Research On The Breeding And Characteristics Of Oil Based Mud Drilling Cuttings Degradation Functional Bacteria

With the development of China's shale gas exploration and development of oil base mud drilling fluid because of its stable rheological properties, lubrication characteristics and enhanced characteristics of borehole stability in shale gas mining process can solve by sidewall instability occurs well leakage, hole collapse and shrink neck problem is widely used, resulting in oil base mud drilling cuttings solid waste more and more, on soil, surface and groundwater causing serious pollution and harm to human health and safety. In the face of the environmental problems which need to be solved urgently, the incineration method and thermal analysis method are the main techniques to deal with the drilling cuttings of oil based mud. To this end, this paper, from the perspective of clean and environmental protection, low cost, high efficiency, easy to use and no two pollution of microbial technology for oil based mud drilling cuttings harmless treatment and has important practical significance.In this paper, the physical and chemical properties and composition analysis of oil base mud drilling cuttings in Gongxian Sichuan shale gas field are analyzed to determine the pollutant and the pollution degree; Combined with physical and chemical methods of functional bacteria for study on physiological characteristics and the use of molecular biological identification of functional bacteria of the genus; directional screened degradating bacteria and to carry out the oil base mud drilling cuttings degradation experiment and research of environmental influence factors, evaluation the under suitable conditions the degree of pollution and the use of instrumental GC-MS analysis of functional bacteria easily degradable group. The results obtained are as follows:(1) Oil based mud drilling cuttings appearance is black and gray, there is a pungent odor, the physical and chemical properties of: pH = 7.02, neutral; the moisture content is 4.427%, the water content is low; chemical oxygen demand(COD) is 187834mg/Kg; biochemical oxygen demand(BOD5) is 52990 mg/Kg; oil content is 67876 mg/Kg; the oil pollution is the main. The oil content in the extraction speed of 180rpm/min, dosage of solid-liquid ratio was 1:2 under the conditions of extraction 6 times by measuring the obtained non dispersive infrared method, oil based mud drilling cuttings accounted for 6.8% of the total, the relative "soil environmental quality standard" maximum standard value of 5000mg/Kg exceed the standard 13.6 times, pollution as the main ingredient of C17~C44 alkanes, branched alkanes, alkenes, enol and naphthenic hydrocarbon and other organic matter.(2) From Gongxian oil base mud drilling cuttings, Gongxian refinery oil refinery wastewater and wastewater treatment plant oil containing wastewater in the selection of five strains of functional bacteria T-1~T-5. T1 is a spherical, gram negative, strong, facultative anaerobic strains, the log phase in 0~9h, 1175 bp sequence, Klebsiella(Klebsiella sp.); T2 is the long rod-shaped, gram positive, weak, facultative anaerobic strains, the log phase 1~15h in, 1053 bp sequence for, Bacillus subtilis(Bacillus subtilis strain.); T3 is rod-shaped, gram positive, strong motility, facultative anaerobic strain, the logarithmic phase in 2~18h, 1167 bp sequence for Bacillus strains(Bacillus tequilensis strain.); T4 is a rod-shaped, gram negative, facultative and weak anaerobic strains,the log phase in 6~27h, 1155 bp sequence, Bacillus strains(Bacillus stratosphericus strain.); T5 is short rod-shaped, gram negative, strong, facultative anaerobic strains, the logarithmic phase in 1~18h, the 1131 bp sequence, for the Acinetobacter genus(Acinetobacter sp.).(3) Five strains of bacteria in 10% inoculation amount, 35 DEG C in response to growth temperature, between the 2:1~4:1 N-P ratio, 0.5% salt concentration conditions, through of oil base mud drilling cuttings degradation experiments showed that, in 3D the degradation rate reached about 30%-37%, 18 D reached 50% tends to be stable, after 30 days. The addition of bacterial suspension, the degradation rate remain unchanged. The oil based mud drilling cuttings before and after the reaction of the crude oil by GC-MS analysis, functional bacteria can use small molecular C15~C24 carbon atoms of straight chain alkanes organic metabolic activities, and produce branched alkanes, esters, acids, alcohols and hydrocarbons such as naphthenic intermediate product; the intermediate product is produced and is difficult to function the content of organic polymer degradation bacteria were C31, C43 and C44 carbon atoms still accounts for the oil based mud drilling cuttings of crude oil in about 3.5% of the total, "the maximum relative standard of soil environmental quality standard" value of 5000mg/Kg exceed the standard 7 times, still belongs to the hazardous waste, the late experimental screening plant investigation can achieve the accumulation of cultivation emission standards and environmental safety assessment.