Over the last decade, three-dimensional (3-D) imaging and modeling of the subsurface through time (4-D) have co-evolved and emerged as a major research focus of the petroleum industry. Virtually all major oil companies have independently recognized the need for 4-D petroleum system models (also called basin models) because they:
- Organize data, allowing deficiencies or inconsistencies to be identified,
- Archive data (data loss due to personnel attrition and reorganization is a major cost factor),
- Facilitate visualization of geologic processes and communication with stakeholders, and
- Add value by converting static data into dynamic processed data and interpretations.
4-D petroleum system models can serve as evolving databases that provide surface and subsurface geologic information for various practical research needs. They allow users to figuratively look within the earth to examine data, appraise the reliability of geological concepts, models, or geochemical input, and extract needed information. Major applications of 4-D geologic models include developing predictive exploration and reservoir models, integrating sequence stratigraphy and assessment units, predicting the extent and timing of petroleum generation in source rocks, structural deformation that disturbs basin architecture, migration pathways, and locations of potential traps and accumulations, and analysis of risk based on different geologic, geochemical, or fluid-flow assumptions. Thus, 4-D geologic models can provide a basic geoscience framework to conduct and record a wide variety of applied and basic research.
As petroleum becomes more difficult to find and reserves become more difficult to replace, 4-D petroleum system modeling has grown because it better quantifies the generation, migration, and entrapment of the remaining resource. It also facilitates interpretation of the stratigraphic and sedimentologic processes that are important to develop a predictive sequence stratigraphic framework. Because of financial and time constraints, large oil companies typically conduct 4-D modeling studies only at scales to suit their immediate needs. These studies commonly cover only the acreage held by each company and seldom cover the full extent of each petroleum system. This knowledge gap represents an opportunity for the proposed 4-D petroleum system modeling group at Stanford because many domestic and international companies are willing to supply data and expertise. Companies will benefit from Stanford studies that extend 4-D interpretations beyond immediate concession areas. For example, many oil companies exhaustively study postage-stamp areas within basins, but 4-D modeling may not have been conducted over the entire area (e.g., Gulf of Mexico, San Joaquin Basin, Permian Basin, Los Angeles Basin, North Caspian Basin).
4-D petroleum system modeling is rapidly growing as a tool to better understand subsurface migration, accumulation, and preservation. The approach is strong as a tool to predict the pod of active source rock, thermal maturity of the source rock, migration pathways, and the timing of petroleum generation. 4-D modeling is currently less successful as a means to predict volumes of trapped petroleum, their detailed compositions, or the effects of secondary processes. However, solutions to these questions could have major impact on the domestic and world economy. 4-D modeling is a tool that will continue to attract new users because of the potential for high-impact solutions to these problems with respect to exploration, development, and assessment. However, these questions are particularly amenable to the proposed program at Stanford because to properly address them will require coordinated, long-term research not generally undertaken by industry.