Methods for using a formation tester
First Claim
1. A method of testing a downhole formation comprising:
- disposing a formation tester on a drill string in a borehole;
performing a formation test procedure with said formation tester comprising;
forming a seal between a formation probe assembly of said formation tester and the formation;
drawing down a drawdown piston within a chamber in said formation tester to create a volume within said chamber;
drawing formation fluid into said volume in said chamber; and
monitoring the pressure within said chamber;
determining if the pressure within said chamber is less than the bubble point pressure of the formation fluid drawn into said chamber;
maintaining the position of said drawdown piston until escaped formation fluid gas recombines into solution with the formation fluid in said chamber; and
continuing drawing down said drawdown piston.
1 Assignment
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Accused Products
Abstract
A method of testing a downhole formation using a formation tester on a drill string. The formation tester is disposed downhole on a drill string and a formation test is performed by forming a seal between a formation probe assembly and the formation. A drawdown piston then creates a volume within a cylinder to draw formation fluid into the volume through the probe assembly. The pressure of the fluid within the cylinder is monitored. The formation test procedure may then be adjusted. The test procedure may be adjusted to account for the bubble point pressure of the fluid being monitored. The pressure may monitored to verify a proper seal is formed or is being maintained. The test procedure may also be performed by maintaining a substantially constant drawdown rate using a hydraulic threshold or a variable restrictor.
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Citations
26 Claims
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1. A method of testing a downhole formation comprising:
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disposing a formation tester on a drill string in a borehole; performing a formation test procedure with said formation tester comprising; forming a seal between a formation probe assembly of said formation tester and the formation; drawing down a drawdown piston within a chamber in said formation tester to create a volume within said chamber; drawing formation fluid into said volume in said chamber; and monitoring the pressure within said chamber; determining if the pressure within said chamber is less than the bubble point pressure of the formation fluid drawn into said chamber; maintaining the position of said drawdown piston until escaped formation fluid gas recombines into solution with the formation fluid in said chamber; and continuing drawing down said drawdown piston. - View Dependent Claims (2, 3, 4)
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5. A method of testing a downhole formation comprising:
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disposing a formation tester on a drill string in a borehole; performing a formation test procedure with said formation tester comprising; forming a seal between a formation probe assembly of said formation tester and the formation; drawing down a drawdown piston within a chamber in said formation tester to create a volume within said chamber; drawing formation fluid into said volume in said chamber; and monitoring the pressure within said chamber; determining if the pressure within said chamber is less than the bubble point pressure of the formation fluid drawn into said chamber; resetting said drawdown piston; performing said formation test procedure with a decreased amount of volume created by drawing down said drawdown piston.
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6. A method of testing a downhole formation comprising:
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disposing a formation tester on a drill string in a borehole; performing a formation test procedure with said formation tester comprising; forming a seal between a formation probe assembly of said formation tester and the formation; drawing down a drawdown piston within a chamber in said formation tester to create a volume within said chamber; drawing formation fluid into said volume in said chamber; and monitoring the pressure within said chamber; determining if the pressure within said chamber is less than the bubble point pressure of the formation fluid drawn into said chamber; resetting said drawdown piston; re-performing said formation test procedure while monitoring the position of said drawdown piston; determining the amount of volume created by drawing down said drawdown piston; determining the bubble point of the formation fluid; resetting said drawdown piston; and re-performing said formation test procedure comprising maintaining the pressure within said chamber above the bubble point pressure of the formation fluid while drawing down said drawdown piston. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A method of testing a downhole formation comprising:
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disposing a formation tester on a drill string in a borehole; performing a formation test procedure with said formation tester comprising; forming a seal between a formation probe assembly of said formation tester and the formation; drawing down a drawdown piston within a chamber in said formation tester to create a volume within said chamber; drawing formation fluid into said volume in said chamber; and monitoring the pressure within said chamber; monitoring the position of said drawdown piston during said formation test procedure; and variably controlling the drawdown of said drawdown piston during a drawdown to maintain a substantially constant drawdown rate. - View Dependent Claims (14)
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15. A method of testing a downhole formation comprising:
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disposing a formation tester on a drill string in a borehole; performing a formation test procedure with said formation tester comprising; forming a seal between a formation probe assembly of said formation tester and the formation; drawing down a drawdown piston within a chamber in said formation tester to create a volume within said chamber; drawing formation fluid into said volume in said chamber; and monitoring the pressure within said chamber; resetting said drawdown piston; creating a pressure drop in said chamber by isolating said chamber from the formation fluid and drawing down said drawdown piston to create a volume within said chamber; allowing the formation fluid to communicate with the volume in said chamber; and drawing formation fluid into the volume in said chamber. - View Dependent Claims (16)
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17. A method of testing a downhole formation comprising:
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disposing a formation tester on a drill string in a borehole; initiating a formation test procedure with said formation tester comprising; extending a formation probe assembly of said formation tester into engagement with the formation; drawing down a drawdown piston within a chamber in said formation tester to create a volume within said chamber; drawing formation fluid into said volume in said chamber; and monitoring the pressure within said chamber; monitoring the pressure in the borehole; transmitting the borehole and chamber pressure data from downhole to the surface; determining if the pressure in said chamber is substantially equal to the pressure in the borehole during the drawdown; transmitting formation test procedure commands from the surface to a controller in said formation tester; aborting said formation test procedure using said controller to retract said formation probe assembly and reset said drawdown piston before said test procedure is complete; and re-performing said formation test procedure.
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18. A method of testing a downhole formation comprising:
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disposing a formation tester on a drill string in a borehole; initiating a formation test procedure with said formation tester comprising; extending a formation probe assembly of said formation tester into engagement with the formation; drawing down a drawdown piston within a chamber in said formation tester to create a volume within said chamber; drawing formation fluid into said volume in said chamber; and monitoring the pressure within said chamber; monitoring the pressure in the borehole; transmitting the borehole and chamber pressure data to a controller in said formation tester; analyzing said data with said controller to determine if the pressure in said chamber is substantially equal to the pressure in the borehole; aborting said formation test procedure by using said controller to retract said formation probe assembly and reset said drawdown piston; and re-performing said formation test procedure.
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19. A method of testing a downhole formation comprising:
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disposing a formation tester on a drill string in a borehole; performing a formation test procedure with said formation tester comprising; forming a seal between a formation probe assembly of said formation tester and the formation; drawing down a drawdown piston within a chamber in said formation tester to create a volume within said chamber; drawing formation fluid into said volume in said chamber; and monitoring the pressure within said chamber; monitoring the pressure in the borehole; transmitting the borehole and chamber pressure data from downhole to the surface; determining if the seal formed by said formation probe assembly is deteriorating; transmitting formation test procedure commands from the surface to a controller in said formation tester; and increasing the force of the formation probe assembly against the formation. - View Dependent Claims (20)
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21. A method of testing a downhole formation comprising:
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disposing a formation tester on a drill string in a borehole; performing a formation test procedure with said formation tester comprising; forming a seal between a formation probe assembly of said formation tester and the formation; drawing down a drawdown piston within a chamber in said formation tester to create a volume within said chamber; drawing formation fluid into said volume in said chamber; and monitoring the pressure within said chamber; monitoring the pressure in the borehole; transmitting the borehole and chamber pressure data to a controller in said formation tester; analyzing said data with said controller to determine if the seal formed by said formation probe assembly is deteriorating; transmitting commands from said controller to increase the force of the formation probe assembly against the formation; and increasing the force of the formation probe assembly against the formation. - View Dependent Claims (22)
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23. A method of testing a down hole formation comprising:
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disposing a formation tester on a drill string in a borehole; performing a formation test procedure with said formation tester comprising; forming a seal between a formation probe assembly of said formation tester and the formation; operating a hydraulic pump to create hydraulic pressure; isolating a drawdown piston from said hydraulic pressure; communicating said hydraulic pressure to said drawdown piston once a minimum hydraulic pressure is produced by said hydraulic pump; drawing down said drawdown piston at a substantially constant drawdown rate with said hydraulic pressure; creating a volume within a chamber within said formation tester by drawing down said drawdown piston; drawing formation fluid into said volume in said cylinder; and monitoring the pressure within said cylinder. - View Dependent Claims (24)
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25. A method of testing a down hole formation comprising:
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disposing a formation tester on a drill string in a borehole; performing a formation test procedure with said formation tester comprising; forming a seal between a formation probe assembly of said formation tester and the formation; operating a hydraulic pump to create hydraulic pressure; controlling the amount of hydraulic pressure communicated to a drawdown piston to be less than the amount of hydraulic pressure produced by said hydraulic pump; drawing down said drawdown piston at a substantially constant drawdown rate with the hydraulic pressure; creating a volume within a chamber within said formation tester by drawing down said drawdown piston; drawing formation fluid into the volume in said chamber; and monitoring the pressure within said chamber. - View Dependent Claims (26)
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Specification