The CarmóPolis Field: A New Structural Modeling for a Mature Field
The Carmópolis Field, discovered in August 1963, is located in the northeast region of Brazil and inserted in the Sergipe-Alagoas Basin. This field is divided into two blocks. In the Basement Block, the production is related to fractures in the pre-cambrian basement rocks. The production of the Main Block is mainly linked to a domic structure and from the siliciclastic rocks of the Carmópolis Member. This field is considered one of the most important of Petrobras (13th STOIIP).
The study aimed to generate a new structural model for the Main Block of the Carmópolis Field, in order to support the expansion project of water injection.
For structural modeling, the faults were reinterpreted based on data from wells and outlined the plans following the failure of major gaps in the reference surfaces (top of Carmópolis Member and top of zone CPS2).
It was equally important to model pre-Carmópolis formations, although it has been performed with a high degree of uncertainty associated with these formations which have a structural pattern rather different from the Carmópolis Member, with an angular unconformity between them. The study focused on a more precise structural modeling for the Carmópolis Member, propagating these faults to the pre-carmopolis formations. This way of spreading faults proved to be consistent, since the event of local structure reaching the Carmópolis Member also affected lower formations.
The methodology adopted to generate the horizons initiated with the construction of the Carmópolis Member top, and proceeded with the adjust of all fault gaps to this horizon. Afterwards, with the help of the well markers, maps of thicknesses were generated for each zone. Finally, these maps were used in the construction of every zone. This methodology is the one that best fits this model as to how to represent the non-occurrence of a zone in some portion of the field and show the angular difference between the Carmópolis Member and the other formations.
Compared to the previous 2D model, the NE-SW regional pattern of the major faults was maintained. However, a second trend NW-SE composed of minor relief faults was included. The curve faults, the "L” shaped and several sigmoids were eliminated from the model.
To conclude, this new structural model has already successfully answered questions about the real positioning of the oil/water contact and the performance of the bacteria injection in some areas of the field.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009