Methods and apparatus for downhole characterization of emulsion stability
First Claim
1. A method for downhole analysis of petroleum formation fluids comprising:
- (a) providing a chamber in a downhole tool suspended in a wellbore;
(b) capturing in the chamber at least two immiscible fluids in a generally segregated state, the at least two fluids including petroleum fluid;
(c) emulsifying the fluids in the chamber by activating a fluid mixing means for mixing the fluids;
(d) allowing the emulsified fluids to segregate by deactivating the mixing means;
(e) transmitting light into the fluids in the chamber and measuring light transmittance values through the fluids over time during (d); and
(f) calculating the duration of a transition time period based upon the light transmittance values measured in (e), the transition time period beginning at the time of deactivation of the fluid mixing means, and the transition time period ending at a time determined by a change in the light transmittance values measured in (e).
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Abstract
A method (and corresponding apparatus) for downhole fluid analysis of petroleum formation fluids. The method includes capturing in a chamber of a downhole tool at least two immiscible formation fluids in a generally segregated state (the fluids including petroleum), activating a fluid mixing means to mix the fluids in the chamber to create an emulsion therefrom, and allowing the emulsified fluids to segregate while measuring light transmittance through the segregating fluids in order to calculate a transition time period based on the light transmittance through the fluids in the chamber. The transition time period is preferably bounded by the time required for the light transmittance values measured by the light detector to reach a baseline light transmittance. The transition time period characterizes the stability of an emulsion formed by the captured fluids. The methods and apparatus can also be used for other fluid testing applications beyond downhole formation fluid testing.
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Citations
30 Claims
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1. A method for downhole analysis of petroleum formation fluids comprising:
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(a) providing a chamber in a downhole tool suspended in a wellbore; (b) capturing in the chamber at least two immiscible fluids in a generally segregated state, the at least two fluids including petroleum fluid; (c) emulsifying the fluids in the chamber by activating a fluid mixing means for mixing the fluids; (d) allowing the emulsified fluids to segregate by deactivating the mixing means; (e) transmitting light into the fluids in the chamber and measuring light transmittance values through the fluids over time during (d); and (f) calculating the duration of a transition time period based upon the light transmittance values measured in (e), the transition time period beginning at the time of deactivation of the fluid mixing means, and the transition time period ending at a time determined by a change in the light transmittance values measured in (e). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for downhole analysis of petroleum formation fluids comprising:
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(a) providing a chamber in a downhole tool suspended in a wellbore; (b) capturing in the chamber at least two immiscible fluids in a generally segregated state, the at least two fluids including petroleum fluid; (c) emulsifying the fluids in the chamber by activating a fluid mixing means for mixing the fluids; (d) allowing the emulsified fluids to segregate by deactivating the mixing means; (e) transmitting light into the fluids in the chamber and measuring backscattered light from the fluids over time during (d); and (f) calculating the duration of a transition time period based upon the backscattered light values measured in (e), the transition time period beginning at the time of deactivation of the fluid mixing means, and the transition time period ending at a time determined by a change in the backscattered light values measured in (e).
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11. An apparatus for downhole fluid testing of petroleum fluid, the apparatus comprising:
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a housing positionable within a wellbore adjacent a formation containing petroleum fluid, the housing supporting a chamber, a probe, at least one valve, fluid mixing means, a light source, a light detector, and a control unit; the probe for drawing at least two generally segregated fluids from the formation into the chamber, the two fluids including petroleum fluid; the at least one valve for sealing the fluids in the chamber; the fluid mixing means for mixing the fluids in the chamber into an emulsified state; the light source for transmitting light into the fluids in the chamber; the light detector for measuring the transmittance of light from the light source through the fluids in the chamber; and the control unit operably coupled to the fluid mixing means and the light detector, the control unit adapted to deactivate the fluid mixing means in order to allow the emulsified fluids to segregate, and the control unit including means for measuring light transmittance values output by the light detector over time while the fluid mixing means is deactivated in order to calculate a transition time period for the fluids captured in the chamber, whereby the duration of the transition time period characterizes emulsion stability for the fluids captured in the chamber. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. An apparatus for downhole fluid testing of petroleum fluid, the apparatus comprising:
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a housing positionable within a wellbore adjacent a formation containing petroleum fluid, the housing supporting a chamber, a probe, at least one valve, fluid mixing means, a light source, a light detector, and a control unit; the probe for drawing at least two generally segregated fluids from the formation into the chamber, the two fluids including petroleum fluid; the at least one valve for sealing the fluids in the chamber; the fluid mixing means for mixing the fluids in the chamber into an emulsified state; the light source for transmitting light into the fluids in the chamber; the light detector for measuring the backscatter of light from the fluids in the chamber; and the control unit operably coupled to the fluid mixing means and the light detector, the control unit adapted to deactivate the fluid mixing means in order to allow the emulsified fluids to segregate, and the control unit including means for measuring light backscatter values output by the light detector over time while the fluid mixing means is deactivated in order to calculate a transition time period for the fluids captured in the chamber, whereby the duration of the transition time period characterizes emulsion stability for the fluids captured in the chamber.
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25. A fluid testing apparatus, comprising:
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a chamber; a probe for drawing at least two generally segregated immiscible fluids into the chamber; at least one valve for sealing the fluids in the chamber; fluid mixing means for mixing the fluids in the chamber into an emulsified state; a light source for transmitting light into the fluids in the chamber; a light detector for measuring transmittance of light from the light source through the fluids in the chamber; and a control unit operably coupled to the fluid mixing means and the light detector, the control unit adapted to deactivate the fluid mixing means in order to allow the emulsified fluids to segregate, and the control unit including means for measuring light transmittance values output by the light detector over time while the fluid mixing means is deactivated, and means for calculating the duration of the transition time period based upon the light transmittance values measured while the fluid mixing means is deactivated. - View Dependent Claims (26, 27, 28, 29, 30)
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Specification