scholarly journals SITE-DEPENDENT GEOLOGICAL MODEL FOR DENSITY ESTIMATION IN THE NIGER DELTA BASIN, NIGERIA

2020 ◽  
Vol 4 (1) ◽  
pp. 01-06
Author(s):  
Atat, J. G. ◽  
Uko, E. D. ◽  
Tamunobereton-ari, I. ◽  
Eze, C. L
Keyword(s):  
Niger Delta ◽  
Seismic Inversion ◽  
Well Log ◽  
Geological Model ◽  
Global Knowledge ◽  
Density Prediction ◽  
Impedance Inversion ◽  
Acoustic Impedance Inversion ◽  
Niger Delta Basin ◽  
Density Modelling

Seismic and Well-log data covering three wells in tau(τ) Field in the Niger Delta were used for density modelling. Using Hampson Russell Software, Gardner’s and Lindseth’s relations were localized and subsequently transformed to obtain local fits constants for sand and shale lithologies which were used to achieved the final models. The seismic inversion was performed using four steps: well-to-seismic tie, geology model, acoustic impedance inversion and density prediction. A relationship was established between impedance and density. Pairing Gardner with those by Lindseth approaches and also obtained the average, the final models are ρ=0.1572Z_p^0.2126-16997Z_p^(-1)+1.5625 and ρ=0.09045Z_s^0.1935-7093.5Z_s^(-1)+1.4706 for sandstones lithology; ρ=0.3185Z_p^0.3103-6510Z_p^(-1)+1.42855 and ρ=0.16145Z_s^0.2308-34203.5Z_s^(-1)+1.42855 for shale lithology. These models yield a new concept which will contribute to global knowledge. In the absence of density log, these equations can be used to estimate density in the area.

Rock Property Cross-Plot Analysis and Post-Stack Acoustic Impedance Inversion for Optimal Reservoir Characterization in Aplha Field, Onshore Niger Delta Basin

2021 ◽  
Author(s):  
George-Best Azuoko ◽  
Amobi Ekwe ◽  
Amulu Emmanuel ◽  
Ayatu Usman ◽  
Eluwa Ndidiamaka ◽  
...  
Keyword(s):  
Acoustic Impedance ◽  
Reservoir Characterization ◽  
Water Saturation ◽  
Seismic Inversion ◽  
Hydrocarbon Reservoirs ◽  
Event Time ◽  
Plot Analysis ◽  
Impedance Inversion ◽  
Acoustic Impedance Inversion ◽  
Niger Delta Basin

Abstract In the quest to recover by-passed hydrocarbons, extend the life of mature fields, increase hydrocarbon reserves and satiate the increasing global demand for energy, the need for robust reservoir characterization using acoustic impedance inversion continues to grow. In this study, petrophysical parameters were evaluated for two sand intervals RX2 and RX5. Detailed cross-plot analysis of robust petrophysical properties, (density, water Saturation, Lambda-rho and Mu-rho and Porosity) facilitated fluid and lithology discrimination. Well to seismic correlations and acoustic-Impedance model-based, 3-D seismic inversion was done using Hampson Russell software, while petrophysical attribute slices and event-time structure maps were extracted at two horizons - H1 and H2. Results show that RX2 is 100ft thick in Well A, ranging from 5860ft to 5960ft, and 141ft thick in Well B, ranging from 5794ft to 5935ft. Interval RX5, 71ft thick, ranges from 6447ft to 6518ft in Well A, and 88ft thick in Well B, ranging from 6447ft to 6535ft. These intervals had average densities of 2.20g/cc for RX2 and 2.23g/cc for RX5 in Well A. In well B, density values are 1.95g/cc in RX2 and 2.06g/cc for RX5. Average porosities of 25.5% and 27.5% in RX2 and RX5 respectively for Well A; 29% and 19% in RX2 and RX5 respectively for Well B were observed. Respectively, average water and hydrocarbon saturation values of 0.31Swand 0.69Shfor Well A; 0.51Swand 0.49Shfor Well B, was recorded in both intervals. From the results, the thicknesses of RX2 and RX5 conform to the standard thickness of hydrocarbon reservoirs in the study area. Furthermore, the discrimination of the reservoir contents into fluid and lithology by the cross plots, and the observations in the attribute slices indicate that the selected intervals RX2 and RX5 are viable conventional hydrocarbon reservoirs.

scholarly journals Application of model-based inversion technique in a field in the coastal swamp depobelt, Niger delta

2018 ◽  
Vol 6 (1) ◽  
pp. 122
Author(s):  
Okoli Austin ◽  
Onyekuru Samuel I. ◽  
Okechukwu Agbasi ◽  
Zaidoon Taha Abdulrazzaq
Keyword(s):  
Niger Delta ◽  
Reservoir Characterization ◽  
Seismic Inversion ◽  
Inversion Method ◽  
Seismic Reflection Data ◽  
Model Based ◽  
Reflection Data ◽  
X 32 ◽  
Niger Delta Basin ◽  
Bypassed Oil

Considering the heterogeneity of the reservoir sands in the Niger Delta basin which are primary causes of low hydrocarbon recovery efficiency, poor sweep, early breakthrough and pockets of bypassed oil there arises a need for in-depth quantitative interpretation and more analysis to be done on seismic data to achieve a reliable reservoir characterization to improve recovery, plan future development wells within field and achieve deeper prospecting for depths not penetrated by the wells and areas far away from well locations. An effective tool towards de-risking prospects is seismic inversion which transforms a seismic reflection data to a quantitative rock-property description of a reservoir. The choice of model-based inversion in this study was due to well control, again considering the heterogeneity of the sands in the field. X-26, X-30, and X-32 were used to generate an initial impedance log which is used to update the estimated reflectivity from which we would obtain our inverted volumes. Acoustic impedance volumes were generated and observations made were consistent with depth trends established for the Niger Delta basin, inverted slices of Poisson impedances validated the expected responses considering the effect of compaction. This justifies the use of inversion method in further characterizing the plays identified in the region.

scholarly journals Rock Physics Formula and RMS Stacking Velocity Calculation to Assist Acoustic Impedance Inversion that Constrain Well Data

2020 ◽  
Vol 5 (2) ◽  
pp. 68-72
Author(s):  
Handoyo ◽  
Mochammad Puput Erlangga ◽  
Paul Young
Keyword(s):  
Acoustic Impedance ◽  
Rock Physics ◽  
Well Log ◽  
Initial Model ◽  
Impedance Inversion ◽  
Acoustic Impedance Inversion ◽  
The Matrix ◽  
Using Data ◽  
Well Data ◽  
Interval Velocities

This research ilustrate the generation of acoustic impedance inversion in the absence of well log using stacking velocity input in Salawati Basin, Papua, Indonesia using data obtained from seismic lines and stacking velocity section. Initial acoustic impedance modelswere first before the inversion process and were created by spreading the value of well log data to the all seismic CDP. The calculated acoustic impedance logs from standard sonic and density logs were used to build the initial model of acoustic impedance.First, the stacking velocities was first interpolated on a grid that has the same size as the seismic data using by means of Polynomial algorithm. This was closely followed by the conversion of the stacking velocities to interval velocities using Dix’s equation. The matrix densities were estimated by simple rock physics approach i.e. Gardner’s equation as a velocity function. The initial model of acoustic impedance was calculated by multiplying the densities section and interval velocities section. The resulting initial model of acoustic impedance was inverted to obtain the best of acoustic impedance section based on reflectivity.

scholarly journals DELINEATION OF HYDROCARBON SATURATED RESERVOIR SAND USING INTEGRATED 3D PRE-STACK SEISMIC AND WELL LOG DATA IN BONGA – FIELD, CENTRAL SWAMP DEPOBELT, ONSHORE NIGER DELTA, NIGERIA

2020 ◽  
Vol 5 (2) ◽  
pp. 64-68
Author(s):  
Innocent Kiani ◽  
Aniefiok Sylvester Akpan
Keyword(s):  
Cross Sections ◽  
Niger Delta ◽  
Gamma Ray ◽  
Water Saturation ◽  
Seismic Inversion ◽  
High Resistivity ◽  
Well Log ◽  
Fluid Properties ◽  
Exploratory Wells ◽  
Depth Ranges

This study has successfully delineated the lateral continuity of hydrocarbon saturated sand reservoir in Bonga field, Niger Delta. 3D pre-stack seismic volume and well logs from two (2) exploratory wells were employed in the pre-stack seismic inversion analysis. The delineated BGA reservoir sand spans across the two (2) wells labelled Bonga-26 and Bonga-30. The reservoir depth ranges from 10490 ft to 10620 ft in Bonga-26 while the reservoir depth ranges from 10390 ft to 10490 ft in Bonga-30. The delineated reservoir is characterized by low gamma ray (< 75 API), water saturation, shale volume and high resistivity as deciphered in their respective well log curves signature. Rock attribute crossplot was carried out to discriminate between the formation fluid and lithology. The crossplot space of VP-VS ratio versus acoustic impedance (AI), discriminates the formation properties into lithology and fluid (gas and brine sand) based on clusters inferring the presence of each formation fluid properties. The inversion cross sections of P-impedance, S-impedance, density (ρ) and VP-VS ratio depicts the spread and lateral continuity of the reservoir sand across the well locations. The delineated zones reveal low P-impedance, density, VP-VS ratio and slight increase in S-impedance which further validate the presence of hydrocarbon in the field.

Application of Post-Stack Seismic Inversion in Discription of the Reservoir Distribution

2013 ◽  
Vol 477-478 ◽  
pp. 1088-1091
Author(s):  
Xu Tao Li
Keyword(s):  
Acoustic Impedance ◽  
Oil And Gas ◽  
Gamma Ray ◽  
Seismic Inversion ◽  
P Wave ◽  
Vertical Resolution ◽  
Oil And Gas Exploration ◽  
Impedance Inversion ◽  
Acoustic Impedance Inversion ◽  
Geologic Setting

Seismic inversion includes different methods. Acoustic impedance inversion is an ordinary method to find reservoir in oil and gas exploration, but in some area the Acoustic impedance inversion is not effective on different geologic setting. In this paper we found the Gamma Ray is effective on distinguish the sand and shale bed by using P-wave and Gamma Ray crossplot analysis. The final Gamma Ray seismic inversion results show that Gamma Ray seismic inversion can improve the vertical resolution. A satisfactory inversion effect is obtained in HM area.

High-Resolution Seismic Acoustic Impedance Inversion with Sparsity-based Statistical Model

Geophysics ◽  
2021 ◽  
pp. 1-129
Author(s):  
Lingqian Wang ◽  
Hui Zhou ◽  
Wenling Liu ◽  
Bo Yu ◽  
Sheng Zhang
Keyword(s):  
High Resolution ◽  
Statistical Model ◽  
Prediction Model ◽  
Seismic Inversion ◽  
Sparse Representations ◽  
Inversion Result ◽  
Model Based ◽  
Inversion Methods ◽  
Impedance Inversion ◽  
Acoustic Impedance Inversion

Seismic acoustic impedance inversion plays an important role in subsurface quantitative interpretation. Due to the band-limited property of the seismic record and the discretization of the continuous elastic parameters with a limited sampling interval, the inverse problem suffers from serious ill-posedness. Various regularization methods are introduced into the seismic inversion to make the inversion results comply with the pre-specified characteristics. However, conventional seismic inversion methods can only reflect fixed distribution characteristics and do not take into account discretization challenges. We propose a new post-stack seismic impedance inversion method with upsampling and adaptive regularization. The adaptive regularization is constructed with two trained dictionaries from the true model and upsampled model-based inversion result to capture the features of high- and low-resolution details, and a sparsity-based statistical model is proposed to build the relationship between their sparse representations. The high-resolution components can be recovered based on the prediction model and low-resolution sparse representations, and the parameters of the statistical prediction model can be obtained effectively with conventional optimization algorithms. The synthetic and field data tests show that the model-based inversion is dependent on the sample interval, and the proposed method can reveal more thin layers and enhance the extension of the strata compared with conventional inversion methods. Moreover, the inverted impedance variance of the proposed method well matches borehole observations. The tests demonstrate the interpolated model-based inversion result combined with the sparsity-based prediction model can effectively improve the resolution and accuracy of the inversion results.

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