Banca de DEFESA: WENDELL ROSSINE MEDEIROS DE SOUZA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : WENDELL ROSSINE MEDEIROS DE SOUZA
DATA : 30/05/2017
HORA: 09:00
LOCAL: Auditório do laboratório de cimentos
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, latex, oil wells cementing, integrity

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

The exposure of oil wells to extreme conditions has led to numerous integrity issues. The use of recovery techniques such as the cyclic injection of steam submits the materials to severe temperature variations reducing the oil well useful life. Heating causes the casing to expand producing stresses on the cement sheath leading to failure. 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 mechanical cement pastes behavior with addition of latex was analyzed. Three groups of cement paste were studied: reference paste with silica, and two other 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, 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. 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. It was found that in a more rigid surrounding area the same cement composition can have the shear stresses reduced.

MEMBROS DA BANCA:
Externo à Instituição - ANA CECILIA VIEIRA DA NOBREGA - UFPE
Presidente - 1298936 - ANTONIO EDUARDO MARTINELLI
Externo ao Programa - 1754344 - MARCOS ALLYSON FELIPE RODRIGUES
Interno - 1149372 - TARCILIO VIANA DUTRA JUNIOR
Externo à Instituição - ULISSES TARGINO BEZERRA - IFPB