Methods for ensuring of stable operate of steam-water wells

Abstract

The conditions for the stable operation of the steam-water geothermal well are considered on the basis of the analysis of the characteristics reflecting the dependence of the bottomhole pressure on the flow rate for the well and the feed aquifer. When the position of the static water level is below the wellhead, these conditions determine the principle possibility of the steam-lift production of the fluid in the self-discharge regime. When constructing the characteristics of the well, it is necessary to take into account the dependence of the external wellhead pressure, determined by the flow downstream from the wellhead, on the flow. A sufficient condition for stable steam-lift operation is the finding of a working point (the intersection of characteristics) on the ascending branch of the characteristic of the well. In the presence of factors that inhibit the development of instability at the wellhead, the possibility of steam-lift operation while finding a working point and on the descending branch near the extremum of the well characteristic is not ruled out. Some methods of changing the characteristics of a well and an aquifer that contribute to the achievement of the required location of the working point are considered. The importance of choosing the method of excitation of a well and the technology of its implementation in the presence of the required location are noted. The reasons for appearance of difficulties of the steam-lift operation of the well are indicated. It is recommended, having faced in practice with such difficulties and having found the reasons for their occurrence, choose the most appropriate ways of eliminating them, preferring the simplest in the implementation the methods that, in case of failure, will not interfere with further attempts to provide the necessary mode of operation.