S. Faramarzi; H. Rahimpour-Bonab; M. Ranjbaran
Abstract
The Sarvak Formation is one of the most important carbonate reservoirs of Iran. The main objective of this study is to evaluate reservoir quality of the formation by integration of petrographic studies and core porosity-permeability data in three key wells in a giant oilfield of the Abadan Plain, SW ...
Read More
The Sarvak Formation is one of the most important carbonate reservoirs of Iran. The main objective of this study is to evaluate reservoir quality of the formation by integration of petrographic studies and core porosity-permeability data in three key wells in a giant oilfield of the Abadan Plain, SW Iran. Petrographic studies led to the identification of 13 microfacies that are grouped into three main facies belts including lagoon, shoal, and open marine (talus and slope) which deposited in an isolated carbonate platform. The main diagenetic processes affecting the Sarvak Formation are micritization, bioturbation, recrystallization, dissolution, cementation, physical and chemical compaction, dolomitization and silicification, along with fracturing. According to the results, the reservoir quality of the Sarvak reservoir is a function of both primary depositional facies and secondary diagenetic processes. Evaluation of impacts of depositional facies on reservoir quality indicated that the rudist-bearing intervals (especially rudist debris zones) have high reservoir quality. Dissolution and cementation are the most pervasive diagenetic processes affecting the formation, and occurred due to widespread meteoric diagenesis. Dissolution and fracturing are the chief factors that lead to the improvement of porosity-permeability, whilst calcite cementation and compaction have destructed reservoir quality of the studied interval. This study may assist better understand the geological parameters controlling reservoir quality of Sarvak Formation in the Abadan Plain oilfields.
K Rezaeeparto; H Rahimpour Bonab; A Kadkhodaie; M Arian; E Hajikazemi
Abstract
Dariyan Formation (Aptian-Albian) is one of the main reservoir units in the South West of Iran which is equivalent to Shuaiba Fm,. Since the first step in the evaluation study of reservoir rock is studying the microfacies, depositional environments and diagenesis processes, in this research we have discussed ...
Read More
Dariyan Formation (Aptian-Albian) is one of the main reservoir units in the South West of Iran which is equivalent to Shuaiba Fm,. Since the first step in the evaluation study of reservoir rock is studying the microfacies, depositional environments and diagenesis processes, in this research we have discussed these parameters in Dariyan reservoir in Salman oil field A, B, C, D and E wells. On the basis of petrographic studies classification of carbonate rocks by Dunham’s method and nomination of microfacies by Flugel’s classification was done and 7 basic microfacies have been identified: Mudstone, Mudstone to fossiliferous wackestone, Orbitolinid wackestone to packstone, Bioclast packstone to grainstone with restricted microfauna, Echinoderm wackestone to packstone, Planktonic wackestone to packstone, Mudstone to Planktonic/echinoderm wackestone, that belong to open marine sedimentary environment, shoal and lagoon. The study of vertical and lateral facies changes and comparing them with modern and ancient sedimentary environments show that Dariyan Formation in this area is deposited in a leeward mud dominated carbonate ramp. Due to numerous diagenetic processes observed in the formation, of their direct impact on the quality of the reservoir to the conclusion that micritization, cementation, compaction (mechanical), neomorphism, and pyritification to block the pores and pore through in the reservoir porosity and permeability decrease while, compaction (chemical), dolomitization, and fracture caused voids and communication between them. Finally, the porosity and permeability of the reservoir increased and led to higher quality.
Z Kalantarzadeh; M.H Adabi; H Rahimpour Bonab
Abstract
After Early Cimmerian orogenic stage, due to marine transgression, the Nayband Formation Norian_Rethian (Upper Triassic) in age deposited in the Central Iran Zone. Because of transforming of aragonite and high Mg calcite into low Mg calcite during diagenesis, recognition of original carbonate ...
Read More
After Early Cimmerian orogenic stage, due to marine transgression, the Nayband Formation Norian_Rethian (Upper Triassic) in age deposited in the Central Iran Zone. Because of transforming of aragonite and high Mg calcite into low Mg calcite during diagenesis, recognition of original carbonate mineralogy based on petrographic studies is difficult. In this research, original carbonate mineralogy and type of carbonates (tropical, temperate and polar) of the Nayband Formation in Darbidkhoon, Tarz, Gitry and Kuhbanan stratigraghic sections have been studied using geochemical evidences. The trace elements (Na, Sr, Fe, Mn) and isotopes (and) data of the Nayband Formation carbonates is located inside or close to the aragonitic tropical Fahlian Formation (Lower Cretaceous), the Ilam Formation (Upper Cretaceous), the Kangane Formation (Lower Triassic) and the Mozduran Formation (Upper Jurassic) limestones, because of aragonitic original carbonate mineralogy. The results of elemental and isotopic analysis correlate with the petrographic evidences and paleogeographic map of the Upper Triassic.
