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Collaborating Authors
Results
Seismic AvO Inversion and Net Sand Estimation in Deep Water Turbidite Sands, Kangaroo Field, Offshore Nigeria
Osayande, Francesca (Shell Nigeria Exploration and Production Company) | Oguntola, Somime (Shell Nigeria Exploration and Production Company) | Sonde, Adenike (Shell Nigeria Exploration and Production Company) | Biambo, Tamunotonye (Shell Nigeria Exploration and Production Company) | Osho, Olaseni (Shell Nigeria Exploration and Production Company) | Okpako, Kelvin (Shell Nigeria Exploration and Production Company) | Musa, Joel (Shell Nigeria Exploration and Production Company) | Anaevune, Austin (Shell Nigeria Exploration and Production Company) | Mora-Glukstad, Miguel (Shell Nigeria Exploration and Production Company) | Yamusa, Idris (Shell Nigeria Exploration and Production Company)
Abstract The Kangaroo is a field located in the Deepwater Nigeria in water depths ranging from 950 to 1,500 meters. Structurally, the field can be described as a NW-SE trending shale-cored anticline with crestal faulting. Several wells have been drilled encountering primarily oil, in a series of Upper to Middle Miocene channelized turbidite reservoirs. The Kangaroo field is a brown field with challenges of unlocking its full potentials. The key subsurface uncertainties identified, were sand distribution and intra-reservoir connectivity. The existing reservoir models did not fully describe the reservoir net sand thickness and as a result, recent drillings have highlighted series of surprises warranting a study, to gain more insights into the sand distribution and reservoir heterogeneity. This study highlights a multi-stack simultaneous seismic inversion used in conjunction with rock physics analysis, for a detailed reservoir characterisation, re-mapping of key reservoirs and prediction of Net-to-gross away from well control. Five offset angle seismic sub-stacks have been inverted with a Simultaneous Inversion algorithm, ultimately converting the reflectivity seismic data into rock property models, generating acoustic impedance (Zp), shear impedance (Zs), and density (ρ). A feasibility study including crossplots of petrophysical and elastic properties from well data was carried out to establish rock property relationships in the interval of interest and this formed the basis for the seismic inversion studies. Key business driving value for this study, is the derivation of a robust estimates of net sand distribution, its impact on modelling reservoir parameters, and consequent estimation of in-place volumes.
- Africa > Nigeria (1.00)
- South America > Brazil > São Paulo > South Atlantic Ocean (0.65)
- Geology > Sedimentary Geology > Depositional Environment > Marine Environment > Deep Water Marine Environment (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.40)
- South America > Brazil > São Paulo > South Atlantic Ocean > Santos Basin > Block SM-1102 > Goia Field (0.99)
- South America > Brazil > São Paulo > South Atlantic Ocean > Santos Basin > Block SM-1037 > Goia Field (0.99)
- South America > Brazil > São Paulo > South Atlantic Ocean > Santos Basin > Block S-M-1166 > Goia Field (0.99)
- (4 more...)
Abstract A review of many oil/gas fields in Nigeria shows that most structures are under-filled (the fluid contact is much shallower than the structural spill point). This could be explained in different ways. Hydrocarbon charge has been suggested as a possible explanation, but we do not believe this to be the main cause in such a rich hydrocarbon province, like the delta, and where there are excellent carrier beds and world class source rocks, all throughout the system. Another possible cause could be what we call a "dynamic top seal," where there is some degree of leakage either due to capillary forces or facilitated by crestal faulting. An ongoing analysis on capillary entry pressure and mechanical strength of the top seal, shows that this could be the case in some shallow reservoirs, but a "leaky" top seal does not appear to be a major issue in relatively deeper reservoirs. An updated seismic interpretation was carried out in field X where part of the focus was to understand what controls the current fluid contacts. This study has direct implications towards predicting fluid contacts in near field opportunities in undrilled blocks for proper placement of development wells. Field X has one single well but there are undrilled blocks with similar structural geometries. These learnings will also help to carry out predictions of in place volumes for near field development. This work showed that more careful and detailed structural mapping of the fault systems provides a view of fault geometry where relay ramps clearly control the position of the fluid level. The position of the initially planned well changed. We are applying these learnings and testing if this observation can be replicated in other fields, once more detailed mapping is carried out.
- Reservoir Description and Dynamics > Reservoir Characterization > Faults and fracture characterization (0.92)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (0.90)
- Management > Asset and Portfolio Management > Field development optimization and planning (0.70)
Substantiation of Reservoir Lateral Hydraulic Connectivity Based on Integrated subsurface and Production test result - Niger Delta Field Experience
Adepoju, Yaqub (SPDC Ltd.) | Anyaehie, James (SPDC Ltd.) | Ogbuli, Andrew (SPDC Ltd.) | Balogun, Olalekan (SPDC Ltd.) | Awa, Chukwunweike (SPDC Ltd.) | Mora-Glukstad, Miguel (SPDC Ltd.) | Kakayor, Omagbemi (SPDC Ltd.)
Abstract Field X is one of SPDC's major gas fields located onshore of Nigeria with six well penetrations and two key reservoirs, A1000X and B4000X,. The field is covered by a 1992 3D seismic reprocessed PSDM with relatively poor imaging quality. This caused uncertainties with respect to the interpretation of possible intra-reservoir fault compartmentilization. These intra-reservoir faults are on the footwall of two major southern and eastern boundary faults. To optimally develop these reservoirs, it was proposed to drill an appraisal well in the eastern fault block, modelled as a reservoir compartment, and subsequently carry out an interference test to establish the lateral hydraulic connectivity of the reservoirs. A new seismic data was acquired and processed to resolve the uncertainties associated with the poor imaging quality of the 1992 seismic. The interpretation of the new seismic showed similar structural trend, albeit with better clarity of the subsurface images in the fault shadow zones. It also showed continuous seismic reflection loops suggesting a more better lateral reservoir connectivity To better understand the reservoir lateral hydraulic continuity, a multidisciplinary integrated study was conducted using all available data (production tests, Seismic and Petrophysical data). This paper covers the multi- disciplinary work carried out to establish the lateral connectivity of the reservoirs and its significant cost reduction to the total project cost.
- Africa > Nigeria > Niger Delta (0.41)
- North America > Canada > Saskatchewan (0.40)
- Asia > Middle East > Israel > Mediterranean Sea (0.40)
- Africa > Nigeria > Gulf of Guinea > Niger Delta (0.40)