Maria Carmen Moreira Bezerra

PCA: uma ferramenta para identificação de traçadores químicos para água de formação e água de injeção associadas à produção de petróleo

This study describes the use of Principal Component Analysis to evaluate the chemical composition of water produced from eight oil wells in three different production areas. A total of 609 samples of produced water, and a reference sample of seawater, were characterized according to their levels of salinity, calcium, magnesium, strontium, barium and sulphate (mg L-1) contents, and analyzed by using PCA with autoscaled data. The method allowed the identification of variables salinity, calcium and strontium as tracers for formation water, and variables magnesium and sulphate as tracers for seawater.

Recuperação Avançada de Petróleo: Potencialidades da Injeção WAG (Water Alternating Gas)

The increase in the recovery factor in an oil reservoir is an essential goal in the oil industry and in this sense, complementary and alternative methodologies have been developed, for example, the alternating injection of water and gas (WAG), which has been used ever as a more advanced method of recovering oil. This method combines the best gas displacement and swept the water efficiencies. Recent discoveries of oil reserves in the Pre-Salt layer, with a significant amount of gas whose CO 2 content is in the range 8-12%, the use of CO 2 gas in WAG injection (WAG-CO 2 ) has emerged as an opportunity for Brazil. Besides the good prospect of increased oil recovery factor of these reservoirs, this process is in line with mitigation actions by greenhouse emissions CO 2 . This article is a compilation of WAG application projects in the literature, as well as issue related to Brazilian initiatives that focuses on numerical simulations using reservoir models, since the carbonate rocks common to the pre-salt reservoirs are reactive the injected fluids . DOI: 10.5935/1984-6835.20160055

Mathematical modelling of scaling in a reservoir which contains impermeable layers

Several different scenario of injected and reservoir water mixing have been proposed: mixing at high velocity near to injectors, mixing at low velocity inside reservoirs, mixing by diffusion via boundaries of layers with different permeabilities, mixing of injected, connate and aquifer waters at high velocity near to producers. Just the latter mechanism results in the accumulation of formation damage, while other mechanisms cause precipitation near to moving concentration front. In the current paper a new mechanism of oilfield scaling by diffusion of Barium from impermeable layer into the reservoir is proposed. The mechanism results in accumulation of precipitant and of formation damage. Viscous dominant regime of waterflooding takes place in the majority of oil fields. The Welge´s method allows calculating the permeability distribution from water cut history. The proposed extension to Welge´s method determines the partition of permeable layers in a reservoir from tracer concentration in production wells. Knowledge of this partition is important for modelling of oilfield scaling accounting for Barium supply from impermeable layers.