Research on Energy Conservation and Consumption Reduction of Oilfield Water Injection Pump

Water injection is the main method for improving oil recovery in oil fields. Water injection can compensate for the underground deficit caused by oil extraction and maintain a reasonable formation pressure. The water injection pump is an important equipment in the oilfield water injection system and is the power source of the oilfield water injection production system. The development and production of Factory A's oilfield have entered the middle and later stages, with continuous increase in water injection volume and pressure, and continuous increase in produced water reinjection volume, resulting in high maintenance frequency, low pump efficiency, and high energy consumption of the original water injection pump. Faced with the serious situation of sustained low oil prices and significant reduction in production costs, Factory A actively introduces and applies energy-saving and consumption reducing technology for water injection pumps, optimizes the operating parameters of water injection pumps, effectively improves the efficiency of water injection pump units, comprehensively improves the efficiency of water injection production systems, and significantly reduces the electricity consumption of water injection systems. This is of great significance for the "quality, efficiency, and sustainable" development of oilfield crude oil production.

Current status of water injection pump operation in Factory 1A

A plant has a total of 2389 water injection wells, 2190 wells have been opened, and the daily water injection volume is 65887m3. In 2016, the annual water injection volume reached 22.67 million m3. There are currently 78 water injection stations, with 295 sets of water injection pumps in use, including 134 sewage injection pumps and 161 clean water injection pumps. The total motor capacity is 54000 kW, and the water injection unit consumption is 6.8 kW • h/m3. The electricity consumption of the water injection system accounts for about 30% of the total electricity consumption (Figure 1). There are four main reasons for the high energy consumption loss of water injection pumps. Firstly, the produced water causes severe corrosion of the pump valve at the hydraulic end of the water injection pump, resulting in high maintenance frequency and low pump efficiency of the hydraulic end of the water injection pump originally designed for clean water; The second issue is the mismatch between the water injection pump and the station's water injection volume, which causes high-pressure water to flow back and waste electrical energy; The third issue is that after the change in station injection volume, the operation mode of the injection pump has not been adjusted in a timely manner in conjunction with the injection volume, making it impossible to operate the injection pump in a good state. The fourth issue is that the water injection pump motor does not meet the requirements of the Energy Efficiency Limits and Energy Efficiency Grades for Small and Medium sized Three Phase Asynchronous Motors (GB18613-2012), and the motor itself has high energy consumption.

Energy saving and consumption reducing technology for water injection pumps

2.1 Main Applied Technologies 2.1.1 Application of Energy saving and Efficient Water Injection Pump Due to factors such as water quality corrosion and particle content during the water injection and production process, the hydraulic end accessories of the water injection pump suffer from severe mechanical wear, frequent maintenance, reduced displacement, and pump unit efficiency below the energy-saving monitoring limit. Ordinary split type valve groups cannot meet the requirements of water injection and production, resulting in a service life of less than 120 hours for the main hydraulic end accessories, far below the design life requirement of 720 hours. A factory has researched and introduced energy-saving hydraulic end, which adopts a T-shaped hydraulic end structure. The T-shaped hole can greatly alleviate the stress concentration phenomenon in the working chamber chamfer and its vicinity compared to the cross hole; Spiral guided composite sealing conical combination valve group, combined with non-metallic sealing materials on the conical surface of the metal valve plate, improves sealing performance; The guide wing of the valve core transitions from a linear shape to a certain angle shape, which can cause the valve core to rotate slightly 360 ° when moving up and down, resulting in uniform wear on the valve joint surface and self repair, thereby improving the service life of the valve (Figure 2); Technologies such as plunger automatic centering technology, plunger packing sealing synchronous isolation technology, improvement of accumulator, modified sealing components, etc,