Traditionally the oil and gas industry has identified formation damage as the one caused by the drilling process such as filtrate and solid's invasion. Other types generated during the completion and production phases normally occur while perforating or during hydrocarbons production, typically fines production, asphaltenes deposition, changes in formation wettability and scaling. On the other hand, mechanical damage defined as that induced by stresses is seldom considered or even measured, it is poorly understood and very difficult to identify. Solid's invasion from the drilling fluid and permeability change at the sand face are the two damage mechanisms discussed in this paper.Both mechanisms are treated using conventional filtration theory and plastic rock behaviour principles.
On this basis our paper presents a methodology developed for the identification, quantification and removal of formation damage caused by these two mechanisms in new wells. Quantification of both types of damage on a continuous basis throughout the sandstone is carried out to determine the location and severity of the combined mechanisms.