Effect of well stimulation on the skin factor in elongated reservoirs

Abstract

Because of fluvial deposition or faulting, many reservoirs around the world may possess a long and narrow geometry in which linear flow is expected to take place once radial flow vanishes, if existed. In any system through which a fluid flows, a change in the path direction causes additional pressure drop. Hydrocarbon reservoirs are not the exception to the rule. A change from radial flow to linear flow will be reflected as an additional pressure drop which may be referred as a skin factor, or more specifically, a geometric skin factor.  A couple of studies in the oil literature have named skin factors due to the change in flow patterns. Besides this, most of the commercial softwares may neither include nor calculate these types of skin factors since the simulations are normally run using the image methods, then, skin factors due to changes in flow path may be neglected.  Using the only methodology available to estimate the linear skin factors, it has been found from the experience on some field cases that this parameter is quite high in some cases and very small in other systems. Therefore, this paper is committed to the determination of the factors affecting the value of the linear skin factor and their impact on reservoir management.  It was found that neither reservoir permeability nor reservoir elongation had a significant impact on the linear skin factor value; however, the well stimulation does play an important role. The more damaged the well, the higher the linear skin factor value. From our simulation study, we found out that no matter if the well has a zero mechanical skin factor, still the linear skin factor has a high value. Besides, we demonstrated that the total skin factor increases as the linear skin factor increases with a ratio of 2,7385: 1,7385. Two Colombian field cases were worked with the purpose of verifying the findings of this article.