Closed feedback injection system for radioactive materials using a high pressure radioactive slurry injector
First Claim
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1. A slurry injection system, comprising:
- injection means for injecting a volume of the slurry at a predetermined rate, and for providing a feedback signal based upon said volume of slurry which has been injected;
local power means for providing a driving force to said injection means; and
control means for controlling an injection rate of said volume of slurry.
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Abstract
A closed feedback control system for injecting radioactive material into a high pressure well stimulation fluid line is provided which allows the injection rate to be controlled based upon desired and actual values. A controller calculates a desired injection rate based upon job characteristics, compares the desired rate, and then uses a PID algorithm to control the injection rate until the actual and desired rates are equal. Additionally, the injection system is controllable by a manual control device affixed to the previously mentioned controller, or by utilizing a separate manual control unit.
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Citations
20 Claims
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1. A slurry injection system, comprising:
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injection means for injecting a volume of the slurry at a predetermined rate, and for providing a feedback signal based upon said volume of slurry which has been injected; local power means for providing a driving force to said injection means; and control means for controlling an injection rate of said volume of slurry. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A system for radioactively tagging a well stimulation fluid, by injecting a radioactive slurry into the stimulation fluid prior to pumping the stimulation fluid down a wellbore, said system comprising:
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an injection unit including; a syringe having a chamber for holding the radioactive slurry therein; a hydraulically operated cylinder having a plunger disposed on an end thereof, said plunger being insertable into said chamber for displacing said radioactive slurry therefrom; and a position sensor which senses a position of said plunger within said chamber and outputs a feedback signal based thereon;
a local power unit including;a variable speed electric motor; a hydraulic pump operatively connected to said electric motor; a rotation sensor which senses a rotational speed of said hydraulic pump and outputs a rotational speed signal based thereon; and a motor control unit which issues a varying speed command to said electric motor; and a controller including a central processing unit which calculates an initial injection rate and issues a control signal, having a variable voltage, varying in accordance with said feedback signal and said rotational speed signal, said electric motor varying its speed in accordance with said control signal received by said motor control unit from said central processing unit. - View Dependent Claims (13, 14, 15, 16)
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17. A system for radioactively tagging a well stimulation fluid, having a pressure greater than a predetermined level, by injecting a radioactive slurry into the stimulation fluid prior to pumping said stimulation down a wellbore, said system comprising:
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injection means for injecting a volume of the radioactive slurry at a predetermined rate, and for providing a feedback signal based upon said volume of slurry which has been displaced; local power means for providing a driving force to said injection means; manual control means for setting said predetermined injection rate, and for manually controlling said injection rate based upon said feedback signal; and cable means for providing a communication path between said manual control means and said local power means. - View Dependent Claims (18, 19, 20)
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Specification