Globally, marine petroleum source rocks dominate; however, lacustrine source rocks are of regional importance. These lacustrine rocks share many common geochemical attributes with their marine counterparts, but typically produce oils which differ both chemically and physically. Their distribution in time and space has been of growing importance as exploration has shifted from known marine provinces. There are three main factors which control the distribution of these economically important rocks: (1) those factors controlling lake development and its chemistry, (2) the level of primary productivity, and (3) the efficiency of organic preservation.

Large lakes capable of producing sufficient volumes of sediment to result in economic hydrocarbon accumulations form as a result of tectonic processes in both extensional and compressional regimes. Maximum potential for source rock development is coincident with maximum subsidence rates when associated with minimum sedimentation rates. Variations in subsidence rate within and across basins is a partial explanation for facies variations within these basins.

Productivity within lake basins is largely controlled by nutrient recycling within a mature lake system. High levels of productivity may also be maintained when the drainage basin contains streams with a high chemical load, in particular phosphate. In basins with a high width/depth ratio, the level of productivity appears to be the driving force with respect to source rock development.

Preservation efficiencies are controlled by biologic and abiologic processes. In general, organic preservation is favored when the lake is stratified and anoxia develops. Such conditions are favored at low latitudes and when salinity contrasts occur. Preservation efficiency appears to be a primary driving mechanism in lakes with a low width/depth ratio.

The integration of these component factors results in a predictive qualitative model. The application of this model is then presented for western Indonesia to explain the observed distribution of lacustrine source rocks within the region, as well as the local variability of the source.