Pulsing remediation method
First Claim
1. A process for bioremediating a contaminated zone by pulsing air into an underground formation containing an in-situ fluid, said process comprising:
- drilling and completing a well which penetrates said contaminated zone;
injecting an air pulse through said well into said contaminated zone at a flowrate of at least about 0.25 SCFM for a first period of time lasting no more than 720 hours at a first average air flowrate;
substantially reducing said average air flowrate to a second average air flowrate during a second recovery period of time following said first period, said second recovery period lasting from about 1 to 720 hours; and
injecting another air pulse at a third average air flowrate greater than said second average flowrate into said contaminated zone for a third period of time following said second recovery period, said third period lasting no more than 720 hours.
1 Assignment
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Accused Products
Abstract
A process for cyclically operating injection and withdrawal wells penetrating contaminated zones. A high flowrate portion of the cycle time preferably does not exceed a transient response period for in-situ formation fluids to achieve a quasi-steady state conditions. A low flowrate portion of the cycle time limits fluid flowrate which allows in-situ formation fluids to at least partially return to the zone affected by the high flowrate portion of the cycle. The cyclic operation produces improved remediation when compared to continuous operation of wells at similar operating conditions.
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Citations
27 Claims
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1. A process for bioremediating a contaminated zone by pulsing air into an underground formation containing an in-situ fluid, said process comprising:
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drilling and completing a well which penetrates said contaminated zone; injecting an air pulse through said well into said contaminated zone at a flowrate of at least about 0.25 SCFM for a first period of time lasting no more than 720 hours at a first average air flowrate; substantially reducing said average air flowrate to a second average air flowrate during a second recovery period of time following said first period, said second recovery period lasting from about 1 to 720 hours; and injecting another air pulse at a third average air flowrate greater than said second average flowrate into said contaminated zone for a third period of time following said second recovery period, said third period lasting no more than 720 hours. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A process for flowing a remediating fluid within a contaminated underground zone containing an in-situ fluid, said process comprising:
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drilling a well which provides a conduit for fluid flow to and from said underground zone; flowing said remediating fluid into said underground zone at a first average fluid flowrate for a first period of time which is no greater than 2160 hours, wherein at least some of said in-situ fluid is displaced during said first period of time by said remediating fluid; and substantially reducing said average fluid flowrate to a second average fluid flowrate during a second period of time following said first period, wherein said second period of time is at least 0.5 hours. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A pulsing process for remediating an underground contaminated zone during a remediation period of time which comprises:
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flowing a remediating fluid into said underground zone at a first nominal fluid flowrate during a pulse time period which lasts no longer than 720 hours; and significantly changing said nominal flowrate at the end of said pulse time period, wherein at least three pulse time periods occur over said remediation period. - View Dependent Claims (18, 19, 20)
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21. A process for treating an in-situ fluid with a remediating fluid using a fluid conduit penetrating an underground contaminated zone having a relative permeability to said in-situ fluids, said process comprising:
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calculating a transient period during which a first average flowrate of said remediating fluid displaces a portion of said in-situ fluid within said contaminated zone and reduces said relative permeability at a reference location within said contaminated zone, said transient period lasting until said relative permeability essentially stabilizes; flowing said remediating fluid at about said first average flowrate during a first period which is no greater than about twice said transient period; and flowing said remediating fluid at a reduced average flowrate during a second period following said first period, wherein said reduced average flowrate allows said relative permeability to increase.
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22. An apparatus for treating an in-situ fluid with a remediating fluid within an underground contaminated zone having a relative permeability to said in-situ fluids, said apparatus comprising:
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a fluid conduit from a surface location to said underground contaminated zone containing said in-situ fluid; means for calculating a transient period during which a first average flowrate of said remediating fluid within said contaminated zone displaces a portion of said in-situ fluid and reduces said relative permeability at a reference location within said contaminated zone, said transient period lasting until said relative permeability essentially achieves a steady state condition; means for flowing said remediating fluid to said underground contaminated zone at about said first average flowrate during a first period; means for controlling the duration of said first period such that said first period is no more than twice said transient period; and means for flowing said remediating fluid at a reduced average flowrate after said first period, wherein said reduced average flowrate allows said relative permeability to increase. - View Dependent Claims (23, 24, 25)
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26. In a process of remediating a portion of an underground aquifer by flowing a remediating fluid into said aquifer at a nominal fluid flowrate, the improvement comprising the steps of:
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significantly reducing said nominal flowrate over a first quiescent period after a first operating time period which lasts no more than 720 hours, wherein said first quiescent period lasts at least 0.5 hours and said first operating time and said first quiescent period form the first of a pulsing series; and pulsing said flowrate at least three times. - View Dependent Claims (27)
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Specification