In spite of the growing interest in Late Ordovician to the Early Silurian Wufeng-Longmaxi black shale for gas production in the southeast of the Sichuan Basin, little data are available on the acoustic properties of these shale reservoirs. Dynamic elastic properties of a suite of shales from this formation with different organic matter content were measured using the ultrasonic transmission technique at a range of confining pressures. The mineralogical features and reservoir space types were studied with the goal to analyze their influence on acoustic properties of the shale samples. The TOC (total organic content) is found to have a positive correlation with the quartz content and a negative correlation with the clay content. Organic matter pores and inter-crystal micro-pores are the main pore types. Organic-rich shales show low P-wave impedance and Vp/Vs due to relatively higher TOC and quartz content; nonetheless, high P-wave impedance is also observed when the quartz content is very high resulting from the variation of load-bearing grains. The velocities and anisotropy of different shale samples show varying pressure dependence. A strong positive correlation is found between the anisotropy and the clay content.
Presentation Date: Thursday, September 28, 2017
Start Time: 9:20 AM
Location: 351D
Presentation Type: ORAL
