Multi Functional Treatment Technology Of Acidic Wastewater In Oilfield

With the development of the times and the technological progress,the depth of oil production in our country is continuously strengthened,and a lot of wastewater are produced every year.In shengli oil field,just the kind of water flooding sewage capacity is 14.9×10⁴ m³?d^-1.Along with the national plan for 13th Five-Year and the people's awareness of environmental protection,the stabilization,resources,harmless and green treatment of oilfield wastewater is becoming more and more important.The research of this subject has important scientific,practice and environmental significance.In this paper,the reinjection treatment of A₂station wastewater from block A,shengli oilfield,has been done.The wastewater shows weakly acidic?pH 5.9⁶.4?,high corrosion rate(0.596mm?a^-1),high suspended solids(58.5 mg?L^-1),many microbial(SRB 1300cfu?mL^-1)and has unstable factors(S^2-and Fe²⁺).Adopting gas-liquid fast mixing reaction technology to achieve the goal of multi function treatment,after treatment,sewage pH value is effectively improved,and stable at 7.2,the problem of black color has been resolved,the corrosion rate gets controlled(less than 0.02 mm?a^-1),suspended solids become less(less than 5 mg?L^-1),Fe²⁺,S^2-and other unstable substances are eliminated(less than 0.1 mg?L^-1),SRB obtains suppressed(6 cfu?mL^-1),reaching the strict requirements of the water quality.The main contents and conclusions of this paper are as follows:1)Combined the oilfield water injection conditions with water features,the water injection quality standard was determined to be B2grade.The wastewater has the problems of corrosion and suspended matters,and the type of wastewater is CaCl₂.Besides,the wastewater has the CaCO₃ and CaSO₄ scaling trend.2)Complex modifier was used for the treatments of wastewater from the station.The removal rate of turbidity was 99.16%,the yield of sludge was 0.22 g?L^-1,and the corrosion rate was 0.025 mm?a^-1.However,the industrial field application can not achieve ideal results.When gas-liquid fast mixing reaction technology is used,water quality indicators have been controlled effectively,the industrialization is running well,achieving multiple goals.When the coagulant is PAC/CPAM,PAC has145 mg?L^-1,and CPAM has 2.3 mg?L^-1,getting the best treatment effect.H₂SO₄ or Ca?OH?₂ used to treat the primary sludge at the pH value of 2.5or 11,can improve the sludge dehydration rate significantly.3)According to the transformation scheme of the station,the type of SV-15/500 gas-liquid reactor and other auxiliary facilities were selected.The operating cost of the project was calculated,equivalentting to 1.76yuan?m^-3.Gas-liquid mixing reaction technology has been running for more than one year in the sewage station stably,daily processing capacity is 3500 m³.The corrosion and suspension problems of the wastewater are solved,and the output water quality meets the requirements of standard,at the same time,there were no serious scaling problems,realizing the special requirements on the reinjection about geological conditions.