Estudo de composições de cimentos Portland comerciais e Silica Flour para cimentação de poço de petróleo.

Abstract

Cementing wells is a routine activity in the oil industry, but requires care series because it is a costly activity that, if not properly conducted, can cause extra expenses as well as environmental damage. These wells, generally, feature high temperatures and pressure, which can destabilize the cement paste causing cracks. This study aims propose through the mixture design and response surface methodology, a composite composition of cement Portland commercial and silica flour (SF), that can replace efficiently, the special Portland cement for oil well, when it is not available in some stage of cementation and there is the need for their immediate use. Initially, the characterization of the raw materials they were made by through the sieve analysis of the laser granulometry, chemical analysis, X-ray diffraction and thermal analysis. Then, were made compositions for cements CP II E, CP III and CP IV more addition of SF through by the mixture design methodology, and subjected to the determination tests of resistance to compressive and thermal analysis, with the purpose to determine optimum composition that most resembles the features of the Portland cement Special for oil wells. From the results obtained with the mixture design, they were selected the compositions constituted of CP III and CP IV with the addition of SF, because they presented better results. These compositions were subjected to tests of water absorption and resistance to attack by sulphates. The cement that showed more stability against attack by of sulfate was CP IV. The addition of the SF as replacement of the Portland cement, improved properties of these pastes against attack and water absorption. This allowed to conclude that the CP IV cement was more effective to replace the special portland cement for oil well and that the addition of silica flour as replacement of the Portland cement improves the properties of the cement pastes against attack and the water absorption. In addition to providing the same thermal stability.