Spectral noise logging (SNL) is an acoustic noise measuring technique used in oil and gas wells for well integrity analysis, identification of production and injection intervals and hydrodynamic characterisation of the reservoir. SNL records acoustic noise generated by fluid or gas flow through the reservoir or leaks in downhole well components.
Development history Noise logging tools have been used in the petroleum industry for several decades. As far back as 1955, an acoustic detector was proposed for use in well integrity analysis to identify casing holes.Enright, R.J. 1955. Sleuth for Down-Hole Leaks, Oil & Gas J.:78-79 In this class of problems, the efficiency of noise logging was comparable to that of temperature surveys. In 1973, McKinley presented his technique for passive noise logging in which signals were recorded in several, e.g. three or four, frequency ranges at every measurement depth.McKinley R.M., Bower F.M., Rumble R.C. 1973. The Structure and Interpretation of Noise From Flow Behind Cemented Casing, Journal of Petroleum Technology, 3999-PA This method, allowing quantitative and qualitative data interpretation, became common across the petroleum industry.
Over many years, downhole noise logging tools proved effective in inflow and injectivity profiling of operating wells,Britt E.L. 1976. Theory and applications of the borehole audio tracer survey, the SPWLA Seventeenth Annual Logging Symposium, Denver, ColoradoSpectral Noise Logging Data Processing Technology leak detection,Leak Detection by Temperature and Noise LoggingInnovative Logging Tool Using Noise Log and High Precision Temperature Help to Diagnoses Complex Problems location of cross-flows behind casing,McKinley, R.M. 1994. Temperature, Radioactive Tracer, and Noise Logging for Well Integrity: 112-156 and even in determining reservoir fluid compositions.Wang J, Alex van der Spek et al. 1999. Characterizing Sound Generated by Multiphase Flow, SPE Annual Technical Conference and Exhibition held in Houston, Texas Robinson (1974) described how noise logging can be used to determine effective reservoir thickness.Robinson W.S. 1974. Field Results From the Noise-Logging Technique, 49th Annual Fall Meeting of the SPE of AIME in Houston, Texas
Physical principles The theory of sound generation by turbulent flow of fluid or gas through a single channel has been well elaborated by many authors, while the generation of acoustic oscillations by fluid flow through porous reservoirs is still poorly understood.Hinze J.O. 1959. Turbulence, McGraw-Hill Book Co., Inc., New York Various physical models have been proposed, including the mechanism of sound generation by transient pulsing of the fluid flowing through pores with randomly varying properties (Zaslavsky, 2005).Zaslavsky Yu. M. 2005. On the theory of acoustical emission accompanying gas filtration by partially fluid-saturated medium, Electronic Journal Technical Acoustics, vol.5 (in Russian) This paper also describes the effect of the elastic compressibility of the rock matrix on the noise signal generated by fluid flow. Especially noteworthy among the many sound generation models is the aerodynamic one based on the turbulence of fluid microflows escaping capillaries and entering wider pores (Lighthill, 1954).Lighthill M.J. 1954. On Sound Generated Aerodynamically: Turbulence as a Sound Source, Proc., Royal Soc. of London Generally, all of these existing models are valid and all of the above phenomena contribute to noise generation.
Applications
Near-wellbore flow characterisation Identification of inflow and injection intervalsBATS Borehole Audio Tracer Survey HALLIBURTONSNL Spectral Noise Logging TGT Oilfield Services Noise Tool Weatherford Identification of inter-reservoir communications including cross-flows behind casingFlowPoint® - Archer ГАК Трехкомпонентный геоакустический каротаж Недра-С Near-wellbore reservoir pressure evaluation in flow intervals including unperforated casing intervalsReservoir Pressure Analysis Well integrity monitoring Detection of leaks in tubing, casing and other well componentsLeakPoint® - Archer Sonan Baker Hughes
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