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Collaborating Authors
Results
Abstract Reworked carbonate caused by the major erosional event of the "Turonian Unconformity" is considered to be distributed around the eastern part of Abu Dhabi, UAE. During 2021-2022, new wells were drilled in a prospective area where the reworked carbonate was deposited. By using the new wells data (wireline logs and cores) and pre-existing wells data, we considered lateral changes in sedimentary character and flow transitions of the reworked carbonate. We conducted a well-well correlation, based on the wireline logs (GR, Neutron, Density, Resistivity and Sonic) of a total of 5 wells which were drilled in the prospective area. To understand the spaciotemporal changes of the reworked carbonate facies and properties, we conducted core observation and description, and routine core analysis (porosity and permeability) for the new wells. In addition, based on the distribution and flow direction of this reworked deposit, we considered the changes of flow regime towards the flow direction. The result of the well-well correlation and seismic interpretation suggests that the wells penetrated the same reworked carbonate body. We can recognize the variety of grain size, sorting, sedimentary structure, and a degree of the bioturbation between the wells: poorly sorted coarse-grained to pebbly carbonate is dominant around the depositional up-dip side, and sharp based well-sorted grainstone with sedimentary structures (grading and lamination) is dominant around the depositional down-dip side, with bioturbation being more intense especially at the upper part of these grading beds. These sedimentary characters suggest that the flow regime changed towards the flow direction: dense flow at the depositional up-dip side and dilute flow at the down-dip side. In addition, several grading beds in the same indicate that the flow repeated several times. Routine core analysis and log calculation (porosity and permeability) results suggest that the sediments in a middle body of the reworked sediments has better reservoir properties. There is remaining exploration potential for this new play concept (reworked carbonate reservoir) around Abu Dhabi. In this time, we drilled new wells to confirm this new play concept, and we suppose that the knowledge of this study may have a big impact to the future exploration.
- Geology > Sedimentary Geology (1.00)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (1.00)
- Geology > Geological Subdiscipline > Stratigraphy (1.00)
- Geophysics > Borehole Geophysics (1.00)
- Geophysics > Seismic Surveying > Seismic Interpretation (0.34)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Core analysis (1.00)
Integrated Approach to Evaluate Unconventional and Tight Reservoirs in Abu Dhabi
Steiner, Stefan (ADCO) | Ahsan, Syed Asif (ADCO) | Noufal, Abdelwahab (ADCO) | Franco, Bernardo (ADCO) | Koksalan, Tamer (ADCO) | Amjad, Kashif (ADCO) | Helja, Emina (ADCO) | Alhosani, Sabah (ADCO) | Adesanya, Akindele (ADCO)
Abstract ADCO has drilled a number of wells and evaluated hydrocarbon potential of the Middle Cretaceous Wasia Group Unconventional reservoirs onshore Abu Dhabi since 2012. Latest logging and core analysis technologies were applied to assess key parameters such as Total Organic Carbon (TOC), source rock maturity, mineral compositions and fluid saturations, as well as geomechanical parameters such as Young's modulus, Poisson's ratio and minimum horizontal stresses. To date more than 2500ft of core has been extracted, described and analysed. We understand that ADCO has, by far, the largest data base among all the OPCOS with regards to unconventional play and has gained a significant local learning curve ahieved over the last 3 years. In addition to triple combo data, log data acquired consists of NMR, high resolution lateralog, dielectric logs, and mineral spectroscopy, cross dipole sonic, borehole imaging and sonic scanner, routine and advanced mudlogging. Core analysis consists of crushed rock analysis, pyrolysis and rock mechanics testing. Significantly high mud gas readings, observation of oil staining, odor, and fluorescence under UV light indicate presence of oil over large sections of the acquired cores and side wall cores from various geographically spread wells. Recently, we have conducted 5000 TOC and 1500 Pyrolysis measurements from core and cuttings samples in 110 wells spread all over Abu Dhabi. This data clearly demonstrate that large sections of Wasia Group bear excellent source rock quality in several wells located in large segments of onshore Abu Dhabi. Visual inspection of core and TOC measurements indicate that high frequency jet black centimeter scale organically rich lamellae often exceeding 20% TOC in several wells are not uncommon. The unconventional reservoir rocks are composed of predominantly clean and tight matrix carbonate mudstones and wackestones. Preliminary results of the current exploration campaign within the ADCO concession are very encouraging, showing indications of hydrocarbon presence. Formation testing is planned in the near future to confirm the Unconventional play in Abu Dhabi. The paper focuses on an integrated multi-disciplinary approach covering petrophysical, geological, geochemical and geomechanical assessment with the ultimate goal to determine optimal parameters for formation testing and production.
- Phanerozoic > Mesozoic > Cretaceous > Lower Cretaceous > Albian (0.66)
- Phanerozoic > Mesozoic > Cretaceous > Upper Cretaceous > Cenomanian (0.49)
- Phanerozoic > Mesozoic > Cretaceous > Upper Cretaceous > Turonian (0.48)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.69)
- Geophysics > Seismic Surveying (1.00)
- Geophysics > Borehole Geophysics (1.00)
- Asia > Middle East > Saudi Arabia > Arabian Gulf > Arabian Basin > Arabian Gulf Basin > Wasia Formation (0.99)
- Asia > Middle East > Qatar > Arabian Gulf > Arabian Basin > Arabian Gulf Basin > Block 6 > Al Khalij Field > Mishrif Formation (0.99)
- South America > Brazil > Rio de Janeiro > South Atlantic Ocean > Santos Basin > Block BM-S-11 > Buzios Field > Guaratiba Formation (0.97)