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Shale gas reservoirs can be divided into three regions, including hydraulic fracture regions, stimulating reservoir volume regions (SRV regions), and outer stimulating reservoir volume regions (OSRV regions). Due to the impact of hydraulic fracturing, induced fractures in SRV regions are often irregular. In addition, a precise description of secondary fractures in SRV regions is of critical importance for production analysis and prediction. In this work, the following work is achieved: (1) the complex fracture network in the SRV region is described with fractal theory; (2) a dual inter-porosity flow mechanism with sorption and diffusion behaviors is considered in both SRV and OSRV regions; and (3) both multi-rate and multi-pressure solutions are proposed for history matching based on fractal models and Duhamel convolution theory. Compared with previous numerical and analytic methods, the developed model can provide more accurate dynamic parameter estimates for production analysis in a computationally efficient manner. In this paper, type curves are also established to delineate flow characteristics of the system. It is found that the flow can be classified as six stages, including a bi-linear flow regime, a linear flow regime, a transition flow regime, an inter-porosity flow regime from the matrix to the fractures in the inner region, inter-porosity flow regime from matrix to fractures in the outer region, and a boundary dominant flow regime. The effects of the fracture and matrix properties, fractal parameters, inter-porosity flow coefficients, and sorption characteristics on type curves and production performance were studied in detail. Finally, production performance was analyzed for Marcellus and Fuling shale gas wells, in the U.S.A. and China, respectively.

In the past few decades, scholars have made great breakthroughs in the study of well test analysis of carbonate rock. The previous studies are based on horizontal wells, straight wells, fractured wells, and inclined wells. With the development of fracturing technology, acid fracturing technology is considered to be the most effective measure to develop carbonate reservoirs. As the carbonate rock is easily dissolved in carbonic acid, multi-branched fractures will be produced near a vertical well. This article presented a semi-analytical model for multi-branched fractures in naturally fractured-vuggy reservoirs for the first time, which laid a theoretical foundation for solving well test analysis for finite conductivity multi-branched fractures. The model can quantify the wellbore flow pressure and applied to obtain more parameters reflecting comprehensive flow characteristics through using history matching procedure. The results were compared with numerical simulation and the existing analytical solutions of a single fracture model. Then in this paper, flow characteristics are recognized and there are five flow regimes found in the type curves, e.g. bi-linear flow region, linear flow region, inter-porosity flow region between vugs and fractures, inter-porosity region between matrix and fractures, and radial flow region. Finally, the influence factors analysis shows fracture number will mainly affect flow behavior of bi-linear flow and linear flow. The angle analysis showed that as the fractures were closer, their interaction became stronger. The conductivity would seriously affect the flow behavior in the early time. Linear flow cannot be observed when the conductivity is less than 1 and bi-linear flow cannot be observed when the conductivity is more than 20. And the effect of fracture length on flow behavior occurs in the early time. Bi-linear flow and linear flow characteristics cannot be observed when the fracture length is reduced.

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Recent collections from six sections in Lanongla area, Tethyan Himalaya allow the establishment of four buchia assemblages. In ascending order, they are Buchia-Buchia spitiensis, Buchia masquensis-Buchia rugasa, Buchia blanfordiana, Buchia piochii and Buchia subokensis assemblages. These Buchia assemblages first demonstrate that not only the Upper Jurassic strata but also the highest Buchia assemblage-Buchia subokensis, which appeared in Lower Cretaceous strata all over the world are present in Lanongla area. This first records the highest Buchia assemblage in Lanongla area.