tool 28. The flow restriction is comprised of the valve means 34 and the actuator means 36. A quantified pressure of drilling mud in the circulation system is applied against the flow restriction for a stable pressure powered by the originating mud pump means 40. The energy from the originating pump 40 supplies the energy for the pulse through the drilling mud, instead of requiring power for modulating the drilling mud. The pressure release encoding of the present invention is based on setting an equilibrium pressure by the pump means 40 across the valve means 34 and then releasing the valve means 34 by the actuator means 36 to a new position, where the equilibrium pressure re-establishes. The change is pressure is the pulse receivable at the surface location 14.
In embodiments of the method, the time between the pressure changes is encoded data related to the downhole information. In the present invention, it is the complex downhole information that is communicated to the surface location 14. In the method, the first downhole condition in the first orientation is measured. For example, the sensing module 32 measures the deviation from vertical by an inclination sensor as the first sensor means 50. A first percentage of pressure within the flow restriction is released at a first time, and the valve means 34 moves to another static position. A pressure drop in the drilling mud is created. A second percentage of pressure within the flow restriction is released at a second time, and the valve means 34 moves to another static position. Another pressure drop in the drilling mud is created. The time between the first pressure drop at the first time and the second pressure drop at the second time is correlative to the first downhole condition in the first orientation. The measurement is communicated to the surface location along with the orientation information, as complex downhole information.
The method further includes determining the second downhole condition at a surface location by sensing the time between another set of pressure drops, according to orientation of the downhole tool. Repeating releases of percentages of pressure, within the flow restriction at additional times, communicates additional downhole conditions, such as the second downhole condition from a second sensor means 52 in the second orientation. The complex downhole information can now be communicated with the same pressure releasing encoding.
Various embodiments of the method include gathering the complex downhole information from other sensing modules 32 and 32′. For one embodiment, a single sensor measures the first downhole condition in the first orientation and the second downhole condition in the second orientation. The azimuth sensor is one type of sensor that provides both first and second downhole conditions. Other sensors that do not deactivate nor require re-calibration to take measurements again, may also be single sensors providing the complex downhole information. Again, the method of the present invention, detects orientation of the downhole tool and the measurement from the sensor to correlate the sensed time between controlled static pressure drops across the valve means to the first and second downhole conditions, according to orientation of the downhole tool. Complex downhole conditions, including orientation data, are conveyed to the surface location by a pressure release encoding system.
The present invention provides a system and method for communicating downhole information through pressure release encoding to the surface. The pressure release encoding based on the originating mud pump powers the transmission through the drilling mud. The changes in pressure communicate complex downhole information gathered from a sensing module at the downhole location. The sensing module can be placed in any downhole tool, including a BHA or drill sub, specifically. Alternate drill collar or stabilizers may also contain the valve, actuator, and sensing module required. There is also a means for detecting orientation of the downhole tool, so that the orientations of the sensors of the sensing module are known. Known bubble or compass devices can detect vertical and lateral orientations. Other sensors may, themselves, be calibrated for certain orientations, such as an inclination sensor with a range of zero to twenty degrees from vertical or another range. The present invention address the orientation as a complicating factor in the interpretation of the plain measurement data previously conveyed. The sensing module in vertical and lateral orientations is now applied to a pressure releasing encoding so that pressure releasing encoding communicates more useful information, especially for directional and steering drilling operations. A drill bit can be more accurately steered through a formation with the MWD or real time data supplied by the complex downhole information of the present invention. Pressure releasing encoding and advanced sensing modules of the present invention allow for more relevant downhole data to be conveyed through drilling mud to the surface.
The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated structures, construction and method can be made without departing from the true spirit of the invention.

Claims

We claim:

1. A system for communicating downhole information through a wellbore to a surface location comprising:

a drill string with a downhole tool at an end thereof, said downhole tool having a first orientation and a second orientation;

a pumping means for pumping drilling mud into the wellbore, said pumping means being positioned at the surface location and being in fluid connection with said drill string; and

a valve means for providing a flow restriction to said drilling mud passing through said downhole tool, said valve means being suitable for controlling a flow of said drilling mud in said downhole tool;

a sensing module being positioned in said downhole tool and being comprised of a first sensor means for measuring a first downhole condition in said first orientation, and a second sensor means for measuring a second downhole condition in said second orientation, said first orientation being different from said second orientation;

an actuator means cooperative with the valve means for fixing said valve means in at least two static positions in timed relation to any downhole information from said sensing module; and

a detector means positioned at the surface location and cooperative with said drilling mud passing through said downhole tool for providing a measurement value at the surface location correlative to time between changes of pressure of said drilling mud.

2. The system for communicating downhole information, according to claim 1, wherein said first orientation is generally vertical, wherein said second orientation is generally lateral,

wherein said first sensor means is comprised of an inclination sensor, said first downhole condition being angle of inclination, and

wherein said second sensor means is comprised of an inclination sensor, said second downhole condition being toolface inclination.

3. The system for communicating downhole information, according to claim 1, wherein said first orientation is generally vertical, wherein said second orientation is more than 20 degrees from vertical,

wherein said first sensor means is comprised of an inclination sensor calibrated for a vertical direction, said first downhole condition being angle of inclination, and wherein said second sensor means is comprised of an inclination sensor calibrated for a toolface direction, said second downhole condition being toolface inclination.

4. The system for communicating downhole information, according to claim 1, wherein said sensing module further comprises:

a third sensor means for measuring a third downhole condition in said first orientation and in said second orientation.

5. The system for communicating downhole information, according to claim 4, wherein said third sensor means is comprised of an azimuth sensor, said third downhole condition being direction of slant in said first orientation, said third downhole condition being direction of toolface inclination in said second orientation.

6. The system for communicating downhole information, according to claim 1, further comprising:

a means for switching between measuring said first downhole condition by said first sensor means and measuring said second downhole condition by said second sensor means, in coordination with said downhole tool switching between said first orientation and said second orientation respectively.

7. The system for communicating downhole information, according to claim 1, said detector means comprising:

means for detecting orientation of said downhole tool;

a logic means for correlating a sensed time between controlled static pressure drops across the valve means to the first downhole condition, the second downhole condition, and orientation of said downhole tool; and

a display means for providing a generally real-time humanly perceivable indication of downhole conditions, according to said orientation of said downhole tool.

8. A system for communicating downhole information through a wellbore to a surface location comprising:

a sensing module being positioned in said downhole tool and being comprised of a sensor means for measuring a first downhole condition in said first orientation and measuring a second downhole condition in said second orientation, said first orientation being different from said second orientation;

9. The system for communicating downhole information, according to claim 8, wherein said sensor means is comprised of an azimuth sensor, said first downhole condition being direction of slant in said first orientation, said second downhole condition being direction of toolface in said second orientation.

10. The system for communicating downhole information, according to claim 8, further comprising:

means for detecting orientation of said downhole tool; and

a logic means for correlating a sensed time between controlled static pressure drops across the valve means to downhole conditions, according to orientation of said downhole tool.

11. The system for communicating downhole information, according to claim 8, wherein said sensor means is selected from a group consisting of an azimuth sensor, a magnetometer, a transducer, a gamma scintillator, nuclear detectors, an accelerometer, and a magnetic resonance imaging device.

12. The system for communicating downhole information, according to claim 11, further comprising:

means for detecting orientation of said downhole tool; and

13. A method for communicating downhole information through a wellbore to a surface location, said wellbore having a drilling mud circulation system therein, the circulation system being through a drill string, a downhole tool, and an interior of said wellbore, the method comprising the steps of:

positioning a valve means in a fluid passageway of said downhole tool;

positioning an actuator means cooperative with said valve means for fixing said valve means in at least two static positions;

forming a flow restriction within the circulation system at said downhole tool, said flow restriction being comprised of said valve means and said actuator means;

sensing said first downhole condition in said first orientation;

applying a quantified pressure of drilling mud in the circulation system against said flow restriction;

releasing a first percentage of pressure within said flow restriction at a first time;

releasing a second percentage of pressure within said flow restriction at a second time, a time between said first time and said second time being correlative to said first downhole condition;

determining said first downhole condition at a surface location by sensing the time between said first time and said second time and according to orientation of said downhole tool;

sensing said second downhole condition in said second orientation, said first orientation being different from said second orientation;

repeating releases of percentages of pressure within said flow restriction at additional times, at least one of said additional times being correlative to said second downhole condition; and

determining said second downhole condition at a surface location by sensing the time between said additional times and according to orientation of said downhole tool.

14. The method for communicating downhole information, according to claim 13, further comprising the steps of:

switching between determining said first downhole condition by said first sensor means and determining said second downhole condition by said second sensor means, in coordination with said downhole tool switching between said first orientation and said second orientation respectively.

15. The method for communicating downhole information, according to claim 13, wherein the step of sensing said first downhole condition in said first orientation comprises taking a measurement with a first sensor, and wherein the step of sensing said second downhole condition in said second orientation comprises taking a measurement with a second sensor.

16. The method for communicating downhole information, according to claim 15, wherein said first sensor is comprised of an inclination sensor, said first downhole condition being angle of inclination, and

wherein said second sensor is comprised of an inclination sensor, said second downhole condition being toolface inclination.

17. The method for communicating downhole information, according to claim 13, further comprising the steps of:

sensing a third downhole condition in said first orientation and in said second orientation;

repeating releases of percentages of pressure within said flow restriction at additional times, said additional times being correlative to said third downhole condition; and

determining said third downhole condition at a surface location by sensing the time between said additional times and according to orientation of said downhole tool.

18. The method for communicating downhole information, according to claim 13, wherein the step of sensing said first downhole condition in said first orientation comprises taking a measurement with a sensor,

wherein the step of sensing said second downhole condition in said second orientation comprised taking a measurement with said sensor.

19. The method for communicating downhole information, according to claim 18, wherein said sensor means is comprised of an azimuth sensor, said first downhole condition being direction of slant in said first orientation, said second downhole condition being direction of toolface in said second orientation.

20. The system for communicating downhole information, according to claim 18, further comprising the steps of:

detecting orientation of said downhole tool; and

correlating a sensed time between controlled static pressure drops across the valve means to first and second downhole conditions, according to orientation of said downhole tool.