Title : An evaluation method for effective perforation cluster opening efficiency using fracturing and production data
Abstract:
In multi-cluster hydraulic fracturing of shale oil horizontal wells, the number of effectively opened perforation clusters may differ substantially from the designed cluster number, directly affecting fracture stimulation efficiency and well productivity. Although diagnostic techniques such as fiber-optic monitoring and production logging can provide direct information on cluster activation, their relatively high cost limits widespread field application. To address this issue, this study develops a practical and field-scalable workflow for quantitatively evaluating the effective number of opened clusters and cluster opening efficiency using routinely acquired fracturing, flowback, and production data. Rate transient analysis and pressure transient analysis (RTA/PTA) are first applied to production data to characterize the effective fracture–reservoir contact capacity after stimulation, which is subsequently converted into an equivalent effective fracture area by incorporating matrix permeability obtained from core measurements and dynamic analysis. Fracture half-length and effective fracture height are determined from hydraulic-fracturing simulations and calibrated using microseismic interpretations when available. The effective number of opened clusters is then estimated by comparing the equivalent effective fracture area with the theoretical fracture area contributed by a single cluster, and the cluster opening efficiency is calculated relative to the designed cluster number. The workflow was applied to two shale oil horizontal wells with contrasting production performance. Well A contained 100 designed clusters, of which approximately 30 were evaluated as effectively opened, corresponding to an opening efficiency of 30%, whereas Well B contained 135 designed clusters and approximately 118 effectively opened clusters, yielding an opening efficiency of 87%. Consistent with these results, Well B exhibited significantly higher production per unit horizontal lateral length than Well A. The agreement between the evaluated cluster opening efficiency and field production performance demonstrates that the proposed workflow can effectively quantify differences in actual hydraulic-fracturing stimulation effectiveness. By relying primarily on routine field data and using microseismic observations only as optional calibration information, the method provides a low-cost approach for post-fracturing diagnosis, identification of low-efficiency wells, refracturing candidate screening, and optimization of subsequent fracturing designs
