Development & Evaluation Of The Self-generated Bubble Foaming Stick With Anti-oil And Anti-salt

With the development of gas field, the gas well production is decreasing in the middle and later. When gas flow is lower than the critical gas flow, bottom and wellbore will produce liquid loading. With the increasemen of the liquid loading, causing partial gas wells flooding and even stop production. Liquid loading is mineralized water, which usually containing condensate oil, methanol. It has a great influence on foaming and foam stability performance. Conventional foaming agent or foaming stick must rely on the gas disturbance. For partial low pressure and low production wells, gas flow can not reach the critical gas flow. Conventional foaming agents or foaming stick can not effectively discharge the liquid loading. Aiming at these difficulties, the paper developed a new type self-generated bubble foaming stick, which suitable for the kind of gas well. It provides the theoretical basis and technical support for the gas field development.Through a large number of literature research, the paper analyzing the foam drainage mechanism. Summarizing the factors of foaming and foam stability performance, such as surface activity, molecular structure, external factors, foaming shape, etc. Through theoretical analysis and experiments, using synergistic effect of surfactant, Ross-Miles method, orthogonal software, screening the best foaming stick formula system. The drainage method is used to collect the gas, determining the optimum ratio. Under normal condition, the 2g sodium bicarbonate (analytical pure) and 2.5g citric acid (analytical pure) reaction generated gas 525ml. Finally, determining the foaming stick formula system, the foaming agent system:0.1% CAB+0.05% WS+0.1%carbowax, the self-generated bubble agent system:sodium bicarbonate (analytical pure):citric acid (analytical pure)= 4:5.According to a lot of experiments, the paper using the oil industry standards, the Ross-Miles, high-speed mixing method, dynamic liquid-carrying method. Respectively, evaluating the foaming agent system performance, such as compatibility, anti-salt performance, anti-calcium performance, anti-condensate oil/anti-gasoline performance, anti-methanol performance, etc. Determining the scope of foaming agent system. Under no gas disturbance condition, evaluating the performance of self-generated bubble foaming stick.The result shows that the density of the foaming stick is adjustable, appearance is white solid. The foaming agent system anti-salt index is 200000 mg/L, anti-calcium ion index is 20000 mg/L, anti-condensate oil/anti-gasoline index is 20%, anti-methanol index is 20%, anti-temperature index is 90℃. It has good compatibility with salinity, methanol, condensate oil/gasoline, and the dissolving time is under control. The salinity is 0-200000mg/L of liquid loading, add in to the foaming agent system, the surface tension decreased to 32.35 mN/m,34.76 mN/m,35.21 mN/m,36.94 mN/m,37.38 mN/m. Under no gas disturbance condition, the results show that the foaming agent and self-generated bubble agent ratio is 1:1, foaming volume is 72 ml. The foaming agent and self-generated bubble agent ratio is 1:2, foaming volume is 103 ml. The foaming agent and self-generated bubble agent ratio is 1:3, foaming volume is 155 ml. The foaming agent and self-generated bubble agent ratio is 1:4, foaming volume is 225 ml. The foaming agent and self-generated bubble agent ratio is 1:5, foaming volume is 285 ml. Therefore, the proportion of self-generated bubble agent has a great influence on foaming performance. When the foaming stick of self-generated bubble apply in the field, the proportion of self-generated bubble agent should be determined by the liquid loading degree.The results of foam drainage experiment show that at temperature 20 ℃, under the condition of salinity is 200000 mg/L, Ca+ is 10000 mg/L, the gas flow increased from 0.5 m3/h to 1 m3/h, the liquid carrying capacity increased from 328ml to 715ml, carrying liquid rate increased from 32.8% to 71.5%, carrying liquid volume increased from 2.73/s to 5.96/s. When 20% methanol in the liquid loading, liquid-carrying rate is 46%, liquid-carrying volume is 3.83/s (> 1.38 ml/s). When the salinity of liquid loading is 200000 mg/L, liquid-carrying rate is 71.5%, liquid-carrying volume is 5.96/s (> 1.38 ml/s). When 20% condensate oil/gasolene in the liquid loading, liquid-carrying rate is 38.7%-36.9%, liquid-carrying volume is 3.08/s-3.23/s (> 1.38 ml/s). When the salinity is 200000 mg/L,10% methanol,10% condensate oil, the liquid-carrying rate is 35.8%, the liquid-carrying volume is 2.98 ml/s (> 1.38 ml/s). The foaming agent system under harsh condition, showing the good liquid carrying performance, and has the anti-oil, anti-salt and anti-methanol performance. Under more harsh conditions, we can appropriately increase the proportion of foaming agent, in order to improve the efficiency of foam drainage.The results of foam drainage experiment show that with the increasement of height, the liquid constantly slipping in the foam drainage process, the liquid holdup gradually decreased. At temperature 20℃, under the condition of salinity is 200000 mg/L, Ca2+is 10000 mg/L, gas flow increased from 0.5 m3/h to 1 m3/h, the liquid holdup of NO.1 exit increased from 12.5% to 18.2%, the liquid holdup of NO.2 exit increased from 10.2%to 15.6%, the liquid holdup of NO.3 exit increased from 8.7%to 13.4%. Gas flow has some impact on the liquid holdup. Between 20～80s, foam is unsteadily spherical, which containing a large number of liquid, liquid holdup from low to high. Between 80～120s, due to the flow disturbance, foaming agent is dispersed in water, foam is small and stable, the change of liquid holdup is little. After 120s, foam is metastable.To sum up, the self-generated bubble foaming stick not only has excellent anti-oil and anti-salt performance, anti-temperature performance, anti-methanol performance, but also has strong foaming and foam stability performance. The topic research can effectively improve the production of liquid loading gas well, making the gas field efficient and reasonable development. For the middle and later periods of gas well development and stable production provides relevant basis and technical support.