While Fracturing Stage Evaluation Workflow

Abstract The goal of hydraulic fracturing in nano-Darcy rock is to create an artificial reservoir, known as a stimulated reservoir volume (SRV), in the source rock. The SRV created in each stage varies in terms of pore-throat size, fracture dimension, and production contribution. Existing evaluation techniques for unconventional hydrocarbon reservoirs, such as rate transient analysis (RTA), chemical tracers, micro-seismic, and fiber optic cables, require long production data, are performed after the hydraulic fracturing job, require extended analysis time, or are expensive to implement (Thompson et al., 2017; Kumar Ashry et al., 2021; Barree et al., 2002). Ibrahim et al. (2020,2021) proposed a technique that provides characterization of hydraulic fracture stages during the plug and perf treatment. This technique, coined here ‘While Fracturing Stage Evaluation’ (WFSE), can estimate several parameters, including permeability, fracture geometry, stimulated surface area, and cluster efficiency for each evaluated stage. The required data for WFSE are treatment time, bottomhole pressure, and hydraulic fluid injection rate. The proposed technique is based on falloff analysis, a well-known practice in well testing. However, in WFSE, the fall-off methodology is applied to characterize fracture attributes for individual stages rather than for the entire well (as in well testing). Additionally, this paper provides a new interpretation of instantaneous shut-in pressure (ISIP), in close agreement with WFSE results and provides valuable insight on the growth of the hydraulic fractures. The new workflow proposed in our study was applied to a hydraulicly fractured well with 41 stages. The results matched the fracture half-length and Ac√k obtained from conventional RTA in 90% of the cases. The results from both techniques led to the identification of fracture geometry (complex or planar fracture), flow regime (spherical, radial, and linear), and fracture parameters (SRV, Ac√k, Xf), which provided an improved understanding of the fracture surface area. The prposd workflow can be used to optimize the design of stimulation, completion, and simulation modeling.