API Publ 4717:2002 pdf download

API Publ 4717:2002 pdf download.Predictors of Water-soluble Organics (WS0s) in Produced Water-
ALiterature Review.
The oil/water separator system is designed to ethetently remove oil droplets from the produced water, therefore, there is a strong inverse correlation between the efficiency of oiIwater separation and the coflcefltrabofl of iiulkanes in produced water.
Polycyclic Aromatic Hydrocarbons (PAHs) Polycyclic aromatic hydrocarbons PHs: also called polyriucicar aromatic hydrocarbonsi. dctined as hydrocarbons containing Iwo or more fuscd aromatic rings. arc the petroleum hydrocarbons of greatest environmental concern in produced waler, because of their toxicity and persistcncc in thc marine emirnnnient (Neff. 1987i. Concentrations of total PAHs in produced water typically range from about (lOX to 3.0 mgL (imhle 2). Naphihalene and occasionally phenanthrene and their alkyl homologucs arc the only PAHs that are s*wnclinies prcscnt at higher than trace concentrations (Thblc II). These lower molecular weight PAl-Is often arc present at higher concentrations in produced water from gas wells than in produced water from oil wells (Stephenson ci aL, i994j.
Individual higher molecular weight PAHs. such as benioapyrene. rarely are present in produced water at concentrations greater than about 0.0001 mgI. The aqueous solubilily olbenioia)pyrene is so low (“ 0.003K mg/I) and its altinity for the oil phase so high (log lç,. 6.04:i that it would not be expected to be present in solution in produced water. Crude oils rarely contain more than about I ppm heniotapyrene (Neff. 1979). Thus, high molecular weight PAHs. such as benzota)pyrene. are not expected in produced water, unless the produced water contains a high concentration of dispersed oil droplets.
Measured crmcentrations of total PAl-Is in Gull of Mexico produced water are in the range of 0.OX to 1.86 mg/I. (Neff. 1997). Concentrations of individual PAH from naphihalenc to chryscnc in produced waters from different sources nearly always are in the range of a few thousandths to about 0.2 mgI. (I’ahic II) cnnceninitkms decrease as molecular weight increases. In most cases, except for naphihalenc. the alkyl honiologucs are moit abundant than the parent PAl-Is. Naphthalenc. because of its high aqueous solul’iility ( 22 mg/Un sea water Whitehouse, 1984). partitions from the oil phase into the produced water. Naphthalenc and alkylnaphihalcncs are the most abundant PAHs in most produced waters.
If the oil/water treatment syvtem is operating etliciently. most of the hydrocarbons in produced water are present at concentrations well below their single.phase aqueous solubilities. The amount of a hydrocarbon that dissolves from the oil phase into produced water depends on the concentration of the hydrocarbon in the oil and the oil/water pau’tition coetlicieiu for the hydrocarbon (Lee et al.. 1992a; Neff and Sauer. 1995a. For example. a No. 2 fuel oil containing 4.000 inØg naphthalene produced a water-soluble fraction (similar to a produced water( containing 0.84 mg/I. naphthalene (Anderson ci aL. 1974 . This concentration is about 4% of the saturation concentration of naphthaiene in seawater.
Other Organic Components of Produced Water. There is little infomiation about thc concentrations of cyclic .ilkancs (naphthcnes and sulfur-. nitrogen-, and oxygen-substituted saturated and aromatic lhclcmcyclic) organic compounds in produced water. These chemicals usually arc more water-soluble than normal or branched alkanes or unsubstituted hydrocarbons of similar molecular weighl(McAuliflc. 1966. Three produced waters from Indonesia contain (rjce. of decalins de hysnrnaphthaknes. dibeivniuran, hnioIhioplwnc. and ditwnihiophcne Table 12). Dccahn i a typical cyclic alkane. composed ol two conjugated, saturated six-ineniber carbon rings. Heni tlt phene and dibeniuthiophene usually are the most abundant sulfur heterocyclic compounds in produced water. Concentrations of thcse compounds in cnide oils and the produced waters associated with them usually vary directly with the concentrabon of sulfur in the oils. Dilwnzoiuran is a typical oxygen-substituted heterix.yclic conipound, and usually is present at low concentrations in produced waler. There is flo information about the concentrations of nitrogen hctci-ocychcs in produced water. Some of the lower molecular weight N-hetenieydics. such as acridine and carhaiole. probably arc present in some produced waters at low concentrations.