Salt Emplacement and Its Impact on the Thermal Maturation of Source Rocks: Application of a Modified 1-D Thermal Indicator Tomography

KAI, ZHAO, and IAN LERCHE, University of South Carolina, Columbia, SC

The presence of salt in various shapes in the subsurface can have a significant impact on the subsurface temperature distribution and thermal maturation of source rocks, due to the contrast in thermal conductivity between salt and typical sedimentary formations. An anomaly can be induced in reconstruction of the thermal and hydrocarbon generation histories for the basin when contrasting the temperature data and maturity markers from salt structures with the areas distant from salt.

Results of using an updated thermal indicator tomography 1-D modeling system that deals with salt emplacement demonstrate that a thermal anomaly and excess maturity can be caused solely by the presence of a salt layer. Further, the timing of salt emplacement and the variation of salt thickness can be determined. As a case history, the technique is applied in the Sogne basin Lulu 1 well, located in the northeast part of the Danish Central graben. By following the regional heat flow pattern for the Sogne basin and considering the effect of salt (maximum thickness about 3000 m) in the well on thermal maturity anomalies, the modeled maturity and hydrocarbon generation become more reliable and accurate.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)