Hydraulic fracture is widely performed to enhance oil and gas production in the development of unconventional reservoirs. This paper proposes a numerical model for the calculation of the unpropped fracture conductivity of shale. This numerical model consists of three basic models, namely, the numerical reconstruction model of fracture morphology, fracture deformation model under closed stress, and fluid flow model. The numerical model can be used to analyze the influencing factors of the unpropped fracture conductivity of shale quantitatively. The results demonstrate that the fracture misalignment of shale is a prerequisite for unpropped fractures with conductivity at high closed stress. Furthermore, the unpropped fracture conductivity of shale decreases exponentially with the increase in closed stress. Moreover, closed stress is the factor having the most significant influence on the unpropped fracture conductivity of shale, followed by roughness and fracture morphology. The negative effect of closed stress can be reduced by increasing the fracture morphology during the fracturing operation.

Perforated wells in ultra‐deep sandstone reservoirs are characterized by high reservoir temperature, high formation pressure, and high production, and sand production will cause severe safety hazards to these wells. Based on Drucker‐Prager (DP) rock failure criterion, a practical analytical model for predicting critical drawdown pressure (CDP) of sanding onset for perforated wells is established by comprehensively considering the influence of drag stress, formation water production, reservoir pressure depletion, temperature difference in the perforated wellbore. The proposed model is verified by field sanding onset monitoring data. The calculation results show that CDP changes with well inclination, and it decreases with the increase in wellbore temperature difference, reservoir pressure depletion, and water saturation. However, the CDP increases with the number of perforations and the ratio of diameter to length. The optimization of perforation parameters has an important influence on sand control. This study can effectively guide the prediction of CDP and provides basis for efficient and safe development of similar ultra‐deep and high yield sandstone reservoirs.

Multicluster fracturing of horizontal wells has evolved into a mature and widely adopted technique for exploiting unconventional oil and gas fields. A well-designed multicluster completion strategy can yield an ideal fracturing outcome, significantly enhancing production rates and potentially delivering substantial economic benefits. Nevertheless, empirical evidence suggests that fractured horizontal wells frequently exhibit pronounced nonuniform production profiles, a prevalent issue stemming from the irregular geometry of propagated fractures. This issue critically constrains production rates. To mitigate the adverse effects of low-uniformity fracture propagation, it is imperative to elucidate the factors influencing uniformity levels and their corresponding patterns. Despite extensive discussions on hydraulic fracture propagation mechanisms and optional factors in hydraulic fracturing engineering, there exists a notable oversight regarding the optimization of perforation parameters to achieve improved fracturing uniformity during well completion procedures. This paper introduces an optimization method for perforation parameters based on a fully coupled pseudo-3D numerical model of multicluster fracturing. The impact patterns of cluster spacing, perforation number, and initial perforation diameter on multifracture propagation results and uniformity levels are thoroughly examined. The multicluster fracturing model, developed using the displacement discontinuous method (DDM), is coupled with material balance, pressure transmission, hole erosion computation, and initiation asynchrony estimation. To quantify the uniformity level of the fracturing result, the modified propagation uniformity index (U_fm) is employed. Simulation results from 20 cases are categorized into six groups based on varied changing patterns of perforation parameters, leading to the identification of five recommendations for optimizing perforation parameters. By implementation of the discussed optimized perforation parameters, successful fracturing outcomes were realized.