Vietsovpetro (VSP) has concluded operations at appraisal well Thien Nga 3X (12/11-TN 3X) in Block 12/11, offshore Nam Con Son Basin, in late March 2017. Gas was successfully tested with the well flowing more than 35 MMcfg/d from the Oligocene Cau sandstones. It was understood that four highly deviated pilot holes were drilled to a depth ranges of 4,500 m to 5,510 m. The well was spudded on or around 20 August 2016 and was drilled to a TD of 5,510 m using the âMurmanskayaâ J/U. It was intended to test the extent of the Dua and Cau sandstones.  The Thien Nga 1X gas and condensate discovery was made in 2001 by Samedan Vietnam under Block 12W. The well flowed 20 MMcfg/d and 150 bc/d from the Upper Oligocene Cau Formation. The discovery was appraised in 2002 with the 12W-TN 2X well which flowed minor gas from the same formation. The last activity in the block was the drilling of 12/11-QF 1X (Quyt 1X). The well, spudded in late October 2015 using the âCuu Longâ J/U did not encounter hydrocarbons in the Lower Miocene to Oligocene Dua and Cau formations. Quyt 1X was plugged and abandoned at a TD of TD 4,360 m in February 2016. A 1,200 sq km 3D seismic survey was completed over the block in Q3 2013, using CGGâs âGeo Coralâ S/V. The Miocene and Oligocene clastics prospects have been mapped within the block. Vietsovpetro is operator of Block 12/11 with a 100% interest. Vietsovpetro is a joint venture between PetroVietnam (51%) and Zarubezhneft (49%). 
Vietnam (Nam Con Son B.) 12/11-QF 1X op. by ZARUBEZ N (60.0%, VIETSOV 0.0%, SOVICO HLD 40.0%) in Block 12/11