AUTHOR=Guo Jianlin , Ning Bo , Yan Haijun , Jia Chengye , Li Yilong 

TITLE=Production Performance Analysis for Deviated Wells in Carbonate Gas Reservoirs With Multiple Heterogeneous layers

JOURNAL=Frontiers in Energy Research

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2022.861780

DOI=10.3389/fenrg.2022.861780

ISSN=2296-598X

ABSTRACT=To improve the well performance in carbonate reservoir with multiple heterogeneous layers, deviated wells are always used and penetrate the “sweet spot” of each layer that is full of fractures and vugs. It is difficult to consider in-layer and inter-layer heterogeneities simultaneously, and predict the production performance for these wells accurately. Therefore, a semi-analytical model to analyze the production performance of deviated well in multilayer heterogeneous stress-sensitive carbonate gas reservoir is proposed. For each layer, the inner region is fractured-vuggy porous medium, while the outer region is tight formation with matrix merely, and formation properties and penetrated inclination angles may be distinct. Pseudo-time/pressure factors are introduced to consider fractures stress sensitivity. Through the application of Laplace transformation, Fourier transform and inverse, Duhamel convolution and Stehfest numerical inversion, the presented model is solved. The validity of this model is verified through the comparisons with single-layer composite formation with different porous mediums and vertical well in multilayer carbonate gas reservoir. Moreover, by matching bottom-hole pressure data collected from a slanted well in Anyue gas field, the applicability of this model is validated. A synthetic case, which has two composite formations that the first (upper) layer is more permeable than second (lower) layer, is used to study the variations of inner region radius, fracture/matrix permeability, and inclination angles on production behaviors. The results show the properties of first layer determine well bottom-hole pressure, whereas the rise of permeability, inner region radius and penetrated angle for second layer can improve gas recovery of this layer. In practice, to keep well bottom-hole pressure with relatively high level and enhance gas recovery of tight layer, the inclination angle should be larger than 60° for each layer, and be increased as large as possible. The findings of this study can help for better understanding of production behaviors of deviated wells in multilayer heterogenous reservoirs, and could provide some guidance for the design of well trajectory.