Systems and methods for detecting leaks in subsea cement and wellbore equipment

Abstract

Methods and systems for detecting subsea cement returns, leaks in subsea cement, leaks in blowout preventer operating systems or other equipment or conduits, or the presence of sweep or spacer media subsea or at the surface, include mixing an indicator, such as sodium fluorescein, with a quantity of cement or other medium, the indicator being insulated from contact with the subsea environment. The medium and indicator can be provided into a subsea wellbore, and upon contact of a portion of the medium with the subsea environment, the indicator can become detectable. Exposing the subsea environment proximate to the wellbore to a detector, such as an ultraviolet light source, enables detection of the indicator, and thereby, detection of the medium, which can indicate a cement return or leak of operating fluids in a subsea blowout preventer system.

What is claimed is: 
     
         1 . A method for detecting leaks in subsea cement or cement returns in a subsea environment, the method comprising the steps of:
 mixing an indicator with a quantity of cement, wherein the indicator is in an inactive state and wherein the indicator is insulated from contact with water;   providing the quantity of cement and the indicator into a subsea wellbore;   permitting the quantity of cement to contact the subsea environment proximate to the subsea wellbore thereby activating the indicator to an active state; and   exposing the subsea environment proximate to the subsea wellbore to a detector adapted for detecting the indicator in the active state to detect the indicator and thereby detect the second portion of the cement.   
     
     
         2 . The method of  claim 1 , wherein the indicator comprises sodium fluorescein, another fluorescein salt, or combinations thereof. 
     
     
         3 . The method of  claim 1 , wherein the quantity of cement comprises a cement return and wherein the subsea environment proximate to the subsea wellbore comprises a subsea floor. 
     
     
         4 . The method of  claim 1 , wherein the step of exposing the subsea environment proximate to the subsea wellbore to the detector comprises exposing the subsea environment to an ultraviolet light source. 
     
     
         5 . The method of  claim 4 , wherein the step of exposing the subsea environment to the ultraviolet light source comprises associating the ultraviolet light source with a remotely operated vehicle, maneuvering the remotely operated vehicle to the subsea environment proximate to the subsea wellbore, and exposing the subsea environment proximate to the subsea wellbore to the ultraviolet light source. 
     
     
         6 . A system for detecting leaks in subsea cement or cement returns in a subsea environment, the system comprising:
 a quantity of cement disposed in association with a subsea wellbore;   an indicator within the quantity of the cement, wherein the indicator is in an inactive state, wherein the indicator is insulated from contact with water, and wherein a leak in the quantity of cement, a cement return in the subsea environment, or combinations thereof, exposes the indicator to water, thereby activating the indicator to an active state; and   a detector adapted for detecting the indicator in the active state, thereby detecting the leak, the cement return, or combinations thereof.   
     
     
         7 . The system of  claim 6 , wherein the indicator comprises sodium fluorescein, another fluorescein salt, or combinations thereof. 
     
     
         8 . The system of  claim 6 , wherein the subsea environment comprises a subsea floor proximate to the subsea wellbore. 
     
     
         9 . The system of  claim 6 , wherein the detector comprises an ultraviolet light source. 
     
     
         10 . The system of  claim 9 , further comprising a remotely operated vehicle having the ultraviolet light source associated therewith. 
     
     
         11 . A method for detecting a non-aqueous substance associated with a subsea wellbore, the method comprising the steps of:
 mixing an indicator with a medium and providing the medium into a subsea wellbore, wherein the indicator is insulated from contact with a subsea environment proximate to the subsea wellbore, and wherein the indicator is thereby insulated from detection,   wherein at least a portion of the medium and the indicator contacts the subsea environment, thereby enabling detection of the indicator; and   exposing said at least a portion of the medium to a detector adapted for detecting the indicator in the active state to detect the indicator and thereby detect the medium.   
     
     
         12 . The method of  claim 11 , wherein the step of mixing the indicator with the medium comprises mixing the indicator with a non-aqueous medium, wherein the indicator is in an inactive state, wherein the indicator is insulated from contact with water, and wherein contact between said at least a portion of the medium and the subsea environment activates the indicator to an active state. 
     
     
         13 . The method of  claim 11 , wherein the step of mixing the indicator with the medium comprises mixing the indicator with liquid cement, wherein at least a portion of the cement contacts the subsea environment as a cement return on a subsea floor, and wherein the step of exposing said at least a portion of the medium to the detector comprises providing the detector proximate to the subsea floor for detecting the cement return by detecting the indicator. 
     
     
         14 . The method of  claim 11 , wherein the step of mixing the indicator with the medium comprises mixing the indicator with fluid within a blowout preventer operating system of a deepwater rig, wherein a leak in the blowout preventer operating system permits at least a portion of the fluid to contact the subsea environment proximate to the blowout preventer operating system, and wherein the step of exposing said at least a portion of the medium to the detector comprises providing the detector proximate to the subsea floor for detecting the leak by detecting the indicator. 
     
     
         15 . The method of  claim 11 , wherein the step of mixing the indicator with the medium comprises mixing the indicator with a sweep, a spacer, or combinations thereof for use during drilling or completion operations, wherein at least a portion of the sweep, the spacer, or combinations thereof contacts the subsea environment, and wherein the step of exposing said at least a portion of the medium to the detector comprises providing the detector at the surface of the subsea wellbore to detect the sweep, the spacer, or combinations thereof by detecting the indicator. 
     
     
         16 . The method of  claim 11 , wherein the indicator comprises sodium fluorescein, another fluorescein salt, or combinations thereof. 
     
     
         17 . The method of  claim 13 , wherein the step of providing the detector proximate to the subsea floor for detecting the cement return comprises associating an ultraviolet light source with a remotely operated vehicle, maneuvering the remotely operated vehicle to the subsea environment proximate to the subsea floor, and exposing the subsea environment proximate to the subsea floor to the ultraviolet light source. 
     
     
         18 . The method of  claim 14 , wherein the step of providing the detector proximate to the subsea floor for detecting the leak comprises associating an ultraviolet light source with a remotely operated vehicle, maneuvering the remotely operated vehicle to the subsea environment proximate to the subsea wellbore, and exposing the subsea environment proximate to the subsea wellbore to the ultraviolet light source. 
     
     
         19 . The method of  claim 15 , wherein the step of providing the detector at the surface of the subsea wellbore to detect the sweep, the spacer, or combinations thereof, comprises providing a portable ultraviolet source proximate to the surface and exposing the sweep, the spacer, or combinations thereof to the ultraviolet light source.