The distribution characteristics of petrolic pollutant in Changqing oilfield

In view of the present situation that a lot of waste drilling fluid polluted soil and water in the process of petroleum exploration and development, the drilling fluids in the 5 well fields which were in the north area of Changqing oilfield were chosen to carry on the pollution characteristics analysis. 35 physicochemical indexes and contamination indexes had been determined in the drilling fluids, and the results showed that the waste drilling fluid was ropiness colloid, paste and viscosity high; the ingredient of drilling fluid were clay, polyacrylamide(PAM) and carboxymethylcellulose(CMC);COD_Cr, mineraloils, NH₄⁺, Cr, Cd, Pb, As, pH, chromaticity and so on all exceeded standard in the drilling fluid, Zn exceeded standard in some individual well fields, and the other over-standard parameters´ superstandard multiple was not much except for COD_Cr and mineral oils which exceeded standard seriously. COD_Cr, mineral oils, NH₄⁺ and so on were from formation, petroleum and the additives such as polyacrylamide (PAM), carboxymethylcellulose (CMC). High pH was related to calcined soda or caustic soda, Cr, Cd, Pb, As, Zn and so on which were from the sidewall material cattied by the circulating mud. All the affecting factors were related to formation lithological composition.