Desenvolvimento de compósitos cimentícios para cimentação de poços direcionais

Abstract

The productive capacity of oil wells is directly related to the quality of cementing. Cementing has the objective to isolate the undesirable areas of the producing zone. In some cases, increasingly frequent and usual, to achieve the desired zone during drilling, are required angle deviations and large horizontal extension, subjecting the well to the high variation in geothermal gradient. The cementing operation of directional and horizontal wells requires specific conditions of cement slurries with greater fluidity and stability, and grip specific times. Another major concern is the mechanical behavior of cemented wells region undergoing stimulation of oil recovery by thermal methods. Where, because of thermal expansion of the metal coating, not accompanied by the same ratio of cement sheath, crack formation occurs in the cementitious material, compromising the mechanical integrity of the void. Cements composite containing polymers has been studied to ensure a better quality of cementing wells subject to high temperature conditions, ensuring greater coefficient of thermal expansion of the cement and greater adherence to coating. In this context were developed cements composite containing polymers for cementing operations directional wells with large horizontal runs, subject to steam injection condition. The influences of polyurethane addition and chitosan were studied in cement slurries in fresh and hardened state, through standardized laboratory tests. Slurries containing polyurethane and chitosan had good fluidity, density stability and assist in the filtrate control.