Multiproxy sedimentary organic matter analysis of the upper Wolfcamp Formation in the Collier-1201 well, southeastern Delaware Basin, Texas

Abstract

Horizontal drilling and multistage fracturing designs have recently made the Wolfcamp shale horizons a highly sought-after and low-cost oil opportunity at a time of market volatility. One current challenge is that the Wolfcamp shale horizons are unpredictable, especially in acreages with limited well control and seismic data. Sedimentary organic matter (palynofacies) analysis can delineate thermal maturity windows, determine kerogen types, and reflect depositional environments to aid in realizing hydrocarbon potential. We palynologically processed 16 samples at roughly 3 m intervals from the upper Wolfcamp section of the Collier-1201 well in Reeves County, Texas. We examined the prepared microscope slides in transmitted light to quantify (point count) and describe the organic facies in each sample. Additionally, we integrated organic geochemical data to corroborate palynofacies analysis. We classified most of the observed organic matter particles as highly degraded phytoclasts with unidentifiable terrestrial palynomorphs. The palynofacies and organic geochemical data indicate a mixed type-II/III kerogen (oil- and gas-prone materials) characterized by substantial terrigenous input. All samples displayed a high degree of thermal maturity from immense overburden as the Delaware Basin subsided and the overlying beds compacted. The lithologic and organic facies of the studied interval reflect fluctuating proximal marine conditions.