Institute of Mining, Far East Branch, Russian Academy of Sciences, Khabarovsk, Russia:

A. N. Shulyupin, Deputy Director, Doctor of Engineering Sciences, ans714@mail.ru

The conditions for stable operation of steam-water geothermal well are considered on the basis of the analysis of characteristics reflecting the dependence of bottomhole pressure on the flow rate for the well and the feed aquifer. These conditions determine the principle possibility of the steam-lift production of the fluid in the self-discharge mode when the static water level is located below the wellhead. The need to take into account the dependence of external wellhead pressure on flow rate is noted when the well characteristic is constructed. External wellhead pressure is determined by flow downstream from the wellhead. In this case, a sufficient condition for stable steam-lift production is the finding of operating point (the intersection of the characteristics) on the upward branch of the well characteristic. Also, the steam-lift production is possible when finding an operating point on the descending branch near extremum point of well characteristic in the presence of factors restraining the development of instability at the wellhead. Two directions are identified to achieve the required location of the operating point: change in aquifer characteristic and change in well characteristic. Some methods are considered for the corresponding change in the characteristics providing for the steam-lift production. It was also noted the importance of choosing the method of excitation of the well and the procedure for its implementation in the presence of the required finding of operating point. Classification of directions in provision of steam-lift production is proposed. The reasons for difficulties of steam-lift production of wells are indicated. It is recommended, having faced with such difficulties in practice and having found the reasons for their occurrence, choose the most appropriate ways of eliminating them, preferring the simplest methods that, in case of failure, will not interfere with further attempts to provide the necessary mode of operation.
The study was supported by the Russian Foundation for Basic Research, Project No. 16-05-00398_a.

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