Gas lift process for restoring flow in depleted geothermal reservoirs
AssigneeUnion Oil Company of California
InventorsGregory R. Andersen, Stephen D. Pye, Alice A. Probst
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Abstract
A method is provided whereby continuous injection of lift gas into a producing geothermal well, preferably from a liquid-dominated reservoir, increases production flow of geothermal fluids from the well by initiating a steam distillation effect within the wellbore. Apparatus is also provided for continuously injecting the lift gas during production from the well.
Claims31
A method for increasing the production flow from a well penetrating a geothermal reservoir from a wellhead, said method comprising:
- (a) continuously injecting a sufficient amount of an inert, non-condensible lift gas into the well during the production of geothermal fluids therefrom to cause a substantial fraction, or to substantially increase a preexisting fraction, of steam in the produced fluids without having to significantly reduce the pressure of the produced fluid at the wellhead;
- and
- (b) recovering increased produced fluids and the lift gas from the well.
A method for restoring production flow rates from a well penetrating, from a wellhead, a liquid-dominated geothermal reservoir having a pressure near or below the bubblepoint of the fluid in the reservoir, said method comprising:
- (a) continuously injecting a sufficient amount of an inert, oxygen-free, non-condensible lift gas into the well during the production of geothermal fluids therefrom to substantially increase the fraction of steam in the produced fluids without having to significantly reduce the pressure of the produced fluid at the wellhead;
- and
- (b) recovering increased produced fluids and the lift gas from the well.
A method for increasing the production flow from a well penetrating, from a wellhead, a geothermal reservoir associated with a binary geothermal power plant utilizing a binary heat exchange medium for extracting heat from geothermal fluids, said method comprising:
- (a) continuously injecting a sufficient amount of an inert, oxygen-free, non-condensible lift gas into the well during the production of geothermal fluids therefrom to substantially increase the fraction of steam in the produced fluids without having to significantly reduce the pressure of the produced fluid at the wellhead;
- (b) recovering increased produced fluids and the lift gas from the well;
- (c) separating the lift gas from the produced fluids recovered in step (b) utilizing heat exchange with the binary heat exchange medium of the power plant;
- and
- (d) recycling the separated lift gas for reinjection in step (a).
The method for increasing production flow from a well penetrating a geothermal reservoir having a steam fraction of less than 1 weight percent and being associated with a co-generation plant burning natural gas, said method comprising:
- (a) continuously injecting a sufficient amount of a lift gas comprising oxygen-free combustible natural gas into the well during production of geothermal fluids to substantially increase the fraction of steam in the produced fluids;
- (b) recovering an increased flow of produced fluids and the lift gas from the reservoir;
- (c) separating the lift gas from the produced fluids recovered in step (b);
- and
- (d) sending the separated lift gas to the associated co-generation plant to be combusted for the purpose of generating electricity.
Dependencies are inferred from the claim text.