Banca de QUALIFICAÇÃO: CARLOS AUGUSTO LEAL DANTAS

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : CARLOS AUGUSTO LEAL DANTAS
DATE: 10/02/2023
TIME: 14:00
LOCAL: videoconferência
TITLE:

Development of Lightweight Slurries Containing Nanosilica for Application in High-Temperature Oil Wells with Low Fracture Gradients

KEY WORDS:

Cementing. High Temperature Wells. Low Fracture Gradient. Nanosilica.

PAGES: 80
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Inorgânica
SPECIALTY: Físico Química Inorgânica
SUMMARY:

Cementing is an essential step in drilling oil wells. The cement used in high-temperature wells needs to be added with silica to avoid the retrogression process of the cementitious matrix that occurs from 110ºC onwards, as it forms hydration products that are deleterious to the cement. In wells with a low fracture gradient, it is necessary to use light cement slurries to avoid formation collapse, for this purpose, water-extending additives are used, the most used currently is sodium bentonite. However, its use implies the reduction of the mechanical resistance of the cement with the increase of its concentration. This work aimed to develop lightweight slurries containing nanosilica for application in high-temperature oil wells with low fracture gradients. Hence, slurries of density were formulated 12.5; 13.0 and 13.5 lb/gal, having nanosilica with a concentration of 0.00; 0.25; 0.50; 0.75 and 1.00 gpc, and reference slurries containing  2.00%  sodium  bentonite,  all  slurries  contained  40%  crystalline silica.  First,  the slurries  were evaluated  using  rheological  tests,  stability, compressive strength, X-Ray Diffraction (XRD), thermogravimetry (TG), and scanning electron microscopy (SEM). Next, the ones considered stable were selected and cured at 41 °C and 14.7 Psi for 24 hours and 28 days and under 300ºC and 2000 Psi for 28 days. Based on the results obtained from rheology, an increase in the rheological parameters can be seen with the rise in the concentration of nanosilica. In the stability tests, verifying that the increase in the NS concentration gradually reduced the top drawdown was possible. In the compressive strength test, it was noticed that the incr ease in the NS concentration increased the compressive strength of cement slurries for both curing temperatures. This is probably due to the greater formation of silica-rich phases and the filling of empty spaces by NS particles, based on the characterization tests. Finally, nanosilica can be characterized as a water-extending additive and its application in high-temperature oil well cementing with low fracture gradient is an up-and-coming alternative.

COMMITTEE MEMBERS:
Presidente - 1804366 - JÚLIO CÉZAR DE OLIVEIRA FREITAS
Interno - 1958858 - LUIZ HENRIQUE DA SILVA GASPAROTTO
Externo ao Programa - 1995142 - RODRIGO CÉSAR SANTIAGO - null