GB1323243A - Method and apparatus for testing wells - Google Patents

Abstract

1323243 Wells &c HALLIBURTON CO 6 Sept 1971 [14 Sept 1970] 41451/71 Heading E1F In the use of a test string 10 to sample fluid from a formation 5 the pressure on fluid in the annulus 16 about the test string is maintained at a low value and the string is closed to the formation, the pressure is increased to open the string to permit flow of formation fluid through the string, and then the pressure is altered to close the string to the formation and trap a formation fluid sample in the string. The string for a subaqueous well includes a test tree 18, a slip joint 20, valve 22, pressure recorder 24, sampler 25, pressure recorder 26 and packer 27. The packer is set with the slip joint partly contracted and the tree 18 supported by rams of a blow-out preventer in the wellhead 7. A hydraulic jar may be incorporated in the string above the packer, a safety joint being placed between the packer and jar. The packer may be separate from the string and be connected to it by a stinger. Initially the parts of the samples are as shown in Fig. 2a to prevent formation fluid flowing through the sampler, the pressure of mud in the annulus adjacent holes 48 being insufficient to move the piston 42 against nitrogen at pressure in the chamber 44 above the piston. On increasing pressure of the mud the piston rises and inlets 37 and outlets 41 are opened so that formation fluid flows through the sample chamber 45, the piston travel being limited by a stop held by a shear pin and the piston speed being restricted. The formation fluid sample is trapped in chamber 45 by further increasing the mud pressure to raise the piston to close the inlets and outlets the piston being held in the further raised position by a latch. Alternatively the sample may be trapped by reducing the mud pressure and allowing the piston to sink.