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Process and device for generating signals which can be transmitted in a wellRelated Patent Categories: Pumps, Motor Driven, Including Means For Selectively Varying Motor Speed Or Rotary Motor DirectionProcess and device for generating signals which can be transmitted in a well description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070274844, Process and device for generating signals which can be transmitted in a well. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The invention relates to a process for generating signals which can be transmitted from above ground to a receiver located below ground in a well, wherein the volume flow of a fluid pump arranged above ground, which conveys fluid from a fluid tank through the interior of a drill string to the bottom of a well, is temporally changed. The invention furthermore relates to a device for executing this process. [0002] In a process of the aforementioned type known from U.S. Pat. No. 5,332,048, the volume flow of the fluid generated by the fluid pump is changed by successively switching the fluid pump on and off. This process has, however, the disadvantage that it is time-consuming and requires an interruption to the drilling operation. There is also the risk that, during the interruption of the fluid current, cuttings may be deposited as a result of which the continuation of the drilling operation is impeded. [0003] It is furthermore known from EP 0 744 527 B1, for transmitting information present above ground to an information receiver located below ground in a well during the drilling operation, to change the volume flow of the fluid generated by the fluid pump so that in a region downstream of the fluid pump a partial flow is diverted from the principal flow of the fluid pump and is returned into the fluid tank. This process is associated with significant energy losses, as, owing to the conveying height of the fluid pump, the diverted partial flow has a significant energy content which cannot be recouped at reasonable cost. [0004] A process for signal generation by changing the volume flow of a fluid pump is known from U.S. Pat. No. 5,113,379, wherein a diverted partial flow of the volume flow conveyed by the fluid pump is received by a buffer reservoir and is then returned from this into the principal flow with the aid of a second pump. This process has the disadvantage that it requires significant equipment costs. [0005] Furthermore, owing to the limited holding capacity of the buffer reservoir, only a very short volume flow change with limited amplitude can be achieved with this known process. [0006] The object of the invention is to disclose a process of the aforementioned type which can be executed without interruption of the drilling operation, which does not cause any high energy losses and whose execution is possible with comparatively low equipment costs. [0007] The object is achieved according to the invention by the process disclosed in claim 1 and by the device disclosed in claim 9. Advantageous embodiments of the process and of the device are disclosed in the subclaims associated with these claims in each case. [0008] According to the process according to the invention, the temporal change of the volume flow of the fluid pump is caused by a change of the drive speed of the fluid pump which does not fall below a minimum speed for maintaining a minimum fluid flow. [0009] The process according to the invention is based on the knowledge that the volume flow of fluid pumps is substantially proportional to the pump speed. In order to achieve a temporal change of the volume flow of the fluid pump, it is thus only necessary to decrease or to increase the speed of the fluid pump in proportion to the required volume flow change. So that a signal, which is based on a change of the volume flow of the fluid pump, can still be received without errors below ground, a change of the volume flow is generally required, for instance, of 15% for a period of, for instance, 10 seconds. To generate a signal of this type it is thus sufficient to decrease the pump speed by 15% for the said period and then to increase the pump speed to the original value again. Speed changes of this type can be easily achieved with the conventional fluid pumps by controlling their drive accordingly. The required changes of the volume flow are also of a magnitude which can be achieved without significant disruption of the drilling operation. [0010] The process according to the invention offers the opportunity to temporarily increase the pump speed after a reduction above the previously set normal value, in order to thus compensate for the volume flow loss caused by the reduction and to maintain on average a constant volume flow. A procedure of this type can be important for practical drilling reasons in order to prevent disruptions caused by inadequate transportation of the cuttings. [0011] According to a further embodiment of the process according to the invention, the temporal changes of the pump speed and thus of its principal flow lie in frequency ranges below 1 hertz. This has the advantage that higher frequency telemetric signals are not distorted, so that transmission of signals of this kind via the drilling fluid in the drill string in the opposing direction, that is, from below ground to above ground is simultaneously possible. Furthermore, low frequency current changes with respect to the transmission ratios in the drill string are attenuated less strongly. The changes of the volume flow required to generate a signal which can be received without errors can thus be of less intensity. [0012] Significant energy losses do not occur in the process according to the invention. The efficiency of conventional fluid pumps changes only slightly in the event of changes of the drive speed of a magnitude of up to 30%. The acceleration and deceleration of the moving masses also does not lead to significant losses, as the deceleration work helps to convey the fluid and relieves the drive of the fluid pump accordingly. [0013] The invention will be described in more detail hereinafter with reference to the embodiments shown in the drawings, in which: [0014] FIG. 1 shows a typical drilling rig, [0015] FIG. 2 shows the general integration of a device for directly influencing the speed of the fluid pump, [0016] FIG. 3 shows a version of a pump drive with a direct current motor with integration of the device for influencing the speed, [0017] FIG. 4 shows a version of a pump drive with a three-phase alternating current motor with integration of the device for influencing the speed, [0018] FIG. 5 shows a version of a pump drive with a diesel motor and a hydraulic torque converter with integration of the device for influencing the speed, [0019] FIG. 6a to 6d show possible signal shapes of the generated telemetric signal and [0020] FIG. 7 shows a possible electric embodiment of the integration of the signal for changing the speed. [0021] FIG. 1 shows a typical rig for deep drilling. A fluid pump 1 is driven by an appropriate drive 2. This can be electric or other motors, for example, diesel motors, with appropriate transmission devices. Accordingly, the required drive energy 3 can be supplied electrically or deriving from a combustible fuel. In order to generate the pumping rate required for drilling, that is, the required volume flow of fluid, the pump speed can be controlled via a desired value transmitter 4 acting electrically, hydraulically or pneumatically on the control unit of the drive 2. [0022] The fluid flow is pumped via the interior of the drill string 5 to the drill head 6 and flows into the annular chamber 7 back to the surface and from there into the reservoir tank 8. For drilling, the drill string 5 is rotated by a rotary table 30 of a rotary drive, which is driven by a motor 31 via a coupling 32. Alternatively, a fluid-driven well motor can also be provided at the drill head to drive the drill bit. [0023] At the lower end of the drill string 5 there is a receiver 9 of a measuring and/or control device which is supposed to receive data from the surface and possibly transmits data to the surface itself, these signals being generated, for example via modulation of the fluid flow, as is known from many examples of deep drilling measuring devices with wireless data transmission. [0024] FIG. 2 shows the fluid pump 1 with its drive 2 which, via a rotational movement with a defined speed, ensures that the pumping rate for the well required for drilling is generated. The required speed is adjusted via the desired value transmitter 4. A signal generator 10 for generating signals, which can be transmitted to the below ground receiver 9, changes the desired value 11 required for drilling with a control signal 12 in an interface 13 in such a way that desired value change 14 transmitted to the drive 2 controls the drive speed 15 of the fluid pump 1 in such a way that the temporal changes of the volume flow 16 of the fluid pump 1 required by the signal generator 10 result. The reciprocating pumps which are predominantly used with fluid pumps directly convert a speed change into a linearly proportional change of the volume flow, this volume flow change being accompanied by a pressure change acting in the same direction owing to the constant flow resistance of the overall system. The signal generator 10 can be, for example, a manually operable voltage divider, an analog curve shape generator or a computer, which generates the required modulation via software and emits said modulation via digital/analog conversion as electric analog voltage or directly as a digital signal. Continue reading about Process and device for generating signals which can be transmitted in a well... Full patent description for Process and device for generating signals which can be transmitted in a well Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Process and device for generating signals which can be transmitted in a well patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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