A mathematical model of multistage fractured horizontal well (MsFHW) considering stimulated reservoir volume (SRV) was presented for tight oil reservoirs. Both inner and outer regions were assumed as single porosity media but had different formation parameters. Laplace transformation method, point source function integration method, superposition principle, Stehfest numerical algorithm, and Duhamel’s theorem were used comprehensively to obtain the semianalytical solution. Different flow regimes were divided based on pressure transient analysis (PTA) curves. According to rate transient analysis (RTA), the effects of related parameters such as SRV radius, storativity ratio, mobility ratio, fracture number, fracture half-length, and fracture spacing were analyzed. The presented model and obtained results in this paper enrich the performance analysis models of MsFHW considering SRV.
For waterflooding oilfields, both the lab experiments and field practices have proved that the physical properties of water-flooding reservoirs would be altered due to the washing of injected water. This condition has not aroused enough attention. There is no proper approaches to describe the change of reservoir parameters against water flux in reservoir simulation. Most commonly used reservoir simulators (Eclipse, CMG, et al.) neglect the alteration of reservoir properties during simulation, and thus, lead to unreasonable history matching and production forecasting.
A new parameter known as Pore Cross-sectional Area Flux (PCAF) is introduced to continuously characterize the time-variation of a property during simulation. This new method overcomes the disadvantage of the previous characterization approach known as Pore Volume (PV), which is strongly dependent on grid size.
A new numerical simulation software in which reservoir properties are considered functions of PCAF is developed based on the black oil model, and the new simulator is validated against Eclipse. Furthermore, the effects of the time-variation of different parameters on the ultimate oil recovery are investigated. Finally, this simulator is applied to SZ-I oilfield in Bohai Bay to demonstrate how this simulator can achieve more accurate simulation.
Inspired by the oriented, gradient, and heterogeneous characters of natural materials, an oriented and gradient cocontinuous structure is designed to obtain excellent mechanical performance via a gradient shear stress and temperature during melt processing. The investigation of hierarchical structure containing phase morphology, crystalline morphology, and lamellae in the cocontinuous structure can clarify the role of gradient shear stress and temperature in promoting gradient and oriented features. Given such oriented and gradient features in the cocontinuous structure, a notable enhancement in the tensile strength, tensile modulus, elongation at break, and impact strength is achieved in the model poly(butylene adipate‐ran‐terephthalate)/poly(butylene succinate) biodegradable cocontinuous blends. Compared with the isotropic cocontinuous structure, homogenous structure and discrete phase structure, oriented and gradient cocontinuous structure provides a promising balance of strength, hardness, and toughness. Local reinforcement is achieved by highly oriented cocontinuous phase, crystal, and lamellae in skin layer. Meanwhile, the toughness is achieved by weakly oriented cocontinuous phase. The tuning of cocontinuous structure with gradient and oriented features is suggested as a new pathway toward the development of “materials systems” with unprecedented mechanical performance.
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