[PDF] Diagenesis And Fracture Development In The Bakken Formation Williston Basin eBook

Author : Oguzhan Ayhan
Publisher :
Page : 638 pages
File Size : 48,12 MB
Release : 2016
Category :
ISBN :

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The Upper Devonian-Lower Mississippian Bakken Formation in the Williston Basin is an important source rock for oil production in North America. The Bakken Formation is comprised of three units: Upper and Lower Bakken black shales and Middle Bakken Member. Upper and Lower Bakken shales are high quality source rocks which source reservoirs in the Middle Bakken, Upper Three Forks and lower Lodgepole Formations. The Middle Bakken Member, consisting of predominantly gray, silty and sandy dolostone, is under investigation in this study. The goals of this study are to determine the regional distribution of lithofacies and depositional environments of the Middle Bakken Member and explain diagenetic sequence and reservoir quality parameters in the Williston Basin. The reservoir quality of the Middle Bakken Member is mainly influenced by mineralogical composition and cementation resulting in low porosity and permeability and linked to lithofacies distribution in the basin. Dolomitization is pervasive throughout the unit, and also occurs as dolomite cement. Moreover, cementation occurred including quartz overgrowths, K-felspar, clay cement and pyrite as both cement and nodules. Not only dolomitization but also pyrite cementation plays an important role in reducing pore space in the reservoir. The pore types that were identified are intergranular, intragranular, fracture and moldic pores. Secondary intragranular porosity generally resulted from dissolution of biogenic fragments and dissolution of other unstable minerals including feldspar and dolomite. In this study, five lithofacies and one sandy interval within lithofacies C were described throughout the North Dakota portion of the Williston basin. The sandy interval in Lithofacies C was interpreted as bars or channel fills, which differentiates this study from previous studies in terms of core description. N-S, W-E, NE-SW, NW-SE oriented cross-sections drawn via cores suggest that the lithofacies of the Middle Bakken Member pinch out towards the edges. However, the anticlines in the basin affect their thickness distributions. Sandy interval in Lithofacies C reaches its thickest succession in the center of the basin. Lithofacies C and D consist of up to 80% of dolomite although the other lithofacies consist of relatively lower dolomite (up to 65%). While well logs indicate 4-8% of porosity, point-counting results show up to 5% of porosity. The sequence of diagenetic events in the North Dakota portion of the Williston Basin is from youngest to oldest: micritization, mechanical and chemical compaction, calcite cementation, dolomitization, pyrite cementation, microcrystalline quartz cementation, syntaxial calcite overgrowth, quartz overgrowth, K-Feldspar overgrowth, dolomite dissolution, feldspar dissolution, dedolomitization, fracturing, anhydrite cementation and hydrocarbon migration.

Author : Sabina E. Deitrick
Publisher : Cornell University Press
Page : 262 pages
File Size : 45,14 MB
Release : 2022-01-15
Category : Technology & Engineering
ISBN : 1501761013

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When Fracking Comes to Town traces the response of local communities to the shale gas revolution. Rather than cast communities as powerless to respond to oil and gas companies and their landmen, it shows that communities have adapted their local rules and regulations to meet the novel challenges accompanying unconventional gas extraction through fracking. The multidisciplinary perspectives of this volume's essays tie together insights from planners, legal scholars, political scientists, and economists. What emerges is a more nuanced perspective of shale gas development and its impacts on municipalities and residents. Unlike many political debates that cast fracking in black-and-white terms, this book's contributors embrace the complexity of local responses to fracking. States adapted legal institutions to meet the new challenges posed by this energy extraction process while under-resourced municipal officials and local planning offices found creative ways to alleviate pressure on local infrastructure and reduce harmful effects of fracking on the environment. The essays in When Fracking Comes to Town tell a story of community resilience with the rise and decline of shale gas production. Contributors: Ennio Piano, Ann M. Eisenberg, Pamela A. Mischen, Joseph T. Palka, Jr., Adelyn Hall, Carla Chifos, Teresa Córdova, Rebecca Matsco, Anna C. Osland, Carolyn G. Loh, Gavin Roberts, Sandeep Kumar Rangaraju, Frederick Tannery, Larry McCarthy, Erik R. Pages, Mark C. White, Martin Romitti, Nicholas G. McClure, Ion Simonides, Jeremy G. Weber, Max Harleman, Heidi Gorovitz Robertson