Development of technology for buılding-up the flow rate of underground gas storage wells

Relevance. The need to understand the mechanisms of reducing effective gas permeability, gas and condensate flow rates due to the formation of a liquid hydrocarbon phase and accumulation of liquid around underground gas storage wells, as well as the entire range of gas condensate wells at bottomhole pressure below the liquid dew point. Aim. To develop a technology for restoring the parameters of gas injection and extraction from underground gas storage wells by cleaning the bottomhole zone of wells from accumulated liquid. Methods. Analytical studies, laboratory analyzes of well fluid samples, field tests, statistical methods. Results and conclusions. It is shown that since underground gas storage facilities are created on depleted gas condensate deposits, their wells have most of the operational characteristics of gas condensate wells in general. Along with this, the article also examines and reflects a number of features characteristic of a underground gas storage well. The authors have proposed a technology for using an inexpensive solvent such as methanol to increase the production rate of wells by cleaning the bottom-hole zone of the well. The criteria for selecting candidate gas condensate wells for applying the technology are indicated. The authors give the recommendations on parametric requirements and methanol consumption rates for wells subject to selection for the application of technology to increase production by cleaning the bottom-hole zone of gas wells from liquid plugs. It was established that in underground gas storage wells with operating pressure in the range of 7.0–16.0 MPa, ideal conditions are created for retrograde settling of liquid. The paper provides the ınformation on the progress of field tests, the results obtained and their analysis. By applying the technology in field conditions, the result obtained was to double the injectivity of a underground gas storage well during gas injection. It is shown that if before the impact the share of the experimental well in the total injection volume was 0.51–0.5.6%, then after the impact this figure changes in the range of 0.84–1.72%, that is, the increase was from 1.5 to 3 once. In this regard, a conclusion was also made about an increase in the well flow rate during the gas withdrawal season.