Well extension in fractured and broken rocks by wire-line tool (SSK-59)

Abstract

Conditions of increasing the drilling rate per run, which influence wire-line tool application efficiency, are analyzed. Decreasing of drilling rate is usually caused by alarm initiation which indicates core blocking. Producing of longitudinal and lateral vibrations during drilling process and initiation of fluid upward flow inside the inner core pipe, significantly increases the drilling rate. For initiating an upward flow inside the inner core pipe it is suggested to install the bottom hole pump inside the wireline inner core barrel to be applied as a mechanical motor of downhole vibrator which starts to operate only in a case of core blocking. It was found out that the bottom hole pump provided the necessary speed of upward flow (0.3 - 0.5 m/s) at the rotation speed of more than 150 rpm. Field test was carried out to drill siltstone and sandstone formations of 9 -10 drilling category and their alternation with the formation dip angle of more than 70° (rough and disintegrated rocks). The upward flow inside the inner core pipe SSK-59 allowed increasing the drilling rate by 10% as well as to increase core recovery ratio. Besides, it was noted that a large amount of the cuttings (sized 8 - 10 mm) were accumulating inside the inner core pipe during downhole pump application, that in its turn, proved the initiation of upward flow inside the inner core pipe.