Print this pageModeling Hydrocarbon Generation and Migration in a Rift Basin: Discussion of Complex Non-Conventional Petroleum Systems in the Miranga Low (RecôNcavo, Brazil)
The Recôncavo Basin is considered a mature basin. According to non-conventional plays concepts there might still be sizeable residual petroleum volumes in this basin. Based on non-conventional plays, petroleum is more disseminated in the basin and the hydrocarbon volumes can be pictured as distributed in a pyramid. At the top of the pyramid are the conventional reservoirs with the best permeabilities and porosities. In the pyramid base would be fine-grained reservoirs with low permeability and low porosity characteristics, but with largest volumes. Besides, the source and sealing rocks characteristics are critical factors to be considered. Owing to the complex rock types, it is important to have a clear understanding of the intrinsic permeability, porosity and capillary pressure of the mudstones. On the other hand, the Recôncavo Basin is a typical rift basin with half-graben geometry with pervasive faults and fractures that imprint a basic migration trend but also adds substantial complexity to hydrocarbon accumulation and distribution. The distribution of these large potential volumes can be discussed by basin simulations. Basin modeling is a single exploratory tool that meets geological data in several scales: from surface geological data to the deepest source rocks. However, lack of knowledge of the thermal and hydraulic properties of the reservoir rocks always have a large impact on the prediction of maturation, migration and timing of petroleum generation and on the expelled volumes. This work aims to build a 3D modeling framework crossing the Miranga Low and to run heat and fluid flow simulations using petrophysical properties measures by HRT Petroleum. The modeling results will support discussions about maturation trends, the migrations paths and hydrocarbon distribution inside of conventional and non-conventional reservoirs. This is an ongoing work, but preliminary results indicate that: (a) the heat flow in the area is normal at present day (~40 mW/m2); (b) petroleum expulsion is estimated to have taken place in two pulses: 135-130 Ma and 120-90 Ma; (c) migration took place along fault planes, by direct reservoir - source rock contact (Gomo SR), along carrier beds (Sergi Fm). The geochemical data indicate the rich source rocks are not clustered in thick layers, but distributed throughout the sedimentary column, which have impact on the petroleum expulsion, amount, and quality and on the distribution inside fine-grained rocks.
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil