A Cuttings Workflow for Scenario Sensitivity Assessment and Completion-Stage Zonation

Reliable completion-stage design in heterogeneous shale oil reservoirs requires integration of geological and mechanical information along horizontal wells, where continuous core coverage is often limited. Cuttings characterization and digital rock analysis provide complementary evidence, but depth uncertainty, nonunique mechanical interpretations and prescribed scoring criteria complicate their translation into completion decisions. A cuttings-based Geo-Engineering Sweet-Spot Score (GESS) workflow is developed to integrate sample quality control, mechanical interpretation ensembles, scenario sensitivity analysis and constrained stage segmentation. Mechanical candidates are scored before averaging to retain the consequences of interpretation variability, while stage boundaries are determined from component scores independently of composite weights. Application to the Lucaogou Formation integrates 360 cuttings bags, 24 core records and production data from 32 wells. The 359 valid sampling points are grouped into 30 stages across a 1401 m interval. Equal weighting preserves 90.0% of stage classifications, and 11 stages retain their classifications across all admissible nonnegative weight combinations. However, mechanical-threshold perturbations reduce stage-class agreement to 13.3% in the most divergent scenario, demonstrating the importance of locally calibrated suitability criteria. For eight fixed holdout wells, root-mean-square error is 3.90 for GESS alone, 2.26 for engineering covariates alone and 1.90 t d−1 km−1 for their combination. The incremental reduction remains uncertain in this small within-cohort comparison. The workflow provides reproducible stage delineation and explicit identification of assumption-sensitive classifications, supporting candidate interval screening and targeted data acquisition in reservoirs with limited core coverage.