Patent Application
20080002525
Embodiments of the present invention will now be described, by way of example only, with reference to the attached Figures, wherein:
The present invention relates to an apparatus and method for actuating a mud pulser telemetry system used during well-drilling or well logging operations. The present apparatus allows a pulser valve to be powered both in opening (e.g. to allow generally unrestricted flow) and in closing (e.g. to generally restrict flow,) and does not rely on a solenoid system.
The powered opening and closing of a windowed restrictor results in various functional and economic advantages, including the ability to clear debris from the restricted portion of the mud flowpath, and faster data rates due to elimination of inherent operating delays in the solenoid systems of previous tools, with the end result of providing a pulser driver which consumes a minimal amount of power (e.g. DC or AC electricity) while providing more force with which to drive the windowed restrictor in each direction. Therefore, the pulser remains functional at a comprehensive range of downhole drilling conditions.
Furthermore, in the embodiment shown in the Figures, the present device is designed to have several independent, interconnected housings, and employs a double seal between the oil compartment and the drilling mud, which simplifies assembly and repair of the tool. The assembly/disassembly is simplified to reduce repair turnaround time by using modular components.
Additionally, the use of a brushless motor, electric load sensors, and control circuitry in a powered-both-directions valve system allows for self-calibration of the tool and self-diagnosis and error correction unavailable in other systems.
Communication of information to the well surface is accomplished by encoded signals, which are translated to produce pressure changes in the downward flow of the pressurized drilling mud. It is recognized that although the drilling fluid is generally referred to as mud, other drilling fluids are also suitable for use with the present invention, as is well known in the art.
With reference to the Figures, the rotary pulser 10 of the present invention generally includes a plurality of serially interconnected housings 20, 30, 40, 50, 60, 70, and 80, an electrical connector 90, and a controller 100 for controlling the operation of the rotary pulser 10.
A preferred embodiment includes a motor 110, such as a brushless motor, AC motor, DC motor, 3 phase motor etc., which may be monitored and controlled by the controller 100, the rotary movement of the motor 110 being converted into rotary movement of a windowed restrictor 120 through a rotary gear reduction system 130, thereby moving the windowed restrictor 120 between an open position (see
The rotary gear reduction system 130 is used to translate the torque from the motor 110 into rotary movement of the windowed restrictor 120, which is preferably a series of gear reductions through gear and pinion or worm gear type gear reductions. The rotary gear reduction system 130 may have a gear reduction generally in the ranges of 10:1, 100:1, or 1000:1. The rotary gear reduction system 130 includes seals which serve to isolate the rotating mechanism from the operating fluids.
In the embodiment pictured in
The output shaft 180 is surrounded by lubricating fluid, which must be pressurized against the downhole hydrostatic pressure. As shown, a pressure compensator in the form of a membrane or bellows 210 allows reservoir fluid to substantially equalize the pressure via a port 220. The pressure compensator may be a membrane, bellows, piston type or other type known in the industry. Seals 230, 235, 240, and 245 maintain the integrity of the lubrication chamber during operation and during replacement of the membrane or bellows 210 during maintenance.
In a preferred embodiment, the construction of the rotary pulser 10 allows a significant number of downhole clogs to be easily cleared, as described below (a clog being an event where debris in the mud may interfere with the windowed restrictor 120 and impede the capability of the windowed restrictor 120 from substantially blocking the window 150 and interfering with the flow passage 160, therefore reducing the ability of the rotary pulser 10 to produce a distinct or sharp pressure pulse in the mud). The serially interconnected housing design allows simplified and reduced repair time of the tool when necessary.
The windowed restrictor 120 and/or at least a portion of the fixed housing 140 are preferably composed of a wear resistant material or coated with a wear resistant material such as tungsten carbide or ceramic to increase the efficiency of the tool and to reduce maintenance of the tool, and is preferably replaceable.
The windowed restrictor 120 preferably comprises a plurality of shutters 170 which correspond to a plurality of windows 150 within the fixed housing 140. Most preferably, the windowed restrictor 120 includes a set of three shutters 170 spaced apart by 120° to correspond to three windows 150 spaced apart by 120° within the fixed housing 140. Preferably, the windows 150 provide a relatively large flow are to allow relatively large debris to flow unimpeded through the windows 150 and to reduce velocity/abrasion related “wash” or wear of components.
Preferably, at least a portion of an edge or edges of the shutter 170 (associated with the windowed restrictor 120) and/or at least a portion of an edge or edges of the window 150 (associated with the fixed housing 140) may be beveled, chamfered, or tapered, or otherwise channeled to adjust the flow characteristics and/or reduce wear.
Preferably, the windowed restrictor 120 is located towards a bottom end of the rotary pulser 10.
Preferably, the mud flow is generally radially inwards (e.g. from outside to center) to match the natural flow of mud, eliminating the apparatus associated “center out” type pulsers that utilize additional flow channeling to take at least a portion of the mud flow naturally occurring outside the tool, channel the mud into a central portion of a tool, and then pass it through the pulser's valve in the central portion of the tool (i.e. center-out), and then release the mud back to the annulus around the tool. In the present invention, abrasion or “wash” is reduced due to the much improved flow path. Decreased turbulence may also provide sharper pulse-edge characteristics in the mud's flow.
When restriction of mud flow through the rotary pulser 10 (i.e. to generate a positive pressure pulse), the motor 110 will be activated by the controller 100 in the direction to move the windowed restrictor 120 into the restricted position (See
Subsequently, when the controller 100 initiates reverse motion by the motor 110 to move the windowed restrictor 120 into the open position (See
Use of a rotary motor powering the windowed restrictor in both directions also allows the system to be more responsive than solenoid systems, resulting in a faster data rate with more accurate or precise pulse-edge timing. Experimental results indicate that data rates of 0.25 seconds/pulse are possible with this system, as compared to 0.8 to 1.5 seconds/pulse in solenoid systems. Faster or modulated pulses may be obtained.
The controller 100 may be programmed to put the rotary pulser 10 in a dormant or power conserving state until a triggering event is detected. For example, the rotary pulser 10 may remain in the dormant or power conserving state until it senses a no flow-to-flow condition without rotation. This combination versus a flow state change with rotation instructs the rotary pulser 10 to create binary weighted flow restrictions, as programmed by the controller 100.
The controller 100 may detect the position of the windowed restrictor 120 against relative to a windowed restrictor stop 250. The windowed restrictor stop 250 may comprise a transverse slot 270 along a at least a portion of the perimeter of the windowed restrictor 120, the slot 270 corresponding generally to the working angle of rotation of the windowed restrictor 120 as it is movable between a restricted position and an open position. A pin 280 may extend from the fixed housing 140 to engage the slot 270.
The windowed restrictor stop 250 allows the controller 100 to sense when the windowed restrictor 120 open position and the windowed restrictor 120 restricted position. In addition, the controller 100 may be programmed to recognize that a certain number of rotations of the motor 110 are needed to move the windowed restrictor 120 between the open position and the restricted position. The controller may also sense rotation of the motor 110 and count rotations and direction of rotation.
Debris may enter the rotary pulser 10 with the mud, potentially causing jamming or other interference. The controller 100 may be programmed to detect and clear jams from the windowed restrictor 120 and/or the window 150 of the fixed housing 140 (e.g. any partial or complete obstruction of the flow passage 160). For example, debris may become lodged between the windowed restrictor 120 and the fixed housing 140, preventing the full opening or restricting of the flow passage 160. In such a situation, the controller 100 could detect an increase in current drawn by the motor 110 at an unexpected position of the windowed restrictor 120 (i.e. an increase in current would be expected when the windowed restrictor 120 is at the open position or the restricted position either end, as the windowed restrictor stop 250 is engaged, but would not be expected elsewhere in the working angle of rotation). This mid-travel increase in current draw may be recognized by the controller 100 as debris, and the controller 100 may then enter a clearing program to attempt to automatically clear the debris. In the clearing program, the windowed restrictor 120 may be reciprocated (e.g. slowly or quickly), or it may be repeatedly moved in an opening direction and moved in a closing direction, in order to “chew” on the debris until it is cut through. Due to the power of the motor 110 and the rotary gear reduction system 130, the windowed restrictor 120 is able to shear right through most types of debris commonly encountered.
The ability to detect and clear most jams within the tool allows a more robust design of the tool in other respects. For example, as the tool can easily clear particulate matter from the assembly, the tool can be provided with larger and fewer mud ports, and may include reduced amounts of screening. Screening is susceptible to clogging, and so reducing screening leads to longer mean time between operation failure of the device in-hole; and will reduce the velocity of any mud flow through the tool, reducing wear on the bladder and other parts. Further, the removal of several previously necessary components (such as the return spring, transformer, and solenoid and related electronics) contributes to a tool of smaller size (in both length and diameter) that is more versatile in a variety of situations. For example, embodiments with outside diameter less than 1⅜″ (approaching 1″) or length less than four feet have been achieved, although these dimensions are not by way of limitation, but by example only.
The rotary pulser 10 has generally been described in creating a positive pressure pulse, that is, moving the windowed restrictor 120 into the restricted position to create an increase in pressure. The rotary pulser 10 may also be used to create a negative pressure pulse, for example by moving the windowed restrictor 120 from the restricted position (or a partially restricted position) to the open position, to create a decrease in pressure. The rotary pulser 10 may also be used to create combinations of positive and negative pressure pulses.
The rotary pulser 10 of the present invention may be received in a landing sleeve 260. The landing sleeve 260 may be compatible with both a vertical tool (or other “event trigger” type monitoring and reporting tools) and real-time MWD tools which allows the rotary pulser 10 of the present invention to be retrieved from the landing sleeve 260 and replaced in the landing sleeve 260 with a real-time MWD tool without having to trip the pipe out of the hole. This feature allows drilling with an event trigger type tool, such as a vertical tool, at a cost savings over the equipment and operations cost of a real-time MWD tool. In the event that the drilling operations run into unexpected circumstances (e.g. a vertical tool detects a vertical deviation outside the parameters and reports that deviation to surface via the rotary pulser 10), the event type trigger type tool can be retrieved from the landing sleeve 260 and a real-time MWD tool seated in the landing sleeve 260 to fully assess the situation and provide telemetry to surface, again via the rotary pulser 10, to allow correction, e.g. through directional drilling.
In addition, the rotary pulser 10 of the present invention is retrievable from the landing sleeve 260 and reseatable in the landing sleeve 260.
Custom software also has the ability to track downhole conditions, and also uses a sensor to detect mud flow. When mud flow is detected, a signal is sent to the Directional Module Unit (not shown), to activate the overall system. The system also has the ability to time stamp events such as start or end of mud flow, incomplete cycles or system errors, low voltages, current, and the like, as well as accumulated run-time, number of pulses, number of errors, running totals of rotations or motor pulses. Wires or conductors may also be easily passed by the pulser section to service additional near-bit sensors or other devices. The software that detects the mud flow can be configured for different time delays to enable it to operate under a larger variety of downhole drilling conditions than its predecessors. The mud flow detection capability can also be used to calibrate or confirm the open position and/or the closed position of the windowed restrictor 120.
In addition, a user may monitor such data as well as any downhole sensors using a user interface attachable to the tool. Such sensors may include pressure or temperature sensors, rotation step-counters, travel or depth sensors, current levels, battery voltage, or timers. The user could monitor each component of the actuator to determine when the tool must be removed from downhole for repair. A user may, in turn, program an activity to cause an action or correction in response to a sensed event.
The present invention has been described as being applicable to measurement while drilling (MWD) systems. As used herein, that includes, but is not limited to, any drilling or well servicing operations involving sending a signal from downhole to surface through the working fluid, and includes “triggering event” type monitoring tools (e.g. as a vertical tool monitoring declination and only reporting in the event of a triggering event, e.g. vertical angle outside of parameters) and includes “polling” type tools that can be polled to send back a reading (e.g. a vertical tool that monitors declination, but only reports to surface when sent a polling signal, such as no flow-to-flow condition without rotation, or at a polling time interval) and includes real-time MWD tools (e.g. that provide continuous or nearly continuous reporting of parameters to surface).
The above-described embodiments of the present invention are intended to be examples only. Alterations, modifications and variations may be effected to the particular embodiments by those of skill in the art without departing from the scope of the invention, which is defined solely by the claims appended hereto.
