Banca de QUALIFICAÇÃO: WENDELL ROSSINE MEDEIROS DE SOUZA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : WENDELL ROSSINE MEDEIROS DE SOUZA
DATA : 09/02/2017
HORA: 09:00
LOCAL: Sala de reuniões do laboratório de cimentos da UFRN.
TÍTULO:

Numerical simulation of oil well cement sheath in a confined state subjected to cyclic steam injection

PALAVRAS-CHAVES:

Cyclic steam injection, numerical simulation, finite elements, Portland cement with latex, cementing of oil wells

PÁGINAS: 100
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Civil
RESUMO:

Cement sheath integrity plays an important role in maintaining the zonal isolation. In the case of wells subjected to cyclic injection of steam, the use of materials with addition of silica and with low modulus of elasticity has been indicated as solution. In the present work the cement sheath integrity when subjected to the cyclic steam injection was studied using an axisymmetric model in a numerical finite element method. The cement pastes behavior with addition of latex was analyzed. Three groups of cement paste were studied: reference paste with silica, and two with latex additive at concentrations of 125 and 250 mL / kg of cement, respectively. The cement sheath thickness influence and the heating rate were observed as well as six coefficients of thermal expansion of the hardened cement paste. The cement paste with 250 mL / kg of latex cement was analyzed in a situation with different temperature gradients, from the ambient temperature to 150 oC, 200 oC, 250 oC, 300 oC and 350 oC, typical temperatures encountered during the steam injection process as well As well as formations with various levels of stiffness. The use of latex was beneficial for situations of wells subjected to thermal load with the increase of normal stresses absorbed, and reduction of shear stresses by up to 13.4%. The study evidenced that for cements with thermal expansion coefficients below 6 x 10-6 / oC, tensile failure occurs in the cement sheath. The geometric factor of increasing the thickness of the cement sheath did not present advantages as a criterion to guarantee the integrity of the cement sheath. Despite reducing the normal stress levels by up to 20%, the circle of stress reaches the failure criterion. It was found that in a more rigid means the same cement composition can have the shear stresses reduced by up to 37%.

MEMBROS DA BANCA:
Presidente - 1298936 - ANTONIO EDUARDO MARTINELLI
Interno - 1149372 - TARCILIO VIANA DUTRA JUNIOR
Externo ao Programa - 1754344 - MARCOS ALLYSON FELIPE RODRIGUES