Diagenetic Clay Minerals and Their Controls on Reservoir Properties of the Shahbazpur Gas Field (Bengal Basin, Bangladesh)

Clay mineralogy and diagenesis affect the reservoir quality of the Neogene Surma Group in the Hatiya trough of Bengal Basin, Bangladesh. X-ray diffraction and scanning electron microscopic analyses of diagenetic clay minerals from Shahbazpur#2 well reveal that on average illite is the dominant clay...

Full description

Bibliographic Details
Main Authors: Md Nahidul Hasan, Rumana Yeasmin, M. Julleh Jalalur Rahman, Sally Potter-McIntyre
Format: Article
Language:English
Published: MDPI AG 2020-06-01
Series:Geosciences
Subjects:
Online Access:https://www.mdpi.com/2076-3263/10/7/250
id doaj-1c67ad827eae41bbb7fc9901566a78ab
record_format Article
spelling doaj-1c67ad827eae41bbb7fc9901566a78ab2020-11-25T02:45:34ZengMDPI AGGeosciences2076-32632020-06-011025025010.3390/geosciences10070250Diagenetic Clay Minerals and Their Controls on Reservoir Properties of the Shahbazpur Gas Field (Bengal Basin, Bangladesh)Md Nahidul Hasan0Rumana Yeasmin1M. Julleh Jalalur Rahman2Sally Potter-McIntyre3Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX 77204, USADepartment of Geological Sciences, Jahangirnagar University, Savar, Dhaka 1342, BangladeshDepartment of Geological Sciences, Jahangirnagar University, Savar, Dhaka 1342, BangladeshDepartment of Geology, Southern Illinois University, Carbondale, IL 62901, USAClay mineralogy and diagenesis affect the reservoir quality of the Neogene Surma Group in the Hatiya trough of Bengal Basin, Bangladesh. X-ray diffraction and scanning electron microscopic analyses of diagenetic clay minerals from Shahbazpur#2 well reveal that on average illite is the dominant clay mineral (50%), followed by chlorite (24%), kaolinite (23%) and smectite (2.50%). The absence of smectite at Core-2 (3259.80 m to 3269 m) results from the total transformation of smectite to illite owing to burial depth and high K–feldspar. The diagenetic changes are a result of chemical processes such as cementation, chlorite authigenesis, dissolution, alteration and replacement that have significantly affected the reservoir properties. Cementation plays an important role in reducing reservoir properties with pore and fracture filling cement. The relative percentage of illite and smectite minerals (> 90% illite in I/S mixed layer) and Kübler index value (0.34° to 0.76° Δ2θ) indicate a diagenetic zone with subsurface temperatures of 120–180 °C in the studied samples. The temperature range determined using clay percentages and the Kübler index as a geothermometer is supported by observed diagenetic features such as quartz overgrowths, smectite to illite transformations and chlorite coatings. The diagenetic features cause variable reservoir porosity and permeability that are critical in planning exploration and development programs of this field or analog fields across the Bengal Basin.https://www.mdpi.com/2076-3263/10/7/250clay mineralsreservoir heterogeneitydiagenesisgeothermometerKübler index
collection DOAJ
language English
format Article
sources DOAJ
author Md Nahidul Hasan
Rumana Yeasmin
M. Julleh Jalalur Rahman
Sally Potter-McIntyre
spellingShingle Md Nahidul Hasan
Rumana Yeasmin
M. Julleh Jalalur Rahman
Sally Potter-McIntyre
Diagenetic Clay Minerals and Their Controls on Reservoir Properties of the Shahbazpur Gas Field (Bengal Basin, Bangladesh)
Geosciences
clay minerals
reservoir heterogeneity
diagenesis
geothermometer
Kübler index
author_facet Md Nahidul Hasan
Rumana Yeasmin
M. Julleh Jalalur Rahman
Sally Potter-McIntyre
author_sort Md Nahidul Hasan
title Diagenetic Clay Minerals and Their Controls on Reservoir Properties of the Shahbazpur Gas Field (Bengal Basin, Bangladesh)
title_short Diagenetic Clay Minerals and Their Controls on Reservoir Properties of the Shahbazpur Gas Field (Bengal Basin, Bangladesh)
title_full Diagenetic Clay Minerals and Their Controls on Reservoir Properties of the Shahbazpur Gas Field (Bengal Basin, Bangladesh)
title_fullStr Diagenetic Clay Minerals and Their Controls on Reservoir Properties of the Shahbazpur Gas Field (Bengal Basin, Bangladesh)
title_full_unstemmed Diagenetic Clay Minerals and Their Controls on Reservoir Properties of the Shahbazpur Gas Field (Bengal Basin, Bangladesh)
title_sort diagenetic clay minerals and their controls on reservoir properties of the shahbazpur gas field (bengal basin, bangladesh)
publisher MDPI AG
series Geosciences
issn 2076-3263
publishDate 2020-06-01
description Clay mineralogy and diagenesis affect the reservoir quality of the Neogene Surma Group in the Hatiya trough of Bengal Basin, Bangladesh. X-ray diffraction and scanning electron microscopic analyses of diagenetic clay minerals from Shahbazpur#2 well reveal that on average illite is the dominant clay mineral (50%), followed by chlorite (24%), kaolinite (23%) and smectite (2.50%). The absence of smectite at Core-2 (3259.80 m to 3269 m) results from the total transformation of smectite to illite owing to burial depth and high K–feldspar. The diagenetic changes are a result of chemical processes such as cementation, chlorite authigenesis, dissolution, alteration and replacement that have significantly affected the reservoir properties. Cementation plays an important role in reducing reservoir properties with pore and fracture filling cement. The relative percentage of illite and smectite minerals (> 90% illite in I/S mixed layer) and Kübler index value (0.34° to 0.76° Δ2θ) indicate a diagenetic zone with subsurface temperatures of 120–180 °C in the studied samples. The temperature range determined using clay percentages and the Kübler index as a geothermometer is supported by observed diagenetic features such as quartz overgrowths, smectite to illite transformations and chlorite coatings. The diagenetic features cause variable reservoir porosity and permeability that are critical in planning exploration and development programs of this field or analog fields across the Bengal Basin.
topic clay minerals
reservoir heterogeneity
diagenesis
geothermometer
Kübler index
url https://www.mdpi.com/2076-3263/10/7/250
work_keys_str_mv AT mdnahidulhasan diageneticclaymineralsandtheircontrolsonreservoirpropertiesoftheshahbazpurgasfieldbengalbasinbangladesh
AT rumanayeasmin diageneticclaymineralsandtheircontrolsonreservoirpropertiesoftheshahbazpurgasfieldbengalbasinbangladesh
AT mjullehjalalurrahman diageneticclaymineralsandtheircontrolsonreservoirpropertiesoftheshahbazpurgasfieldbengalbasinbangladesh
AT sallypottermcintyre diageneticclaymineralsandtheircontrolsonreservoirpropertiesoftheshahbazpurgasfieldbengalbasinbangladesh
_version_ 1724761870130216960