Production Profile Calibration of Effective Composite Drilling Encounter Rate in Shale Gas Horizontal Wells: A Case Study of the Wujiaping Formation, Northeast Sichuan Basin

Geometric drilling encounter rates may not represent the productivity of vertically heterogeneous shale reservoirs. This study develops a production-profile-calibrated effective composite drilling encounter rate (Rce) for the Wujiaping Formation, Northeast Sichuan Basin. The database contains 13 wells, including 11 commercial production wells and two appraisal wells. Production logging data from three benchmark wells are used to estimate sublayer productivity relative to reference Sublayer 4 and assign bounded effective-length weights. Sublayers 3 and 4 provide complementary production, whereas the contribution of Sublayer 5 depends on local gas content and porosity. Low-efficiency combinations and poorly productive intervals receive reduced weights. An illustrative 1377 m interval yields an effective length of 1283.4 m and an Rce of 93.2%. Application to the commercial wells illustrates why geometric encounter rates alone cannot explain differences in estimated ultimate recovery. The previously proposed 90% cutoff is treated as a provisional local screening criterion rather than a universal economic threshold. The method distinguishes reservoir exposure from stimulation coverage and supports trajectory and completion assessment. Its transferability remains limited by overlapping calibration and application samples, production logging uncertainty, and differences in stimulation design.