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Collaborating Authors
Jasmi, Sami Al
The Application of Geological Concepts for Various Types of High-Permeability Streaks to the Full-Field Simulation Model History Matching of Carbonate Reservoir, Offshore Abu Dhabi
Shibayama, Akira (INPEX Corporation) | Hamami, Mohamed Tariq (ZADCO) | Yamada, Tatsuya (ZADCO) | Kohda, Atsuro (INPEX Corporation) | Farhan, Zahra Abdulla (ZADCO) | Bellah, Sameer (ZADCO) | Shibasaki, Toshiaki (ZADCO) | Jasmi, Sami Al (ZADCO)
Abstract This paper presents a case study of full-field simulation model history matching by applying geological concepts for various types of high-permeability (high-K) streaks. An Upper Jurassic reservoir in "Field-A" is domal shape structure and reservoir fluid is under saturated with bubble point. Field-A has been producing oil from the reservoir for 30 years with total 20 oil producers, by evolved through the secondary recovery stage, such as crestal auto gas injection (non-miscible gas), then shifted to crestal water injection to maintain reservoir pressure. The fluid monitoring results and water-cut/GOR evolution trend indicate complexity and heterogeneity of the reservoir. Two type of high-permeability streaks associated with stromatoporoid lithofacies in the upper part and fault related fractured dolomite in the lower part of reservoir were identified through the reservoir characterization studies. The zones having the high-permeability streaks show higher well-test KH compared to the core plug based matrix KH. Model KH of the zones including high-permeability streaks were conditioned by maps of the excess KH with the following concepts: Stromatoporoid lithofacies: Excess KH map was generated based on the relationship between well-test KH and stromatoporoid lithofacies thickness. Fault related fractured dolomite: Core observation indicates high density of open fractures is detected in dolomite of specific layers in the lower part of reservoir. Excess KH map was generated based on the relationship between excess KH and fracture density distribution estimated by 3D seismic dip attribute (fault location dependent) Through model history matching, stromatoporoid thickness distribution in-between well control points were adjusted to modify excess KH map as one of the major uncertain parameter in the global level matching phase, considering its significant impact on pressure communication between crestal gas/water injectors and flank oil producers at overall area and history period. When it comes to local area (well-by-well level) matching phase, independent fine tuning process of excess KH maps derived from two different high-permeability streaks allowed us to achieve good matching quality for pressure, water-cut and GOR, especially for multi-lateral completion wells where injection water/gas breakthrough was occurred at different timing at each horizontal branch. The permeability modification along with the geological concepts of various high-permeability streaks contributed to achieve reasonable quality of history matching without extreme and un-realistic adjustment of the permeability model.
- Asia > Middle East > Kuwait > Jahra Governorate > Arabian Basin > Widyan Basin > North Kuwait Jurassic (NKJ) Fields > Marrat Formation > Upper Marrat Formation (0.98)
- Asia > Middle East > Kuwait > Jahra Governorate > Arabian Basin > Widyan Basin > North Kuwait Jurassic (NKJ) Fields > Marrat Formation > Sargelu Formation (0.98)
- Africa > Middle East > Libya > Murzuq District > Murzuq Basin > Block NC 186 > Field A Field > Silurian Tanezzuft Formation (0.97)
- Africa > Middle East > Libya > Murzuq District > Murzuq Basin > Block NC 115 > Field A Field > Silurian Tanezzuft Formation (0.97)
Characterization of High-Permeability Streaks Associated with Heterogeneous Stromatoporoid Reefal Facies and Establishment of Modeling Workflow in Carbonate Reservoir, Offshore Abu Dhabi
Kohda, Atsuro (INPEX Corporation) | Bellah, Sameer (ZADCO) | Shibasaki, Toshiaki (ZADCO) | Farhan, Zahra Al (ZADCO) | Shibayama, Akira (INPEX Corporation) | Hamami, Mohamed Al (ZADCO) | Jasmi, Sami Al (ZADCO)
Abstract The understanding of heterogeneous rock properties especially high-permeability streaks is very important to predict fluid behavior in carbonate reservoirs. An Upper Jurassic reservoir in "Field A" has been producing for 30 years with different production scheme such as crestal water and gas injection at the different stage. The observed water/gas breakthrough and the evolution trend in water cut/GOR indicate reservoir heterogeneity caused by geological complexity. To replicate such complicated fluids behavior in reservoir model, the characterization study for high-permeability streaks was conducted. Multiple data sources were used to identify and characterize high-permeability streaks. Interpreted injected gas/water sweep intervals utilizing cased-hole production logging. Identified potential high-permeable lithofacies and its stratigraphic positions by detailed core and thin section descriptions with petrophysical observations. Defined high-permeability streaks based on the integrated interpretation of multiple data sources. Characterized the high-permeability streaks in reservoir model with excess flow capacity estimated from model and well-test permeability. This study revealed that multiple types of high-permeability streaks present in the reservoir. In particular, it was recognized that a specific thin layer comprises stromatoporoid (epibenthic calcified sponges) patch reef deposits acts as the main contributor for fluids movement. This paper shows how to characterize the high-permeability streaks in reservoir model focusing on stromatoporoid lithofacies. Thickness of stromatoporoid lithofacies shows heterogeneous variation of 0 to 14 feet. The complex pore system in stromatoporoid lithofacies associated with heterogeneously distributed skeletal fragments with centimeter-scale makes difficulty for capturing accurate permeability from conventional plug measurement. The plug permeability was generally underestimated comparing with actual flow capacity estimated from well-test. Hence the modeled permeability which generated from porosity-permeability correlation coming from plug measurement was required further conditioning based on the pre-established concept for high-permeability streaks. To fill the gap between modelled and well-test permeability-thickness (KH) i.e. excess KH, the relevance between excess KH and stromatoporoid lithofacies was investigated. As a result, it was found that the zonal well-test KH increases as stromatoporoid lithofacies thickness (STR-H) increases, and there is a good correlation between STR-H and STR-KH estimated as "zonal well-test KH" minus "zonal modeled KH except stromatoporoid lithofacies intervals". Therefore, excess KH was allocated to only into the part of stromatoporoid lithofacies. The prepared STR-H map was directory transformed to STR-KH distributions by the revealed correlation. Through dynamic history matching, permeability distribution was iteratively modified by updating STR-H map in concordance with depositional concept. Detailed observations and integrated interpretation for multiple data sources allowed identifying high-permeability streaks and establishment of a model workflow for representing its heterogeneity and associated permeability distribution. This workflow enabled geologically reasonable permeability conditioning and iterative model update in conjunction with the depositional concept during dynamic history matching.
- Phanerozoic > Paleozoic (1.00)
- Phanerozoic > Mesozoic > Jurassic (0.87)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (1.00)
- Geology > Sedimentary Geology > Depositional Environment > Marine Environment > Reef Environment (0.54)
- Asia > Middle East > UAE > Arab Formation (0.99)
- Asia > Middle East > Saudi Arabia > Eastern Province > Al-Ahsa Governorate > Arabian Basin > Widyan Basin > Khurais Field (0.99)
- Asia > Middle East > Saudi Arabia > Eastern Province > Al-Ahsa Governorate > Arabian Basin > Widyan Basin > Ghawar Field > Lower Fadhili Formation (0.99)
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