Abstract: The present disclosure discloses a method for calculating a safe drilling fluid density in a fractured formation, including the following steps: S1, performing image processing to identify a downhole fracture; S2, establishing three-dimensional (3D) geological models based on parameters of the downhole fracture, and establishing a drilling wellbore model based on a size and length of a wellbore; S3, assigning the model with material parameters, boundary conditions, and upper and lower bounds of an initial drilling fluid density, and calculating accuracy; S4, solving the 3D geological models using a 3-dimension distinct element code (3DEC) and determining stability of a well wall; S5, determining upper and lower bounds of a drilling fluid density using dichotomy; S6, repeating steps S4 to S5; and S7, after set accuracy conditions are reached, saving and outputting the safe drilling fluid density.

Abstract: The present disclosure discloses a method for calculating a safe drilling fluid density in a fractured formation, including the following steps: S1, performing image processing to identify a downhole fracture; S2, establishing three-dimensional (3D) geological models based on parameters of the downhole fracture, and establishing a drilling wellbore model based on a size and length of a wellbore; S3, assigning the model with material parameters, boundary conditions, and upper and lower bounds of an initial drilling fluid density, and calculating accuracy; S4, solving the 3D geological models using a 3-dimension distinct element code (3DEC) and determining stability of a well wall; S5, determining upper and lower bounds of a drilling fluid density using dichotomy; S6, repeating steps S4 to S5; and S7, after set accuracy conditions are reached, saving and outputting the safe drilling fluid density.

Abstract: An apparatus for selling cigarettes and a system for accessing cigarettes are described herein. The apparatus comprises a vending machine and a smoke purification system. The smoke purification system includes a housing, an extraction device, a smoke purifier, and an exhaustion device. An upper face of the housing is provided with an air inlet for sucking in air in an upper space of a smoking room, and a front face of the housing is provided with a fresh air outlet. An intake port of the extraction device is coupled with the air inlet, an escape port of the exhaustion device is coupled with the fresh air outlet through an exhaust channel, and two ends of the smoke purifier are coupled with an escape port of the extraction device and an intake port of the exhaustion device, respectively.

Abstract: An apparatus for selling cigarettes and a system for accessing cigarettes are described herein. The apparatus comprises a vending machine and a smoke purification system. The smoke purification system includes a housing, an extraction device, a smoke purifier, and an exhaustion device. An upper face of the housing is provided with an air inlet for sucking in air in an upper space of a smoking room, and a front face of the housing is provided with a fresh air outlet. An intake port of the extraction device is coupled with the air inlet, an escape port of the exhaustion device is coupled with the fresh air outlet through an exhaust channel, and two ends of the smoke purifier are coupled with an escape port of the extraction device and an intake port of the exhaustion device, respectively.