Acoustic and Signal Processing Techniques To Estimate Rock Properties Through Casing: Preliminary Results SPE 69604
Language: Inglés Series: García-Osuna, F ; Publication details: Dallas, Texas Society of Petroleum Engineers 2001Online resources: Summary: This paper reports preliminary results of the development of acoustic and signal processing techniques to estimate rock properties through casing. In general, the major factors influencing compressional (P) and shear (S) wave velocities of unconsolidated and consolidated sedimentary rocks are porosity, bulk density, and effective stress. The acoustic impedance of the viscoelastic porous media behind the cemented casing will also depend on these factors, being higher for rocks under water or oil-saturated conditions than for rocks under gas-saturated condition. Stronger local-borehole compressional-wave reflectivity is expected from gas-rock reservoirs than from water or oil-rock reservoirs. In the case of the wet-Berea sandstone, the formation acoustic impedance is similar to the acoustic impedance of the cement layer. Experimental and theoretical studies of ultrasonic wave transmission and reflection for cemented casings and steel-plates with cemented sedimentary rocks were undertaken. Results provide a quantitative means to use acoustic energy to evaluate pore fluid saturant and detect gas, oil, and water interfaces through casing. A time and frequency domain analysis of a selected portion of the reflected signal at normal and oblique incidence is carried out. Laboratory measurements of ultrasonic wave attenuation and penetration into the rock formation through casing are also described and discussed.| Current library | Status | Barcode | |
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This paper reports preliminary results of the development of acoustic and signal processing techniques to estimate rock properties through casing. In general, the major factors influencing compressional (P) and shear (S) wave velocities of unconsolidated and consolidated sedimentary rocks are porosity, bulk density, and effective stress. The acoustic impedance of the viscoelastic porous media behind the cemented casing will also depend on these factors, being higher for rocks under water or oil-saturated conditions than for rocks under gas-saturated condition. Stronger local-borehole compressional-wave reflectivity is expected from gas-rock reservoirs than from water or oil-rock reservoirs. In the case of the wet-Berea sandstone, the formation acoustic impedance is similar to the acoustic impedance of the cement layer. Experimental and theoretical studies of ultrasonic wave transmission and reflection for cemented casings and steel-plates with cemented sedimentary rocks were undertaken. Results provide a quantitative means to use acoustic energy to evaluate pore fluid saturant and detect gas, oil, and water interfaces through casing. A time and frequency domain analysis of a selected portion of the reflected signal at normal and oblique incidence is carried out. Laboratory measurements of ultrasonic wave attenuation and penetration into the rock formation through casing are also described and discussed.
