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EAGE Workshop on Quantitative Geoscience as a Catalyst in a Carbon Neutral World
- Conference date: May 31 - June 1, 2022
- Location: Kuala Lumpur, Malaysia
- Published: 31 May 2022
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Embedding Thermodynamics Within Rock Physics Modelling for CO2 Injection
Authors M. Paydayesh and M. BabaeiSummaryWe employed fluid thermodynamics and the equation of state to calculation of the speed of sound and density of fluid mixture in the complex fluid system. Using this technique, the predictability of rock physics modelling, and subsequent seismic modelling are significantly improved. The choice of equation of state is dependent on its predictability of available experimental data, and its calculation stability for the mixture of interest. The technique is embedded within the rock physics model for carbon capture and enhanced oil recovery studies where the feasibility of the seismic monitoring is studied.
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Hydrocarbon Pre-Drilling Prediction based on Seismic using Unsupervised Learning: Example from Malaysian Basin Field
Authors L. Alif Syahputra, M. Hermana, A.H.A. Latiff, M.F. Abdurrachman and M.H.R. PutraSummaryDuring the pre-drilling phase of hydrocarbon exploration, only seismic data is available for study to determine the presence of hydrocarbon. Currently, to identify potential hydrocarbons, amplitude interpretation often used. However, because of the complexity of structures and lithologies, there is a great deal of ambiguity or difficulty in interpreting the amplitude resulting failed well drilling is a typical occurrence that has been documented throughout the world. The amplitude traps become the most significant variables in influencing the inability to estimate the hydrocarbon location accurately. The proposed method aims to address the issue of hydrocarbon discovery during the pre-drilling stage. Self-Organizing Maps has been offered as an unsupervised learning technique for examining the objective in this proposed method. The algorithm uses a combination of pre-stack seismic features to distinguish between non-hydrocarbon and hydrocarbon prospective areas. Self-Organizing Maps can detect potential anomalies that point to the presence of hydrocarbon without training to detect potential hydrocarbon, which makes it suited for this phase because no unlabeled data or prior information is available. The suggested method is evaluated using Marmousi2 model and both well and seismic data from many fields in the Malaysian basin, and it is demonstrating excellent performance and a promising result.
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Where are My Injected Gasses? Feasibility Workflows for Effective Seismic Monitoring of Reservoirs Injected with CO2
Authors A. Mur, F. Sinclair Smith and W. HarbertSummaryA feasibility workflow for seismic quantitative analysis using synthetic seismic forward modeling along with the Vernik-Kachanov rock physics model realized for CO2 injection scenarios, calibrated on representative carbonate and siliciclastic reservoirs.
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A Monte Carlo Dropout Based Deep Learning Model to Quantify Uncertainty in Facies Classification
Authors T.M. Hossain, M. Hermana, M. Sandra Jaya and S. JadidSummaryBy measuring the parameter uncertainty of the deep neural net. weights and biases by adding an additional Monte Carlo Dropout layer, the proposed Monte Carlo Dropout based Deep Neural Net. quantifies the uncertainty in the process of facies classification using seismic data and outputs a better classification than the traditional Deep Learning model.
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Full Waveform Seismic Imaging: Drastically Reducing the Project Lifecycle
Authors T. Rayment, A. Azmi, J. McLeman and K. DancerSummaryFull waveform inversion (FWI) is a well-established tool for velocity model building as part of a conventional seismic processing and imaging workflow. However, recent advances in multi-parameter FWI have shown the technique is able to estimate many parameters, including reflectivity. This FWI imaging approach uses the raw field data as input and requires little to no processing effort. It uses the parts of the wavefield (primaries, multiples and ghosts) that are typically removed from the data during a conventional workflow to generate high-resolution images of the subsurface. The reduction in processing effort means the FWI imaging approach is primarily constrained only by compute and it is therefore possible to generate results in a fraction of the time compared to legacy methods. These higher resolution images generated in a shorter timeframe allow for better decision making and reduce risk.
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How Geophysics Can Become a Key differentiator for a Field Development Plan with Limited Data
Authors C.L. Lai, R. Alai, A. Fahmi Abdullah, R. Sutattyo Djumeno, A. Mokhtar, K.C. Goh and M. ChooSummaryB field is an HP carbonate gas field with limited data; a single exploration well and a legacy 3D seismic data. This field is challenging not only due to limited data availability but also from geological perspective. The field is overlain by an over-pressure shale inducing a very low velocity, thus leads to high depth uncertainty and drilling risk. A tight layer is observed within the carbonate that potential acts as barrier between upper and lower zone. Seismic reflectivity within the carbonate is distorted leading to inaccurate reservoir properties simulation. Thus, to develop this field with its current available data, it is crucial to have a good understanding and application on utilizing on these data. The science behind seismic processing and QI have greatly improved over the last decade. Therefore, it is sensible to revisit on the seismic data. The results from the seismic reprocessing and QI studies are great and it is worthy as minimal budget was spent. Decision making on development well was relatively easy with well defined sweet spot and drilling risk is minimized.
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CO₂ Prediction in Offshore Sarawak Basin Through Petroleum System Modelling Approach
Authors A. Kumar, Z.Z. Tuan Harith, S.C. Kurniawan, J. Hoesni, M.S. Firdauz, N. Faradilla, P. Gou, A. Fakrudin, P. Chenet, M. Dubille, S. Granet and G. Perez DragoSummaryHigh contaminant gas fields always associated with potentially high corrosion risk to the topside facilities and pipelines including increase in project economics taking into consideration full separation technologies to be deployed to these fields. In fact, at exploration-development stage, gas fields’ operators find difficulties to estimate the content of contaminants in their undrilled prospects for their better-informed decision making strategy. As such, latest techniques of estimating the content of contaminants at undrilled prospects of gas assets to provide a better understanding to operators on their assets’ risks prior to any further development strategy
The basin model help improved the understanding on nature of CO2 (i.e. source, generation, migration etc.) and allowed for concentration and risk map to be developed to further identify the next low CO2 concentration risk exploration area. It was possible to define the uncertainty range on the CO2 concentration in all identified undrilled structures.
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The Importance of Geohistory for SGR Threshold Calibration; A Case Study from Sarawak & Sabah Basins
Authors H. Ismail, H. Mohamad, S. Sulaiman Mustahim, L. Mei Lu and S. SherkatiSummaryAnalysis of 470 drilled wells in Sarawak and Sabah basins- Malaysia; shows 41.87% of failures are related to seal and trap effectiveness. Sand against shale juxtaposition along fault plan is the primary mechanism of sealing ( Allan 1989 & Knipe et al 1997 ). However, fault rocks seal which get entrained in the faulting process can also act as a secondary sealing mechanism when sand juxtapose sand ( Fristad et al 1997 , Yielding et al 1997 & Yielding 2002 ). Shale Gouge Ratio (SGR) is a quantitative parameter that was first introduced to predict fault seal capacity by Fristad et al 1997 and Yielding et al 1997 . Later based on compilation of fault related seal and leak observations for the North Sea, Yielding (2002) presented the SGR minimum threshold required to have an effective seal. He also established an empirical relationship between SGR and across fault pressure difference which later incorporated buoyancy pressure data ( Bretan et al., 2003 ). These data and relationships have been incorporated and it is calibrated to the North Sea. We have now conducted SGR calibration for Sarawak & Sabah more accurately reflect the risk in fault dependent traps and probable range of HC column in these basins.
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Optimizing the Use of Structure-Guided 3D CSEM Inversion to Characterize Fractured/Karsted Carbonates in Offshore North-West Borneo
More LessSummaryFractured and/or karsted carbonates (FKC) are commonly associated with reservoir effectiveness and is useful in the study for carbon dioxide storage sites. We have performed a 3D seismic guided CSEM inversion to map boundaries of carbonate and identify fractures and karstification of carbonates. The resistivity results matched the resistivity well log from a nearby well satisfactorily, providing geological justification to interpret the presence of karst features in the resistivity volumes. Lateral boundary of the carbonate prospects was mapped based on resistivity characteristic. Resistivity slices of the models clearly demonstrated that the areal distribution of low and high resistive zones can be mapped and useful deductions such as the presence of fractures and karsts. From this study we have demonstrated the usefulness of integrating seismic and CSEM quantitatively for FKC mapping which helps understand porosity better in carbonates contributing positively to carbon dioxide storage studies.
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Application and Interpretation of AVO for NFE and Infills
By W.D. GanSummaryProblem Statement - in mature asset the potential of low hanging fruit (a.k.a big structure) was already fully tested, what’s left to test are the more challenging smaller traps whose success must highly be dependent on presence of good reservoir and prolific HC charge - is our data able to see it? Can AVO offer a fresh perspective? In this paper, we will discuss about the application of AVO, a well-established theory to best detect anomalously porous and friable rocks (Good quality sandstone). We’ve built a comprehensive calibrated approach to visualize AVO and screen for remaining potentials. Promising leads are identified, but at the same time new puzzles are created. We’ll share some examples of these from our observation, can our current understanding of geology and rock physics offer us with a plausible explanation to these puzzles? Let’s Investigate these hypotheses.
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Optimized Seismic-Guided Low-Carbon Footprint 3D Marine Magnetotelluric Imaging of Complex Fold-Thrust Belt in NW Borneo, Malaysia
Authors A.S. Saleh, M. Meju, S. Shahar and S. KumarSummary3D magnetotelluric (MT) imaging offers potential as a cost-effective, relatively low carbon footprint solution to imaging subsurface for new energy exploration, such as geothermal ( Soyer et al., 2018 ). In this paper, we studied several practical aspects of seismic-guided marine MT inversion to improve them. Firstly, we establish the suitable regularization weights based on a suite of synthetic inversion tests. Secondly, we compare the use of structure tensors derived from anisotropic pre-stack depth migration (APSDM) reflectivity, high-fidelity full-waveform inversion (FWI) velocity and acoustic impedance inversion volumes to guide cross-gradient anisotropic resistivity inversion with initial half-space resistivity starting models. Thirdly, we determine post-facto the optimum structure tensor weights using well logs as the ground truth. We found that utilizing initial model built using horizon-based interpolated resistivity logs from multiple wells and seismic FWI velocity as guide gave the best match to well logs as compared to a model which used standard smoothness constraint only. For new frontier exploration areas with inadequate well control, our study suggests that the structure tensor from APSDM reflectivity data will be the preferred structural guide since the APSDM reflectivity data have well-defined structural information.
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Challenges and Opportunities in Selecting Depleted or Saline Aquifers as CO2 Sequestration Site
More LessSummaryThis paper discusses the challenges in selecting CO2 sequestration site - which can be broadly characterized into 2 categories - Depleted fields and Saline Aquifers. Both categories have their own advantages and disadvantages. The paper include the discussion on the criteria used to evaluate them and the learnings gathered during the process.
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Gas Hydrates Qualitative Seismic Attributes Mapping in Deep Water Sabah
Authors H. Mohamed, G.H. Liew and N.F. Ahmad SharifSummaryMethane gas hydrates as unconventional hydrocarbon exploitation has been discussed for more than a decade as energy-dense gas resource. Their abundance in nature means that methane hydrates represent one of the largest known unconventional energy sources, and a much cleaner alternative to crude oil or coal ( You et al., 2020 ). However, exploitation of this resource is highly debated as high drilling risk due to seafloor stability and unstable composition at different pressure. Mechanism of methane hydrates formation in Geological Systems studied by You, et al (2019) has categorize natural gas hydrates occurrences into five types based on their physical and geological environments ( Fig.1 ). Lee, et al (2001) performed quantitative analysis of concentration gas hydrate with well elastic logs has shown reduction of porosity with increase of gas hydrates concentration can be correlates with seismic amplitude response. Surface geochemistry study result in Deep Water Sabah confirmed presence of Methane gas hydrates from soil sample and gas chromograph correspond to amplitude seismic at several prospect locations. Study of their physical occurrence intent to assist on understanding of their presence as drilling hazard and/or as potential hydrocarbon seal.
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Geoscience Challenges and Opportunities Associated with Trapping Mechanism in CO2 Sequestration Projects in Malay Basin, Malaysia
More LessSummaryCarbon Capture and Storage (CCS) can help Malaysia meet its carbon dioxide equivalent (CO2e) reduction commitment cost-effectively. However, there are challenges in the geologic mapping of the storage capacity. In the Malay basin, promising candidates for CCS are both to-be-depleted fields and saline aquifers. To store CO2 in geologic formations and abundant reservoirs require robust subsurface understandings and specific geoscience knowledge which can help in safeguarding the value of CCS by identifying effective trapping containment, finding prolific reservoirs, and designing a Measurement, Monitoring, and Validating (MMV) plan. The challenges for CCS subsurface assessment include data availability and quality, lack of regional comprehensive study as well as a quantitative estimate of storage capacity. This paper will not only discuss these challenges with specific examples but also bring insight into several opportunities and a way forward to transform the challenges into opportunities for CCS potentials in the Malay Basin. With the focus on combining the quantitative estimates of geological subsurface CO2 retention and surface CO2 leakage, the results suggest that geological storage of CO2 can be a secure carbon-neutral option, but we note that the long-term behavior of CO2 in the subsurface remains a key uncertainty.
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Using Inversion to predict the CO2 distribution in West Luconia, Sarawak
Authors F. Amiruzan, M.S. Sams, S.N.W. Jamil and M.A. M AriffSummaryThe application of the Inversion methodology enhanced the confidence level of mapping the CO2 presence in Cycle V of West Luconia area. This allows for better risk assessment on CO2 presence in this area, however, predicting the saturation of CO2 content is remain a challenge.
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3D Petrophysical Modeling and Volumetric Estimation of Major Reservoirs of the Maui Gas Field, New Zealand
Authors N.A. Siddiqui and A.K.M.E. HaqueSummaryMaui Gas field is one of the most important gas/condensate fields in the Southern Taranaki Basin (STB). Maui Gas Field includes an area of about 150 square kilometres and represents one of the largest hydrocarbon accumulations in the New Zealand peninsula with average total production rate of ∼3600 bcf of gas and 190 mmbbl oil / condensate[1–2]. Mangahewa Formation was interpreted to have porosity range (12–19%) with higher intergranular permeability (∼100–500mD) whereas Farewell Formation contained slightly higher porosity within the range of 11–20% with lower permeability ranging from ∼40–90mD. The petrophysical modeling used a modified workflow for better volumetric estimation which gave a improved recovery factor of the major reservoirs of the Maui Gas Field.
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Geostatistical Seismic Inversion Derived Integrated Reservoir Connectivity Analysis to Maximize Secondary Oil Recovery
Authors I. Abdullah, S. Rajput and W.A.S. W IsmailSummaryThe past two years placed the oil and gas industry at an inflection point and many international companies reframed their purpose while responding to the current economic discontinuities. However, the quest to supply energy to the growing demand while competing as the world transitions to a low-carbon future has become the core focus. In this scenario, the Oil and gas industry is searching for the answers to four very important questions:
- How to understand the reservoir connectivity and spatial distribution to maximize oil recovery?
- How to improve returns from mature assets?
- How to mitigate the risk of declining new giant discoveries?
- How to operate efficiently in a Volatile, Uncertain, Complex, and Ambiguous (VUCA) world.
The first two questions are interrelated with each other as increasing production leads to more revenue generation which improves the returns from mature fields. This paper addresses the first two questions.
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Geomechanics Approach to Quantify Subsurface Uncertainties and Risks of Water Injection in Marginal Deepwater Development
Authors N. Muslim, Z. Johar and I.H. IdrisSummaryDeveloping marginal deepwater offshore Sabah remains an insurmountable challenge for major operators due to its regional geology formed along fold thrust belt that are heavily deformed by many thrusts faults and folds. Thin interbedded reservoirs prove to be challenging for deepwater development program due to the volume and therefore, water injection has been selected as the most effective Improved Oil Recovery (IOR) method to sweep the recoverable oil in place for the Field Development Plan (FDP) monetization. To increase the propensity of water injection operation to succeed, quantifying subsurface uncertainties and risks analysis pertaining to geoscience interpretation is the key. There aren’t any branches that is more relevant to address this challenge other than Geomechanics, the study of rocks mechanical behaviors in response to Earth’s pressure and stresses. Understanding the criticality of Geomechanical inputs into water injection design (matrix injection) and its operation is crucial since the opposite comes at the cost of risking the caprock seal breach and well integrity. The question this paper is trying to address is to quantify the uncertainties of water injection from Geomechanics perspective by establishing safe pressure threshold of injection.
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