Caracterização de chaminés de gás nas bacias do Parnaíba, Paraná e Tacutu: uma nova ferramenta exploratória

Abstract

This study aims to apply a special processing in the investigation of gas chimneys in the Parnaíba, Paraná and Tacutu Basin and, through an interpretation in seismic sections that have been improved by a special seismic processing that facilitates the visualization of these seismic features, thus helping future hydrocarbon research in these basins. The new processing methodology aims to facilitate the interpretation process in seismic data with gas chimneys through the expansion of the frequency spectrum of the seismic signal in the Hilbert domain. This research methodology, by allowing an amplification of the information concerning the petroleum system, becomes a new exploratory tool because it reduces the high exploratory risks inherent to the border basins with a high territorial extension, such as the Parnaíba and Paraná Basins. Another basin that was also visited in this dissertation, aiming to investigate the presence of gas chimneys, was the Tacutu Basin. Often the seismic response of gas chimneys is treated as noise or even their presence is not even perceived in conventional PSTM seismic processing. This work shows a processing methodology that seeks to highlight the gas chimneys and make their interpretation in the seismic profiles unequivocal. Its sismofacies consists of chaotic and low frequency disturbances that interrupts the lateral continuity of good reflectors and its origin is related to migration of fluids or free gas, in its path between the source rock and the reservoir rock. In addition, this research, by observing the rooting of the gas chimneys in the basin grabens, strongly indicates a new active petroleum system associated with the pre-silurian deposits present in the grabens. To facilitate the management of future exploratory process by directing the new seismic programs to be acquired, a table was elaborated with different types of traps associated to gas chimneys found in this basin and their respective probabilities of success considering the results obtained in this basin and in other parts of the world. Those most likely to succeed should be those chosen for further seismic detailing. Considering the quantity of gas chimneys encountered with this special processing, the significant area of the structures found and the other direct hydrocarbons indicators revealed in the work, it can be affirmed that one faces a basin with a high potential for commercial discoveries of hydrocarbons and with relatively low risk. Considering the quantity of gas chimneys encountered with this special processing, the significant area of the structures found and other direct hydrocarbons indicators revealed in the work, it can be affirmed that one faces a basin with a high potential for commercial discoveries of hydrocarbons and with relatively low risk. Although few lines of the Paraná Basin were studied, the seismic sections also showed a highly attractive basin with many gas chimneys and other direct hydrocarbons indicators. The Tacutu Basin was the only one that did not received the seismic processing here called PEEF. However, comparing the seismic interpretation of the sections processed with the application of the WIT / CRS System with sections of SEMBLANCE attribute and geochemical surveys of the ANP, suggest a great possibility of being actually gas chimneys the interpreted seismic features.