| 1 | Offshore Carbonate Facies Characterization and Reservoir Quality of Miocene Rocks in the Southern Margin of South China Sea显示文摘Carbonate rocks are important hydrocarbon reservoirs around the globe and in Southeast Asia a key one,particularly,is the Central Luconia province.Understanding the internal characteristics,distribution,geometry and lateral extent of these rocks is essential for exploration and production success.Detailed work on Miocene carbonate reservoir facies,north of Bintulu,offshore Sarawak includes qualitative and quantitative analysis of photomicrographs and reservoir quality,considering especially microporosity.Stratigraphically,these carbonates are known as Cycles IV and V and are represented by eight major facies types(F-1 to F-8).They comprise:coated grain packstone(F-1)(av.Ф=3%,av.Kh=0.5 m D)(av=Average;?=total porosity,and Kh=permeability);massive coral lime grainstone(F-2)(av.Ф=14.7%,av.Kh=6 m D);oncolite lime grain-dominated packstone(F-3)(av.Ф=10%,av.Kh=4 m D);skeletal lime/dolo-packstone(F-4)(av.Ф=15%,av.Kh=4.6 m D);coral(platy)lime mud-dominated packstone(F-5)(av.Ф=4%,av.Kh=0.5 m D);coral(branching)lime-dominated pack-grainstone(F-6)(av.Ф=15%,av.Kh=1 m D);cross-bedded skeletal lime packstone(F-7)(av.Ф=20%,av.Kh=2 m D);and bioturbated carbonate mudstone/chalk(F-8)(av.Ф=8%,av.Kh=0.8 m D).Study of thin sections reveals that red algae,foraminifera,and corals are the dominant fossil components with a minor admixture of skeletal fragments of echinoderms,bivalves,bryozoans,and green algae.All parameters,e.g.,facies characterization,petrography,porosity–permeability value,and microporosity value were utilized to obtain a reliable reservoir quality.The microporosity value was quantified using digital image analysis software and is significant for recognition of good reservoir quality.Consideration of the presence of microporosity against the total porosity in the carbonate rocks has improved the correlation coefficient(R2)value,which has increased from 0.51 to 0.82. | Hammad Tariq JANJUHAH Abubaker ALANSARI | 2020 | Acta Geologica Sinica(English Edition)2020，94，5： | 4 |
| 2 | Biostratigraphy,Depositional and Diagenetic Processes in Carbonate Rocks from Southern Lebanon:Impact on Porosity and Permeability显示文摘Carbonate rocks contain prolific hydrocarbon reserves all over the world,particularly in the Middle East.For exploration and production strategies,it is essential to understand carbonate reservoirs in terms of their internal characteristics,depositional environment,relative age,diagenetic processes and impact on petrophysical properties.This study has been performed on exposed Cretaceous,Paleocene and Miocene marine carbonate sedimentary sequences in two localities(Maghdoucheh and Qennarit)near the city of Sidon(Southern Lebanon).It represents the first comprehensive study that takes into consideration the carbonate reservoir facies,diagenetic history and reservoir quality in the area.Rocks at Maghdoucheh are mainly dominated by limestone beds showing sedimentary structures and erosive bases alternating with microfossil-rich silty marls,related to a shallowing upward sequence in a restricted marine platform environment.Shells of benthic foraminifera and mollusks dominate the fossil assemblage extracted from the studied rocks.The microfossil and nannofossil assemblage detected in the Maghdoucheh sections indicates a middle Miocene age.Rocks at Qennarit are composed of mudstone/wackestone limestone beds rich in planktonic foraminifera and nannofossils related to open marine conditions.Based on the nannofossil content,rocks from Qennarit 1 and 2 are Paleocene and Cretaceous in age,respectively.Four main types of microfacies have been identified,i.e.(1)microbioclastic peloidal calcisiltite,(2)pelagic lime mudstone and wackestone with planktonic microfossils,(3)grainstone/packstone with abundant foraminifera and(4)fenestral bindstones,mudstones and packstones with porostromate microstructures.The porosity-permeability(poro-perm)analysis of representative samples reveals moderate to good porosity but very low permeability.This is mainly due to the presence of large moldic pores that are isolated in nature.The diagenetic features are dominated by micritization and dissolution(both fabric selective and non-fabric selective).Among all diagenetic features,dissolution in both localities contributes to porosity enhancement,while micritization,cementation,compaction and the filled fractures have negative impacts on permeability;hence the overall reservoir quality. | Hammad Tariq JANJUHAH Josep SANJUAN Mohammad ALQUDAH Mohamed K.SALAH | 2021 | Acta Geologica Sinica(English Edition)2021，95，5： | 0 |
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