Application Research On Velocity String Drainage Gas Recovery Technology In The CBM Wells

In recent years,along with a lot of exploitation of conventional oil and gas resources,people come to realize that conventional energy sources can't to meet today's growing demand for energy.And then people shift attention to unconventional coal bed methane gas,which has long been treated as hazardous gases and discharged to the ground and then again as a waste discharge into the air,causing environmental pollution.CBM have attract governments more and more attention,and its production capacity and efficiency has also been accepted by the community,its will also be important for China's economic development.In the mining process of CBM,the drainage gas is a very important aspect,but our CBM drainage technology is not mature,we can meet a series of problems,which severely restricted the development of China's CBM industry,such as pulverized coal seriously,pump damage,maintenance cycle is short,gas production is not ideal.So,to choose a reasonable drainage gas recovery process for improving drainage CBM production,to change the existing industrial layout,ease the country's oil and gas tense situation is important.Firstly,the theoretical analysis of the CBM baking commonly used technical advantages and disadvantages of drainage technology,combined with the mechanism of coalbed methane drainage and well conditions to choose velocity string and gas lift drainage process according to the usual process.By calculating the coiled tubing critical flow,friction coefficient,friction losses and erosion flow preferred the most appropriate tubing diameter,its downhole mechanical analysis process to calculate the elongation.Based on well conditions to choose downhole depth,and check its safety.Secondly,according the theory of gas lift to design gas lift valve and improve its structure,With the analysis software ANSYS Fluent,the numerical simulation of flow field distribution of steam injection phase gas-lift valve and verify the reasonableness of structural improvements,using finite element analysis software ANSYS to bellows for static analysis,and get the bellows compression law.Then,using the analysis software ANSYS CFX for tubing erosion rate density,and study on flow field analysis to get the influence of coal particles on the erosion rate density under different diameter and velocity.