Elimination of liquid supply and pressure pulsations during the operation of piston pumps

Abstract

The widespread use of reciprocating pumps in the oil and gas industry requires periodic upgrades to improve their performance and eliminate their shortcomings. One of the disadvantages of positive displacement pumps, especially drilling piston pumps, is the pulsation of fluid pressure and flow. This has a negative impact on the entire high-pressure line of the pumping and circulating system, including downhole equipment (drill pipes, downhole motors, rock-destroying tools, etc.), as well as the walls of the uncased well. After analyzing the graphs of instantaneous flow rates of different types of pumps, it was found that the lowest coefficient (1.047) of uneven flow rate is observed for a triple-acting pump (three-piston single-stroke drilling pump). However, double-acting two-piston pumps with a flow coefficient of 1.1 are still in use today. Pneumatic compensators are usually used to eliminate pressure and flow pulsations. However, even with pneumatic compensators, fluid flow and pressure pulsations are still observed. To eliminate this phenomenon, the article proposes a piston pump scheme that uses a modified rack-and-pinion transmission and an additional cylinder-piston pair. The peculiarity of the additional piston drive is that it is driven by a cam with a special profile. After theoretical studies and comparison of the obtained instantaneous flow curves of the modernized and the existing (two-piston double-acting) pumps, it was found that the modernized pump has no flow and pressure pulsation. A schematic diagram of the modernized double-acting piston drilling pump is also presented, which can serve as a basis for the design of the proposed pump drive.