Complementary Surveillance Microseismic and Flowback Data Analysis: An Approach to Evaluate Complex Fracture Networks

Abstract

Abstract This paper presents an integrated workflow which complementarily utilizes flowback data analysis and surveillance microseismic analysis to characterize fracture networks and stimulated reservoir volume (SRV). The workflow helps to 1) differentiate !"effective" and "ineffective" SRV and fracture half-length (ye) respectively, 2) understand how effective fracture volume (Vf) changes during flowback, and 3) explore the effects of key operational parameters on the fracture network created after well stimulation. The workflow comprises four main steps: 1) estimating SRV and fracture parameters from surveillance microseismic interpretation and flowback data analysis; 2) comparative analysis of estimated SRV, ye and Vf values; 3) Calculating volumetric ratios (e.g. flowback load recovery) to evaluate the effectiveness of fracturing and flowback operations; and 4) investigating possible relationships between operational designs and estimated reservoir and fracture parameters. The application of this workflow on an eight-well pad completed in the Horn River Basin (HRB) shows that the SRV and ye from microseismic interpretation are generally several times larger than those from flowback data analysis. This indicates that over half of the stimulated rock does not contribute to gas production. Besides, a large percentage of the effective fracture network closes during early-time (the first 200 hrs) flowback. The results show that SRV increases as total perforation clusters increases, and this relationship appears to be formation-dependent. Also, the estimated Vf seems to be smaller for wells that are opened later for flowback. This observation might be due to inter-well communication and wellbore storage effects.