چكيده به لاتين
The unloading of wellbore fluids or the inability of gas to carry fluids accumulated along the well shortens the life of natural gas wells and reduces the company's income. Hydrocarbon condensate and water are usually produced along with the natural gas flow. With the passage of time and with the reduction of the formation pressure, the gas velocity decreases, which causes the accumulation of liquids in the bottom of the well and, as a result, production decreases. One of the common methods of draining gas well liquids is surfactant injection or foaming. The injected surfactant helps to drain the well due to the penetration between the flowing liquids and gas and reducing the surface tension between them and forming a foam. This method is especially useful in low-pressure gas reserves.
Most of the oil wells also need artificial production to increase the life of the field and increase the production. Conventional methods such as artificial gas injection are not effective in depleted reservoirs with high water cut. In such a situation, a high gas injection rate is required, and in other words, a lot of work pressure is applied to the gas injection system, while we have a low production oil flow rate, and the desired result may not be achieved. As a result, surfactants that were used to deliquesce gas wells can be used in depleted oil wells with a high water cut. In such a tank, foam helps to reduce the density of the liquid and, as a result, to reduce the hydrostatic pressure of the liquid column, and as a result, the use of surfactant improves the performance of the gas injection process and increases the flow rate of oil production, with a lower operating cost.
gas lift with the help of foam is a relatively modern and developed method, and although there is a growing global need for this technology, it has been less addressed to date. Gas wells with a high water cut, as well as depleted oil wells with a high water cut where gas injection is performed, are good choices for foam recovery. The presence of water increases the production of foam and helps in evacuation, but the presence of gas condensate and oil in the well column reduces the efficiency of the surfactant in foam lift operations. The purpose of this study is to experimentally evaluate the performance of different surfactants in the presence of water and hydrocarbon phase, taking into account the importance of draining the wellbore fluids.
In this research, a laboratory system is designed to implement the process of artificial lift with gas with the help of foam, and the efficiency of lift with foam and its relationship with the properties of the used surfactant are investigated. Four types of anionic, cationic, nonionic and amphoteric surfactants have been selected to study this process. The series of laboratory work includes surface tension measurements and liquid column extraction tests with surfactants and their different concentrations. Liquid discharge process in laboratory scale for different amounts of water and oil cutting and in constant flow rate of air injection for foam production are completed and investigated. Among the results of these tests, the amount of discharged liquid, foam density, foam height, and half-life of foam have been recorded. If the water cut decreases, a relative drop in the amount of discharged liquid is observed, which indicates a decrease in the foam generation efficiency. The amount of this reduction is different for different surfactants, which has been fully investigated.
In addition to testing the performance of these surfactants at room temperature, which is in the range of 25-30 degrees Celsius, the effect of high temperature on the liquid lift process is studied for the selected concentration range and selected water cut. The relevant tests are performed in a thermal insulation set, in the temperature range of 60-70 degrees Celsius, and the results are fully checked.
