Fracture and Sub-Seismic Fault Characterization for Tight Carbonates in Challenging Oil-Based Mud Environment—Case Study From North Kuwait Jurassic Reservoirs

Li, Bingjian; Al-Awadi, Mishari; Perrin, Christian; Al-Khabbaz, Mohammed; Al-Ashwak, Samar; Al-Qadeeri, Bashar

doi:10.2118/120424-ms

Cited by 8 publications

(1 citation statement)

References 3 publications

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“…The image logs also have their own limitations, i.e. limited resolution compared with the cor e as wel l as difficulty in telling open from healed fractur es with the electronic image logs alone in a synthetic-based mud environment (Li et al, 2009).…”

Section: Fracture Characterization Based On Core and Obmi Imagesmentioning

confidence: 99%

Interpreting Electro-facies And Fractures For An Oligocene Sandstone Reservoir Using Borehole Images Acquired In Oil-base Mud With Full Core Calibration: A Case Study From Songkhla Basin, Thailand

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et al. 2011

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The Oligocene reservoirs in the Songkhla Basin of Thailand are predominantly fluvial-deltaic deposits. There are several geological challenges describing these reservoirs. Firstly, it is som etimes difficult to determine lithology from conventional open-hole logs. Seco ndly, defining facies can b e challenging due to the lack of sedim entary structure information from any of the conventional open-hole logs. Thirdly, natural fractures and sub-seismic faults exist in the formation which adds more complexity to the reservoirs. Geoscientists have traditionally incurred high operating costs to acquire conventional cores needed to resolve these challenges. This paper presents an alternative technique for sedimentary characterization of the Oligocene sandstone reservoirs in the Songkhla Basin utilizing electrical image logs acquired in synthetic-based drilling fluids, along with Elemental Capture Spectroscopy (ECS) and Nuclear Magnetic Resonance (NMR) data. Lithology has been defined a lot more accurately using ECS data than by using conventional open-hole logs alone. Electro-facies have been successfully determined by integrating sedimentary structure and texture information interpreted from image and NMR logs with lithology information from ECS. In addition, the natural fractures have been interpreted from image logs. These interpretations of lithology, elec tro-facies and fractu res have been calibrated with core data acquired in the same well. The output from this pilot study was a cost-effective solution for electro-facies and fracture analysis. It also provided input to constrain the sedimentological settings and reservoir modeling for the field.

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Section: Fracture Characterization Based On Core and Obmi Imagesmentioning

confidence: 99%

Interpreting Electro-facies And Fractures For An Oligocene Sandstone Reservoir Using Borehole Images Acquired In Oil-base Mud With Full Core Calibration: A Case Study From Songkhla Basin, Thailand

Peace²,

MayKho³

et al. 2011

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3D Geological Modeling of a Tight Naturally Fractured Carbonate Reservoir as an input to Reservoir Simulation – A Case Study from North Kuwait Jurassic fields

et al. 2009

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Dedicated exploration efforts targeted on the Jurassic reservoirs in North Kuwait culminated in the discovery of six separate fields, encompassing an area of approximately 1,772 km 2 . These reservoirs are known to hold commercial accumulation of gas, gas condensate and volatile oil and are currently in an early phase of development. The producing Jurassic reservoirs belong to the Marrat, Sargelu and Najmah Formations of Toarcian to Tithonian ages. These reservoirs consist of tight carbonates with several other complex lithologies and are naturally fractured with fractures acting as a driver to production in the Najmah and Sargelu formations and fractures acting as production assist in the Marrat Formation. A 3D geological model was developed for these reservoirs. The static geological model consists of a matrix model capturing the facies, and other matrix reservoir properties like porosity, permeability and water saturation; and the fracture model captures the fracture properties like fracture porosity, permeability and matrix to fracture coupling parameters. The model framework was guided by seismic horizon interpretation from 3D seismic data while the model vertical resolution was optimized to adequately capture the log defined reservoir properties. Electro facies were interpreted at wells with extensive core calibration and were used to develop a 3D facies model capturing the worked out depositional environment. This facies model was used to develop the porosity, permeability and water saturation models using the processed wireline log data, core plug based measurements. The 3D fracture model was developed capturing the areal distribution of fractures using the calibrated 3D seismic volume curvature attribute as soft data and constrained vertically by hard data from image log and cores from wells, thus bringing robustness and reliability for planning the development wells. This 3D geological model was optimally upscaled depending on the aerial well density for use of flow simulation studies.

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Modeling Naturally Fractured Tight Carbonate Reservoirs – A Case Study

et al. 2011

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Kuwait Oil Company (KOC) is engaged in an early phase of development of a giant, tight, fractured carbonate play within the State of Kuwait, spread over a large area covering six fields. The producing reservoirs belong to the geological Formations of Toarcian to Tithonian age. Some reservoirs are characterized by very low porosity and permeability and productivity of these reservoirs is driven by the natural fracture system. This paper described the approach followed in developing a 3D fracture model for these reservoirs. Carefully planned data acquisition resulted in a rich suite of dataset consisting of image logs, conventional cores covering the target pay zones in a number of wells. Analysis of these data gave a clear understanding about fracture orientation, density, aperture, and other fracture parameters. Special 3D seismic processing was carried out to derive a volume curvature attribute, which was able to detect and identify the fracture corridors away from the wells. Structural geological analysis resulted in an understanding of the tectonic history of the area, which helped in genetically relating the identified fracture orientations with the structural evolution. A discrete fracture network was developed for these reservoirs combining the well and seismic attribute data. Parameters like aspect ratio, orientation and aperture of fractures was assigned to different fracture sets based on this analysis. The apertures were corrected for the present day stress effect based on the borehole breakout data. This fracture model was upscaled into the 3D geological model to get the fracture porosity and the permeability tensors. The fracture model was validated by history matching pressure build up and production data and was used for dynamic flow simulation studies for the field development planning.

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Fracture and Sub-Seismic Fault Characterization for Tight Carbonates in Challenging Oil-Based Mud Environment—Case Study From North Kuwait Jurassic Reservoirs

Cited by 8 publications

References 3 publications

Interpreting Electro-facies And Fractures For An Oligocene Sandstone Reservoir Using Borehole Images Acquired In Oil-base Mud With Full Core Calibration: A Case Study From Songkhla Basin, Thailand

Interpreting Electro-facies And Fractures For An Oligocene Sandstone Reservoir Using Borehole Images Acquired In Oil-base Mud With Full Core Calibration: A Case Study From Songkhla Basin, Thailand

3D Geological Modeling of a Tight Naturally Fractured Carbonate Reservoir as an input to Reservoir Simulation – A Case Study from North Kuwait Jurassic fields

Modeling Naturally Fractured Tight Carbonate Reservoirs – A Case Study

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