Abstract

Optimizing infill development is often a delicate balance between maximizing reservoir utilization and minimizing operational costs. This project evaluated two targets (Upper Woodford, or UW and Middle Woodford, or MW) within the Woodford formation in the SCOOP play of the Anadarko Basin. The UW target generally yields lower rates of penetration (ROP) and increased bit wear which results in higher capital expenditure wells compared to the MW targeted wells. These operational and capital discrepancies raise questions regarding the benefit of staggered targeting. To evaluate reservoir utilization of each target, time-lapse geochemistry was conducted to provide quantitative zonal contribution and its change through time, as well as drainage frac heights of these targets.

Three infill development wells were drilled in a "wine rack" pattern, alternating between the middle and upper Woodford, to minimize fracture half-length and drainage overlap. Standard geo-steering practices and ED-XRF data were used to confirm stratigraphic wellbore position. Multi-dimensional gas chromatography (GCxGC) analyses were performed on oil extracts from pilot well cuttings to characterize the stratigraphic intervals contributing to production at 10' vertical resolution. These analyses were then conducted on a series of produced oil samples to provide time-lapse production allocation (PA) analysis of the producing wells for the first 9 months of production. Similarity Index (SI) was calculated on produced oils to identify potential frac-wing overlap between neighboring wells.

Observations: 1) PA for the three infill wells is statistically similar, showing that different Woodford landing targets have similar sub-member contributions in the first 9 months of production. 2) Though the center well outperforms the two outer wells due to neighboring parent well depletion, reduced pressures in outer wells did not impact zonal contributions. 3) SI study reveals larger Drainage Rock Volume overlap coincides with poorer well performance likely due to competition for resources. Well 1 & 2 saw poorer performance than Well 2 & 3 (SI: 3.7-5.2 vs 2.1-3.0). Overall, factors other than UW or MW landing zone influence reservoir drainage patterns. A cost-effective infill development program may include exploitation of the MW target when under similar geologic conditions.

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