As the oil and gas industry strives to find better gas hydrate management methods, it is necessary to better understand the hydrate formation and plugging trend in multiphase flow.The high?pressure visual flow loop is used to study the formation of carbon dioxide gas hydrate and the properties of hydrate slurry under the flow conditions of complete dispersion and partial dispersion system.The results show that for the fully dispersed phase system with high water content, the contact area between gas molecules and water is larger, and hydrate can be fully generated, which has a great impact on the flow in the loop. For the two systems with different water content, because of the oil?water interface in high water content is damaged more violently, a large amount of hydrate is easier to block the loop.The oil?water interface in low water content can be supplemented after being damaged, so the risk of pipe plugging is low.

Based on the discrete element method, this paper uses modeling software Solidworks and discrete element simulation software EDEM to simulate the transport movement of solid particles in a single?screw extruder. The research includes the influence of material parameters such as the shape and size of the particles, the screw speed, and structural parameters such as the number of screw edges and the inclination angle of the screw edges on the solid transport capacity, as well as the movement and filling of the particles inside the barrel. The results show that the single screw?barrel model has the best particle size and the best particle shape; the smaller the particle size, the better the filling effect; the maximum particle transport capacity is when the spiral angle is 105°.

Drainage continuity is very important for coalbed methane extraction. However, the well shut?in is unavoidable when draining. How to drain and draw up a reasonable drainage system after reopening the well are significant to increase gas production. Based on the analysis of coalbed methane production stage theory, combined with the field data about well shut?in, at the same time, numerical simulation method was used to study the change of reservoir parameters during well shut?in. The results show that well shut?in obviously changes the reservoir physical parameters,which causes the water saturation of the coal near the wellbore to increase, and the well bottom pressure increases. At the same time, it causes the re?adsorption of free gas near the wellbore and reduces the gas seepage capacity. Therefore, rapid drainage after reopening the well is helpful to dredge the flow channel of gas, improve gas flow capacity and increase gas production.

In order to improve the accuracy of leakage volume calculation of product oil pipelines, the error analysis of the input parameters used to calculate the leakage volume of product oil pipelines is carried out, including the time lag error of the pipeline operation data, the numerical error of the pipeline inner diameter and the numerical error of the oil physical properties. Through the sensitivity analysis of the input parameters, it is found that the leakage volume is the least sensitive to flow rate. The variation rate of pipeline leakage is positively correlated with time lag rate, pressure change rate and inner diameter change rate, while it is negatively correlated with flowrate change rate. The sensitivity of pipeline leakage volume to each input parameter is different within the range of variation rate of parameters.