Print this pageSensitivity Analysis of Thermal and Hydraulic Properties and Their Impact from Petroleum Systems: Example from a Brazilian Case Study
Petroleum system modeling is a multidisciplinary activity that integrates geological data from various scales. It requires information of rock physics to define its variation in depth and over time such as porosity, permeability, capillary pressure and thermal conductivity of the main rocks. The thermal history of sedimentary basins depends on two key factors: firstly, heat flow variations in the basement, secondly, the means by which this basements derived heat is transferred through the sediments. Sedimentary rocks have a wide range of thermal conductivity, from low values for slightly compacted rocks to high values for consolidated rocks. The lack of knowledge of the thermal conductivity values and its variations in the past often causes misfit between estimated temperature and vitrinite reflectance data with respect to measured ones. Therefore, the differences are normally reduced by increasing or decreasing the heat flow that is imposed as a boundary condition in the basement of the model. This procedure usually causes errors in estimating the timing of oil formation in the source pods. Similar problems happen when petrophysical properties (i.e. capillary pressure and permeability) are unknown and just selected from a default library of commercial software. The properties of all the rocks that exist between the generating and reservoir rocks must be known with a minimum certainty because they control the prediction of the amount of hydrocarbon and its quality within a studied basin. This work aims to make a risk analysis of heat and hydraulic properties using measurements carried out by HRT Petroleum and to show the effects caused by the lack of knowledge of petrophysical properties in the model. It is possible to draw some preliminary results of this work: (1) the lack of thermal data measured used to calibrate the thermal model generated uncertainties in the maturation of source rocks; (2) two thermal scenarios were analyzed; the first has higher than average thermal boundaries and second has relatively cold thermal conditions, and both have different expelled volumes; and (3) the lack of direct hydraulic data measured that governs the velocity of petroleum migration are critical in predicting the timing of petroleum expulsion, their predicted composition, quality and volume accumulated.
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil