In the paper, the gas lift process of lifting of well fluid is investigated under the assumption of the dependence of its efficiency on the physical and chemical characteristics of the formation fluids. A statistical study of field data was used to determine the effect of oil gas and the degree of water cut on the productivity of gas lift wells. The effect of the flow structure on the productivity of gas lift wells is estimated. It is shown that the optimization of the operation mode of gas lift wells should be performed taking into account the degree of water cut and the volume of oil gas in the fluid flow.
It is shown that in establishing optimal well performance process for gas lift wells, it is necessary to take into account not only water cut, but also the physical and chemical characteristics of the produced water. Commercial studies at numerous wells have established that the main reason for the decrease in the efficiency of gas lift operation with increasing water cut is the formation of unfavorable gas-liquid flow structures. Large water cuts impair the process of fluid lifting due to faster coalescence and enlargement of gas inclusions. With the change in the operation mode, with the increase in the supply of working agent, the effect of the gas solubility on the additional injection of the gas and on increasing the hydraulic resistances to the mixture flow is enhanced. Gas dissolution and desorption will occur not only in the fluid in tubing, but also in the fluid being lifted.
On the actual oil data, it was demonstrated that as the water cut of the well production increases, the efficiency of the gas lift lifts is reduced due to an increase in the flow of high-pressure gas and a decrease in the oil production rate. To test the assumption, the regime parameters of gas lift wells of two fields differing in the nature of the preparation of compressed gas were analyzed. Characteristic curves are considered when establishing the optimal regime parameters of gas lift at the Gunashli and Sangachal fields (SOCAR, Azerbaijan).
Taking into account the salinity of the water phase in the gas-lift mixture provides the ability to control the efficiency of the gas lift by control of the physical and chemical properties of the gas.
As an instrument to regulate the efficiency of the gas lift, an artificial increase in the moisture content of the injected gas is proposed, this minimizes the energy loss in the flow by desalting the aqueous phase with high salinity of the produced water. It was revealed that taking into account the salinity of the water phase in the gas-lift mixture provides the possibility to control the efficiency of the gas lift. Gas lift, an artificial increase in the moisture content of the injected gas, which allows to minimize the energy loss in the flow due to desalination of the aqueous phase, is proposed.
References
1. Mirzadzhanzade A.Kh., Shakhverdiev A.Kh., Dinamicheskie protsessy v nefegazodobyche: sistemnyy analiz, diagnoz, prognoz (Dynamic processes in oil and gas production: system analysis, diagnosis, forecast), Moscow: Nauka Publ., 1997, 254 p.
2. Patent no. 2122106 RF, Method of gas-lift well operation, Inventors: Mirzadzhanzade A.Kh., Shakhverdiev A.Kh., Panakhov G.M. et al.
3. Fleshman R., Lekic H.O., Artificial lift for high-volume production, Oilfield Review,1999, Spring, pp. 49–63.
4. Beiranvand M.S., Morshedi S., Hossein M., Sedaghat and Sepehr Aghahoseini design of a gas lift system to increase oil production from an iranian offshore well with high water cut, Australian Journal of Basic and Applied Sciences, 2011, V. 5(11), pp. 1561–1565,
5. Li G.S., Bashin V.A., Analysis of the operation of gaslift wells at Pravdinskoye field (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 1976, no. 4, pp. 33–35.
6. Bin Hu, Characterizing gas-lift instabilities, Norway, Department of Petroleum Engineering and Applied Geophysics Norwegian University of Science and Technology Trondheim, 2004, 168 p.
7. Gamaud F., Casagrande M., Fouillout C., Lemetayer P., New field methods for a maximum lift gas efficiency through stability, SPE 35555,1996.
8. Guet S., Ooms G., Oliemans R.V.A., Influence of bubble size on the transition from low-Re bubbly to slug flow in a vertical pipe, Proceedings of Fourth International Conference on Multiphase Flow (ICMF4), 2001, May–June.
9. Gimatudinov Sh.K., Fizika neftyanogo i gazovogo plasta (Physics of the oil and gas reservoir), Moscow: Nedra Publ., 1971, 310 p.
10. Namiot A.Yu., Rastvorimost' gazov v vode (Solubility of gases in water), Moscow: Nedra Publ., 1991, 167 p.
