| Natural gas hydrate is regarded as one of the most potential energy sources in the future.Because of its characteristics of small pollution,high calorific value and high reserves,natural gas hydrate has attracted the attention of governments and organizations.However,the depressurization of natural gas hydrate may lead to the formation of hydrate(secondary hydrate)or pore water icing in the reservoir,which affects the production of hydrate.The method of auxiliary heating in the well can improve the temperature of the formation near the well section and avoid the formation of secondary hydrate.In this paper,using the self-designed natural gas hydrate well heating simulation test device,a number of different conditions of the well auxiliary heating simulation experiment,different conditions of the well auxiliary heating numerical simulation research.The main research contents are as follows:(1)The auxiliary heating device in the well is designed.Combined with the method of natural gas hydrate depressurization production,this paper analyzes the operating conditions of auxiliary heating device in the well,designs the auxiliary heating device in the well,and puts forward the design parameters of the device in combination with the indoor experimental conditions.The device consists of the following parts:heating simulation system in the well,gas supply system to provide gas source,water supply system to provide water source,monitoring system,data acquisition and processing system.(2)The simulation experiment of auxiliary heating device in well was carried out.Based on the research foundation of numerical simulation,the experimental elements are processed,the indoor experimental platform is built,and the changes of the heating range of the formation under different heating power of the heater are studied.The experimental results show that:with the increase of heating power,the rate of temperature increase around the well is in a positive proportion to the heating power,but when the distance from the well wall is greater than 0.3m,the rate of temperature increase is not related to the heating power Obviously,1.65kw can have good effect.(3)The numerical simulation of the auxiliary heating in the well under different boundary conditions is carried out.This paper studies the factors that affect the effect of auxiliary heating device on formation heating,and compares the changes of formation heating range under different heating power of heater.The numerical simulation results show that the main factor affecting the heating effect of the heater is the daily water output,followed by the heating power,and the gas production has little effect on the heating effect.According to the relationship between heating influence radius and heating power under specific conditions(n=500,q=10m~3/D),if the heating influence radius is to reach 1.75m,the required heating rate is 2.4kw/m.The conclusion of this paper provides theoretical support for the auxiliary method of gas hydrate depressurization production,and also provides data support for the design of auxiliary heating device in the well. |
