Mecanismos de retenção do ácido aminofosfônico em microconstituintes de uma rocha arenítica

Abstract

In order to increase the recovery of fluids present in oil reservoirs, the oil industry applies several techniques, including the seawater injection in offshore exploration fields, to control the pressure drop in the reservoir during production. This technique provides a mixture of injected water (seawater) and water initially present in the reservoir, connate water. The mixture of water may result in formation of insoluble compounds, causing damage to the reservoir, pipes and equipment, bringing losses to oil companies. To prevent the formation of insoluble deposits, the most technic used is the squeeze, which the scale inhibitor is retained in the rock formation and prevents the formation of precipitates. Thus, in order to study the interaction between the inhibitor and the rock bath experiments were carried out using two minerals present in sandstone reservoir rock Berea, biotite and quartz, and nitrilotrismetylenephosphonic acid (NTMP) as inhibitor. Inhibitor retention tests studied the influence of temperature, pH and inhibitor concentration. The experiments also evaluated the possibility of obtaining a retention curve of a mixture of two minerals from their individual curves. The technique Optical Emission Spectroscopy Inductively Coupled Plasma (ICPOES) was used to determine the concentration of inhibitor in analyzed solutions. The results showed that the retention of NTMP in the rock biotite at 25 °C is controlled by adsorption and at 70 ° C by precipitation. At 25 °C, high retention values were obtained at pH 4. At 70 ° C the better retention was achieved at pH 7. It was found that prediction of multicomponent retention curves using monocomponent curves presents limitations when retention occurs by precipitation phenomenon.