Application of Walnut Shell in Oilfield Wastewater Treatment

The total reserves of my country’s proven low-permeability oil fields account for 21.39% of the country’s total proven reserves. The development and utilization of low-permeability oil fields has become an important aspect of the development of my country’s onshore petroleum industry. The development ratio of oil fields will gradually increase. In the development of low-permeability oilfields, the main exploitation method is secondary oil recovery, which mainly involves water injection into the clastic rock formations. According to estimates by relevant experts, this water injection exploitation method will take about 20 years and requires a large amount of water injection. It can be seen that the use of oilfield oily sewage to replace clean water, and to carry out scientific and technological research on the advanced treatment technology of low-permeability oilfield reinjection produced water, so that the water quality of the injected oil layer meets the recommended indicators and analysis methods of water injection quality in clastic rock reservoirs SY/T5329-94 Water quality standards above A2 level are required for the sustainable development of oil fields
. The traditional methods of treating oily sewage at home and abroad include adsorption, oil separation, filtration, air flotation, flocculation, coagulation and biological treatment. After the treatment reaches the standard, the formation is reinjected, which not only slows down the pollution, but also reduces the development cost. However, it is difficult for these methods to make the suspended solids and oil in the treated water meet the requirements of SY/T5329-94 for low permeability and ultra-low permeability oil layers for the injected water quality. The hollow fiber microfiltration membrane is used to treat oily wastewater from the oilfield, and the effluent can meet the water injection quality requirements of low permeability oil layers; but the oil removal effect is unstable and the membrane flux decays too fast. The walnut shell filter-ultrafiltration device combined process treats oily wastewater from oil fields, and the process's oil removal, dirt interception, particle removal capabilities and cleaning effects have been tested to find a new, stable and efficient oil removal and turbidity removal The high-performance integrated technology of oily sewage treatment further reduces the oil content and suspended particles in the effluent of the equipment, so that the quality of the effluent after treatment can meet the requirements of low permeability and ultra-low permeability oil layer injection water.