engleski

Wellbore Instability: Causes and Consequences

Wellbore instability is one of the main problems that engineers meet during drilling. The causes of wellbore instability are often classified into eithermechanical (for example, failure of the rock around the hole because of high stresses, low rock strenght, or inappropriate drilling practice) or chemical effects which arise from damaging interaction between the rock, generally shale, and the drilling dluid. Often, field instances of instability are a result of a combination of both chemical and mechanical. This problem might cause serious complication in well adn in some case can lead to expensive opertaional problems. The increasing demand for wellbore stability analises during the planing stage of a field arise from economic considerations and the increasing use of deviated, extended reach and horizontal wells. This paper presents causes, indicators and diagnosing of wellbore instability as well as the wellbore stresses model.

well; instability; stress

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