Understanding Dynamic Behavior of Reservoirs During Microseismic Monitoring

Abstract

Summary URTeC 1619217 Changes in the physical properties of a reservoir during hydraulic fracturing of the hydrocarbon bearing layer are performed to increase the productivity of oil-and-gas wells. These changes in physical properties were studied using analyses of seismic recordings of perforation shots carried out on two monitored wells within the Fort Worth Basin, North Texas (USA). Seismic recordings obtained from monitor wells distributed at a distance not exceeding 1000m from the source were chosen for analysis. The process of hydraulic fracturing included multiple stages; perforation shots were set off before the start of the process as well as between stages. The signals were recorded using a system of 12 three-component seismic receivers, installed vertically in the monitor well. The analysis of waveforms and spectral characteristics of P-waves has shown that the character of the recorded signal and the P-wave spectrum are being repeated with high precision (correlation coefficient >0.95) for shots that are close in time (interval between shots < 10mins) and in space (distance between blasts < 15m). Lower correlation coefficients (<0.3) and spectral differences were observed for signals diffusing from the same point (distance between shot locations – 12m), but separated in time by hydraulic fracturing. These results confirm that the process of hydraulic fracturing leads to substantial changes in the physical properties of the reservoir that can be shown experimentally and analyzed theoretically.