Study on foam transport mechanism and influencing factors in foam drainage gas recovery of natural gas well

Abstract

In order to study the distribution and flow pattern of foam in the wellbore during the process of foam drainage and gas recovery, A coupled model of gas and foam flow in wellbore was established. The distribution characteristics of foam in the wellbore during the process of foam drainage and gas recovery were analyzed through experiments. The concept of foaming efficiency and bubble carrying efficiency were introduced, and the drainage time and liquid accumulation time of foam drainage gas recovery in wellbore were calculated. The research results show that: In the process of foam drainage, there are two states of heterogeneous foam flow and homogeneous foam flow in the wellbore. Under the influence of the high flow rate of natural gas in the wellbore, the migration rate of bubbles near the wellbore is slow. High gas yield and low bubble density are beneficial to the rapid initiation of foam. Due to the double influence of gas carrying force and gravity, bubbles will show relatively complex motion characteristics, and the fluid level height in the wellbore is linearly related to time under different influencing factors in the process of gas well drainage. The research in this article is of great significance for precise drainage of foam drainage gas recovery.