Imaging Unconventional Reservoir Pore Systems
This Memoir covers recent advances in the acquisition and application of high-resolution image data to unconventional reservoirs. The value of integrating multiple techniques is a common theme. Chapters address imaging methods, recognition of artifacts, and case studies that explore nanopore systems within particular depositional settings. The importance of mineralogy, organic matter content, and fabric to reservoir quality issues such as wettability, porosity, and formation damage are addressed. This volume will prove useful to anyone interested in the methods for observing and quantifying the pore systems that control hydrocarbon storage and flow in unconventional reservoirs. Unconventional reservoirs studied include Bakken, Barnett, Bossier, Eagle Ford, Geneseo, Green River, Horn River, Marcellus, Mississippi Lime, Monterey, Niobrara, Wolfcamp, and Woodford formations.
Unconventional Gas-Oil Shale Microfabric Features Relating to Porosity, Storage, and Migration of Hydrocarbons
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Published:January 01, 2016
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CiteCitation
Neal R. O’Brien, Carol A. McRobbie, Roger M. Slatt, Elizabeth T. Baruch-Jurado, 2016. "Unconventional Gas-Oil Shale Microfabric Features Relating to Porosity, Storage, and Migration of Hydrocarbons", Imaging Unconventional Reservoir Pore Systems, Terri Olson
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Abstract
There are a variety of pore types in unconventional resource mudstones and shales. The currently preferred method by geologists and petrophysicists is to examine and analyze these mudstones and shales by argonion and focused ion-beam milling to produce an ultrasmooth surface, coupled with observation under the field emission scanning electron microscope (FESEM). Potential issues with Ar-ion milled/FESEM preparation and imaging include (1) the small size of sample cubes for upscaling, (2) loss of structural fabric during the milling–imaging process, (3) fewer non-inorganic pore types observed than when observed with an unpolished surface, (4) analog use of pores from one shale to another, although the pore types and composition might differ, and (5) the creation of potential artifacts related to desiccation and rock expansion because of core retrieval and sample preparation. Conventional FESEM images obtained from freshly broken surfaces reveal much more textural detail than those obtained from ion-milled (polished) surfaces. Although conventional FESEM methodology may share some of the same limitations as Ar-ion beam-milled/FESEM technology, FESEM methodology should not be overlooked because it provides a more cost-effective and potentially more accurate analysis for estimating porosity and determining pore types and their distribution in shales. Comparison of FESEM images from ion-milled and fresh, non-ion-milled surfaces reveals that organic matter and internal organoporosity are best viewed on ion-milled surfaces, but shale microfabric and non-organoporosity is best viewed under non-milled surfaces. Complete FESEM imagery for shale characterization should include both types of analyses.
- algae
- Atlantic Ocean
- Carboniferous
- characterization
- chemical composition
- Chlorophyta
- clastic rocks
- Coccolithophoraceae
- cracks
- Devonian
- diatoms
- electron microscopy data
- fabric
- fecal pellets
- Lower Mississippian
- measurement
- microcracks
- microfossils
- migration
- Mississippian
- mudstone
- natural gas
- Oklahoma
- Paleozoic
- petroleum
- Plantae
- Porifera
- porosity
- quantitative analysis
- Radiolaria
- sample preparation
- sedimentary rocks
- SEM data
- shale
- shale gas
- shale oil
- spicules
- Tasmanites
- textures
- thin sections
- United States
- Woodford Shale