High-resolution Sequence Stratigraphy Research Articles

High resolution Sequence Stratigraphy of Baikouquan Formation in Mahu Sag, the Junggar Basin

High resolution Sequence Stratigraphy of Baikouquan Formation in Mahu Sag, the Junggar Basin

High-resolution sequence stratigraphy of the Maastrichtian-Paleocene succession in the Sokoto Basin

High-resolution sequence stratigraphy of the Maastrichtian-Paleocene succession in the Sokoto Basin

Constructing high-resolution stratigraphic frameworks by the application of signal analysis techniques: Example of Balbuena IV sequence, Yacoraite formation, Salta Basin

One of the most essential and valuable applications of high-resolution sequence stratigraphy is reservoir zonation and characterization. Establishing a hierarchical chronostratigraphic framework comprising sequences at multiple scales is crucial to identify main reservoir heterogeneities that compartmentalize the fluid flow in the subsurface. In this context, this paper proposes a workflow that integrates different signal analysis techniques to identify sequences of multiple hierarchies from a series of stratigraphic data. The Continuous Wavelet Transform (CWT), Detrend Error Log (DTEL), and Integrated Detrend Error Log (INDTEL) techniques are utilized to process gamma-ray data obtained from outcrops of the Yacoraite Formation, which are conventionally employed as analogs for reservoir characterization. Our results suggest that CWT fits better with higher frequency cycles, while INDTEL shows a good fit with medium frequency cycles. In addition to these techniques, Hidden Markov Models were also applied, predicting T-R cycles as hidden states from the facies transition matrix and possible occurrence of missed beats. All these methods were scripted in the Python programming language, enabling the generation of fast and interactive outputs. This approach brings parameters that can guide the construction of stratigraphic models by automated processes.

High-resolution sequence stratigraphy of clastic shelves IX: Methods for recognizing maximum flooding conditions in shallow-marine settings

Maximum flooding conditions in high-frequency sequences are associated with a condensed section, a generally cryptic maximum flooding surface, and with facies contacts marked by grain size changes, shell beds and bioturbation; i.e., the downlap surface and the local flooding surface. Conditions of maximum water depth usually occur above the condensed section, in the early highstand systems tract. Due to its importance in sequence stratigraphic analysis, the identification of the precise position of the maximum flooding surface, which separates the transgressive and highstand systems tracts, is critical. This is particularly true in high-resolution studies based on field and core data, where only facies contacts that are older and younger than the maximum flooding surface are recognizable. An integration of several criteria, including sedimentological (facies analysis), diagenetic, micropaleontological, geophysical and geochemical, represents the best approach to define a relatively thin uncertainty interval within high-frequency sequences, in which the cryptic MFS should lie. Among the available criteria, those sedimentological and diagenetic are the ones best suited to recognize facies contacts, whereas those micropaleontological are the most reliable ones to identify the position of the maximum flooding surface. Future studies on the integration of these methods with those geophysical and geochemical have the potential to improve the ability to identify the maximum flooding surface, and improve the available tools in the high-resolution sequence stratigraphic analysis.

High resolution sequence stratigraphy of the Mishrif Formation (Cenomanian-Early Turonian) at zubair oilfield (al-rafdhiah dome), southern Iraq

The Mishrif Formation (Cenomanian -E Turonian) is one of the most important geological formations in the Middle East and Iraq because it contains enormous petroleum accumulations. It is considered to be the first reservoir in the region, and is still being studied because of its economic significance. The carbonate of the Mishrif Formation derives from a variety of depositional settings, including mid-ramp, shoal, lagoon, and intertidal. The five main microfacies discussed in this paper are wackestone, packstone, grainstone, floatstone, and bindstone. The most frequent fossilised components found in the Mishrif Formation are rudists, benthic foraminifera, echinoderms, burrows molluscs, and algae. According to the microfacies and analysed wireline log data, the sequence stratigraphy of the studied formation is composed of two regression cycles. Five parasequences of transgressive–regressive cycles make up the depositional sequence of the Mishrif Formation. The standard depositional environments seem to demonstrate a gradual regression, beginning with a short period of the outer ramp, then a steady period of the mid-ramp, and ending in the intertidal environment. Additionally, the study recorded two regional maximum flooding surfaces: K-135 and K-140. The former is present in the lowermost part of the formation, while the other lies in the middle. This study shows a close relationship between facies (environments) and hydrocarbon accumulation. The increased accumulation focuses on the lower part of the studied formation, and seems to be lower in the upper part of the formation as a result of changes in the environment of deposition.

Reconstruction of Tournaisian-Viséan tectonic and climatically induced event histories of the Mobarak carbonate platform along depositional strike in the northeastern margin of Gondwana: Constraints from high-resolution cycle and sequence stratigraphy

Cyclic successions are one of the most important types of deposits in the carbonate platform of the Mississippian (Tournaisian-Viséan) in Gondwanan and Laurussian margins. The importance of climatically induced events impact on the amplitudes and frequencies of sea-level fluctuations in Mississippian of Iran is significant because the beginning, extent, duration, and significance of periods of climatically induced events in northern margin of Gondwana are not well recognized. A high-resolution sequence architecture in integration with paleoenvironmental reconstruction and foraminiferal biozonation from the Tournaisian-early Visean carbonate successions of the Mobarak Formation in Alborz basin along depositional strike (E-W- a distance of c. 340 km) suggests a mosaic-like pattern of deposition and compartmentalization of the depositional settings (homocline ramp to distally steepened ramp). According to the recognized facies, the stacking pattern of high-frequency cycles across the platform, and major accommodation events recognized on the correlated Fischer plots, six 3rd-order sequences (DS1–DS6) were identified. Detailed analysis on high-frequency cycles representing a highly variable number of shallowing-upward cycles, types, thicknesses, and facies heterogeneity along depositional strike. A combination of the episodic tectonic events along faults interacting with autocyclic processes, and inherited topographic irregularities are suggested as the driving mechanism for the cycle development. Six stages of Mobarak carbonate platform evolution based on understand the interplay of autocyclic and allocyclic controls are recognized in a hierarchical 3rd-order sequence stratigraphic framework and a chronological order: (1) early Hastarian corresponds to post-glacial transgressive episode with progressive backstepping of facies belts of early TST of DS1 throughout the region; (2) middle to late Hastarian corresponds to a major transgressional phase of DS1 following global temperature rise superimposed on different subsidence/uplift rates with the deformation of the platform along depositional strike; (3) Hastarian–Ivorian boundary corresponds to TST of DS2 with facies heterogeneity along depositional strike related to continuation of different subsidence/uplift rates. The absence of any systematic changes in the amplitude and period of cyclicity or lowstand deposits and subaerial surfaces during this phase shows the lack of influence of mid-Tournaisian glaciation and concurrent eustatic regression in northern margin of Gondwana. (4) early to middle Ivorian coincides with the RST of DS2 and TST of DS3 showing by remarkable topographic irregularities in the basin physiography and change in the position of the depocenter axis from a E–W trend to the center; (5) late Ivorian-early Moliniacian coincides with the RST of DS3 and DS4 showing by the Late Tournaisian thermal period and eustatic rise superimposed on uplift and subaerial exposure of the western part and subsidence in the central and eastern parts of the basin; (6) Moliniacian coincides with DS5-DS6 sequences showing by change from fault-related topography to major tilted fault-block topography accompanied by eustatic sea-level fall caused indirectly by the Viséan and Serpukhovian glaciations phases.

Application of Seismic Stratigraphic Slice Continuous Browsing Technology to Delicately Characterize River Sedimentary Microfacies

On the basis of understanding the regional tectonics characteristics and stratigraphic sedimentary characteristics of the study area, the sequence stratigraphic framework within the region is gradually studied by applying the principle of high-resolution sequence stratigraphy, and G4 oil formation is divided into three sets of sand formations, namely, G4 upper, G4 middle, and G4 lower sand formations, and divided into small layers in detail. Through comprehensive analysis of lithofacies, logging facies, and seismic facies, the sedimentary facies of the G4 oil formation are comprehensively analyzed. The main sedimentary facies type of the G4 oil formation is the delta front facies belt, and the most important sedimentary microfacies in the delta front facies belt are underwater distributary channel sedimentary microfacies. Using seismic sedimentology methods, make stratigraphic slices of each sub layer of the G4 oil formation, and use the rapid browsing method of stratigraphic slices to trace river sand in detail.

High-Resolution Sequence Stratigraphy of the Mauddud Formation Southern Iraq

Inner ramp carbonate and dolomitic limestone made up the late Albian Mauddud reservoir in Iraq. An age estimate for the Mauddud Formation is late Albian to early Cenomanian, with it overlying the Nahr-Umr Formation and underlying the Ahmadi Formation. The integration of microfacies with wireline logging data to predict the high resolution of the sequence stratigraphy framework. The microfacies description included more than 150 thin sections that covered the study area in southern Iraq. That results in five main microfacies. There are divided into eleven submicrofacies, as a result, for the microfacies, the depositional environment is gradual, from mid-ramp to shallow open marine, shoal-restricted lagoon. The study divided the formation into four orders of sequence stratigraphy: MSL1, MSL2, MSL3, and MSL4. The study includes identifying the maximum flooding surface (K110), which is identified as the original transgression in sea level that covered Arabian Plate. MSL1 represents the lower part of formation and evidence of environmental change to shall the marine environment with argillaceous limestone. The maximum flooding surface (K110) is signifying the deepest depositional environment (mid-ramp). Also, the study marked three marine flooding surfaces by changes as increased gamma ray and density logs values, whilst the highstand system reflects decreasing in logs values, This change was used in conjunction with microfacies data to construct the sedimentological environments that led to the documentation of the Mauddud high-resolution sequence stratigraphy framework.

Disentangling orbital, sub-orbital, and tectonic signatures from lacustrine sediments developed upon a half-graben (Lake Ifrah Basin, Northwest Africa): Insights into lowest-rank T-R sequences in low accommodation basins

Lacustrine settings constitute a unique environment that preserves detailed expressions of allocyclic signals such as those of climate and tectonics. Possible decryption of these signatures stems from careful scrutiny of the sedimentation dynamics (temporary base-level variations), lake-level fluctuations (accommodation), and resulting strata bounding surfaces that are used to build a conventional sequence stratigraphic framework. However, due to discrepancies between marine, to which this approach has been initially dedicated, and lacustrine settings (especially regarding the physical scale), deciphering climate from tectonic forcing becomes unwieldy in such interior basins. The present work deals with this challenge and provides insights from a case study where lacustrine sedimentation occurs on a tectonically active half-graben within a key climate region (Lake Ifrah, Northwest Africa). We conducted conventional sedimentological and high-resolution sequence-stratigraphic analyses, integrated with palaeolimnological proxies (geochemical elements and ostracod species). Up to five facies models (accounting for lithological domination, wind-driven energy, and lake-level state) and three lowest rank T-R sequences, deposited since the Marine Isotope Stage-3 (MIS-3), have been identified. Periods with sustained high lake levels appear to be mainly precession-paced (as during MIS-3 and the Early Holocene), although the role of obliquity is shown to influence the hydrological budget as well. Furthermore, sedimentation dynamics are shown to respond to millennial timescale climate variability associated with North Atlantic cooling events (Dansgaard-Oeschger stadials, Heinrich Events) and, interestingly, to enhanced Saharan winds during the deglacial period. On the other hand, tectonism had a rather instantaneous effect on lake level and sedimentation. Two tectonic pulses marking instantaneous differential hanging-wall subsidence have triggered a sharp drop in relative lake level, hence conditioning a forced regression.We highlight the importance of the conventional high-resolution sequence stratigraphy in shaping our understanding of the cyclic interplay between orbital/sub-orbital and tectonic forcings, so as the resulting sedimentation dynamics and lake-level cycles in lacustrine settings. We stress the role of the forced regression concept and associated systems tract and bounding surfaces, as well as the importance of using ostracods and geochemical proxies to trace transgressions and cryptic surfaces with sequence-stratigraphic significance, such as the maximum flooding surface, in lacustrine settings.

High-resolution sequence stratigraphy applied to reservoir characterization of the Brazilian Cretaceous pre-salt section, Campos Basin: Guidelines for geological modeling and reservoir management

The giant accumulations in the pre-salt section of the Brazilian sedimentary basins stand out among the recent world discoveries of oil and gas provinces. The purpose of this case study was to provide inputs to refined 3D geological modeling and reservoir management by characterizing a pre-salt reservoir in the Marlim and Voador fields in the Campos Basin using high-resolution sequence-stratigraphic methodology. This methodology was strong enough to combine different data types, such as seismic and well data, into a high-resolution chronostratigraphic framework. The investigation classified the geological record of the reservoir within a sequence-stratigraphic framework with at least five hierarchies. The 1st- and 2nd-order sequences relate to distinct phases of the Basin's tectonic evolution. Sequences of carbonate lake sedimentation within the post-rift tectonic configuration, where the reservoir is found, were attributed to multiscale transgressive-regressive (T-R) cyclicity. Lake T-R cycles observed in any hierarchical setting are generally governed by faciological tendencies that determine petrophysical features. Regressive tracts produce a more significant proportion of facies with high porosity, whereas transgressive tracts produce facies with reduced porosity. The proposed detailed stratigraphic zoning satisfactorily explains the depletion behavior of the reservoir, revealing that high-resolution sequences condition the fluid flow. Several recommendations for 3D geological modeling, development planning, and reservoir management are made based on these results. The detail highlighted in this study is fundamental in searching for additional oil reserves, production factors, and final recovery.

High resolution sequence stratigraphy of Lower Cretaceous rocks of the Jaisalmer Basin

High resolution sequence stratigraphy is a useful tool to understand the nature of reservoirs and dispersal patterns in relation to the genesis of these clastic reservoirs. Such analyses are performed by integrating the geophysical (electrolog and seismic) and geological (core and sedimentological) data. This study enables us to understand the nature of reservoirs in the 2nd order Lower to Upper Cretaceous sediments of the Jaisalmer Basin, by configuring it into further higher orders (3rd/4th order). The analysis results in identification of ten depositional facies deposited in the lowstand system tract, the transgressive system tract and the high stand system tract. The log based interpretationswere carried out to identify the 4th order sequences; visual gamma log interpretation supported with CWT indicates eight to nine higher order parasequences within the Pariwar Formation. Similarly, seven higher order sequences were identified within Lower Goru and four in Upper Goru and Parh formations. These identified parasequences will help in petroleum system modelling of the Jaisalmer Basin.

High-resolution sequence stratigraphy of complex gas reservoirs: Patao and Dragon fields, offshore Venezuela

The stratigraphic complexity of near-shore depositional systems, together with the occurrence of submarine mass-failure deposits in the area of the Patao and Dragon fields, represents a challenge for devising a development plan for the gas reservoirs identified in the area. The high drilling costs in offshore areas and the sparse knowledge in this frontier basin require an integration of all available data to optimize the development of production projects. This work aims to refine the geological model, particularly with respect to understanding the complexity of the sedimentary deposits in this area and its impact on the exploitation of the associated reservoirs. The Patao and Dragon fields belong to the Carupano Basin, offshore northeastern Venezuela, and contain hydrocarbon accumulations mostly trapped in late Miocene and early Pliocene clastic reservoirs. Existing well data in the area are still relatively scarce, but provide valuable calibration of the available seismic data. This study involves the construction of a sequence stratigraphic framework, based on the integration of sedimentological and petrophysical studies, vertical proportion curves of lithofacies (VPC), seismic-stratigraphic interpretation, petro-acoustic characterization, and reservoir analysis, which enable the identification of stratigraphic units and the correlation between wells. Seven systems tracts have been identified, including the FSST3 (falling-stage systems tract 3) and TST3 (transgressive systems tract 3) which host the most prolific gas reservoirs in the area, comprised of coalescent sands with distinctive rocks properties. There is evidence that the FSST3 is affected by syn-depositional submarine mass movement that distorted the sedimentary architecture and the internal structure of the deposits. These considerations, as well as the identification of potential permeability barriers associated with marine flooding surfaces, allowed the establishment of different scenarios of hydraulic unit configuration, key for the evaluation of these gas reservoirs in terms of their storage capacity and subsequent production.

High-resolution sequence stratigraphy applied to turbidites: The case study of jurassic los molles formation, Neuquén basin, Argentina

High-Resolution Sequence Stratigraphy is fundamental for attaining a refined and representative geological 3D model for oil and gas reservoirs. For its application on turbidite systems it is essential to have a robust facies and facies association framework, recognizing architectural elements and the cyclicity in different frequencies on the stacking pattern. This study is widely based on a multi-scale approach (4th and 5th orders), integrating satellite image, outcrop descriptions and microscopic data to achieve a predictive depositional model through time. The Jurassic Los Molles Formation, Neuquén Basin, was chosen as a case study due to its outcrop quality of offshore shelf (Carreri section) and slope/basin plain settings (La Jardinera section). This enabled a rich comparison between facies associations, architectural elements, stacking patterns and cyclicity on turbidite systems of different palaeo physiographic settings. The Carreri offshore shelf turbidites display higher confinement with predominance of tractive structures and coarser grain-sizes as opposed to deepwater deposits. Their base level variations are recorded by the stacking of turbidite channel-overbank systems to delta front deposits and tidal bars that culminate important regressions. In contrast, in La Jardinera slope and basin plain succession, the falling stage system tract of turbidite sequences is characterized by amalgamated composed lobes and wide composed channels with coarser grain-sizes and erosive contacts. The lowstand system tract is represented by less amalgamated lobes and interlobes, suggesting the system backstepping until the muddy transgressive system tract. The workflow of this study allows a better understanding of the evolution of a sedimentary system, correlating this to important stratigraphic surfaces that can represent fluid flow barriers and reservoir heterogeneities that could impact on production data. High resolution sequence stratigraphy, especially in turbidite systems, is key for more accurate reserve estimates and for developing predictive and economic exploration and production strategies in the petroleum industry.

Identification of maximum flooding surfaces at different scales: The case of the Piacenzian to Gelasian Cutro Clay and Strongoli Sandstone (Crotone Basin, southern Italy)

The Piacenzian to Gelasian deep- to shallow-marine succession cropping out in the NE part of the Crotone Basin, southern Italy, is ideal for applying integrated sedimentological and micropaleontological criteria to recognize cryptic surfaces of sequence stratigraphic significance, such as the maximum flooding surface (MFS), and other surfaces devoid of physical expression, such as the maximum water-depth surface (MWDS). The micropaleontological criteria consist in the calculation of parameters such as the % fragmentation of benthic foraminifera, the ratio between distal and proximal benthic foraminifera, and the plankton/benthos ratio. In any sequence, the offset between the lowest values of % fragmentation and the highest values of the distal/proximal ratio defines a relatively thin uncertainty interval in which the MFS should lie. Moreover, the MWDS is inferred to correspond to the peak of the plankton/benthos ratio, which may coincide with the MFS or it may be slightly above it. Notably, the method allows to recognize MFSs and MWDSs of different hierarchical ranks, and therefore it is effective in the study of sequences of any scale, including modern studies of high-resolution sequence stratigraphy.

Facies sedimentology, high-resolution sequence stratigraphy, and depositional environment in the Imini Triassic basin (southern High Atlas of Marrakech, Morocco)

Facies sedimentology, high-resolution sequence stratigraphy, and depositional environment in the Imini Triassic basin (southern High Atlas of Marrakech, Morocco)

High-resolution sequence stratigraphy and facies assemblage in flood-dominated and mixed deltaic systems: Insights from early Eocene Figols Group, South-central Pyrenean basin

The upper part of the Early Eocene Figols Group cropping out near the town of Tremp (province of Lerida, Spain), is a wonderfully exposed sedimentary succession mainly constituted by mouth bar deposits and delta-front sandstone lobes, forming a fluvio-deltaic system dominated by catastrophic fluvial floods. These deltaic sandstones are vertically associated with carbonate and hybrid (mixed carbonate and siliciclastic) sediments that are physically related to a carbonate ramp platform which crops out in the southernmost part of the study area. The vertical and lateral juxtaposition of these depositional systems allows investigating how the stratigraphic controls (as climate and relative sea level) affect the resulting facies assemblages. The studied succession has been subdivided following a pragmatic physical stratigraphic approach into three 3rd order large-scale depositional sequences (FG2, FG3, and FG4), six 4th order small-scale depositional sequences and 21 EDSs (elementary depositional sequences). The latter are considered the stratigraphic building block of the succession, made of 10s of meter scale forestepping sandstones followed by, backstepping sandstones, bioclastic and mudstone sediments. During the lowstand system tract (LST), the depositional sequences FG2 and FG3 are characterized by the occurrence of flood-dominated deltaic systems (mouth bars and lobes). These deltaic deposits mainly developed in the northern sector characterized by higher subsidence. The overlain transgressive system tract (TST) is dominated by hybrid sediments and carbonates that initially accumulated in the southern zone and then progressively spread out over the entire area. The highstand system tract (HST) is mainly constituted by shelfal fine-grained sediments reflecting the reactivation of the fluvial input and deltaic clastic deposition in a more landward position. This sequential model resulted to be applicable at all hierarchical scales and in particular to the EDS scale. In FG4, the fluvio-deltaic systems became coarser-grained and channelized, the carbonate production on the shelf decreased and lagoonal fines were accumulated so as to separate vertically the fluvio-deltaic bodies. Syn-sedimentary tectonic activity capable to produce local variations of the available accommodation space is inferred by the geometry and facies distribution shown in the high-resolution correlation framework, particularly if considered at the physical scale of EDSs.

High-resolution taphonomy and sequence stratigraphy of internally complex, bakevelliid-dominated coquinas from the Aptian Romualdo Formation, Araripe Basin, NE Brazil

The Aptian Romualdo Formation (Araripe Basin, NE Brazil) was deposited in a restricted epeiric sea, during the opening of the South Atlantic Ocean, with a coeval record to that in the Brazilian Pre-Salt succession. The upper part of the Romualdo Formation encompasses the Highstand Systems Tract of a third-order stratigraphic sequence, and contains shell beds interbedded with shale, siltstone, and fine-grained sandstone. Based on distinct taphonomic features (shell sorting, fragmentation, abrasion, rounding, and orientation), sedimentological criteria (shell abundance, type of matrix, sedimentary structures, and presence/absence of quartz grains), and stratigraphic attributes (bed thickness, geometry, contacts), the paleoenvironmental conditions and the bed-by-bed accumulation history of the coquinas is disentangled. Eight carbonate microfacies were recognized, including ostracod carbonate mudstone, bivalve-gastropod wackestone, gastropod-bivalve packstone, bivalve-gastropod grainstone, bivalve-gastropod floatstone, bivalve-gastropod rudstone, bakevelliid floatstone, and bakevelliid rudstone, which are organized in six, cm-thick shell concentrations. Mudstone and wackestone facies mark the settling of carbonate muds without significant bottom currents and wave action, probably below storm wave base, whereas packstone, floatstone, and rudstone, with fragmented, rounded, and oriented shells, were deposited in agitated waters, between the fair-weather and the storm wave bases. Ripple cross-laminated grainstone is interpreted as high-energy facies deposited above fair-weather wave base. The shell beds are internally complex and consist of cm-scale alternations of microfacies differing in packing, sorting, and composition. They tend to fine upwards within dm-thick shell beds, generating shallowing-upward facies sequences. The concentrations, the uppermost one with in situ bakevelliid shells in the top, record high-frequency base level oscillations influenced by eustasy and climate changes. These bioclastic accumulations originated by the superposition of sedimentologic and primary biologic processes (e.g., post-deposition meiofaunal bioturbation). The cm-thick, low-diversity shell beds are excellent examples of multiple-event carbonate deposits generated in a siliciclastic-dominated, restricted epeiric sea, revealing high-frequency cycles in proximal to distal restricted marine settings.

Geoscience Poster G9: Optimising value in the mature Turrum Field: integrating modern seismic, high-resolution sequence stratigraphy and production data in a 3D geological model

Poster G9 The Turrum Field in the offshore Gippsland Basin has been a significant producing field since first development in 2004 and remains a keystone gas resource for the future as many of the Gippsland assets continue to deplete. The Turrum Field is a faulted anticlinal structure with multiple, stacked, Paleocene-aged fluvial to lagoonal reservoirs that stratigraphically sit below the overlying Marlin Field gas cap. This field was developed in two phases with drilling campaigns in 2004 and 2015 and includes a dedicated platform (Marlin B) for the higher pressure, higher CO2 gas. Leveraging the 2018 reprocessed Northern Margins 3D seismic survey with a modern broadband processing workflow and wider bandwidth and higher signal-to-noise ratio has led to a seismic image with greater resolution and allowed improved reservoir characterisation. The uplift in seismic data together with the colour blending capabilities in GeoTeric®, has led to the seismic identification of large-scale fluvial reservoir systems. These products have been integrated with a revised field-wide sequence stratigraphic framework, petrophysical analysis and incorporated into a full-field 3D geological model of the Turrum Field. The resultant geological model has improved our understanding of reservoir connectivity and will enable rapid integration of production and surveillance data to optimise gas deliverability. This will also provide increased confidence for future field depletion planning including the identification of potential bypassed gas opportunities prior to end of field life. To access the poster click the link on the right. To read the full paper click here

3D Quantitative Prediction of the Groundwater Potential Area-A Case Study of a Simple Geological Structure Aquifer.

The Ordos Basin is a sedimentary basin located in Inner Mongolia, China, where coal and uranium coexist. Water inrush disasters have always been one of the main disasters that threaten the safety of coal mine production, and thus, the study and division of groundwater potential regions are of great significance for the prevention of water inrush disasters and in situ leaching of sandstone-type uranium ore. A new method combining truncated Gaussian simulation and sedimentary facies control was established to predict the groundwater potential area. Taking a typical aquifer, the Zhiluo Formation, as an example, based on high-resolution sequence stratigraphy, geophysics, sedimentary geology, and geostatistical theory, the plane distribution of sand bodies was predicted. Furthermore, the relationship between rock porosity and electricity porosity was established to calculate the regional porosity. Combined with truncated Gaussian simulation and facies-controlled modeling methods, a facies-controlled heterogeneous property model was established to analyze the heterogeneous effective porosity of the aquifer in the study area. Groundwater potential areas were quantitatively evaluated by 3D modeling analysis. The results of the evaluated model were verified by actual data and provide a geological guarantee for the accurate mining of deep coal and uranium ore. A 3D distributed model of chemical elements, which is meaningful for in situ leaching uranium mining, is expected in future research.

Optimising value in the mature Turrum Field: integrating modern seismic, high-resolution sequence stratigraphy and production data in a 3D geological model

The Turrum Field in the offshore Gippsland Basin has been a significant producing field since first development in 2004 and remains a keystone gas resource for the future as many of the Gippsland assets continue to deplete. The Turrum Field is a faulted anticlinal structure with multiple, stacked, Paleocene-aged fluvial to lagoonal reservoirs that stratigraphically sit below the overlying Marlin Field gas cap. This field was developed in two phases with drilling campaigns in 2004 and 2015 and includes a dedicated platform (Marlin B) for the higher pressure, higher CO2 gas. Leveraging the 2018 reprocessed Northern Margins 3D seismic survey with a modern broadband processing workflow and wider bandwidth and higher signal-to-noise ratio has led to a seismic image with greater resolution and allowed improved reservoir characterisation. The uplift in seismic data together with the colour blending capabilities in GeoTeric®, has led to the seismic identification of large-scale fluvial reservoir systems. These products have been integrated with a revised field-wide sequence stratigraphic framework, petrophysical analysis and incorporated into a full-field 3D geological model of the Turrum Field. The resultant geological model has improved our understanding of reservoir connectivity and will enable rapid integration of production and surveillance data to optimise gas deliverability. This will also provide increased confidence for future field depletion planning including the identification of potential bypassed gas opportunities prior to end of field life.