Application of in-situ anisotropic parameters in 3D seismic velocity analysis for improved pre-drill pore pressure prediction in the onshore Niger Delta basin, Nigeria

2021 ◽  
Vol 14 (8) ◽  
Author(s):  
Jerome Asedegbega ◽  
Alexander Opara ◽  
Juliet Emudianughe ◽  
Meshach Omudu
Keyword(s):  
Pore Pressure ◽  
Niger Delta ◽  
Seismic Velocity ◽  
Velocity Analysis ◽  
3D Seismic ◽  
Pore Pressure Prediction ◽  
Niger Delta Basin

scholarly journals Pore pressure prediction in Niger Delta high pressure, high temperature (HP/HT) domains using well logs and 3D seismic data: a case study of X-field, onshore Niger Delta

2021 ◽  
Vol 11 (10) ◽  
pp. 3747-3758
Author(s):  
Abdulquadri O. Alabere ◽  
Olayemi K. Akangbe
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Pore Pressure ◽  
Niger Delta ◽  
Seismic Velocity ◽  
Sedimentary Basins ◽  
Geothermal Gradient ◽  
Pore Pressure Prediction ◽  
Fracture Gradient ◽  
High Temperature High Pressure

AbstractFew wells targeting high temperature, high pressure intervals in most tertiary sedimentary basins have achieved their objective in terms of technicalities and cost. Since most shallow targets have been drilled, exploration focus is drifting into deeper plays both onshore and in deep offshore areas. To ensure safe and economic drilling campaigns, pore pressure prediction methodologies used in the region needs to be improved. The research aims at generating and testing a modification of Eaton’s equation fit for high temperature, high pressure intervals on a field. The evolution of pore pressure in the field was established from offset well data by making several crossplots, and fracture gradient was computed using Mathew and Kelly’s equation. Eaton’s equation parameters were then calibrated using several wells until a desired field scale result was achieved when compared with information from already drilled intervals i.e., kicks and RFT data. Seismic velocity data resulting from high density, high resolution velocity analysis done to target deep overpressured intervals were then used to predict 1D pore pressure models at six selected prospect locations. Analyses reveal depths shallower than 3800 m TVD/MSL with geothermal gradient 3.0 °C/100 m and pressure gradient less than 1.50sg EMW are affected mainly by undercompaction; depths greater than 3800 m TVD/MSL with geothermal gradient of 4.1 °C/10 m and pressure gradients reaching 1.82–2.12sg EMW are affected by unloading with a narrow drilling margin for the deep highly pressured prospect intervals. Eaton’s n-exponent was modified to 6, and it proved accurate in predicting high overpressure in the first prospect wells drilled.

scholarly journals Estimation of overpressures from porosity based method : a theoretical approach applied to the central/coastal swamp depo-belts of the Niger delta basin

2017 ◽  
Vol 6 (1) ◽  
pp. 14
Author(s):  
Ubon Mkpese
Keyword(s):  
Bulk Density ◽  
Pore Pressure ◽  
Theoretical Approach ◽  
Niger Delta ◽  
Sonic Velocity ◽  
Pore Pressure Prediction ◽  
Formation Resistivity ◽  
Pressure Regime ◽  
Niger Delta Basin

The Depth-dependent compaction theory that variations in certain geophysical properties with depth; bulk density, formation resistivity together with sonic velocity being a reflection of the pressure regime is the basis for pore pressure prognosis study. Pore pressure prediction (PPP), when done accurately can be used to avert disaster and helps in safe drilling. A porosity-based model has been applied to predict overpressured zones in an onshore environment of the Niger delta basin. Zones with hard overpressures greater than a magnitude of 0.7 psi/ft are generally within 10000ft and below. Top of overpressures for studied wells ranges between 7000ft and 10000ft. Porosities in shale are of typical values ranging between 0.05 to 0.46. A robust concordance between PPP and MPP profiles for each of the wells validates the results here and confirms suitability of model to the studied area.

scholarly journals Seismic Velocity Analysis for Improved Geopressure Modelling in Onshore Niger Delta

2019 ◽  
Vol 7 (2) ◽  
pp. 179
Author(s):  
Emmanuel Bassey Umoren ◽  
Etim Daniel Uko ◽  
Iyeneomie Tamunobereton-Ari ◽  
Chigozie Israel-Cookey
Keyword(s):  
High Resolution ◽  
Pore Pressure ◽  
Acoustic Impedance ◽  
Niger Delta ◽  
Seismic Velocity ◽  
Seismic Inversion ◽  
Velocity Analysis ◽  
Pressure Data ◽  
Model Based ◽  
Inversion Technique

In this study, an improved evaluation of pore pressure using a model based seismic inversion technique has been carried out. Across six wells in the Onshore Niger Delta Basin, post stack seismic volume, angle stack gathers, seismic horizons, check shot, wireline logs, drilling and pressure data were analysed and interpreted. The model based inversion technique was applied to improve the seismic resolution as well as derive acoustic impedance using well velocities along with stacking velocities from velocity analysis of the 3D seismic data. Bowers’ Vp-VES coefficients of 7.43 and 0.77 were used to transform the derived seismic acoustic impedance velocity into seismic pore pressure cube. The seismic acoustic impedance interval velocity reveals much of the geology and resulted to a high resolution seismic pore pressure cube when compared at well location with direct pressure data. The Derived Seismic Pore Pressure (DSPP) also revealed that pore pressure and overpressure can reach or exceed 4000 and 1000psi respectively in the field. The results obtained have demonstrated that seismic acoustic impedance volume can offer high resolution seismic pore pressure cube in both time and space.  

scholarly journals Characterization of reservoir sands using 3D seismic attributes in the coastal swamp area of Niger Delta Basin

2021 ◽  
Author(s):  
Oluwatoyin Khadijat Olaleye ◽  
Pius Adekunle Enikanselu ◽  
Michael Ayuk Ayuk
Keyword(s):  
Seismic Data ◽  
Niger Delta ◽  
Seismic Attributes ◽  
Effective Porosity ◽  
High Porosity ◽  
Hydrocarbon Accumulation ◽  
3D Seismic ◽  
Seismic Attribute ◽  
Niger Delta Basin

AbstractHydrocarbon accumulation and production within the Niger Delta Basin are controlled by varieties of geologic features guided by the depositional environment and tectonic history across the basin. In this study, multiple seismic attribute transforms were applied to three-dimensional (3D) seismic data obtained from “Reigh” Field, Onshore Niger Delta to delineate and characterize geologic features capable of harboring hydrocarbon and identifying hydrocarbon productivity areas within the field. Two (2) sand units were delineated from borehole log data and their corresponding horizons were mapped on seismic data, using appropriate check-shot data of the boreholes. Petrophysical summary of the sand units revealed that the area is characterized by high sand/shale ratio, effective porosity ranged from 16 to 36% and hydrocarbon saturation between 72 and 92%. By extracting attribute maps of coherence, instantaneous frequency, instantaneous amplitude and RMS amplitude, characterization of the sand units in terms of reservoir geomorphological features, facies distribution and hydrocarbon potential was achieved. Seismic attribute results revealed (1) characteristic patterns of varying frequency and amplitude areas, (2) major control of hydrocarbon accumulation being structural, in terms of fault, (3) prospective stratigraphic pinch-out, lenticular thick hydrocarbon sand, mounded sand deposit and barrier bar deposit. Seismic Attributes analysis together with seismic structural interpretation revealed prospective structurally high zones with high sand percentage, moderate thickness and high porosity anomaly at the center of the field. The integration of different seismic attribute transforms and results from the study has improved our understanding of mapped sand units and enhanced the delineation of drillable locations which are not recognized on conventional seismic interpretations.

Sign in / Sign up

Export Citation Format

Share Document