Rock physics template (RPT) is a relative new tool of reservoir characterisation that can aid interpretation of well log data to help reduce the risks in seismic exploration and prospect evaluation. One of the popular RPTs is the crossplot of Vp/Vs (Compressional wave velocity/Shear wave velocity) versus AI (acoustic impedance) that proved to be very successful in reservoir characterisation of shallow unconsolidated sediments in the North Sea. However, construction of a RPT is very site dependent, thus when one extends the application of this type of RPT to other sites for those reservoirs that might be located deeper or consist of more consolidated or cemented sediments an adequate attention has to be given to the parameters in the rock physics models that are at the foundation of a RPT construction. This study deals with construction of a new RPT for the Middle Miocene sand (MMS), a gas-bearing sand located around 3,500m TVDSS (True vertical depth subsea) at Hai Thach field, Nam Con Son basin. In this resea