Herlander Mata-Lima

A New Parallelization Approach for Sequential Simulation

The procedure for spatial sequential simulation – bi-point or multi-point stochastic simulation – of any type of variable starts with the definition of a random path which the simulation should follow in order to generate a structured image of a given attribute. One problem of these algorithms is related to the effort a single processor is required to undertake, especially when applying them to very large grids of nodes.

Comportamento hidrológico de bacias hidrográficas: integração de métodos e aplicação a um estudo de caso

This article intends to present different methods to calculate the concentration time (tc) and discharge in watersheds. The methods are divided into empirical and process-based and were applied to the Livramento watershed in Portugal. Due to the watershed’s spatial heterogeneity and space-time variability, one suggests use of the processbased method rather than the empirical in order to achieve more accurate results, since watershed occupation does not remain the same over time. The time of concentration obtained by empirical and process-based methods are then used to compute watershed discharge through the Rational and Soil Conservation Service methods. With this procedure one can predict the impact of man-made projects on watershed hidrology. The results show that process-based methods can be useful to assess the impact of a project in hydrologic system.

The use of sensory perception indicators for improving the characterization and modelling of total petroleum hydrocarbon (TPH) grade in soils

This paper proposes a multistep approach for creating a 3D stochastic model of total petroleum hydrocarbon (TPH) grade in potentially polluted soils of a deactivated oil storage site by using chemical analysis results as primary or hard data and classes of sensory perception variables as secondary or soft data. First, the statistical relationship between the sensory perception variables (e.g. colour, odour and oil–water reaction) and TPH grade is analysed, after which the sensory perception variable exhibiting the highest correlation is selected (oil–water reaction in this case study). The probabilities of cells belonging to classes of oil–water reaction are then estimated for the entire soil volume using indicator kriging. Next, local histograms of TPH grade for each grid cell are computed, combining the probabilities of belonging to a specific sensory perception indicator class and conditional to the simulated values of TPH grade. Finally, simulated images of TPH grade are generated by using the P-field simulation algorithm, utilising the local histograms of TPH grade for each grid cell. The set of simulated TPH values allows several calculations to be performed, such as average values, local uncertainties and the probability of the TPH grade of the soil exceeding a specific threshold value.

Analysis of the Self-Consumption Regulation for Photovoltaic Systems with Battery Banks in the Portuguese Residential Sector

Following recent trends in the developed countries, Portugal recently cut down the Feed-in tariffs for photovoltaic energy. They are now based on the Iberian market average (around 0.04€/kWh) while the final consumer electricity price is 0.16€/kWh. In this view, the PV system should be dimensioned for self-consumption since injecting into the grid produces less revenue. The motivation for the current work was to analyse the changes due to this new regulation, through the analysis of the economic feasibility of different size PV systems (1kW, 3kW, and 5kW), considering the selfconsumption regime with a battery bank as an option. We also compare the most profitable cities in Portugal with and without the use of a battery bank. The results show that the PV systems with battery banks are not as profitable as standalone PV systems in the Portuguese self-consumption regime. This is mainly due to the high price of the battery bank. In general, the mainland results are better than the islands for the 1kW and 3kW PV systems. In spite of the higher initial investment cost, the islands present better results for the 5kW PV system. In general, it can be stated that the investment in PV systems is highly conditioned by external economical factors that continuously change and the current work analyses the current situation in Portugal for different installed powers with or without battery banks.

Desafios ambientais e estratégias para condução da investigação e programas de intervenção social

This article discusses challenges concerning contemporary society with respect to social vulnerability. The role of holistic approach to face socio-environmental problems by integration of the sustainability dimensions is also addressed. Finally, an approach that combines qualitative and quantitative methods is recommended as the appropriate way to understand socio-environmental processes, and perform sustainable programmes.

Geostatistical History Matching with Direct Sequential Transformation of Images

The integration of production data in the stochastic modeling of internal reservoir properties is usually approached by an inverse problem. The inverse methodology consists on an optimization process of perturbation of the fine grid values of permeability and porosity in order to match the synthetic response of the model with the real production data. But as the relationship between internal properties, that one wish to model, and the dynamic data is highly non-linear, the solution passes always for the exercise of running a dynamic simulator, to obtain a simulated response, each time one perturb the values of permeability and porosity. This can lead to prohibitive time consuming in industrial applications. Hence the challenge in this field has been focused in the use of fast simulators or more efficient history matching approaches. In this study, a new approach of geostatistical history matching with a sequential perturbation of original variables (permeability field) is proposed. The field perturbation, is done by Direct Sequential Simulations and Co-simulations. Local models of co-regionalization allow for regional optimization of several producer wells responses.