Fault seal analysis of fault F2 and its influence on oil and gas migration for VS prospect area, block 16-1/15, Cuu Long Basin, Viet Nam

Tóm tắt

Cross-fault sealing analysis is commonly done by direct and indirect assessments. The former evaluates fault sealing capacity by analyzing MICP (Mercury injection capillary pressure) of samples taken directly from fault zones, which is easy for surface-exposing faults, but difficult to carry out for subsurface fields. The latter method indirectly evaluates cross-fault sealing capacity by establishing a relationship(s) of Buoyancy pressure (BP) or Across fault differential pressure (AFDP) /or Across fault pressure difference (AFPD) with properties of fault plane such as Shale-Gouge-Ratio (SGR) and will be applied for this study. Each fault with a SGR value (higher than the sealing vs non-sealing cut-off) can hold a certain maximum AFDP value related to a maximum hydrocarbon column, and the fault will start leaking if the actual hydrocarbon in formation exceeds the maximum limit. The study’s purpose is to evaluate fault F2 seal capacity and its influence on oil and gas migration of the Miocene-Oligocene fault-bounded VS structure in block 16-1/15, Cuu Long basin, offshore Vietnam. Seismic and petrophysical data are used to build a 3D structural framework and stratigraphy model in the VS structure and adjacent areas. The authors will use parameters such as age, fault throw, Vshale (volume of shale), lithology, bed thickness, burial depth history, fluid density, and pressures… for fault seal analysis. Maximum hydrocarbon column height estimation can be held by fault F2 using the empirical relationship between threshold pressure and SGR (Shale Gouge Ratio), combined with the petroleum system model result from previous studies to evaluate fault F2’s influence on hydrocarbon migration into the VS structure, therefore helping to assess the hydrocarbon potential in undrilled structures in further exploration plan