Borehole microseismic, completion and production data analysis to determine future wellbore placement, spacing and vertical connectivity, Eagle Ford Shale, South Texas

Abstract

Hydraulic fracture stimulation and proppant placement increases well deliverability for shale gas reservoirs. Microseismic data, as well as completion and production diagnostics, were used to analyze the hydraulic fracture behavior of a horizontal well in the Eagle Ford Shale. The objective of this study was to understand the appropriate wellbore spacing between two wells, and the impact that a clay-rich layer, a potential fracture barrier between two intervals, has on the slick water single-well completion method. Based on production data, the analysis described in the following sections shows that propped fracture half-lengths for adjacent horizontal wells is likely less than 660 feet. The microseismic results, as well as chemical fluid tracer results, suggest a larger half-length than indicated by the production data. The difference in the results suggests that the stimulated rock volume (SRV) calculated from microseismic data is not a direct indicator of the actual drainage area of a horizontal well. The SRV may represent the volume associated with hydraulic and/or natural fracture networks stimulated by completion fluid, and it is not a good indicator of where the proppant has been placed. Also, it was determined that there may not be a fracture barrier between the two intervals in the Eagle Ford Shale. For the vertical well, results from the hydraulic fracture model, microseismic data, chemical fluid tracers, and production data show that there is pressure communication between the two intervals that are separated by a clay barrier. Other useful conclusions were made in addition to the two objectives stated above. For example, the number of microseismic events per simulated fracturing stage correlated with production distribution, measured by production logs, for each interval. More importantly, this multifaceted study and analysis has provided useful information in the develop of the Eagle Ford Shale.