Screening And Evaluation Of Foam Drainage Aids For Gas Wells At High Temperature And High Pressure

Foam drainage gas production technology is a chemical method to solve serious bottom hole effusion in the middle and later stages of gas well production,and the optimization of foam drainage agent is the key to this technology.The basic principle of foam drainage gas production technology is to inject a certain amount of foam drainage agent into the bottom of the well,and generate a large amount of low-density water-containing foam with the stirring of natural gas flow.These water-containing foam will be carried from the bottom of the well to the ground with the gas flow,thus achieving the purpose of drainage gas production.In this paper,through the high temperature and high pressure evaluation,liquid carrying capacity and oil resistance evaluation,the foaming agent with relatively high temperature and high pressure resistance,strong liquid carrying capacity and certain oil resistance will be screened out,which will be applied to the natural gas well of Nanpu No.5 structure,thus achieving the purpose of discharging bottom hole effusion and improving gas production.Six foaming agents were preliminarily screened and evaluated by Waring-Blender method under normal temperature and pressure.On this basis,the oil resistance evaluation followed and the relationship between surface tension and the concentration of foaming agent and temperature was measured.A high temperature and high pressure foaming agent performance evaluation device and an experimental method were established to evaluate foaming performance and foam stabilizing performance of the foaming agent under high temperature and high pressure,with the highest experimental temperature reaching 160? and the highest experimental pressure reaching 10 MPa.At the same time,the liquid carrying capacity of different foaming agents was evaluated at 160?,and the optimum concentration of foaming agent was selected with the water-air ratio and the concentration of foaming agent as variables.Finally,the defoaming agent used together was selected.The results show that the increase of oil content will inhibit foamability of foaming agent,with the increase of oil content,the foam stability of foaming agent firstly weakens and then becomes stronger.UT-6 and XM-3D have strong oil resistance.High temperature will inhibit foamability and foam stability of foaming agent.UT-11 C,nano-particle foaming agent and UT-6 have high temperature resistance.UT-6 and bubble bar 3 have strong pressure resistance.The higher the pressure,the better the foaming agent performance.The optimal concentration of XM-3C and UT-6 is 0.3%,UT-11 C and XM-3D is 0.5%,and the current optimal concentration of nano-particle foaming agent and bubble bar 3 is 0.7%.With the concentration of foaming agent increasing,the liquid carrying capacity increases first and then decreases or slows down in the later period.It is recommended to use defoamer 1 as defoaming treatment liquid after foaming,and the concentration is 0.01%.Considering the temperature resistance,pressure resistance,oil resistance and liquid carrying capacity of foaming agent,it is recommended to select sulfonate composite surfactant(UT-6)for the natural gas well of Nanpu No.5 structure,with the optimal concentration of 0.3%.