On May 2nd, it was reported that in the demonstration area of Jiyuan Oilfield, with the application of microbial treatment technology and integrated devices for small site produced water, after testing, the oil content in the effluent is 6 milligrams per liter, suspended solids are less than 2 milligrams per liter, and the median particle size is less than 1.5 microns. All technical indicators are operating normally and meet national industry standards. The application of this device is of great significance for the effective reinjection of produced water in low-permeability reservoirs.

Xia Zheng, the general manager of Changqing Science and Technology Engineering Company, said, "For the 'three low' oil fields, the underground natural energy is low and must be developed by water injection. The research, development and application of this process technology have improved the efficiency of oil field development, realized the effective reinjection of produced water up to the standard, saved groundwater resources, and reduced the mining output of groundwater by about 30 million cubic meters every year."

The operating area of Changqing Oilfield is characterized by deep mountains and ravines, and the inherent geographical conditions determine that the produced water treatment and reinjection station has the characteristics of multiple points, wide coverage, and small processing scale. At present, Changqing Oilfield has built 246 produced water treatment stations, using first and second stage sedimentation+filtration, biochemistry, air flotation, and integrated processes. During operation, traditional produced water treatment processes are unable to meet the needs of oilfield scale development, and safety and environmental protection are also facing new pressures.

In order to adapt to the low-cost technology development strategy, Changqing Oilfield actively revolves around the working ideas of "fine water injection and effective water injection" to effectively utilize the produced water. To ensure 100% reinjection of oilfield produced water, surface construction tends to adopt a decentralized dehydration and nearby reinjection construction mode. This model has the limitations of small water treatment capacity, multiple and dispersed stations.

Therefore, technology personnel urgently need to develop an integrated produced water treatment process and equipment that is resistant to impact loads, has high operating efficiency, is easy to manage, has low operating costs, is fast to construct, occupies a small area, and is environmentally friendly and energy-saving, to meet the requirements of oilfield produced water reinjection. The effluent quality meets the requirements for low permeability oilfield reinjection and can replace small and medium-sized produced water treatment reinjection stations as a whole.

In January 2013, Changqing Science and Technology Engineering Company organized a research team to focus on tackling the bottleneck of produced water technology. Based on the summary of the existing achievements and experience in the design and operation of oilfield produced water treatment processes, the "microbial oil removal technology" was used as the core. The microbial oil removal technology has good impact resistance, high efficiency of multiphase air flotation oil removal technology, and does not require the addition of flocculants. It draws on the advantages of shallow medium filtration in municipal water treatment, UV sterilization technology for good water quality treatment, and convenient management. It also adopts integrated and intelligent control technology, with short construction period, convenient construction, and achieves oilfield production.

The R&D team adheres to the principle of "personalized design, organic integration of intelligence and technology", innovates the technological process, and adopts a three-stage extraction and treatment process of "non medicated dissolved air flotation+biochemical treatment+shallow medium filtration"; The pre-treatment adopts a non medicated multiphase dissolved air pump dissolved air flotation process, mainly using pre cooling microorganisms for oil removal, shallow sand continuous filtration for filtration, ultraviolet sterilization for sterilization, equipment outdoor layout insulation, fixation and other technologies. The core technology has reached an advanced level.

In May 2014, the integrated device for oilfield produced water was tested in four dehydration stations in Jiyuan oil area, and the reinjection water quality reached the design value. At the West 259 Dehydration Station in Huaqing Oilfield, a continuous 6-month operation test was conducted on the integrated production water treatment device. Compared with the same scale production water treatment process, the average land area was reduced by 37%, the construction period was shortened by 50%, and the engineering investment was reduced by 20%.

At present, after more than 3 years of operation, this device has been promoted and applied in the Jiyuan ultra-low permeability reservoir comprehensive utilization demonstration base. The Huanjiang Oilfield and Longdong Oilfield have also been put into operation one after another, standardizing the technical standards for fine water injection and effective water injection, and improving the precision of produced water treatmentHigh.

Standard, precision of produced water treatmentHigh.