From Hydrocarbon to CO 2 Storage: Unveiling the Potential of the Miocene Lille John Member in the Danish North Sea

This research focuses on studying the Surma Group sediments with an integrated approach of using wireline logs and 2D seismic data from Sylhet structure and outcrop analogy from the Zaflong-Tamabil-Jaintiapur area to explain the geological evolution in the context of sequence stratigraphic framework and its implications to identify the hidden potential of hydrocarbon traps that remains overlooked. The 'SYL-07' well logs divided the encountered sedimentary strata by sequence boundaries (SB) and flooding surfaces (FS) into an upper third-order Lowstand System Tract (3_LST), followed by the third-order Highstand System Tract (3_HST), and underlying third-order Transgressive System Tract (3_TST) which correspond to the Tipam, Boka Bil, and Bhuban formations, respectively. The 3_HST has further been subdivided into fourth-order sequences. Well-to-seismic ties helped in identifying the sequence boundaries in the regional context. Three new prospects in the nose and flank area of the Sylhet structure have been detected based on seismic attributes and log responses. Seismic sweetness attribute anomalies confirmed the existence of these prospects. Rigorous fieldworks provided nineteen facies and seven sets of sedimentary facies associations and helped to establish the sedimentological stacking patterns and corresponding depositional environments. About 2250m lithocolumn constructed from field data revealed four third-order sequence stratigraphic system tracts roughly corresponding to Renji (3_LST), Bhuban (3_TST), Boka Bil (3_HST), and Tipam (3_LST) formations in the bottom-up order, while the obtained facies associations aid in identifying four fourth-order sequences including fourth-order system tracts in the 3_HST. The lithologic column corresponds well with the seismic sections and validates the seismically interpreted third-order system tracts and fourth-order sequences. However, the high-frequency fourth-order system tracts can only be correlated with the log motif patterns due to sub-seismic resolution. The erosional remains of the fourth-order sequences in 3_HST, for instance, the coarsening upward shoreface and shelfal facies topped by transgressive shale, have yielded potential future drilling sites based on seismic attribute and log response analysis. The analogy of field data with well log and seismic data helped the overall evaluation of the hydrocarbon prospectivity of the area. The Dhaka University Journal of Earth and Environmental Sciences, Vol. 11(1), 2022: 95-110

Hydrocarbon 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.

Integrated wireline log and seismic attribute analysis for the reservoir evaluation: A case study of the Mount Messenger Formation in Kaimiro Field, Taranaki Basin, New Zealand

3D seismic data and wireline logs from thirteen boreholes were used to establish a sequence stratigraphic analysis of Miocene depositional systems of the Otu Field in the onshore area of the Niger Delta. The subsurface facies of the field revealed three sequences that are bounded by four sequence boundaries (SBs) which are interpreted as erosional unconformities with three maximum flooding surfaces (MFSs). Sequences delineated are composed of lowstand systems tracts (LST), falling stage systems tracts (FSST), transgressive systems tracts (TST) and highstand systems tracts (HST) revealing depositional systems deposited during different phases of base level changes. Deposits identified within the LSTs are fluvial channel sands while TSTs capped the LST facies. HSTs are composed of coarsening and shallowing upwards intervals including deltaic fluvial sands. The sequences were deposited in transitional to shallow marine environments. A seismic geomorphological study carried out on all the SBs and MFS 3 shows a relationship between depositional environments, channel type and direction of palaeo-flow in relation to faults. The reservoirs of the LST and HST and seals from marine shale of the TST and HST could form stratigraphic traps for hydrocarbon accumulation in the Otu Field. This study has integrated 3D seismic and borehole log data to develop a sequence stratigraphic framework that would be a profitable means to guide hydrocarbon exploration and production strategies.

Petroleum system elements within the Late Cretaceous and Early Paleogene sediments of Nigeria's inland basins: An integrated sequence stratigraphic approach

Sedimentary characteristics of thick layer lacustrine beach-bars in the Cenozoic Banqiao Sag of the Bohai Bay Basin, East China

The Baldwin Hills reservoir failure

The decline in the chance of finding commercial quantity of hydrocarbon necessitated the integration of more geophysical tools in order to properly assess the reservoir quality. This study integrated rock physics and seismic attribute to assess the reservoir quality in ‘Solid’ field, offshore Niger Delta. The objectives of this study are to use rock physics analysis to quality check the seismic attribute results and to locate the best productive zones in the field. 3D seismic data and well log data for six wells were used for Formation evaluation, Petrophysical analysis, Structural analysis, Seismic attribute extraction. These results were then checked qualitatively using rock physics analysis. Six sand units (Sand 1, 2, 3, 4, 5 and 6) were correlated across six wells. Petrophysical analysis indicated that the reservoirs have high porosity (20.9% to 25.4%), high permeability (1897 to 2557 mD), high net-to-gross sand (84.7% to 99.0%), and low volume of shale (0.13 to 0.48). This shows that the reservoirs are of good quality. The depth structure map indicates that the reservoirs are mainly fault assisted closures. The seismic attribute extraction for the sand reservoirs shows high amplitude for Sand 1 in areas where wells have been drilled and also in some closures in Sand 2, 3 and 4 which is indicative of hydrocarbon presence. The crossplot of acoustic impedance against shear impedance of Well S5 helped to differentiate sand and shale in the reservoirs. Crossplot of acoustic impedance against Vp/Vs ratio was then used to predict the fluid type in Well S5. The crossplot of acoustic impedance against Vp/Vs ratio of Sand 2 in Well S5 and Sand 1 in Well S4 follows a regular trend with depth. The overall results portrayed that Sand 1, 2, 3 and 4 are of good quality and are oil bearing.

With the recent development of three-dimensional (3D) seismic edge detection attributes for the identification of faults and stratigraphic boundaries, there has been an increased interest in how best to use the various seismic attributes available to the interpreter. A useful technique has been implemented for combining attributes into displays for enhanced 3D seismic interpretation. The multi-attribute technique is based on the intensity, hue and saturation (IHS) description of color. Using the IHS properties of color to combine different attributes of 3D seismic data into a single display greatly advances our ability to interpret the vast volumes of data contained within a 3D seismic data set. Different seismic attributes are mapped to different color properties. For example, edge detection attributes can be mapped to intensity and amplitude mapped to hue. The resulting multi-attribute cube is composed of unique color values that contain the information from both the edge detection and amplitude data. Seismic attributes that are suitable for mapping to intensity include edge defection and dip azimuth attributes. Seismic attributes suitable for mapping to hue include seismic amplitude, instantaneous phase and rms amplitude. The multi-attribute technique can be used to make a number of key attribute combinations that can be used at different stages in the interpretation work process. Combinations of instantaneous phase and dip azimuth enable rapid appraisal of structural form; instantaneous phase and edge detection multi-attribute cubes are powerful tools for structural framework interpretation; amplitude or rms amplitude and edge detection combinations can be used for reservoir mapping and stratigraphic analysis. Edge detection technology using displays of attribute combinations enables rapid and high-resolution evaluation of 3D seismic data at all stages of exploration and exploitation of reservoirs.

Buried late Quaternary channel systems in the Danish North Sea – Genesis and geological evolution

This study comprises two parts intended to improve understanding of the lower and middle Miocene depositional history of the New Jersey continental shelf. The first, lower Miocene-based part, aims to determine lateral variations in lithofacies between holes drilled by IODP Expedition 313 using seismic attributes and artificial neural networks. The second provides detailed seismic sequence stratigraphy of mid-Miocene successions. Neural networks are used in the first part to search for a relationship between seismic attributes and gamma log measurements of the lower Miocene section. Using this relationship, the networks generate 'pseudo gamma logs' that predict lateral changes in lithofacies based on accompanying changes in seismic attributes. A successful test of the technique is demonstrated using 3D seismic data and 6 closely-spaced gamma raylogs from the Denver Basin. A similar application to lower Miocene successions offshore NJ is unsuccessful, most likely due to an insufficient number of wells, complexity of lithofacies variations between wells up to 12 km apart, and/or an incorrect selection of attributes. In the second part, candidate sequence boundaries are identified in a grid of high- resolution, densely spaced profiles. In addition to a more detailed history than derived from prior studies, this part reveals previously unreported records of sediment erosion and possible global climate influence on the middle Miocene stratigraphic evolution offshore New Jersey. Eleven candidate sequence boundaries, three not documented by previous studies, are identified. System tract positions of each sequence are determined, while only one transgressive system tract and no lowstand fans are observed. Age estimates based on published studies show that the 11 mid Miocene sequences reported here span the interval between ~11.8-12.9 Ma, suggesting an average interval between each of 100 kyr. Clinoform rollovers prograded SE during the development of the oldest sequence of the study area beginning at a time that coincides with a major shift in !18O towards heavier values (represented by Mi4) and at about the time of the permanent East Antarctic ice sheet development. Grain size distribution of the prograding clinoforms is predicted by extrapolating IODP Expedition 313’s lithostratigraphic analysis of lower Miocene succession.

An Upper Cretaceous carbonate reservoir, onshore oil field in Abu Dhabi is characterized by its vigorous surface topography and subsurface complex structural setting. The studied reservoir is a highly fractured elongated anticline trending NE-SW. Fracture occurrence and distribution have influenced the reservoir performance in terms of oil production and water cut from the field. Seismic attributes integrated with well log data and well performance have provided a good understanding of the lineament/fracture distribution within the reservoir. In addition, this integration enhanced the Full Field Development Plan (FFDP) optimization in terms of well placement and reservoir performance to avoid early water break through (EWBT) due to fractures. 3D seismic data was acquired with high fold and wide azimuth over the field in 2007. The 3D seismic data was processed in 2008 with some processing issues. In 2012, new algorithms were applied over a pilot area in order to resolve the processing issues and to preserve relative true amplitude for further reservoir characterization purposes. The pilot products have better identified short falls in the 2008 processed data. Seismic attributes were analyzed and the interpreted lineaments/fractures distribution will help better understand fracture orientation and their impact on oil production and water cut for full field development. The Seismic attributes successfully captured additional information and guided the well planning to avoid the highly lineament/fractured area. In addition, the new identified fracture system provides essential information for the ongoing and future development plans for this field. This 3D seismic input for fracture detection and well trajectories optimization resulted in better well performance and delay of water production especially in mid flank wells. The preliminary results of the attribute extraction at the reservoir targets are encouraging and new 3D seismic reprocessing data is considered a potential solution for the quantitative seismic interpretation and the reservoir characterization which achieved optimum well locations and orientation in this complicated onshore field.

Seismic sedimentology of lacustrine delta-fed turbidite systems: Implications for paleoenvironment reconstruction and reservoir prediction

Summary High quality 3D seismic data over a large UAE field combined with high-end geophysical techniques resulted in spectacular porosity detail from seismic data over this carbonate field. By using special post stack filtering techniques to improve data continuity and discontinuity, two optimal data sets were generated. One data volume was optimized for structure and stratigraphic interpretation and the other for event mapping and quantitative seismic attribute analysis. A multi-attribute calibration method was used to estimate the porosity from the seismic data. Attributes used include seismic and geologic or interpretative attributes. The result was a porosity prediction that was 20% improved over the traditional single attribute approach, as measured on hidden well data. The predicted porosity volume provided high quality detail of reservoir heterogeneity and was very useful in understanding flood front advance in the platform interior and flow patterns in the clinoforms. In addition, the seismic porosity volume provides a means to place future wells to tap by-passed oil and to optimize the location of planned injector and producer zones. Introduction Seismic data is often used as a means to estimate rock properties between well controls. A typical method is to calibrate seismic attribute information with rock properties, such as porosity, from well log information. The seismic attribute data can then be transformed using the calibration function into an estimate of rock properties. In our study a multi-attribute neural network calibration is used to produce a 3D volume of rock property predictions from the seismic data (Hampson 2001).This seismic-scale rock property volume is then used to place new wells in favorable locations or in building geologic models for reserve estimation and/or reservoir simulation. Geologic Setting The study field is located in Abu Dhabi within the United Arab Emirates. The field is positioned over a low relief doubly plunging anticline that is oriented N-NE. The reservoir interval is comprised of a low relief, prograding carbonate platform. The main producing interval is in the Lower Cretaceous. The complex stratal architecture is driven largely by the longer-term (second-order) accommodation history. The field is characterized by significantly different stratal geometries that are clearly imaged by the enhanced 3D seismic. The northern part of the field is characterized by strong basinward progradation that occurs in the late highstand and falling-stage systems tracts. Clinoforms exhibit spatial variability in geometry, composition and texture that significantly impact reservoir geometry and quality. The southern part of the field is characterized by aggradational platform facies that show variations in stacking patterns and composition keyed to position in the sequence-stratigraphic hierarchy. Most notably, strong aggradation during the highstand sequence set, coupled with proliferation of rudist "reef" builders, resulted in development of a complex system of moderate relief, higher-energy rudistid shoals (moderate to high reservoir quality). These shoals are separated by low relief, restricted lagoonal "ponds" that are filled largely with low-energy, mud-prone facies (low reservoir quality).

espanolLa demanda de energia aumenta a diario ya que la poblacion mundial esta aumentando, por lo tanto, es necesario identifcar perspectivas nuevas u omitidas en otros para satisfacer estas necesidades. El campo "KOA" se encuentra en tierra frme en el Delta del Niger, Nigeria. Esta cuenca se compone de tres formaciones; La Formacion Akata (roca fuente), las unidades de arena / lutita en la Formacion Agbada (los reservorios y sellos), la falla en la Formacion Agbada proporciono vias para la migracion del petroleo y formaron trampas estructurales y estratigrafcas, y la Formacion Benin (unidad de arena). En este trabajo, se aplicaron atributos sismicos con el objetivo de mejorar la imagen de las estructuras para mejorar la interpretacion estructural y la identifcacion de nuevas perspectivas. Se encontraron nueve arenas de yacimientos y se encontro que eran lateralmente continuas a traves del campo. El analisis petrofisico de las arenas de yacimientos identifcadas mostro que la porosidad efectiva promedio vario de 13.3 a 24.9%, la permeabilidad promedio vario de 38.4 a 3340.6 md y la saturacion promedio de hidrocarburos vario de 61.8 a 93.0%. Los atributos de volumen sismico se aplicaron a los datos sismicos 3D para mejorar la imagen de fallas. La interpretacion de fallas y el mapeo del horizonte se llevaron a cabo para generar mapas estructurales que fueron analizados en busca de cierres capaces de atrapar acumulaciones de hidrocarburos. La interpretacion estructural revelo fallas sinteticas, fallas antiteticas y una falla crestal. Los horizontes que correspondian a la parte superior de los pozos de las arenas de yacimientos mas viables en el campo se cartografaron despues del pozo a la union sismica. Los mapas de atributos de superfcie se generaron a partir de los mapas de estructura, esto se hizo con el fn de identifcar areas con acumulaciones de hidrocarburos que fueran conformes a las estructuras. Se identifcaron tres prospectos (P1, P2 y P3) y un cliente potencial. El analisis volumetrico revelo que las perspectivas P1, P2 y P3 contenian 161.49, 271.79 y 128.79 mil barriles de petroleo, respectivamente. El estudio concluyo que la aplicacion de analisis de atributos sismicos mejoro signifcativamente las imagenes y la interpretacion de las estructuras, lo que fue util en la identifcacion de nuevas perspectivas en el area de estudio. EnglishThe demand for energy increases daily since the world’s population is increasing, therefore there is a need to identify new or by-passed prospects in other to meet these needs. The “KOA” feld is located onshore Niger Delta, Nigeria. This basin is made up of three formations; Akata Formation (source rock), the sand/shale units in the Agbada Formation (the reservoirs and seals), the faulting in the Agbada Formation provided pathways for petroleum migration and formed structural and stratigraphic traps, and Benin Formation (sand unit). In this work, seismic attributes were applied with the aim of enhancing the imaging of structures for improved structural interpretation and new prospects identifcation. Nine reservoir sands were encountered and found to be laterally continuous across the feld. Petrophysical analysis of the identifed reservoir sands showed that the average efective porosity ranged from 13.3 to 24.9%, average permeability ranged from 38.4 to 3340.6 md and average hydrocarbon saturation ranged from 61.8 to 93.0%. Seismic volume attributes were applied to the 3D seismic data to enhance the imaging of faults. Fault interpretation and horizon mapping were carried out to generate structural maps which were analyzed for closures capable of trapping hydrocarbon accumulations. Structural interpretation revealed synthetic faults, antithetic faults and a crestal fault. Horizons that corresponded to the well tops of the most viable reservoir sands in the feld were mapped after well to seismic tie. Surface attribute maps were generated from the structure maps, this was done in order to identify areas with hydrocarbon accumulations which were conformable to structures. Three prospects (P1, P2 and P3) and a lead were identifed. Volumetric analysis revealed that prospects P1, P2 and P3 contained 161.49, 271.79 and 128.79 thousand barrels of oil respectively. The study concluded that the application of seismic attribute analyses signifcantly improved the imaging and interpretation of structures which was useful in the identifcation of new prospects in the study area.