METHOD FOR DETECTION OF COMPLICATIONS IN WELLBORE AND DEVICE FOR ITS EMBODIMENT Russian patent published in 1997 - IPC

FIELD: oil and gas producing industry and geological prospecting, particular, drilling of wells with possible gas emission from their interbeds. SUBSTANCE: the offered method includes determination of mud pump pressure differential and output of drilling mud from well annular space. Gas emission is confirmed additionally in course of drilling by weight indicator that effects weight of drilling tool due to reduced density of drilling mud in annular space of wellbore caused by dissolving of gas in drilling mud. This parameter is also determined twice as accurate by weight indicator 3 at short time stopping of well drilling and displacement of a part of drilling mud from pipe space into annular space. In addition, presence of complication is very accurately detected during, for instance, adding of drilling tool, by the level of drilling mud inside pipe string 7. The device for embodiment of the offered method has movable tape with controlled speed of rotation on which pump characteristics are recorded for different values of average densities of drilling mud. Characteristics are shifted by horizontal relative to one another for a preset value depending on mud pump pressure differential and output of discharge of drilling mud through annular space. Noncoincidence of recorder with one of curves and its transition to underlaying curve is indicative of showings of gas which is also confirmed by fluid level from inside pipes 7. EFFECT: higher efficiency. 2 cl, 4 dwg