The distribution of good reservoir quality and its causes is the main challenges in carbonate reservoir characterization.This study investigates the effects of diagenetic processes on the reservoir quality of the carb...The distribution of good reservoir quality and its causes is the main challenges in carbonate reservoir characterization.This study investigates the effects of diagenetic processes on the reservoir quality of the carbonate successions of the Asmari Formation,in the Marun oil field,southwest Iran.The study applies an integrated approach including core petrography,petrophysical rock typing,stable carbon and oxygen isotopes as well as major and trace elements analyses.Petrographic studies and geochemical analyses express that the Asmari limestones have been affected mainly by compaction,dissolution,recrystallization,calcite and anhydrite cementation and dolomitization.Among those diagenetic overprints,dolomitization and dissolution played an important role to enhance the reservoir quality of the formation.Moreover,four types of dolomites were recognized and the rate of dolomitization increases toward the top of the Asmari carbonate successions.Possible models for dolomitization include mixing zone,brine reflux,seepage reflux and tidal pumping of seawater.Employing Flow Zone Index and Discrete Rock Type concepts led to classification of the Asmari reservoir into seven reservoir rock types.Integrating reservoir rock typing with petrographic studies and geochemical analyses also confirms that reservoir quality of the Asmari Fm.would have been mainly controlled by diagenetic processes.Moreover,stable isotopes,trace elements and facies analyses support the idea that carbonate intervals of the Asmari Formation were deposited in a warm,shallow-water environment under a saline condition.展开更多
After sea level rises during the Early Cretaceous, upper parts of the Khami Group sediments （Fahliyan, Gadvan, and Dariyan Formations） deposited over Jurassic sediments. The Lower Cretaceous （Aptian） Dariyan Forma...After sea level rises during the Early Cretaceous, upper parts of the Khami Group sediments （Fahliyan, Gadvan, and Dariyan Formations） deposited over Jurassic sediments. The Lower Cretaceous （Aptian） Dariyan Formation （equivalent to the Shu＇aiba Formation and Hawar Member of the Arabian Plate） carbonates, which have hydrocarbon reservoir potential, form the uppermost portion of the Khami Group that unconformably overlays the Gadvan Formation and was unconformably covered by the Kazhdumi Formation and Burgan sandstones. Detailed paleontological, sedimentological, and well log analysis were performed on seven wells from Qeshm Island and offshore in order to analyze the sequence stratigraphy of this interval and correlate with other studies of the Dariyan Formation in this region. According to this study, the Dariyan Formation contains 14 carbonate lithofacies, which deposited on a ramp system that deepened in both directions （NE-wells 5, 6 and SWIwells 1, 2）. Sequence stratigraphy led to recognition of 5 Aptian third-order sequences toward the Bab Basin （SW-well 1） and 4 Aptian third-order sequences toward Qeshm Island （NE-wells 5 and 6） so these areas show higher gamma on the gamma ray logs and probably have higher source rock potential. Other wells （wells 2-4 and 7） mainly deposited in shallower ramp systems and contain 3 Aptian third-order sequences. On the other hand, rudstone and boundstone lithofacies of studied wells have higher reservoir potential and were deposited during Apt 3 and Apt 4 sequences of the Arabian Plate. The Dariyan Formation in Qeshm Island （well 6） and adjacent well （well 5） was deposited in an intrashelf basin that should be classified as a new intrashelf basin in future Aptian paleogeographic maps. We interpret that salt-related differential subsidence, crustal warping, and reactivation of basement faults of the Arabian Plate boundary were responsible for the creation of the intrashelf basin in the Qeshm area.展开更多
Ardak Watershed with an area of about 497 km<sup>2</sup> is one of the tributaries of Kashaf Rud River Watershed in north east Iran,which consists of two main rivers.This catchment is located in the Kopet-...Ardak Watershed with an area of about 497 km<sup>2</sup> is one of the tributaries of Kashaf Rud River Watershed in north east Iran,which consists of two main rivers.This catchment is located in the Kopet-Dagh structural zone and Ardak Watershed is surrounded by Chaman Bid, Mozduran,Shurijeh,Tirgan,and Sarcheshme Formations.The lithofacies and architectural elements show that two main rivers are gravel-bed braided river in their most parts.The major erosion types in this watershed are rock fall,rill,surface erosions,and gully and channel bank erosion.In the study area,the amount of sediment yield estimation in GIS framework using MPSIAC model is about 130.749 m<sup>3</sup>·km<sup>-2</sup>·a<sup>-1</sup>or 1.77 t·h（-1）and most parts of the basin（more than 90%）has low erosional rate.Mozduran and Tirgan Formations展开更多
基金Ferdowsi University of Mashhad for their logistic and financial support during this study(Project No.3/27852)NSERC for their support.
文摘The distribution of good reservoir quality and its causes is the main challenges in carbonate reservoir characterization.This study investigates the effects of diagenetic processes on the reservoir quality of the carbonate successions of the Asmari Formation,in the Marun oil field,southwest Iran.The study applies an integrated approach including core petrography,petrophysical rock typing,stable carbon and oxygen isotopes as well as major and trace elements analyses.Petrographic studies and geochemical analyses express that the Asmari limestones have been affected mainly by compaction,dissolution,recrystallization,calcite and anhydrite cementation and dolomitization.Among those diagenetic overprints,dolomitization and dissolution played an important role to enhance the reservoir quality of the formation.Moreover,four types of dolomites were recognized and the rate of dolomitization increases toward the top of the Asmari carbonate successions.Possible models for dolomitization include mixing zone,brine reflux,seepage reflux and tidal pumping of seawater.Employing Flow Zone Index and Discrete Rock Type concepts led to classification of the Asmari reservoir into seven reservoir rock types.Integrating reservoir rock typing with petrographic studies and geochemical analyses also confirms that reservoir quality of the Asmari Fm.would have been mainly controlled by diagenetic processes.Moreover,stable isotopes,trace elements and facies analyses support the idea that carbonate intervals of the Asmari Formation were deposited in a warm,shallow-water environment under a saline condition.
基金the National Iranian Oil Company,Exploration Directorate,for the support of this researchthe Department of Geology at Ferdowsi University of Mashhad for their support
文摘After sea level rises during the Early Cretaceous, upper parts of the Khami Group sediments （Fahliyan, Gadvan, and Dariyan Formations） deposited over Jurassic sediments. The Lower Cretaceous （Aptian） Dariyan Formation （equivalent to the Shu＇aiba Formation and Hawar Member of the Arabian Plate） carbonates, which have hydrocarbon reservoir potential, form the uppermost portion of the Khami Group that unconformably overlays the Gadvan Formation and was unconformably covered by the Kazhdumi Formation and Burgan sandstones. Detailed paleontological, sedimentological, and well log analysis were performed on seven wells from Qeshm Island and offshore in order to analyze the sequence stratigraphy of this interval and correlate with other studies of the Dariyan Formation in this region. According to this study, the Dariyan Formation contains 14 carbonate lithofacies, which deposited on a ramp system that deepened in both directions （NE-wells 5, 6 and SWIwells 1, 2）. Sequence stratigraphy led to recognition of 5 Aptian third-order sequences toward the Bab Basin （SW-well 1） and 4 Aptian third-order sequences toward Qeshm Island （NE-wells 5 and 6） so these areas show higher gamma on the gamma ray logs and probably have higher source rock potential. Other wells （wells 2-4 and 7） mainly deposited in shallower ramp systems and contain 3 Aptian third-order sequences. On the other hand, rudstone and boundstone lithofacies of studied wells have higher reservoir potential and were deposited during Apt 3 and Apt 4 sequences of the Arabian Plate. The Dariyan Formation in Qeshm Island （well 6） and adjacent well （well 5） was deposited in an intrashelf basin that should be classified as a new intrashelf basin in future Aptian paleogeographic maps. We interpret that salt-related differential subsidence, crustal warping, and reactivation of basement faults of the Arabian Plate boundary were responsible for the creation of the intrashelf basin in the Qeshm area.
文摘Ardak Watershed with an area of about 497 km<sup>2</sup> is one of the tributaries of Kashaf Rud River Watershed in north east Iran,which consists of two main rivers.This catchment is located in the Kopet-Dagh structural zone and Ardak Watershed is surrounded by Chaman Bid, Mozduran,Shurijeh,Tirgan,and Sarcheshme Formations.The lithofacies and architectural elements show that two main rivers are gravel-bed braided river in their most parts.The major erosion types in this watershed are rock fall,rill,surface erosions,and gully and channel bank erosion.In the study area,the amount of sediment yield estimation in GIS framework using MPSIAC model is about 130.749 m<sup>3</sup>·km<sup>-2</sup>·a<sup>-1</sup>or 1.77 t·h（-1）and most parts of the basin（more than 90%）has low erosional rate.Mozduran and Tirgan Formations
