Geological Concepts Research Articles

Three-Dimensional Subsurface Model of Luk-Ulo Melange Complex, Karangsambung, Indonesia: Insights from Gravity Modeling

The Luk-Ulo Melange Complex (LMC) is characterized by a chaotic assemblage of mixed rocks with a block-in-matrix fabric. The exposed blocks consist of various scattered rock types, trending in an ENE-WSW direction. In the case of Mt. Parang, the origin of the diabase remains uncertain, with ongoing debate as to whether it is associated with in situ volcanic activity or represents an exotic block within the melange deposit. Subsurface data obtained through geophysical investigation can aid in modeling the geometry of intrusive bodies using inverse modeling techniques. In this study, we conducted a gravity survey and performed 3D inverse modeling to investigate the subsurface beneath Karangsambung. A total of 818 gravity data points and 28 rock density measurements were integrated with existing geological data to construct an a priori 3D geological model. To ensure the results align with geological concepts, the 3D inversion utilized a stochastic approach, allowing for the incorporation of multiple geological constraints over fifty million iterative procedures. Ultimately, the inversion successfully reduced the misfit between observed and calculated data from 2.71 to 0.55 mGal. Based on the inverted 3D model, the diabase rock in Mt. Parang is identified as having an intrusive origin. The intrusion model exhibited minimal changes in density, volume, and shape during the inversion process. Additionally, the model suggests the presence of a solidified magma reservoir at a depth of approximately 3 km, potentially related to Dakah volcanism. The inverted model also reveals the block-in-matrix structure of the Luk-Ulo Melange Complex in the northern area.

Field geology under the sea with a remotely operated vehicle: Mona Rift, Puerto Rico

We implemented concepts of field geology at great ocean depths by constructing virtual outcrops from a string of overlapping video frames collected by remotely operated vehicles (ROVs). This lower-cost alternative to drilling boreholes allows stratigraphic extension into the offshore and regional interpretation of marine seismic profiles. The imagery was collected along a dive transect on the western wall of Mona Rift, a deep and narrow rift northwest of Puerto Rico, between water depths of 1560 m and 3927 m. The northern coast of Puerto Rico and its large offshore area are underlain by a mid-Eocene and younger forearc basin topped by a thick carbonate platform. There are no drill holes offshore, and tying seismic lines across the shoreline there is problematic. We describe our virtual outcrop and constrain its age and stratigraphy using seven rock samples collected by ROV and compare the outcrop’s stratigraphy to deep boreholes and outcrops on land. Our formation descriptions and ages agree, for the most part, with those on land, but we identified a 100-m-thick section that is represented on land by an unconformity. Our stratigraphic interpretation indicates lateral variations in formation thicknesses and establishes a cross-section for additional sampling of the Eocene–Pliocene geology. It also suggests that Mona Rift has formed since the mid-Pliocene. The presence or absence of ferromanganese (Fe-Mn) crust on rocks along the transect may be correlated with the smoothness of the rock surface.

‘Welcome to the Anthropocene’

The geological concept ‘the Anthropocene’ circulates widely outside Earth System Science – in museum communities, public culture, social sciences, and amongst social science and humanities scholars, artists, activists and public historians too. It is an evident idea for public historians today working with environmental history to engage with a concept that successfully and popularly bridges academic and public interests. This article discusses the concept of the Anthropocene within public environmental history’s historiography and brings in Dipesh Chakrabarty’s influential discussions from the academic field of history and theory about the non-synchronous temporalities geological time and historical time. The article categorizes public environmental history’s methodological approaches since the field emerged in the 1990s, revealing the important concepts being landscapes, human-nature interactions, climate change, sustainability and the Anthropocene. It concludes that the Anthropocene is a concept that can further develop public environmental history but that it also a paradox to the field potentially affecting a core idea in public history – relationships to publics. This has to do with temporal implications of the concept: it squeezes the temporality of memory important to public history and humans out of view; it imposes an extremely slow and long chronological time that is unfamiliar if not foreign to ordinary people to perceive of; it carries with it the idea about a future without humans and other species of today.

Potencial petrolífero remanescente do Brasil - Estado da arte 2023

Petroleum and its byproducts will continue to be humankind’s primary energy source for at least 50 years. Brazil is already one of the main suppliers of this raw material and will continue as such for the next decades. Several large sedimentary basins in Brazil are practically untouched by exploration, especially in the deep and ultra-deep water realms. There are also large tracts of unexplored areas in basins that already have discoveries, reserves and hydrocarbon production. The objective of this work is to make predictions about the remaining petroleum potential of the Brazilian basins. The predictions are made based on the big data bank acquired by the petroleum industry in Brazil in the last 83 years, based on the most updated concepts in petroleum geology, and mainly on my 45 years of experience as an explorationist. Our final forecast for the remaining petroleum potential of Brazil lies in the range of 50-100 billion barrels of oil equivalent recoverable (boer) (prospective resources, already identified or not, but still needed to be discovered). The basins that will contribute the most to realizing this potential are Santos/Campos, Pará-Maranhão/Foz do Amazonas/Barreirinhas, Pelotas and Paraná; besides, in a lesser scale, but still significant, Sergipe-Alagoas, Espírito Santo, Camamu-Almada, Solimões and Parnaiba. We are perfectly aware that Geology is a complex and astounding science. New data, innovative new technologies and creative concepts never formulated can quickly destroy these predictions, for better or worse.

The triassic formations of Kuwait: From geological concepts to numerical forward stratigraphic modelling applications

The Triassic exploration campaign onshore Kuwait initiated during the 1980s was mainly based on the evaluation of regional 2D seismic data. To date, few scattered wells have penetrated this succession reaching the Minjur, Jilh and Sudair mixed clastic and carbonate formations. The latter reservoirs are expected to hold potential gas and condensates that are yet to be proven. This communication aims at deciphering the spatial and temporal evolution of sedimentary architectures and associated Triassic depositional environments and facies along Kuwait. An integrated G&G assessment utilizing multi-disciplinary and multi-scale dataset allowed to identify the major petroleum system elements and develop sequential conceptual depositional models. The proposed models are then tested using numerical process-based forward stratigraphic applications. The seismic interpretation points to dominantly south to north oriented progradations centered on the Dibdibah low with thicknesses reaching around 1300 ft in the Sudair. In addition, progradations oriented from East to West highlight the location of the basin margins around the Kuwait Arch and its northern extension. These prograding tendencies are also identified in the overlying Jilh Formation. Onlapping reflectors point to transgressional systems related to flooding events that are expected to deposit marine fine-grained carbonatesand thus act as potential seals. Minjur Formation on the other hand, shows thick siliciclastic deposits along the southern sector of the Kuwait Arch. These fluvio-deltaic deposits are 150 feet thick and thin towards the west. Stratigraphic modelling allowed to test and constrain the paleobathymetric evolution of the system. The latter ranges between 0 and 20 m (inner ramp) and 20–40 m (Middle ramp) and reaches up to 80 m in the deeper sectors of the basin. The resultant facies at 3rd- 4th stratigraphic order highlights the evolution of lithologies and facies with regards to the various system tracts leading to a better understanding of the timing and spatial extent of mixed carbonate systems, evaporites and siliciclastics. Future works will focus on a higher resolution mapping of geobodies and prospects using integrated shared earth approaches including seismic multi-attribute assessment and 3D inversion and characterization driven by novel artificial intelligence workflows.

The geological footprint of plastics

The significant impact of plastics on Earth's environments has transformed from being a symbol of modern innovation to a major ecological concern. This perspective paper explores the integration of plastics into geological contexts, emphasizing their role in contemporary sedimentary processes. It examines the lifecycle of plastics, from production to disposal, and their subsequent interaction with natural sedimentary cycles. The production and usage of plastics have led to considerable environmental repercussions. One of these, is their incorporation into geological systems and the formation of novel geological materials. Such a phenomenon challenges traditional geological concepts and necessitates a multidisciplinary approach encompassing geology, chemistry, and environmental science.

Quantitative prediction methods and applications of digital ore deposit models

With the depletion of surface mineral deposits, attention has shifted to deep mineral exploration prospecting. The emergence of three-dimensional digital ore deposit models, facilitated by the advancement of computer technology, has transformed traditional two-dimensional geological models into computer-recognizable numerical-symbolic digital models. This transformation allows qualitative geological concepts, originally expressed in natural language, to be quantitatively expressed, thereby enhancing the accuracy of deep mineral exploration. This paper first outlines the development from traditional ore deposit models to digital ore deposit models, asserting that digital ore deposit models can encompass a more comprehensive array of multidisciplinary geological information, including mineralogy, ore deposit types, structural geology, geochemistry, and geophysics. Building upon digital ore deposit models, a three-dimensional geological model is constructed, combining regional metallogenic regularities, identifying ore-forming favorable information, and conducting quantitative extraction. Subsequently, a comprehensive prospecting model is established, followed by the integration of deep learning methods for deep-seated mineral exploration, forming a unified system of quantitative prospecting methodology for hidden mineral deposits under the framework of geological prospecting models, three-dimensional geological modeling, and three-dimensional quantitative prospecting. Finally, using the Zaozigou gold deposit in Gansu Province as a case study, this approach is applied to mineral exploration prospecting, delineating prospective target areas and providing valuable reference for future exploration efforts.

Improving Reservoir Characterization and Prediction Via Machine Learning-Driven Integration of Subseismic Geologic Concepts, Geophysical Attributes, and Wells

Summary Reservoir dynamic performance is affected by subseismic (below the resolution of seismic imaging) geologic features such as submeter thin barriers and baffles, or high-permeability streaks. Here, we present an application of machine learning that has the potential to improve and significantly accelerate the workflow for generating reservoir realizations and scenarios with relevant subseismic features consistent with both well-log and 3D/4D seismic data and/or attributes. We leverage unsupervised machine learning methods, in particular, a modification of diffusion probabilistic modeling (DPM).

Warstwy czasu i antropocen. Metafory geologiczne w pamięcioznawstwie

The article describes the use of geological metaphors in humanistic and social memory studies. It shows how geological concepts are used in contemporary research and theoretical reflection on memory: what phenomena and processes they describe, how their use in a distant scientific discipline is justified, and how comparisons are made between the meaning of a given term in geology and its meaning in memory studies. The considerations are illustrated with the example of two metaphors: sediments of time and the Anthropocene.

Supporting Student Learning and Understanding of Geoscience Using Virtual Reality and Video Demonstrations

We examined the impact of geoscience demonstration and virtual reality field trip videos on student assessment confidence, performance, and their overall attitudes towards learning geology using a mixed methods sequential explanatory design. Participants were 111 undergraduate students enrolled in an introductory geology course in one of four consecutive semester offerings. Repeated for 13 videos, students would watch a video of a demonstration or virtual field trip and answer select-response questions. Then during a later exam students answered questions specifically associated with the video content while also rating their answer confidence using a ten-point scale. Open-ended student comments were collected from a four-question survey at the end of each semester. Findings of student responses to four of the videos suggest that the use of the demonstration videos and virtual reality field trips had a positive impact on student learning of geological concepts. Qualitative findings affirmed the voice and personalization principles of the Cognitive Theory of Multimedia Learning.

DETERMINATION OF OPTIMAL OBSERVATION NETWORK PARAMETERS FOR MAPPING PALEOCHANNEL BY THE ELECTRICAL RESISTIVITY TOMOGRAPHY METHOD BASED ON NUMERICAL AND PHYSICAL MODELING

Link for citation: Osipova P.S., Olenchenko V.V., Chekryzhov A.V. Determination of optimal observation network parameters for mapping paleochannel by the electrical resistivity tomography method based on numerical and physical modeling. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 10, рр. 232-242. In Rus. The relevance of the study is explained by the need to determine the methodological features of applying the electrical resistivity tomography method to map paleochannels when prospecting for placer gold. The main aim: to determine the necessary and enough parameters of the observation network for paleochannel mapping based on numerical and physical modeling. Object: electrical fields on the physical and numerical model of the paleochannel. Methods: electrical resistivity tomography, physical experiment, numerical simulation. Results. Electrical soundings by electrical tomography were carried out on a physical model of a river valley. In addition, a numerical experiment was performed on a three-dimensional model of a river valley fragment with a paleochannel. The unit of the survey scale is the distance between two electrodes, which in the experiment is 1 cm and is equivalent to 5 m in real field studies. The distance between the profiles varied from 2 to 12 cm with a step of 2 cm, which corresponds to different survey scales. In accordance with geological concepts, the authors formed a model of a river valley with a segmentally gently stage of channel formation. Three-dimensional inversion was carried out for the data set obtained at the maximum density of the observation network, and then for the data sparse to the desired scale. On the resistivity map, the paleochannel is recognized by a ribbon-shaped high-resistivity anomaly. The analysis of the maps showed that to determine the shape of the paleochannel in plan, it is necessary to use the observation network scale of 1:3000, at which the distance between the profiles is 30 m. The physical experiment results were confirmed by mathematical modeling. The scale should be reduced to 1:5000 with detailing in individual areas to improve the economic efficiency of geophysical research.

Assessment of Knowledge and Learning Difficulties in Metamorphism Among Future Teachers

The present research focuses on evaluating the knowledge and learning difficulties in metamorphism among future teachers. To address our issue, we selected a sample from students at the Ecole Normale Supérieure de Marrakech and employed a questionnaire as our investigative tool. The obtained results indicate that students face learning problems in metamorphism. These difficulties arise in understanding certain key concepts of metamorphism, such as metamorphic facies and migmatite. We also observed that students struggle to establish connections between metamorphism and other geological phenomena. These learning difficulties can be attributed to language barriers, didactic transposition, the persistence of certain misconceptions, and the discipline itself, such as problems in comprehending geological space and time. This research could aid university professors in understanding these difficulties and in designing teaching scenarios that would help students better grasp geological concepts.

Using Indigenous research frameworks to enhance connections between Traditional Knowledge and Western science at Acoma Pueblo, NM

A day-long geoscience educational module, “Sharing and Learning: The Natural Environments of Acoma Pueblo,” provided an opportunity to explore the various connections that Acoma Pueblo community members make between their cultural values and geologic concepts. The purpose of such an exploration is to make explicit the cultural understandings of the geologic environment that bring meaning to the Western scientific knowledge, for both future Acoma Pueblo community members and other Indigenous scholars. A mixed-methods approach [sequential transformative design] was used to collect quantitative and qualitative data during the project concerning participants’ sense of place and perception of geoscience concepts in relation to Acoma Pueblo cultural values. Indigenous research frameworks informed the analysis of the datasets and provided opportunities during the module for Western science to enhance the Indigenous knowledge system celebrated within the Acoma Pueblo community. In this article, we focus on the analysis of the qualitative portion of the larger mixed-methods study. The qualitative data analysis of a group interview after implementation of the Sharing/Learning program distinguished six primary themes: Traditional Knowledge, Western Geoscience, Education, Stories, Natural Resources, and Geoconnections that persisted throughout the group interview. Results from the study support the idea that a brief intervention which presented geoscientific information alongside Traditional Knowledge did have an impact, with newly recognized “geoconnections” as evidence. Furthermore, engaging Indigenous communities through connections between culture and geoscience has the potential to foster respectful relationships between academic researchers and Indigenous community members, especially when research practices are informed by Indigenous research frameworks. These respectful relationships are the foundation for authentic future research collaborations between Indigenous and non-Indigenous Peoples.

Introducing conceptual geological information into Bayesian tomographic imaging

AbstractGeological process models typically simulate a range of dynamic processes to evolve a base topography into a final two‐dimensional cross section or three‐dimensional geological scenario. In principle, process parameters may be updated to better align with observed geophysical or geological data. However, it is hard to find any process model realisations that fit all observations if data sets are complex and sparse in space or time because the simulations typically depend highly non‐linearly on base topography and dynamic parameters. As an alternative, geophysical probabilistic tomographic methods may be used to estimate the family of models of a target subsurface structure that are consistent both with information obtained from previous experiments and with new data (the Bayesian posterior probability distribution). However, this family seldom embodies geologically reasonable images. Here we show that the posterior distribution of tomographic images obtained from travel time data can be fully geological by injecting geological prior information into Bayesian inference and that we can do this near‐instantaneously by using trained mixture density networks (MDNs). We invoke two geological concepts as prior information about the possible depositional environment of an imaged target structure: a braided river system and a set of marine parasequences. Each concept is parameterised by the latent parameters of a generative adversarial network. Data from a target structure can then be used to infer the family of compatible latent parameter values using either geological concept using MDNs. Our near‐instantaneous MDN solutions closely resemble those found using relatively expensive Monte Carlo methods. We show that while the use of incorrect geological conceptual models provides significantly less accurate results, a classifier neural network can infer which geological conceptual model is most consistent with the data. It is thus demonstrated that even apparently barely related geophysical data may contain information about abstract geological concepts, and that geological conceptual models are key to creating reasonable images from geophysical data.

Uncertainty Analysis of Reservoir Static Modelling: A Case Study of KMJ Oil Field

This case study explains the uncertainty of Original Oil in Place (OOIP) calculations in reservoir static modeling of KMJ Oil Field. This field consists of 4 (four) wells in an area of ± 600 acres with high heterogeneity, so in building a 3D Model, it is necessary to analyze the sensitivity and uncertainty of geological concepts, calculations of petrophysical properties, and fluid contact. The OOIP calculation uses a probabilistic method and determines reserves related to field development. The uncertainty analysis study begins by identifying the parameters with the most significant influence (Sensitivity Analysis) in calculating OOIP in the static reservoir model. To determine the ranking of reservoir uncertainty parameters, several geological, geophysical, and petrophysical factors in building a static model must be tested according to the method used in each parameter. The OOIP calculation in the static model is calculated into three scenario categories, namely low estimate (P10), base estimate (P50), and high estimate (P90). The combination of determining facies (shale volume) porosity, fluid contact, and the cut-off is a variable/parameter that is very influential in volumetric multi-scenario calculations (probabilistic method) in the KMJ Oil Field. The results of the uncertainty analysis of the KMJ Oil Field have a low OOIP estimate (P10) of 10.86 MMSTB, a base estimate (P50) of 11.49 MMSTB, and a high estimate (P90) of 12.01 MMSTB. Furthermore, the static model used for reservoir simulation (dynamic model) in the KMJ Oil Field is the base estimate model (P50) of 11.49 MMSTB.

Peculiarities of the total content of metals in oil deposits of the Dnipro-Donetsk depression

Purpose. To establish the peculiarities of the total content of metals in oil deposits of the Dnipro-Donetsk depression and to develop a classification of deposits by this indicator. Methodology. The factual basis of the research was the results of analyzes of metals in oil from 36 deposits of the Dnipro-Donetsk depression. With the help of X-ray fluorescent analysis, at least 30 oil samples from each deposit for metals content were investigated. The deposits are selected according to the principles of maximum completeness of geochemical information, their finding in different oil and gas areas of the Dnipro-Donetsk depression, different composition of the oil system, different geological types of traps, different structure of deposits and different ages of oil collectors. X-ray fluorescent analysis was performed on the energy-dispersive spectrometer "SPRUT" SEF 01. The time of accumulation of the spectrum 600 sec. Preparation and analysis were carried out according to the standard of ASTM D 4927 - "Determination of the elemental composition of components of lubricants by X-ray fluorescent spectroscopy with dispersion by wavelength". Correlation and regression analysis was carried out by methods that were implemented in the most popular professional statistical software platforms "Statistica" and "SPSS" and their analysis in geological concepts. Findigs. To evaluate the central characteristics of the total content of metals in oil, the deposits considered more correctly use not the arithmetic mean, but the median. It is proved that the total content of metals in oil considered is associated with a reverse correlation connection with resin content, the values of the modern temperature of the productive horizon, the modern depth of productive horizon, the mineralization productive horizons; and direct correlation with the concentrations of nickel, manganese, mercury, chromium, vanadium, aluminum, cobalt, zinc, iron, paraffin, asphalt, sulfur and oil viscos boiling and oil density. Scientific novelty. It consists in the development of the natural classification of oil deposits by the overall content of metals, and to establish a connection of this indicator with the concentration of individual elements of impurities, the main components of oil and the main geological and technological indicators of deposits of the Dnipro-Donetsk depression. Practical significance. Is to establish the concentrations and the possibility of forecasting the total content of metals in the Dnipro-Donetsk depression, which in turn provides the opportunity to solve the topical problems of practical direction. The solution of a number of industrial-raw materials based on the assessment of oil as an ore raw material, since the content of some elements in them sometimes exceeds ore concentrations, so there is a possibility of their concomitant industrial removal from by-products during processing processes. The solution of technological issues, which are caused by the negative impact of some elements contained in oil, on the geological environment, production technologies and the equipment used in the course of their extraction and processing.

Characteristics of subvolcanic intrusion: a case study at Tempel Hill, Kalisonggo, Girimulyo, Kulonprogo, Yogyakarta

The genesis of Mount Tempel which is part of Mount Mujil is still being debated by some geologists discussing the Kulon Progo Mountains. The surface and subsurface measurements must be done to know a geological aspect that building the area around Mt. Mujil, precisely in Tempel Hill on the northeast side of Mt. Mujil, Girimulyo, Kulonprogo, Yogyakarta. The geology of this location is still a mystery and has always been a hot topic regarding origins, geotourism, and disasters. The general problem in this study is related to the occurrence of the northeast side of Mt. Mujil which is still not final and much debated, so it is necessary to approach the concept of volcanic geology to help answer these problems. The purpose of this study was to identify the physical characteristics of igneous rocks in Tempel Hill based on surface and subsurface data. The approach method is carried out through geological mapping, geophysical resistivity measurements, and petrological, petrographic and geochemical analysis. The results of the petrological analysis show that the igneous rock has a porphyroafanite – microcrystalline texture without a flow texture, some scoria – massive structures, geochemically it shows that calc – alkali refers to subduction products. On the other hand, resistivity analysis shows the presence of volcanic rocks with density values and resistivity values of intrusive rocks and volcanic breccia in the vicinity. Indications of the presence of volcanic rocks with an area the size of Tempel Hill are defined as magma fossils or subvolcanic intrusion rock bodies. Tempel Hill has potentially for tourist attractions that can improve the welfare of local residents.

Application of CCUS in India: Designing a CO2 EOR and storage pilot in a mature field

Numerous mature oil and gas reservoirs around the world, along with added financial benefit, present a tremendous benefit of CO2 EOR and storage, especially in the regions where tax benefits and policies related to the CCS is limited. This work presents the first effort of CO2 EOR and storage in a mature oil field in India through a comprehensive application of laboratory study, reservoir static modeling, dynamic simulation, pilot design, and techno-economic sensitivity analyses. Through this case study, the technical feasibility of CO2 EOR and associated storage was assured for the first time through a novel approach of combining various subsurface and surface data with laboratory analyses. Almost no analog was available for CCUS on the same-age rock from a young thrust belt setting. The various vintages of core to seismic scale data posed a great challenge for effective integration. The solution approach to these issues included combining flow physics, fluid chemistry, geological concepts and digital modeling with practical engineering data analyses. Temporal change of oil composition in this reservoir due to the long production history had created some challenges for determination of CO2 miscibility. It was estimated through the lab study and modeling that the miscibility can be achieved near 3000 psi due to its altered oil composition resulted by years of production. To arrest the reservoir pressure decline, a pre-EOR water injection was identified as an immediately need to re-pressurize the reservoir and achieve miscibility of injected CO2. Comprehensive analysis of various subsurface and surface data integrating geoscience and engineering techniques have allowed for a consistent and applicable 3D description of reservoir, which was critical to identify suitable areas with appropriate remaining oil saturation, chemistry, and reservoir pressure. The history matching-calibrated-simulation model was utilized to evaluate the performance of various development scenarios of the identified area. Specifically, CO2 injection in a sector of geological model was performed using Todd-Longstaff miscible flood scheme. Upon comparing the proposed scenarios, a CO2 injection pilot in Pattern-1 was identified, with one injector and three producers over ∼60 acres area. This pilot uses 150 Metric Ton/day (MT/D) of CO2 captured and processed from an existing facility and transported about 70 km to the field location. The CO2 will be injected continuously into this pilot area for 5 years, and the well switches back to water injection afterward. Around 1.1 MMSTB incremental oil will be recovered in next 10 years, corresponding to 11.7% of OOIP in the flooded area. Up to 268,275 MT of CO2 will be sequestered in the reservoir. The learnings from this first ever study of its kind in India set the benchmark for data analysis, integration, and case specific approaches. The success and knowledge base from this endeavor will tremendously help and encourage further expansion of CCUS activities in India.

Rapid flow diagnostics for prototyping of reservoir concepts and models for subsurface CO2 storage

Sketch-based interface and modelling is an approach to reservoir modelling that allows rapid and intuitive creation of 3D reservoir models to test and evaluate geological concepts and hypotheses and thus explore the impact of geological uncertainty on reservoir behaviour. A key advantage of such modelling is the quick creation and quantitative evaluation of reservoir model prototypes. Flow diagnostics capture key aspects of reservoir flow behaviour under simplified physical conditions that enable the rapid solution of the governing equations, and are essential for such quantitative evaluation. In this paper, we demonstrate a novel and highly efficient implementation of a flow diagnostics framework, illustrated with applications to geological storage of CO2. Our implementation permits ‘on-the-fly’ estimation of the key reservoir properties that control CO2 migration and storage during the active injection period when viscous forces dominate. The results substantially improve the efficiency of traditional reservoir modelling and simulation workflows by highlighting key reservoir uncertainties that need to be evaluated in subsequent full-physics reservoir simulations that account for the complex interplay of viscous, gravity, and capillary forces.The methods are implemented in the open-source Rapid Reservoir Modelling software, which includes a simple to use graphical user interface with no steep learning curve. We present proof-of-concept studies of the new flow diagnostics implementation to investigate the CO2 storage potential of sketched 3D models of shallow marine sandstone tongues and deep water slope channels.

Improved Understanding of Minor Reservoirs Optimizes Full-Field Productivity

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 21225, “Defining Heterogeneity and Compartmentalization Predictions of Minor Reservoirs in Fluvial Environments: Geological and Dynamic Context,” by Nur Azah Zulkifli, Lisa C. Chisholm, and Amy M.M. Yusoff, Petronas, et al. The paper has not been peer reviewed. Copyright 2021 International Petroleum Technology Conference. Reproduced by permission. _ Reservoirs in the MN field offshore Malaysia consist of predominantly fluvial delta deposits. Several modeling studies have been performed for major reservoirs. After more than 20 years of production, a project for minor reservoirs has been created. The primary objective of this study was to improve the understanding of the uncertainties affecting well performance and reservoir connectivity and to identify potential infill opportunities. Introduction From the initial analysis of a 2017 full-field review (FFR), the team decided that a detailed subsurface evaluation was necessary. This study was completed with the integration of subsurface data to ensure that hydrocarbon volume and geological knowledge have been calibrated with production performance. The field is 160 km north-northeast offshore peninsular Malaysia in a water depth of 69 m. This field is divided into five areas: Main, West, North, South, and Southwest. The depositional environment of this field is fluvial coastal plain and consists of multistacked oil and gas reservoirs with an average net thickness of 2–20 m, interbedded with shale and coal in a coastal plain setting. Geological Concept and Overview Reservoir X is one of 26 major and minor hydrocarbon-bearing units in the field. Twenty-two minor reservoirs were analyzed for the FFR with an integrated study work flow. Geological analysis concluded that these reservoirs were deposited in a fluvial environment consisting of meandering channels, point bars, overbanks, and abandoned channel-sand mouth bars with deltaic influence (Fig. 1). Seismic data have been used extensively to tackle key uncertainties with either quantitative or qualitative approaches, depending on the seismic detectability limit of the reservoir. The use of seismic in this case was challenging because seismic attributes are not optimal and mostly are used as soft data guided by primary well data. Additionally, several reservoirs required stratigraphic compartmentalization to be introduced. Heterogeneities in the Fluvial Environment Capturing and preserving the different level of heterogeneities was complex because of varied data resolution, grid definitions, and hierarchies of impact. This field has relatively large net-to-gross (NTG) ranges from 20 to 98% with individual channel width averaging from 20 to 100 m. Because the existing dynamic models struggled to replicate field performance, the model created in this study had limited predictive capabilities. The four levels of fluvial heterogeneities of megascopic, mesoscopic, macroscopic, and microscopic scales were used to better understand the heterogeneities of these minor reservoirs. This has helped to compartmentalize the reservoir based on interpretation of the dynamic data without compromising geological understanding.