In recent years, a need has been recognized to develop pressure transient technology for slanted wells in single and multiple layered systems. To date, none of the published results pertains to the pressure transient response of a slanted well in a layered system. Moreover, the published pressure transient response of a slanted wellbore for single layered systems is based on a uniform flux assumption along the wellbore surface. Therefore, a 3-D finite element numerical model utilizing the infinite conductivity wellbore assumption was developed to study the pressure transient behavior of slanted wells in both single and multiple layered systems.
The purpose of this paper is to present pressure transient responses for a variety of cases using the finite element and the analytical solutions. The slanted wellbore cases include the effect of partial penetration, wellbore storage, and reservoir heterogeneity for single layered systems, and typical pressure transient responses for multiple layered systems. The important parameters which influence the pressure behavior of slanted wells in a layered reservoir, with and without interlayer cross-flow, will be presented. In addition, the response of a slanted well in a naturally fractured (dual porosity) system will be discussed. Finally, the pressure transient analysis of the data using field examples will be shown to demonstrate the usage of the developed model.
The present study of the pressure transient responses of slanted wells in both single and multiple layered systems should enhance our understanding and add to our capability to design and analyze well tests.