Mesozoic source rocks and petroleum systems of the northeastern Qaidam basin, northwest China

This case study of the San Andres Formation in the mature Vacuum shows how seismic data can be used to target New Mexico field,, bypassed pay with horizontal wells. These dual-lateral wells were the first attempt at horizontal development in the Vacuum San Andres field and in the San Andres Formation in New Mexico. The primary reservoir facies consist of ramp crest and outer ramp dolomitized peloidal packstones, skeletal and ooid grainstones, and fusulinid packstones. Vertical facies successions form numerous high-frequency carbonate depositional cycles and cycle sets that create distinct reservoir zones. Structural blocks created by small-scale faults (less than or equal to25 ft [8 m] vertical displacement) and bypassed pay located in thin depositional cycles were identified with three-dimensional compressional-wave seismic amplitude and coherency volumes and p well data and targeted using medium-radius horizontal wells. Horizontal wells penetrated fault blocks and depositional cycles that were not adequately drained by existing vertical wells. Production curves show a significant increase in production from the horizontal wells and no interference with production from offset vertical wells. This suggests that the faults are partially sealing.