Study Of Longdong Oilfield Horizontal Well Fracturing Wastewater Recycling Technology And Application

The fracturing process is a key initiative to increase production of oil and gaswells， horizontal well fracturing is an effective measure of the low-permeability oiland gas field production capacity. Due to the special nature of horizontal well fracturingoperations， fracturing wastewater and pollutant emissions also increased significantly.At the same time, water consumption is the ordinary hydraulic fracturing waterconsumption several times. However, due to Longdong Oilfield is located in the aridand semi-arid loess plateau area of ravines, rugged road, the relative scarcity ofresources, the problem of water supply of fracturing operations become steadyproduction constraints. Therefore, to fracturing wastewater treatment and recyclingtechnology research, is of great significance for the protection the normal productionand sustainable development of the oil field.Longdong Oilfield operations block system， the paper analyzes the evaluation ofhorizontal well fracturing wastewater pollution characteristics that fracturingwastewater has a high SS, high viscosity and high COD characteristics. SS in thewastewater comes mainly from the increase in the working process debris, viscositymaterial is mainly caused by the fracturing fluid hydroxypropyl guar gum, analysis ofthe main components of the water COD can be drawn, petroleum hydrocarbons organicmatter the highest content, wherein up to C8to C25organic. In addition, thefracturing wastewater also contains more organic species of higher fatty acids andaldehydes and ketones.Preparation of fracturing fluid to the the Longdong field horizontal well fracturingwastewater recycling conditionality, the water matrix and the right to re-analysis, clearfracturing wastewater recycling critical control factors were iron, calcium, magnesium and organic matter. The results show that the use of pre-oxidation—adjust pH—coagulation—filter—to adjust the pH value of the iron removal process can make theiron content of the horizontal well fracturing wastewater from the initial15to25mg/Lreduced to0.5to0.8mg/L, chemical complexation reaction supplemented with citricacid or EDTA, calcium and magnesium ions from the initial160to200mg/L controlwithin the range of20~25mg/L. Above process, to optimize the screening strongoxidant and coagulant and reaction conditions, the use of pre-oxidation and coagulationtreatment, and the middle supplemented by advanced oxidation, fracturing wastewaterCOD raw water20to6000mg/L, drop to100to300mg/L or less. Iron, calcium,magnesium and organic matter removal oilfield water-based fracturing fluid standardpreparation, fracturing fluid, the test fully meet the relevant requirements of thefracturing operations.The combination of these studies to determine the Pre-oxidation-Adjust thepH-Coagulation-Sedimentation-Advanced Oxidation-Filter-Adjust the pH of thefracturing wastewater treatment process, the design and development of of fracturingwastewater modular processing equipment, the equipment set flocculation,sedimentation, filtration, advanced oxidation, sludge disposal and other auxiliary unitmodule as one of the horizontal well fracturing wastewater regeneration treatment,vehicle-mounted mobile approach. Field experimental study in Longdong Oilfield threehorizontal wells, handled a total volume of1400m~3, fracturing wastewater recyclingeffect is significant to prove the practicability and feasibility of the treatment process,horizontal well fracturing wastewater Longdong Oilfield technical support.