Method and apparatus for determining subsurface conditions using a

Abstract

A method and apparatus are provided for permitting an instrumentation package to be repeatedly locked and unlocked at any number of desired depths inside a subsurface production tube for the determination of the shut-in physical conditions at those depths. An instrumentation package is located below a tube packoff tool. The instrumentation package and tube packoff tool combination are lowered into the tube. At the desired depth, a longitudinal force is exerted on the tube packoff tool, causing the tube packoff tool to wedge against the inside of the tube, locking the tube packoff tool at that depth, and creating a seal which isolates the instrumentation package below. The instrumentation package then begins its determination of the shut-in physical conditions inside the tube at that depth and transmits the acquired data to a surface recording and processing facility. When sufficient data has been collected, the tube packoff tool can be unlocked by relaxing the upward force on the tube packoff tool, breaking the isolating seal, and unlocking the tube packoff tool from its position inside the tube. At this point, the tube packoff tool and instrumentation package may either be taken to another location inside the tube and relocked using the same procedure for determination of the physical conditions at the tube at an additional depth or removed from the tube. The locking and unlocking procedure may be repeated as many times as desired prior to the removal of the tube packoff tool and the instrumentation package from the tube. An emergency release mechanism is incorporated in the tool that allows the tool to be safely released from the tubing locked position by exerting an upward force on the tube packoff tool. This will allow pressure to equalize across the tube packoff tool before disengaging the tool form the locked position by a downward motion.