API RP 45:1998(R2012) pdf download.Recommended Practice for Analysis of Oilfield Waters
1 Scope
This document is directed toward the determination of dis- solved and dispersed components in oilfield waters (produced water, injected water, aqueous workover fluids, and stimula- tion fluids). Bacterial analyses, bioassay (toxicity tests for marine animals), NORM determination, and membrane filter procedures are outside the scope of this document. Biological determination of the species and concentration of bacteria are covered in NACE TM0194-94, Field Monitor- ing of Bacterial Growth in Oilfield Systems . Determinations of Naturally Occurring Radioactive Mate- rials (NORM) in oilfield waters is discussed in API Bulletin E2, Bulletin on Management of Naturally Occurring Radio- active Materials (NORM) in Oil and Gas Production . Membrane filter procedures are covered in NACE TM01- 73, Test Methods for Determining Water Quality for Subsur- face Injection Using Membrane Filters . Analyses for residuals of proprietary organic treatment chemicals, such as corrosion inhibitors, demulsifiers, scale inhibitors, water clarifiers, biocides, etc. are also outside the scope of this document. However, analyses for generic com- ponents of proprietary chemicals, such as phosphate (scale inhibitor), are included in this document. Lastly, analyses of nonhazardous oilfield waste (NOW), such as drilling fluid, soil, cores, etc. are outside the scope of this document. However, analyses of separated water (includ- ing filtrates) from such sources are within the scope. The analytical methods presented in this document were selected for their accuracy, reproducibility, and applicability to oilfield systems. For most constituents, several methods of varying degrees of complexity and accuracy are presented to provide the analyst with the opportunity to choose the most appropriate and cost effective method pertinent to his/her needs. While the cited methods may also be used as indicators of the environmental quality of oilfield waters.
3.3.1 Waterflood Evaluation and Monitoring
3.3.1.1 Water injected into underground formations can result in formation damage if the injected water and connate water are incompatible. Formation damage may be predicted by analyzing injection and connate water prior to initiating injection. Two examples of incompatibilities that can result in formation damage are: a. The two waters contain dissolved salts and may precipitate solids when mixed. The most damaging precipitated solid is an insoluble scale that plugs the formation, i.e., Ba 2+ and SO 4 2– which form barium sulfate. b. The two waters differ greatly in total dissolved solids such that upon mixing, ionic concentration changes within the for- mation result in the swelling of clay minerals and the reduction of formation permeability. 3.3.1.2 During the course of an injection project, a water sample whose composition is identical to that found in situ in the reservoir provides a snapshot of the steady state condi- tions occurring in the reservoir. However, the process of obtaining a representative reservoir water sample is not a trivial one. While bottom hole samples are most desirable, such samples are seldom available since the act of bringing a sample to the surface creates physical and chemical changes. For example, decreases in temperature and pressure affect both dissolved gas equilibria and individual ionic species equilibria.
API RP 45:1998(R2012) pdf download
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