Water-Gas Two-Phase Flow Behavior of Multi-Fractured Horizontal Wells in Shale Gas Reservoirs

Abstract

Hydraulic fracturing is a necessary method to develop shale gas reservoirs effectively and economically. However, the flow behavior in multi-porosity fractured reservoirs is difficult to characterize by conventional methods. In this paper, combined with apparent porosity/permeability model of organic matter, inorganic matter and induced fractures, considering the water film in unstimulated reservoir volume (USRV) region water and bulk water in effectively stimulated reservoir volume (ESRV) region, a multi-media water-gas two-phase flow model was established. The finite difference is used to solve the model and the water-gas two-phase flow behavior of multi-fractured horizontal wells is obtained. Mass transfer between different-scale media, the effects of pore pressure on reservoirs and fluid properties at different production stages were considered in this model. The influence of the dynamic reservoir physical parameters on flow behavior and gas production in multi-fractured horizontal wells is studied. The results show that the properties of the total organic content (TOC) and the inherent porosity of the organic matter affect gas production after 40 days. With the gradual increase of production time, the gas production rate decreases rapidly compared with the water production rate, and the gas saturation in the inorganic matter of the ESRV region gradually decreases. The ignorance of stress sensitivity would cause the gas production increase, and the ignorance of organic matter shrinkage decrease the gas production gradually. The water film mainly affects gas production after 100 days, while the bulk water has a greater impact on gas production throughout the whole period. The research provides a new method to accurately describe the two-phase fluid flow behavior in different scale media of fractured shale gas reservoirs.

Production Performance Simulation of the Fractured Horizontal Well Considering Reservoir and Wellbore Coupled Flow in Shale Gas Reservoirs

“…34 Although the initial water saturation of the shale gas reservoir is ultra-low, the fracturing fluid left in the stimulated reservoir volume (SRV) results in a two-phase gas-water flow during shale production. 35 Therefore, simulation approaches, including the finite difference method with local grid refinement, 4 the embedded discrete fracture model, 36,37 and the finite element and control volume finite element methods (CVFMs) with unstructured grids, 26,30 have been developed to predict the production performance and optimize the production technique based on the occurrence of the two-phase gas-water flow. However, these models do not consider the fluctuations in the characteristics of the actual reservoir and the influence of two-phase gas−liquid flow in the wellbore on the production performance.…”

Novel Treatment for Mitigating Condensate Bank Using a Newly Synthesized Gemini Surfactant

“…Alternatively, hydraulic fracturing is used to mitigate the condensate bank by inducing conductive channels between the wellbore and the reservoir matrix [18][19][20]. The created fractures improve the flow paths available and decrease the drawdown pressure [20][21][22]. However, after several months of production, the condensate bank may develop around the wellbore due to the reduction in reservoir pressure [3,4].…”

Condensate-Banking Removal and Gas-Production Enhancement Using Thermochemical Injection: A Field-Scale Simulation

“…Alternatively, hydraulic fracturing may be used to mitigate condensate banking by creating longer conductive paths between wellbore and formation [9,11,22]. Fractures induce help to reduce pressure drop, and delay condensate dropout [11,23].…”

“…Notably, though, this procedure needs to be repeated about every 6 to 9 months to maintain its effectiveness, giving rise to logistical challenges associated with CO2 procurement, transportation, and on-site handling challenging its economic viability [3,9,21]. Alternatively, hydraulic fracturing may be used to mitigate condensate banking by creating longer conductive paths between wellbore and formation [9,11,22]. Fractures induce help to reduce pressure drop, and delay condensate dropout [11,23].…”