** Oil producer Gulf Keystone Petroleum Ltd's shares down about 16 pct; co expects to default on bond payments asstandstill agreement with notes and bond holders expired on July1
** Co says it does not intend to make April coupon payments;restructuring discussions ongoing despite expiration ofstandstill agreement
** Co has been struggling with low oil prices and paymentdelays from Kurdistan regional government for its oil; signed astandstill agreement in April pushing its shares down 35 percentthen
** More than 16 mln shares traded, more than 3x 30-daymoving avg
** Up to Friday's close, stock had fallen 69 pct this year (Reuters Messaging:pranav.kiran@thomsonreuters.com@reuters.net)