scholarly journals Prediction of pore pressure using well logs and seismic data in Fabi Field, Onshore Niger delta, Nigeria

2016 ◽  
Vol 4 (2) ◽  
pp. 76 ◽  
Author(s):  
Aniwetalu Emmanuel ◽  
Anakwuba Emmanuel ◽  
Ilechukwu Juliet N ◽  
Chidozie Okoye
Keyword(s):  
Pore Pressure ◽  
Seismic Data ◽  
Niger Delta ◽  
Control Point ◽  
Well Logs ◽  
Depth Level ◽  
Well Control ◽  
High Impedance ◽  
Impedance Inversion ◽  
Elastic Impedance

The variations of pore pressure in Fabi Field Onshore Niger delta have been investigated using well log and seismic data. The both data were calibrated to ensure reasonable match in depth. Zones of overpressure were predicted from the well logs based on the deviations of petrophysical measurement from normal compaction trends. The lateral variations of the overpressure were delineated from seismic data through elastic impedance inversion. Overpressure cube was delineated from the inverted volumes through points of picked horizons. The results of the study revealed overpressure occurrence in well logs at depth level of 8625ft to 9000ft. The elastic impedance inversion presents overpressure variations beyond well control point at the depth level of about 1940-1140ms corresponding to very high impedance value of about 25540-27067ft/s*g/cc. The area extents of the positive anomalies (increase in elastic impedance) are mostly consistent with overpressure zones. Overpressure zones were also estimated from the seismic data between 1560ms -1600ms within the TRK-1 and TRK-2 horizon which also correspond to the well control points (8625ft to nearly 9000ft). The velocity and density crossplots revealed that undercompaction is the main overpressure generating mechanism in Fabi Field, although other parts of the field revealed unloading mechanism.

scholarly journals Integration of Well Logs and Seismic Data for Prospects Evaluation of an X Field, Onshore Niger Delta, Nigeria

2012 ◽  
Vol 03 (04) ◽  
pp. 872-877 ◽  
Author(s):  
Godwin Emujakporue ◽  
Cyril Nwankwo ◽  
Leonard Nwosu
Keyword(s):  
Seismic Data ◽  
Niger Delta ◽  
Well Logs

scholarly journals Post Drill Pore Pressure Prediction for Geo-hazard Assessment of Offset Wells in Hamoru Field

2020 ◽  
Vol 17 (2) ◽  
pp. 97-103
Author(s):  
A. Ogbamikhumi ◽  
O.M. Hamid-Osazuwa ◽  
E.A. Imoru
Keyword(s):  
Pore Pressure ◽  
Hazard Assessment ◽  
Seismic Data ◽  
Field Analysis ◽  
Well Logs ◽  
Formation Pressure ◽  
Pore Pressure Prediction ◽  
Pressure Regime ◽  
Formation Pore Pressure ◽  
Subsurface Formation

Understanding the distribution and variation of subsurface formation pressure is key to preventing geo-hazards associated with drilling activities such as kicks and blow out. To assess and prevent such risk in drilling offset wells in the Hamoru field, prediction of pore pressure was done to understand the pressure regime of the field using well logs in the absence of seismic data. Two commonly used methods for formation pressure prediction; Bower’s and Eaton’s methods were adopted to predict pore pressure and determine the better of the two methods that will be more suitable for the field. The cross-plot of Vp against density disclosed that compaction disequilibrium is the prevalent overpressure mechanism. The prediction of Pore pressure with Eaton’s method gave results comparable to the acquired pressure in the field, typical of what is expected when compaction disequilibrium is the dominant overpressure mechanism. Since the result of Bower’s method over estimated formation pressure, Eaton’s method appears to be the better choice for predicting the formation pore pressure in the field. Analysis of the predicted pore pressure reveals the onset of overpressure at depth of 2.44 km. The formation pressure gradient ranges from 10.4 kPa/m to 15.2 kPa/m interpreted as mild to moderately over pressure. Keywords: Geohazard, over-pressure, Eaton’s method, Bower’s method, normal compaction trend

Reservoir characterization over the Lille Prinsen and Ivar Aasen fields in the Norwegian North Sea using ocean-bottom-node seismic data — A case study

2021 ◽  
pp. 1-64
Author(s):  
Satinder Chopra ◽  
Ritesh Kumar Sharma ◽  
Mikal Trulsvik ◽  
Adriana Citlali Ramirez ◽  
David Went ◽  
...  
Keyword(s):  
North Sea ◽  
Seismic Data ◽  
Reservoir Characterization ◽  
Water Saturation ◽  
Late Triassic ◽  
Ocean Bottom ◽  
Impedance Inversion ◽  
High Area ◽  
Elastic Impedance

An integrated workflow is proposed for estimating elastic parameters within the Late Triassic Skagerrak Formation, the Middle Jurassic Sleipner and Hugin Formations, the Paleocene Heimdal Formation and Eocene Grid Formation in the Utsira High area of the Norwegian North Sea. The proposed workflow begins with petrophysical analysis carried out at the available wells. Next, model-based prestack simultaneous impedance inversion outputs were derived, and attempts were made to estimate the petrophysical parameters (volume of shale, porosity, and water saturation) from seismic data using extended elastic impedance. On not obtaining convincing results, we switched over to multiattribute regression analysis for estimating them, which yielded encouraging results. Finally, the Bayesian classification approach was employed for defining different facies in the intervals of interest.

scholarly journals Transition zones analysis using empirical capillary pressure model from well logs and 3D seismic data on ‘Stephs’ field, onshore, Niger Delta, Nigeria

2019 ◽  
Vol 10 (3) ◽  
pp. 1227-1242
Author(s):  
O. Abiola ◽  
F. O. Obasuyi
Keyword(s):  
Capillary Pressure ◽  
Seismic Data ◽  
Niger Delta ◽  
Time Structure ◽  
Well Logs ◽  
3D Seismic ◽  
Seismic Section ◽  
Transition Zones ◽  
Mobile Water ◽  
3D Seismic Data

AbstractCapillary pressure is an important characteristic that indicates the zones of interaction between two-phase fluids or fluid and rock occurring in the subsurface. The analysis of transition zones (TZs) using Goda (Sam) et al.’s empirical capillary pressure from well logs and 3D seismic data in ‘Stephs’ field, Niger Delta, was carried out to remove the effect of mobile water above the oil–water contact in reservoirs in the absence of core data/information. Two reservoirs (RES B and C) were utilized for this study with net thicknesses (NTG) ranging from 194.14 to 209.08 m. Petrophysical parameters computed from well logs indicate that the reservoirs’ effective porosity ranges from 10 to 30% and the permeability ranges from 100 to > 1000 mD, which are important characteristics of good hydrocarbon bearing zone. Checkshot data were used to tie the well to the seismic section. Faults and horizons were mapped on the seismic section. Time structure maps were generated, and a velocity model was used to convert the time structure maps to its depth equivalent. A total of six faults were mapped, three of which are major growth faults (F1, F4 and F5) and cut across the study area. Reservoir properties were modelled using SIS and SGS. The capillary pressure log, curves and models generated were useful in identifying the impact of mobile water in the reservoir as they show the trend of saturating and interacting fluids. The volume of oil estimated from reservoirs B and C without taking TZ into consideration was 273 × 106 and 406 × 106 mmbbls, respectively, and was found to be higher than the volume of oil estimated from the two reservoirs while taking TZ into consideration which was 242 × 106 and 256 × 106 mmbbls, respectively. The results have indicated the presence of mobile water, which have further established that conventionally recoverable hydrocarbon (RHC) is usually overestimated; hence, TZ analysis has to be performed for enhancing RHC for cost-effective extraction and profit maximization.

Distinguishing gas-bearing sandstone reservoirs within mixed siliciclastic-carbonate sequences using extended elastic impedance: Nile Delta — Egypt

2016 ◽  
Vol 4 (4) ◽  
pp. T427-T441 ◽  
Author(s):  
Ahmed Hafez ◽  
John P. Castagna
Keyword(s):  
Nile Delta ◽  
Rock Physics ◽  
Seismic Inversion ◽  
Anomalous Behavior ◽  
Well Logs ◽  
High Impedance ◽  
Bright Spots ◽  
Fluid Properties ◽  
Elastic Impedance ◽  
Gas Bearing

In the Abu Madi Formation of the Nile Delta Basin, false bright spots may be misinterpreted as being indicative of hydrocarbons due to mixed clastics and carbonates. However, rock-physics analysis of well logs in a particular prospect area where such ambiguity exists suggests that attributes derived using extended elastic impedance (EEI) inversion may help identify hydrocarbons because they better show anomalous behavior in particular directions that are readily related to pore fluids and lithology. The EEI attributes calculated from well logs correlate extremely well to lithology and fluid properties, thereby differentiating amplitude anomalies caused by gas-bearing sandstones encased in shale from similar amplitudes caused by juxtaposition of high-impedance carbonates over lower impedance water-filled sandstones. Comparing seismically derived EEI attributes to well logs from a productive well and a nonproductive well indicates that seismic inversion can successfully identify lithologies such as shales, sandstones, carbonates, and anhydrite and distinguish gas-bearing from water-bearing sandstones. The technique can thus potentially be used to better delineate and risk prospects in the area, as well as assisting exploration efforts in other locations where similar ambiguities in amplitude interpretation exist.

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