Al Atwah, Ibrahim (2019-06). Geochemistry and Basin Modeling Of Devonian-Mississippian Petroleum Systems in the Anadarko Basin. Doctoral Dissertation.
Thesis
The Woodford Shale and the overlying Mississippian Limestone constitute one of the prolific unconventional and conventional hydrocarbon targets in Northern Oklahoma. Technological advancement in drilling and production has allowed for the economic recovery of hydrocarbon from tight source-rock reservoirs. However, many challenges remain unexplained related to the variation in well performance and hydrocarbon composition. Many factors control hydrocarbon producibility from Devonian-Mississippian reservoirs, including rock mineralogy, thermal maturity and organic-richness. A collection of rock, crude-oil and fluid-inclusion samples were geochemically investigated to gain insight into their origin and thermal maturity. This study introduces an entirely new geochemical approach for the correlation of high-temperature fluid inclusions with their source rocks, using quantitative extended diamondoid analysis (QEDA). Mississippian mudrocks exhibit organic-rich units capable of generating hydrocarbon. Petroleum from Mississippian rocks is proven through source-rock and crude-oil correlation, sharing similar biomarker fingerprints. A collection of Mississippian biomarkers has been identified, including diterpenoids and extended tricyclic terpenes, reflecting the organic-matter source and depositional environment. Macerals of Mississippian rocks are characterized by the amorphous morphologies, whereas Woodford Shale macerals exhibit intact structures. According to mineralogy and sedimentology, six main facies were identified within the Mississippian mudrocks. Furthermore, Organic and sedimentological characteristics suggest shoaling-upward sequences in the Mississippian formation. Examined crude oil was grouped into three major families, each of which exhibits a unique geochemical signature. The first crude-oil family is derived from Mississippian end-member source rocks, while the third family is closely related to Woodford Shale source rock, and the second oil family represents a mixture of the two end-members. Diamondoids shed light into on mixed hydrocarbons at various levels of maturity, in which oils within the Anadarko Shelf and Sooner Trend Anadarko Basin Canadian and Kingfisher Counties (STACK) plays are mixed oils of uncracked and cracked hydrocarbons, whereas oils within central Oklahoma are unmixed and uncracked hydrocarbons. Based on geochemical evidence derived from fluid inclusions and crude oil, petroleum-migration timing is defined over four major episodes, with long-distance petroleum migration west of the Nemaha Uplift, and shortdistance petroleum migration at the east of the Nemaha Uplift. All generated geochemical data were integrated into a basin and petroleum systems approach with the aim of understanding major factors controlling the distribution and quality of hydrocarbons across the Devonian-Mississippian petroleum systems.
