Cement Sheath Evaluation in Nonconventional Environment—Case History

Abstract

fax 01-972-952-9435. AbstractSonic and ultrasonic tools have been widely used for cement sheath evaluation along the last decades. The evaluation main goal is the definition of the presence of cement in the annulus and its ability of promoting hydraulic isolation among different permeable zones, regardless of its density, compressive strength or even quality of the slurry. The challenges interpreting those logs are enormous because the influence of many variables in the acoustic signal. The difficulties increase dramatically if the well configuration is not conventional. In those cases, huge mistakes can occur requiring from the interpreter experience, understanding of the tools and acoustic principles, and detailed information about the well, casing, cement, and so on. The paper describes in detail three well documented cases histories where nonconventional conditions in the wellbore prevailed and required extreme care and experience to obtain the correct log interpretation. The first case reports the evaluation of an annulus with cement between two concentric casings; the disturbances caused by reflections from the second interface in the CBL signal are discussed and recommendations presented to bypass this obstacle. In the second case, the challenges to evaluate the cement sheath in a fiber glass casing are presented; usually in this case, the first signals arriving at the receiver do not come from the casing. Finally, the last case history describes the difficulties to come up with the right evaluation logging a liner cemented with lightweight slurry. For all cases, guidelines and recommendations are suggested to avoid misinterpretations and assure correct decisions about cement sheath evaluation.

Comparação De Métodos De Extração De Curvas De Dispersão Baseados Em Transformada De Fourier 2-D E Através Do Método Matriz Pencil

“…A avaliação do cimento por meio de ondas acústicas é complexa devido ao número de variáveis envolvidas e depende diretamente da configuração de camadas do poço (21). Atualmente, a verificação da cimentação de um poço para abandono depende da remoção da coluna de produção para que se obtenha maior grau de confiança com respeito às informações sobre a qualidade do isolamento.…”