Specialized ESP Layouts for the Operation of Deep Wells Confined to the Category of Hard-to-Recover Reserves

Abstract

The article is devoted to the selection of a specialized configuration of submersible equipment to minimize downhole pressure in order to intensify the flow of fluid to the wells of Gazpromneft-Orenburg. The depth of the wells and the design features of the well do not allow sufficient depth of the pumping equipment (top of the perforation interval 3800-4200 m). In addition, the operation of the fund is complicated by abnormally low reservoir pressures (60-120 at), low filtration-capacity properties and high linear pressures of single-standing wells (20-30 at). To increase the productivity of wells, the ESP layout was used with a two-way engine, two submersible pumps and a shank. The layout is chosen in such a way as to reduce the density of the liquid column under the pump due to the circulation of the liquid by the lower pump. A special feature of the design was the selection of the length and the limit of the descent of the shank, the ratio of performance and pressure of the upper and lower pumps and a number of pre-connected devices as part of the layout. Pilot tests were conducted at three wells of the Gazpromneft-Orenburg field. After the installation and commissioning work in the process of bringing the wells to the established mode, the features of the ESP that differ from the standard operation, leading to an increase in the period of stable well production, were revealed. According to the results of the tests, an increase in the oil flow rate of an average of 16 tons per day was obtained. The study of the characteristics of a complete installation directly on the test wells allowed us to determine the technical capabilities of the equipment, the volume-flow characteristics of the fluid under the pump and PVT. The aspects of natural separation and free gas content at the inlet of both pumps are studied, which is also a boundary condition for well intensification. The tests allowed us to assess the technological limit of the layout with two ESP in the conditions of the Gazpromneft-Orenburg field. In contrast to other options for the operation of hard-to-recover wells, the proposed layout has a number of advantages, such as a minimum increase in the cost of construction, simplicity of construction, which ensures high operating time of equipment and low specific energy consumption. Based on the results of testing the pilot installations, a decision was made to replicate this approach in the Company.