DBPapers
DOI: 10.5593/sgem2017/14/S06.077

EFFECT OF FRACTURING AND PROPERTIES OF DRILLING MUD ON A CORE BLOCKING DURING THE CORING FROM DEEP WELLS

B.T. Ratov, D.R. Korgasbekov, B.V. Fedorov, B.F. Sabirov, A. R. Baiboz
Monday 11 September 2017 by Libadmin2017

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7408-00-3 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 14, 609-616 pp, DOI: 10.5593/sgem2017/14/S06.077

ABSTRACT

A mechanism of core blocking that is drilled out during the coring from deep wells in the direct and indirect flushing with drilling mud is examined. Using methods of technical mechanics and hydromechanics, a formula for flow rate excluding a core blocking is obtained during the backwashing. The value of necessary flow rate depends on not only a direction and intensity of fracturing of rocks, geometrical and density parameters of core pieces, but also on structural strength of drilling mud. A mechanism of core self-jamming is examined with consideration for structural strength of drilling mud. In determination of flow rate of the reverse flushing fluid flow for an exclusion of core self-jamming is necessary to consider not only the intensity and direction of the fracture, the density of flushing fluid and drilled rock, geometrical dimension of a core, but also structural strength of solution must be accounted for. In drilling deep wells in the fractured rocks to improve core recovery is necessary to apply the drill with backwashing mud with increased structural strength.

Keywords: Drilling, a well, a core receiver, core head, a core-sample, the backwashing, fractured rocks, a core blocking.