Conventional numerical simulators cannot accurately predict the production of fractured horizontal wells in tight sandstone gas reservoirs due to the threshold pressure gradient (TPG) and stress sensitivity. Additionally, non‐Darcy flow in hydraulic fractures further complicates the prediction. Therefore, a numerical simulation model was developed to accurately predict the production of fractured horizontal wells that considers the TPG, non‐Darcy flow, and stress sensitivity using the embedded discrete fracture model. The model was solved using the automatic differentiation framework of MATLAB Reservoir Simulation Toolbox. The numerical simulation demonstrated that the Darcy flow model provided an optimistic prediction of the productivity of fractured gas wells in tight reservoirs. The TPG, non‐Darcy flow, and stress‐sensitive phenomena reduced the productivity of gas wells to varying degrees and severely affected the production of gas wells. The TPG effect, non‐Darcy effect, and stress sensitivity phenomenon reduced the gas well production by 1.66%, 12.9%, and 42.42%, respectively, compared with that of the Darcy flow. In contrast to the conventional Darcy flow model, the model established in this study can accurately predict the production of gas wells in production history matching.
Formation pressure is an essential parameter for calculating the dynamic geological reserves, evaluating the development effect of oil and gas fields, conducting the daily dynamic analysis of oil and gas Wells and predicting the dynamic of oil and gas fields. Generally, the calculation of reservoir average formation pressure is to use the pressure in the infinite formation to solve the formation pressure. This paper presents a new method for calculating the pressure at any point of one source and one sink by using wellhead pressure. This method has been well applied in the Saertu-Putaohua industrial area.
The invasion of aquifers into fractured gas reservoirs with edge water aquifers leads to rapid water production in gas wells, which reduces their gas production. Natural fractures accelerate this process. Traditional reservoir engineering methods cannot accurately describe the water influx, and it is difficult to quantitatively characterize the influence of aquifer energy and fracture development on production, which prevents aquifer intrusion from being effectively addressed. We divided the water influx of edge-water aquifers in fractured gas reservoirs into three patterns: tongue-like intrusion in the matrix, tongue-like intrusion in fractures, and channel intrusion in fractures. Detailed numerical modeling of the water influx was performed using an embedded discrete fracture model (EDFM) to predict gas production. Because the strength of the aquifer and the conductivity of natural fractures have different effects on water influx, the effects of aquifers and natural fractures on the gas production of wells under the three water influx modes were studied. The results show that tongue-like intrusions lead to a stronger initial gas production of gas wells, which then become weaker after the wells are flooded, and the intrusions such as channeling in fractures cause the gas well to be flooded quickly. However, not all water influxes are unfavorable for gas production. Aquifers with a water energy similar to gas formation and natural fractures with weak conductivity can improve the production of gas wells.
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