Abstract: An end cover assembly, an air cylinder, a tread sweeper and a railway vehicle.

Abstract: The present invention relates to a three-dimensional acid fracturing method for carbonate reservoirs in long intervals, which sequentially comprises the following steps: S1: based on the distribution characteristics of porosity and permeability of the reservoir where the candidate well is located, the reservoirs are divided into Class I, Class II and Class III, and the required acid fracturing fracture density range ?ir of different types of reservoirs is determined according to the increase of production; S2: Determine the most economical fracture number Ne when the economic net present value NPV of candidate wells reaches the maximum in the fifth year based on interval length of different types of reservoirs in candidate wells and acid fracturing fracture density range ?ir determined by S1; S3: Determine the three-dimensional acid fracturing segmented fracture arrangement technology according to the completion mode of the candidate well and the most economical fracture number Ne determined by S2; S4: Based

Abstract: The present invention discloses a method for experimentally determining the influence of acid liquor on the Young modulus of compact carbonate rock.

Abstract: The invention discloses a testing device and method for evaluating effects of CO2 reaction rate of acid rock plate. The testing device includes an acid fluid conveying unit, a CO2 conveying unit, a mixing tank, a plate holder, a recycling fluid tank, and a vacuum pump. The mixing tank includes an acid fluid inlet, a CO2 inlet, and a miscible fluid outlet. The acid fluid inlet is connected with the acid fluid conveying unit, the CO2 inlet is connected with the CO2 conveying unit, the miscible fluid outlet is connected with the plate holder, the plate holder is connected with the recycling fluid tank, and the recycling fluid tank is connected to the vacuum pump. The CO2 conveying unit includes a CO2 cylinder and a gas booster pump which is connected to the cylinder. The outlet of the pump is connected to the gas inlet of the mixing tank.

Abstract: The invention introduces a method of calculating etching profile of acid-etched fracture system considering complex filtration media, which mainly considers dynamic filtration caused by natural fractures and acid-etched wormholes in acid fracturing, calculates the above filtration process by a numerical method, and finally calculates acid etching profile of acid-etched fracture system based on acid concentration profile. Calculation equations include fluid pressure in natural fractures, filtration velocity in natural fractures, fracture geometry of hydraulic fractures, fluid pressure in matrix rock, acid concentration profile in natural fractures and hydraulic fractures, acid etching width in hydraulic fractures and natural fractures, and length of acid-etched wormhole, etc.

Abstract: The invention discloses a plate holder for simulating flowing of multiphase fluids in fractures, comprising a rectangular box, provided with a fluid inlet and a fluid outlet at the left and right sides respectively, the fluid inlet is connected to a piston at the fluid inlet, the fluid outlet is connected to a piston at the fluid outlet, an internal flow channel of the piston is arranged as a flared guide groove, and the cavity between the pistons is a rock plate cavity; a pair of horizontally-overlapped rectangular rock plates are installed in the rock plate cavity, four sides parallel to the length direction of the rock plate are completely attached and covered with rubber, the outer side of the rubber is covered with steel plate, fastening screws are installed vertically on the four sides of the box that are directly opposite to the steel plate.

Abstract: The invention introduces a method of calculating etching profile of acid-etched fracture system considering complex filtration media, which mainly considers dynamic filtration caused by natural fractures and acid-etched wormholes in acid fracturing, calculates the above filtration process by a numerical method, and finally calculates acid etching profile of acid-etched fracture system based on acid concentration profile. Calculation equations include fluid pressure in natural fractures, filtration velocity in natural fractures, fracture geometry of hydraulic fractures, fluid pressure in matrix rock, acid concentration profile in natural fractures and hydraulic fractures, acid etching width in hydraulic fractures and natural fractures, and length of acid-etched wormhole, etc.

Abstract: The present invention discloses a method for experimentally determining the conductivity distribution of an acid-fractured fracture a carbonate rock oil and gas reservoir, including the following steps: by an acid fracturing simulator FracproPT, simulating and acquiring distribution data of fracture width, fracture height, temperature and acid liquor mass concentration in a hydraulic fracture length direction; selecting fracture width, fracture height and temperature data of total 10 feature points with the acid liquor mass concentrations being from 100% to 10% of the initial mass concentration; converting site acid injection displacement into laboratory acid injection displacement; preparing experimental acid liquor according to the acid liquor mass concentration data of the 10 feature points; and simulating the acid etching process, and experimentally testing the conductivity under the condition of reservoir closed pressure, and drawing a distribution diagram of the acid-etched fracture conductivity in the

Abstract: The invention discloses a plate holder for simulating flowing of multiphase fluids in fractures, comprising a rectangular box, provided with a fluid inlet and a fluid outlet at the left and right sides respectively, the fluid inlet is connected to a piston at the fluid inlet, the fluid outlet is connected to a piston at the fluid outlet, an internal flow channel of the piston is arranged as a flared guide groove, and the cavity between the pistons is a rock plate cavity; a pair of horizontally-overlapped rectangular rock plates are installed in the rock plate cavity, four sides parallel to the length direction of the rock plate are completely attached and covered with rubber, the outer side of the rubber is covered with steel plate, fastening screws are installed vertically on the four sides of the box that are directly opposite to the steel plate.

Abstract: The invention discloses a testing device and method for evaluating effects of CO2 reaction rate of acid rock plate. The testing device includes an acid fluid conveying unit, a CO2 conveying unit, a mixing tank, a plate holder, a recycling fluid tank, and a vacuum pump. The mixing tank includes an acid fluid inlet, a CO2 inlet, and a miscible fluid outlet. The acid fluid inlet is connected with the acid fluid conveying unit, the CO2 inlet is connected with the CO2 conveying unit, the miscible fluid outlet is connected with the plate holder, the plate holder is connected with the recycling fluid tank, and the recycling fluid tank is connected to the vacuum pump. The CO2 conveying unit includes a CO2 cylinder and a gas booster pump which is connected to the cylinder. The outlet of the pump is connected to the gas inlet of the mixing tank.

Abstract: The present invention discloses a method for experimentally determining the influence of acid liquor on the Young modulus of compact carbonate rock.

Abstract: The present invention discloses a method for experimentally determining the conductivity distribution of an acid-fractured fracture a carbonate rock oil and gas reservoir, including the following steps: by an acid fracturing simulator FracproPT, simulating and acquiring distribution data of fracture width, fracture height, temperature and acid liquor mass concentration in a hydraulic fracture length direction; selecting fracture width, fracture height and temperature data of total 10 feature points with the acid liquor mass concentrations being from 100% to 10% of the initial mass concentration; converting site acid injection displacement into laboratory acid injection displacement; preparing experimental acid liquor according to the acid liquor mass concentration data of the 10 feature points; and simulating the acid etching process, and experimentally testing the conductivity under the condition of reservoir closed pressure, and drawing a distribution diagram of the acid-etched fracture conductivity in the