METHOD FOR GENERATION OF DRAW-DOWN PRESSURE IN ORDER TO CONDUCT BOREHOLE INVESTIGATIONS Russian patent published in 2013 - IPC E21B47/00 E21B34/14 

FIELD: oil and gas industry.

SUBSTANCE: method includes simulating of formation and recording of data on borehole processes by a geophysical instrument run-in into the tubing string at a logging cable and self-contained instruments installed at the lower end of the tubing string. At that simulation of formation is made by breaking a breakable drain valve made of a brittle material of hemisphere shape and installed with a convex part downwards in the lower part of the tubing string; for this purpose a drill stem is fixed under the geophysical instrument and the geophysical instrument is run-in with the stem into the interval with speed sufficient to break the breakable drain valve. At that upper part of the tubing sting above the breakable drain valve is not filled with water and a packer is installed in tubular annulus at the level of the tubing string lower part.

EFFECT: increase of information content and reliability for borehole investigations; reduction of labour intensity, time consumption and equipment costs; possibility to use in wells with any producibility of the investigated formation.

1 dwg