Resolving Challenges in Analyzing Iron-Rich Samples by X-Ray Diffraction
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| Natura: | Recurso digital |
| Lingua: | inglese |
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2023
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| author | Al-Ofi, Salah Ma, Shouxiang |
| author_facet | Al-Ofi, Salah Ma, Shouxiang |
| contents | <p>Rock mineralogy is the foundation of formation evaluation and X-ray diffraction (XRD) is considered the gold standard for rock mineralogical analysis. The main objective of this study is to address challenges in analyzing iron rich rocks using the commonly used XRD method, by systematically study sample preparations, measurement procedures, raw data processing, and data interpretation and quantification. An XRD test can be described in three steps: sample preparation and testing, mineral identification, and mineral quantification. Rock samples used in this study are from US subsurface Chelsea sandstone (CSST), consisting of shales, shaly sands, and sideritic sandstone. To prepare for a XRD test, core plugs were pulverized using the traditional pestle and mortar, planetary ball mill machine, and Mortar Grinder RM 200. The sample powders were analyzed with the commonly used Rigaku Ultima IV and PANalytical Empyrean diffractometer systems. X-ray tubes with copper Cu anode materials were utilized as the radiation source for the two systems. Jade Software was used to identify mineral phases using ICDD PDF4+ library. The mineral phase quantification was performed using Rietveld refinement method in Jade software and utilizing three different libraries: ICDD PDF4+, MDI, and AMCSD, and different data simulation models: Current Background, Refinable Polynomial and Variable Spline. Results show that high background noise affects measurement due to secondary copper radiation associated with the content of sideritic in the sample as they fluoresce and create polychromatic radiation. The more siderite (FeCO3) presence in the sample the higher the background level which distorts other mineral phases present in the sample. The diffractogram from the shaly sandstone showed multiple mineral phases which are repressed in the mixed samples diffractogram of 50% of shaly and sideritic sandstone. Also, our investigation showed the influence of both mineral library and fitting model section on the accuracy of minerals quantification. Results show Cu radiation diffractograms can be a source of measurement uncertainty that need to be accounted for by careful selection of mineral library and fitting model. This observation is used to enhance the quality of XRD analysis of iron rich rocks using copper radiation.</p> |
| format | Recurso digital |
| id | zenodo_https___doi_org_10_5281_zenodo_15882286 |
| institution | Zenodo |
| language | eng |
| publishDate | 2023 |
| publisher | Zenodo |
| record_format | zenodo |
| spellingShingle | Resolving Challenges in Analyzing Iron-Rich Samples by X-Ray Diffraction Al-Ofi, Salah Ma, Shouxiang 2023 SCA Poster Core Analysis and Log Interpretation <p>Rock mineralogy is the foundation of formation evaluation and X-ray diffraction (XRD) is considered the gold standard for rock mineralogical analysis. The main objective of this study is to address challenges in analyzing iron rich rocks using the commonly used XRD method, by systematically study sample preparations, measurement procedures, raw data processing, and data interpretation and quantification. An XRD test can be described in three steps: sample preparation and testing, mineral identification, and mineral quantification. Rock samples used in this study are from US subsurface Chelsea sandstone (CSST), consisting of shales, shaly sands, and sideritic sandstone. To prepare for a XRD test, core plugs were pulverized using the traditional pestle and mortar, planetary ball mill machine, and Mortar Grinder RM 200. The sample powders were analyzed with the commonly used Rigaku Ultima IV and PANalytical Empyrean diffractometer systems. X-ray tubes with copper Cu anode materials were utilized as the radiation source for the two systems. Jade Software was used to identify mineral phases using ICDD PDF4+ library. The mineral phase quantification was performed using Rietveld refinement method in Jade software and utilizing three different libraries: ICDD PDF4+, MDI, and AMCSD, and different data simulation models: Current Background, Refinable Polynomial and Variable Spline. Results show that high background noise affects measurement due to secondary copper radiation associated with the content of sideritic in the sample as they fluoresce and create polychromatic radiation. The more siderite (FeCO3) presence in the sample the higher the background level which distorts other mineral phases present in the sample. The diffractogram from the shaly sandstone showed multiple mineral phases which are repressed in the mixed samples diffractogram of 50% of shaly and sideritic sandstone. Also, our investigation showed the influence of both mineral library and fitting model section on the accuracy of minerals quantification. Results show Cu radiation diffractograms can be a source of measurement uncertainty that need to be accounted for by careful selection of mineral library and fitting model. This observation is used to enhance the quality of XRD analysis of iron rich rocks using copper radiation.</p> |
| title | Resolving Challenges in Analyzing Iron-Rich Samples by X-Ray Diffraction |
| topic | 2023 SCA Poster Core Analysis and Log Interpretation |
| url | https://doi.org/10.5281/zenodo.15882286 |