Integrated Basin Evaluation Using Two-Dimensional Simulation of Fluid Flow, Thermal Transport, Hydrocarbon Production: Application to Northern North Sea

Wei Zengpu, Christian Hermanrud, Ian Lerche

Vertical line-fault behavior is allowed within a two-dimensional basin simulation model. The fault model permits relative movement of the faulted blocks (normal and reverse) and open or closed fluid-flow conditions. Simultaneous simulation of a number of vertical line faults, horsts, and grabens is included, increasing the two-dimensional model's flexibility.

Application of this model to the Sleipner area, northern North Sea, reveals several points. (1) Temperature differs from Sleipner east (horst) to Sleipner west (graben) at the same depth. The difference is about 5°C. The cause of the temperature difference is the thermal effects of both salt and convention. (2) The mature source rocks are at depths ranging from 3,000 to 4,000 m in the graben centers. (3) Salt has a major effect upon the basinal geologic history. (4) Hydrocarbons accumulate in both structural and stratigraphic traps.

Our simulation shows how the model can (1) handle rather complex geologic structures such as faults, horsts, and grabens as well as general structural styles (anticlinal or synclinal); (2) simulate sedimentation processes, including normal sedimentation, erosion, and hiatuses; (3) predict the geothermal history and evolution of geologic parameters such as formation temperature, fluid pressure, abnormal pressure, and vitrinite reflectance (from these, maturation of organic matter is assessed); and (4) quantify oil generation, migration, and accumulation through geologic time. The model behaviors are shown to be consistent with downhole data taken at the present time. The resolution provides an estimate of the rugged stability of the detailed behaviors.

The results can be output as graphs either in one dimension or in two dimensions, providing a pictorial representation of evolution of the area.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.