Publications

The petroleum system of the South Sumatra Basin in Indonesia was modelled using deterministic basin modelling techniques. Modelling any system involves approximation of the parameters that describe its components. Even in the South Sumatra Basin, a mature province where the components of the petroleum system are well constrained, the uncertainty associated with those approximations needs to be taken into account to ensure the basin simulation results are more reliable.A detailed evaluation of the hydrocarbon generation, migration and entrapment processes in the study area has been carried out using 2D and 3D basin modelling software. The simulation of hydrocarbon migration was made along a 2D section that passed through three hydrocarbon fields: Matra, Benakat and Jirak. Benakat and Jirak (500 MMboe in place volumes) were used as calibration points in the modelling process. The modelling of the Matra Field was undertaken as a “blind test in that the results of the exploration well, drilled in 2000, were not known to the modelling team.The uncertainties related to some petroleum system components (source rock richness, carrier bed properties, seal efficiency) were analysed using an innovative workflow featuring experimental design and response surface methodology available in the software application. The sensitivity analysis involved only 45 simulations and a computing time of less than two hours using four parallel processors. Typically, conventional Monte Carlo Simulation (MCS) would have required 10,000 simulations or more to achieve a comparable result.The large number of dependent variables, the geographically large area of interest and the nonlinear and interdependent relationships between many system components relationships mean that MCS is unrealistic, even with todays computing power.A hydrocarbon accumulation of approximately 40 MMbbl oil in place was predicted in the Matra structure. This is in good agreement with the actual resource (25 MMbbl oil in place). The risk analysis indicated that there was almost no chance that the structure was dry. The mass of hydrocarbons in the Matra structure is predicted to range from 410 kg/m2 (P90) to 1120 kg/m2 (P10) with a median value of 700 kg/m2. The result has provided increased confidence in the basin model of the South Sumatra Basin and has allowed improved estimates of probability of success and range of hydrocarbon volumes to be made at undrilled structures. This technique may be used to better constrain basin modelling results for other quantitative predictions such as reservoir pressure and temperature.