Water Quality Characteristics And Ecological Utilization Potential Assessment Of Fracturing Flowback Fluids

At present,a large amount of sewage will be produced in the process of oil and gas production.However,due to the lack of standard support for the ecological utilization of sewage in oil and gas fields,the recycling rate of sewage is not high,and it cannot be used in large-scale ecological restoration projects with greater social benefits.However,the production of fracturing flowback fluid in Xinjiang Mahu Oilfield is huge,and the disposal of the flowback fluid has become a bottleneck restricting the oilfield.Considering the use of fracturing flowback fluid for ecological environment improvement has become the best of both worlds.In this paper,the fracturing flowback fluid after re-injection treatment in the joint processing station of Xinjiang Oilfield is used as the water sample,and the water quality of the flowback fluid is routinely analyzed,and two methods for measuring the concentration of guar gum in the water quality are compared and analyzed.Characteristic pollutants in water quality as the research object.By preparing simulated sewage containing characteristic pollutants,especially using soil itself as crude oil emulsifier to prepare oily sewage,the method is innovative.A separation and extraction method of guar gum in soil is established,and an aqueous medium is studied by indoor simulated soil column experiments Longitudinal migration law of salt and petroleum hydrocarbons in soil and migration and transformation law of guar gum in soil.Through soil cultivation,alfalfa was selected as the test plant,and the ecotoxicity of characteristic pollutants to typical plants in Xinjiang desert area was studied by germination test and pot experiment,and the toxicity concentration threshold of characteristic pollutants was determined,so as to evaluate fracturing regression.The potential of drainage ecological utilization,and put forward a feasible scheme.The research results show that the water quality of the treated fracturing flowback fluid still exhibits the characteristics of high salinity and high COD,and the pollutant salt,petroleum hydrocarbon and guar gum are screened out as characteristic pollutants;The accumulation of salinity in the high moisture content of the clay reaches the peak,and the petroleum hydrocarbons are easily absorbed by the clay and accumulate on the soil surface,and a large amount of petroleum hydrocarbons are difficult to migrate to a depth of 20 cm below the soil.It is easily degraded into small molecular substances in the environment;in addition,high concentrations of guar gum can significantly promote the germination of alfalfa seeds and plant growth.In the short term,in order to ensure the germination of alfalfa seeds and the growth of seedlings,other characteristic pollutants in the water quality in order to ensure the normal growth of alfalfa mature plants,the concentration of other characteristic pollutants in the water quality should be controlled at: salt concentration <6000 mg/L,the concentration of petroleum hydrocarbons is less than 100 mg/L.Finally,through the evaluation of the potential of the fracturing flowback fluid,a feasible plan for ecological utilization is proposed.The treated fracturing flowback fluid is mixed with the external drainage of the Karamay Municipal Sewage Treatment Plant at a ratio of 1:3,which can be used to irrigate alfalfa plants and increase the potential for ecological use.