System and method for separating, monitoring and sampling coiled tubing flow back returns

Abstract

The invention relates to a system and method for separating, and safely monitoring and sampling flow back fluid returns from coiled tubing operations in oil and natural gas wells. The system comprises a flow back tank; one or more gas diffusers; one or more shale shakers; and a chute, which diverts flow from the gas diffusers to a sampling site positioned near the perimeter of the flow back tank. The system also has a volume level indicator on or near the perimeter of the flow back tank. The method comprises piping fluid returns from a wellbore, separating the trapped gases from the fluid returns, directing the degassed fluids to a shale shaker to separate the solids and directing the separated solids and liquids into separate tanks for analysis and reconditioning, if necessary. Cleaned liquids may be recirculated back to the wellbore.

1 . A system for separating, monitoring and sampling flow back fluid returns in coil tubing operations for an oil and natural gas well comprising a wellbore, the fluid returns comprising gases, liquids and solids, the system comprising:
 one or more gas diffusers for removing gases from the fluid returns;   means adapted to connect the wellbore to the one or more gas diffusers;   a flow back tank for receiving liquids and solids from each gas diffuser, the flow back tank comprising a perimeter;   a chute adjacent to each gas diffuser for collecting the fluid returns after the gases are removed, the chute slanted towards the perimeter of the flow back tank;   a sampling site positioned adjacent the perimeter of flow back tank for monitoring flow back fluids within the flow back tank; and   means for analyzing samples of flow back fluid returns to determine conditions down the wellbore.   
   
   
       2 . The system of  claim 1  wherein each gas diffuser is rigidly and removably attached to the flow back tank. 
   
   
       3 . The system of  claim 2  wherein each gas diffuser is rigidly and removably attached to the flow back tank with quick disconnects, the disconnects positioned adjacent ground level. 
   
   
       4 . The system of  claim 1  further comprising a means for ascending the flow back tank, the means for ascending the flow back tank is a stairway, a ramp, or a ladder. 
   
   
       5 . The system of  claim 4  wherein the means for ascending the flow back tank further comprises a personnel access platform, the platform positioned adjacent the area of the perimeter approximate the chute. 
   
   
       6 . The system of  claim 1  further comprising means for sampling the flow back fluids within the flow back tank, the sampling site for the means for sampling positioned adjacent the perimeter approximate the chute. 
   
   
       7 . The system of  claim 1  further comprising a volume level indicator to determine the volume of fluid within the flow back tank. 
   
   
       8 . The system of  claim 7  wherein the volume level indicator comprises an external sight glass, the external sight glass comprises a U-shaped cylinder, the cylinder comprising two contiguous columns, a first column positioned internal to the flow back tank, the second column positioned external to the flow back tank. 
   
   
       9 . The system of  claim 1  further comprising one or more shale shakers for separating the liquids and solids discharged from each gas diffuser, each shale shaker positioned to receive the liquids and solids discharged from the gas diffuser. 
   
   
       10 . The system of  claim 9  wherein each shale shaker comprises a liquid discharge channel so that the liquids are directed to the flow back tank and a solids discharge channel so that the solids are directed to a collection bin. 
   
   
       11 . The system of  claim 10  further comprising a liquid sampling site positioned between the shale shaker and the flow back tank for observing and sampling liquids leaving the shale shaker. 
   
   
       12 . The system of  claim 10  further comprising a solids sampling site positioned between the shale shaker and the collection bin for observing and sampling solids leaving the shale shaker. 
   
   
       13 . The system of  claim 10  further comprising a liquid treatment and makeup tank for reconditioning the liquids prior to returning the liquids to the wellbore. 
   
   
       14 . A system for separating, monitoring and analyzing flow back fluid returns in coil tubing operations for an oil and natural gas well comprising a wellbore, the fluid returns comprising gases, liquids and solids, the system comprising:
 one or more gas diffusers for removing gases from the fluid returns;   a means adapted to connect the wellbore to the one or more gas diffusers;   a flow back tank for receiving liquids from the gas diffuser, the liquids comprising particulate matter, the flow back tank comprising a perimeter;   the one or more gas diffusers rigidly and removably attached to the flow back tank;   a chute fixedly attached to the one or more gas diffusers for collecting the fluid returns after the gases are removed, the chute slanted towards the perimeter of the flow back tank;   a sampling site positioned adjacent the perimeter of the flow back tank for monitoring and sampling liquids within the flow back tank;   a means for ascending the flow back tank, the means for ascending positioned adjacent the perimeter of the flow back tank in the area of the chute;   a means for sampling the liquids within the flow back tank, the means for sampling positioned adjacent the perimeter approximate the chute;   a volume level indicator positioned on or near the perimeter of the flow back tank;   one or more shale shakers for separating the liquids from the solids discharged from the gas diffuser, the solids directed to a collection bin and the liquids directed to the flow back tank;   means for sampling the solids directed to the collection bin; and   means for analyzing the liquids and solids to determine conditions down the wellbore.   
   
   
       15 . A method for separating, monitoring and sampling flow back fluid returns in oil and natural gas wells, the method comprising:
 a. piping fluids from a wellbore to one or more gas diffusers, the fluids comprising gases, liquids and solids, the one or more gas diffusers rigidly and removably attached to a flow back tank;   b. separating the gases from the fluid returns within each gas diffuser and releasing the gases to the atmosphere;   c. discharging the remaining liquids and solids from each gas diffuser by directing the liquids and solids down a chute leading from each gas diffuser to one or more shale shakers;   d. separating the liquids from the solids as they pass through each shale shaker;   e. directing the liquids down a liquid discharge channel to the flow back tank and sending the solids down a solids discharge channel to a collection bin;   f. monitoring and sampling the liquids as the liquids flow down the liquid discharge channel; and   g. monitoring and sampling the solids as the solids flow down the solids discharge channel.   
   
   
       16 . The method of  claim 15  further comprising positioning a platform adjacent a perimeter of the flow back tank to facilitate monitoring and sampling of the liquids within the flow back tank. 
   
   
       17 . The method of  claim 15  further comprising analyzing the liquids after they are sampled to determine composition of liquids. 
   
   
       18 . The method of  claim 17  further comprising the step of reconditioning the liquids prior to returning the liquids to the wellbore. 
   
   
       19 . The method of  claim 15  further comprising visually inspecting the solids at a solids sampling site positioned between the shale shaker and the collection bin. 
   
   
       20 . The method of  claim 19  further comprising analyzing the solids to determine conditions down the wellbore. 
   
   
       21 . The method of  claim 15  further comprising positioning a volume level indicator on the perimeter of the flow back tank.