Casing mounted method used for geotechnical drilling in Lavan

摘要

The paper aims to present a modified casing mounted method for geotechnical drilling used in Persian Gulf. The present geotechnical investigation was undertaken for a SBM project which is located at 4.5 km South-West of Lavan Island in a water depth of 55 m. The geotechnical investigation of the project includes the drilling of 5 boreholes, undisturbed sampling and also CPT probing adjacent to boreholes. The depth of boreholes into the seabed was 60 m. A floating barge of 12000kN was utilized for geotechnical investigation. The horizontal movements of the barge were minimized by means of mooring anchors. Tension forces of mooring cables were measured during the drilling operation to predict any horizontal movement of the barge. The vertical movements were compensated by installing the drilling machine on a modified vertical casing pipe. The following results were achieved out of successful implementation of the project: 1. Accurate active control on horizontal movements of the barge by four anchors and force measurements were successfully experienced. 2. A light casing mounted method for installation of drilling system was designed and experienced.