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Description
Tight oil is petroleum that accumulates in relatively impermeable reservoir rocks,often shale or tight sandstones. Globally, tight oil resources provide signi?cant amount of petroleum for the world's energy needs. The flow behavior of tight oil in unconventional reservoirs are described by peculiar complexities that presents a challenging task in ?nding immediate solutions for reservoir engineers. It is there-fore critical to implement approaches that solve such problems without loosingvital information of the flow phenomenon. This study demonstrates a general concept to explain the behavior of tight oil in unconventional reservoirs. In this study, an investigation into the application of similarity transformations for the analysis of complex unconventional reservoirs exhibiting two phase phenomena during transient radial flow is done. The similarity transformation is carried out with the Boltzmann variable. The techniques adopted in the transformation process aids in converting highly nonlinear partial-differential equations (PDEs) governing the two phase flow phenomenon, to nonlinear ordinary di?erential equations (ODEs). The resulting ODEs, consequently simplify the determination of the reservoir performance and avoid the tedious calculation ingrained in solving the original PDEs. From a theoretical point of view, the successful conversionof the highly nonlinear PDEs to ODEs permits the derivation of saturation andpressure equations as unique functions of the Boltzmann variable, which in turn,guarantees the expression of saturation as a unique function of pressure. Further research is carried out to investigate the constant gas-oil ratio (GOR) that is typically observed in some hydraulically fractured tight oil reservoirs during constant pressure two-phase production. The similarity transformation approach sets up a foundation to develop an analytical solution to the model adopted in this study. The analytical solution yielding from this work is used to obtain similar forms to well-known equations (flow rate and cumulative production) for single phase flow, which enhance our understanding of multiphase flow behavior.
