Banca de QUALIFICAÇÃO: Haris Raza

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : Haris Raza
DATE: 17/11/2022
TIME: 14:00
LOCAL: ON LINE (TEAMS)
TITLE:
KEY WORDS:

Irapé,Nova Ponte, numericalmodeling, Reservoirtriggeredseismicity, stress, velocity model, porosityandpermeability 

PAGES: 68
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

The Magnitude 4 Reservoir triggered seismicity mechanism at Nova Ponte is still important to understand, the second-largest known case of Reservoir triggered earthquake (RTS) in Brazil.  The main event occurred in the year 1998 along predominantly reverse faulting and roughly oriented NE-SW. But it still remained to understand whether it occurred by state pore pressure or undrained response of excess loading of the reservoir is such low permeable rocks that are needed to induce RIS/RTS. If the pore pressure diffusion could not propagate deep into vertical low permeable rocks and it can take hundreds of years to reach the depth of the earthquakes. So, in such above conditions, the two major events of triggered earthquakes occurred in 1995 and 1998 just after 1.5 years after the impoundment of the reservoir when the water reaches the highest level. To explain the causal relationship between the reservoir water level fluctuations at the surface and earthquakes at hypocentral depths and at the basement in terms of stress changes. In such cases apart from seismology then it is necessary to understand the fault mechanism by other methods such as numerical modeling of an area. Thus, in this paper, we made the first time an attempt in this area to explore the casual mechanism by creating the 3D Reservoir model and its effect on the subsurface both in terms of pore pressure and stress changes with the help of numerical modeling. We have seen that our findings can explain the triggered seismicity by the undrained response of excess loading of the reservoir filling due to pore pressure perturbation such in deep underground low permeable rocks. It is observed that a fault in the granitic basement is more prone to slip with the strike-slip component of reverse faulting. The results presented provide a comprehensive analysis of subsurface strength during reservoir loading impacts and implement a systematic approach to determining the effect of RTS. The comparison of our model with the fault plane solutions from the earthquake data provides valuable insight into the nature of the seismogenic fault mechanism. The second case study is HPP Irapé becomes an important issue to understand reservoir-triggered seismicity. The seismicity here started to increase in a short time after the impoundment of the reservoir and completion of the dam with the largest event on 14 May 2006 of 3.0 magnitude felt at the reservoir area. The general procedures of porosity and permeability creation in rock masses through increased pore pressure are principal keys in many areas of geoscience, as popular one of the most important roles in RTS too. The main focus of this study is proposing preliminary findings of the porosity & permeability based on petrophysical analysis and geological aspects, hydrological and structural interpretation. So, we did a permeability and porosity test of cylindrical plugs from the hard and intact samples that were extracted near the RTS zone to identify and describe the primary role of porosity and permeability. This study and analysis suggest a better understanding of the seismic events; thus, we reported porosities values from our data vary from 6.340 to 14.734 %, and the mean permeability of about 1.0923 mD (millidarcy) that is correlating with the range of permeability for the characteristic of RTS (0.1-10 millidarcy). Our preliminary evaluation assessment encouraged the results and provided a better understanding of RTS in this area. 

BANKING MEMBERS:
Externo ao Programa - 2156153 - ELDER YOKOYAMA
Presidente - 1542246 - GEORGE SAND LEAO ARAUJO DE FRANCA
Interno - 2370895 - LUIS GUSTAVO FERREIRA VIEGAS
Externa ao Programa - 3165215 - MONICA GIANNOCCARO VON HUELSEN
Externa ao Programa - 1780820 - SUSANNE TAINA RAMALHO MACIEL