Determinação das propriedades da torta de filtração de fluido de perfuração e estimação de parâmetros

Abstract

The undesirable fluid invasion into the reservoir rock can cause irreversible damage to the rock formation. In order to avoid such problems, solid particles are used as bridging and weighting agent in drilling fluid formulations. The physico-chemical characteristics of these materials have a strong influence on cake formation and therefore on filtration rate and mud-filtrate invasion in rock formations. Thus, the control of filter-cake properties is critical in the oil well drilling process. The focus of this research was to evaluate the effect of calcium carbonate particle size and the concentration of two different types of polymeric viscosifier on static filtration tests. The experiments were performed in a HTHP cell (High Temperature, High Pressure) manufactured by OFI Testing Equipment®. This apparatus was previously used by Calabrez (2013), Martins (2013), and Ferraz (2014). The filter cake parameters evaluated were: porosity, permeability, cake thickness, filtrate volume, growth rate, and compressibility index. The particle size distribution of calcium carbonate, the viscosifier and its respective concentration influenced the rheology of the fluids and the filtration process. Equations that describe the filtration phenomenon and which allow the calculation of the filtration parameters were evaluated. Experimental data obtained in other studies were assessed in order to validate the studied model. Based on literature models, the simulation of drilling fluid filtrate invasion was performed in an oil well connecting the filtration and filtrate invasion equations. Using the simulation result of each fluid behavior it was possible to predict the characteristics of the fluid which will cause less damage to the oil well in this context.