FORMATION TESTER Russian patent published in 2003 - IPC

FIELD: well testing by formation testers on pipe strings. SUBSTANCE: formation tester provides conditions in course of testing under which testing of fractured formations is possible by multicycle technology with step increase of depression from cycle to cycle. Formation tester has body, rod, slide valve reciprocating under action of mechanism for slide valve switching, valves located in bushings, piston engageable with load- bearing rods, floating separating piston, post with shaped recess carrying movably installed branch pipe with pin. Body is comprised of welded body and control unit body interconnected to each other by screws, piston engageable with load-bearing rods and made hollow with external detachable ends of same diameter and provided with compensator in its cavity which separates piston cavity from intrapipe medium. Piston cavity is isolated from medium of annular space by floating separating piston installed in welded body and embracing piston installed in welded body and embracing piston external surface. Valves located in bushings are made movable in form of differential rods whose large diameter sectional area exceeds sectional area of small diameter by a factor of 2. Differential rods have four rows of sealing rings on external surface, blind axial hole and two radial holes intersecting the axial hole, and closed with bushings rigidly secured to control unit body. In this case, the first radial hole is located between the second and third rows of sealing rings, and the second radial hole is located under large diameter of differential rod. Branch pipe with pin is spring-loaded and movable in axial direction relative to post with engagement with slide valve. EFFECT: provided multicycle process with step increase of depression from cycle to cycle, higher operate reliability of tester in course of formation tester, and simplified design of formation tester. 2 dwg