One of the most popular methods to improve oil recovery factor is reservoir hydraulic fracturing, which means pumping in the fluid creating additional fractures in the rock. This technology may be implemented by using several piston-type pumps simultaneously pumping the fluid under high pressure.
The frac job is especially difficult in horizontal wells featuring high length: high pressure and a big number of pumps are required to propel the fluid through the entire well. Due to different speed of the pistons, pressure variations emerge together with strong surges of feeding the fluid. This negatively affects the pumping process and often leads to failures.
The development of the scientists from Perm Polytechnical University allows for solving this problem and for assuring steady operation of two and more pumps. This is about calculating in advance the moment in time, when the shift occurs in the position of rotating shafts, and regulating it via a control unit. The shaft is a movable part of the piston-type pump transmitting rotary motion to other elements.
This new technology works as follows: every pump engaged has its own drive/motor; the shafts inside the pumps are connected with the shafts of electric motors. “The essence of the development is in installing additional sensors measuring the position and the rotating speed of the shafts. This information is transmitted to the control unit supporting the pre-set phase (position) differential of the shafts. In case the operation of the pumps is for any reason disturbed, the control unit can recognize it based on the sensors’ readings. Then the control unit can change the rotation speeds for a short period (can increase or reduce the speed) until the phase differential gets back to the pre-set value”, Perm Polytechnical University is citing Vadim Kartavtsev, the engineer of the mining electrical engineering department.
Overall, the key advantage of the new technology is in decreasing the irregularity of feeding fluid to piston-type pumps combined in one group. In case one of the pumps fails, this development provides for stable pumping of fluid with the help of the remaining pumps. This guarantees stable operation of all the equipment.
