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EAGE Conference on Reservoir Geoscience
- Conference date: December 3-5, 2018
- Location: Kuala Lumpur, Malaysia
- Published: 03 December 2018
61 - 80 of 87 results
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Full Wavefield Propagation Simulations And The Effects On Elastic Mode Conversion In Strong Heterogeneous Media for Better Multi-Component Processing And Reservoir Characterization
Authors F.S. Dzulkefli, A.R. Ghazali, K. Xin and M.H. Mad ZahirSummaryRecently, PETRONAS has acquire high density rich azimuth OBN multi-component seismic in Bokor field, Offshore Sarawak Malaysia (Ghazali et. al, 2018). It is found that the PP image is much superior compared to the PS image where PS suffers even more strong ‘gas clouds’ effect ( Figure 1 ). The amplitude attenuation in PS image is also worse than PP image. These obtained data are basically opposing to our current understanding on the multicomponent seismic data. Hence, in this paper we are investigate the possible reason on PS scattering and amplitude attenuation seen in the PS image section by modelling the full elastic wavefield using 2nd order finite difference staggered grid scheme with advance HPML technique. This analysis may help in the interpretation of the seismic data to distinguish between the reflections and the multiples for better reservoir characterization and may help in quality control of multicomponent processing.
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A New Approach To Fractured Damage Zone Evaluation Using Wavelet Transform And Variance Attribute
More LessSummaryDetailed evaluation of the faults and fractures has a great importance in evaluation of hydrocarbon prospects before any decision is made. Seismic data is the only type among lots of available data from geological studies to well logs and cores and to reservoir data that can provide a complete image of the subsurface structure.
Therefore, lots of studies has been done to extract information for identifying the damaged zones from these data. Variance is one of the seismic attributes that can reveal information about discontinuities in the seismic cube. However, its capability depends on the input data quality. In this paper, a new approach based on hybrid application of the wavelet transform and variance analysis is presented. The method is applied on three-dimensional seismic survey from Malaysian basin and the results show how this method particularly improves the fracture identification.
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Fast-Track Reservoir Characterisation Using Bayesian Classification At A Mature Gas Field: A Case Study
Authors M.M.B. Sahjamal, P. Juntamat, A. Rachmadi, O. Pakpahan, M. Simatupang, R. Costam and A. FadjarijantoSummarySeismic AVO along with rock physics technology has been widely used specially for hydrocarbon exploration for the past three decades, this technology has been proven to increase the understanding of the uncertainties and reduce the risk of dry wells. In this study we present a rock physics driven reservoir characterization workflow with special emphasis in describing the application of Bayesian classification to deliver a robust approach to understand and predict reservoir characteristics in a mature gas field. Bayesian classification is applied by combining the AI/EI inversion and probability density functions from well data to generate probable and most-likely lithology cubes. The results from Bayesian classification exhibit significantly good correlation with the well data and show good reservoir delineation away from the wells.
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Finely Layered Anisotropic Media Effect On Seismic Reservoir Characterization
Authors A. Babasafari, D. Ghosh, T. Ratnam and A. SalimSummaryAnisotropic terms of elastic wave equations make it much more complicated, that is why usually earth is assumed isotropic. Anisotropy effect arising from shale layers (clastic and also unconventional reservoirs) need to be corrected in seismic imaging as a function of travel time and in seismic reservoir characterization as a function of amplitude. In this study the influence of anisotropy on amplitude variation with offset (AVO) is analyzed. In AVO response, the amplitude changes should be evaluated and determine that how much originates from hydrocarbon and how much is due to anisotropy effect. In order to overcome the plausible misleading of interpretation after seismic simultaneous pre-stack inversion, anisotropy correction on seismic data is carried out. To do so, Backus averaging is performed to predict anisotropic parameters. Afterwards, in different seismic angle stacks, amplitude correction is exerted according to the specified incident angle and estimated Thomsen parameters. The inversion results derived from corrected data reduce the uncertainty of hydrocarbon prediction and leads to far more accurate reserve estimation which in turn positively affects on drilling costs.
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Injectivity Impairment Due To Geochemical Reaction And Its Effect On Laboratory Interpretation
Authors N.Z. Mat Razali, K.A. Mustapha, S. Gödeke, M.A. Abu Bakar, S.S. Md Shah, Z.A. Abu Bakar and S. MisnanSummaryOverestimation and underestimation of injectivity impairment due to salt precipitation and mineral dissolution would risk the mathematical modelling for estimating the potential CO2 sequestration in Malaysian Limestone. In-depth knowledge to minimize the misinterpretation of laboratory data is critical to reduce the uncertainties during CO2 pilot injection. Therefore, a set of coreflooding experiment under reservoir conditions using representative native cores, supercritical CO2 and synthetic formation brine was conducted to understand the effect of induced salt precipitation towards injectivity result. Stabilization time in differential pressure (∆P), analysis of effluent collected after CO2 Water Alternating Gas (WAG) injection and pH reading are key indicators of laboratory data reliability for simulation. The experimental result demonstrated the existence of scale formation and halite precipitation after the samples were subjected to supercritical CO2 WAG for a duration of two weeks. In conclusion, proper experimental procedure and coreflood design during CO2 flooding are the main factors that would affect the reliability of injectivity data and the injection study must be conducted continuously as chemical reaction between CO2 and the fluid-rock system would impact the physical changes of the core samples.
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Effect Of Water Saturation On Diffusion Of Ions And Membrane Efficiency Of Reservoir Shale
More LessSummaryIn this paper, the characteristics of shale water saturation are considered. Based on the triple-layer model of clay-water interfaces, a computational model of unsaturated shale membrane efficiency is established in this paper by using the coupling constitutive equations of heterogeneous porous media. Taking water saturation into account, the change law of the membrane efficiency and diffusion coefficients of ions of clay-rich porous media is analyzed by numerical calculation. Diffusion coefficients of ions and membrane efficiency of unsaturated shale depend on the excess charge density of the surface of the solid in different water saturations. The analysis of factors influencing shale membrane efficiency in unsaturated reservoirs shows that the shale membrane efficiency decreases with the increase of water saturation under unsaturated conditions. The effective diffusion coefficients of ions will increase with the increase of water saturation. Cation exchange capacity (CEC) and solute concentration in pore fluid will affect the membrane efficiency and diffusion coefficients of ions of unsaturated shale.
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Automatic First Break Picking And Refining Of Bad Picks: Median Filter Approach
More LessSummaryThis paper presents an algorithm based on special case of Coppens’ method for automatic first break picking and its quality control using median filter. The algorithm works in two steps; in the first step, the algorithm picks up the first break and in the second step, it refines the bad picks with the help of a median filter. Once all the bad picks are identified, their first breaks are searched within a smaller window. The entire process is automated and faster than Coppens’ technique, hence minimum human intervention is required without compromising the quality of the first break picks.
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Application Of Empirical Wavelet Transform In Coherent Noise Attenuation In High Frequency Marine Seismic Data
Authors L. Wei Yi, R. Hamidi, D. Ghosh, M. Hermana, H. Soleimani and M.H. MusaSummaryOne of the recent approaches regarding on building adaptive wavelets known as Empirical Wavelet Transform (EWT) which extract various signal modes by designing suitable adaptive wavelet filter bank for signal processing. EWT is self-adapting based on the input data itself and without using prescribe basis function. In this paper, a filter is designed based on EWT method for coherent noise attenuation in marine seismic data. EWT modes for each trace is calculated and the ones containing the noise energy are selected. Next, the selected modes are zeroed out and the remaining modes are used in reconstruction of the data. Comparison of the amplitude spectra before and after filtering application shows that EWT method provides high precision and efficiency for noise attenuation.
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The Impact Of A Shallow, Low-Velocity Shale Wedge On Depth Conversion And Field Definition In El-Obayied Field, Matruh Basin
By A. HafeezSummaryIn hydrocarbon exploration and development, quality seismic time to depth conversion is required to accurately define subsurface geometries and hence the gross rock volume of reservoir in closure.
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Monitoring Co2 Plume In Carbonate: Is It Doable?
Authors S. Mad Sahad, M.H. Mad Zahir, Z.A. Abu Bakar and A.I. AzahreeSummaryAlthough significant oil and gas deposits in the porous facies, porosity within the carbonate reservoir has been observed to vary widely between tight facies and highly porous reefal facies, making initial prediction of porosity an important exploration/development objective. Major monitoring challenges arise when carbonate reservoirs in X Field, Central Luconia, Sarawak, offshore Malaysia have very high complexity due to different pore shapes, heterogeneity and diagenesis, thus differentiation of injected CO2 with existing background gas/into aquifer will be creating another issue. This paper outlines the findings using various geophysical methods at this site, especially with respect to monitoring of CO2 plume migration in the subsurface. One of the main advantages of this methodology is the ability to integrate various kind of information obtained at different scales and provide the best solution for the deployment at the field scale.
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Integrated Approach For Stratigraphic Characterization Of Lower Cretaceous Carbonate Reservoir In North Kuwait
Authors P.K. Nath, J. Coronado, S. Bhukta, A. Najem, S.K. Singh, A. Al-Ajmai and A. Ali SajerSummaryRatawi Limestone in the study area was dposited under transgression and high stand occurences within protected mud dominated condition.The prograding and retrograding (back stepping) geometries controlled the reservoir distribution and entrapment as well as the late digenetic process. The depositional model of the area was constructed using the integrated approach and calibrated with the analogue from cuba. The lateral patchy distribution of the reservoir , that developed by the nature of depositional setting was also reflected at the reservoir quality scale. This was captured from core to seismic scale and feed into the static model to delineate the stratigraphic sweets in the study area for further exploration and development activities .
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Deciphering Carbonate Complexity Through 3D Reservoir Modelling For Effective Well Placement In Drilling Operation: Case Study From F Field In Central Luconia Province, Sarawak
Authors Y.A.M. Zaharudin and M.F. MostapaSummaryCarbonate fields are well known for their complex heterogeneity. The F carbonate field is no exception. F field which is located in Central Luconia, offshore Sarawak, is a platform carbonate with areal extension of 9km X 5km. The maximum hydrocarbon column is around 120m. In total, there are five (5) wells available in the field, which include one exploration well, F-1 which was drilled in 1969, an appraisal well, F-2 which was drilled in 2009, and three development wells which had been drilled recently to provide 250 MMscf/d of gas to the nearest facility, named as F-A1, F-A2 and F-A3. During the development wells drilling campaign, the team was disappointed when the first well drilled, F-A3 penetrated the poor quality reservoir. This has negatively impacted the production capacity of the well. Therefore, the team has made some initiatives by updating the property model of the two (2) remaining wells, based on the results obtained from the first well, to improve the static model and to propose new trajectories to ensure the reservoir properties could be improved tremendously. As a result, the team has successfully drilled into a terrific reservoir quality area in the two (2) remaining wells with flying colours, and the targeted production rate has been successfully achieved.
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The Formation Density Influence And Correction Method Of Pulsed Neutron Porosity Logging
More LessSummaryThe effect of the inelastic scattering cannot be ignored in the pulsed neutron porosity logging. The impacts of lithology and bulk density on the porosity measurement are remarkably increased compared with neutron porosity logging based on chemical source. The connection of the slowing-down length of neutron with bulk density and hydrogen index was deduced and simulated to correction the influence of bulk density in pulsed neutron porosity logging. As the results suggest, the application of bulk density correction in the pulsed neutron porosity logging will increase the sensitivity to formation porosity and decrease the impact of lithology and shale effect.
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What Next For Bco — Unlocking Potential Production Gain Thru Low Resistivity Opportunities In Balingian And Baram Delta Basins
Authors M.A.N. C A RAZAK, M.N. KAMARULZAMAN, A. ALI and J. M SHAHSummaryWe are currently facing the stage where the field production is declining and the idle well inventories is rising day after day. To revive the idle wells, behind casing opportunities are sought as it requires minimal operating expenses and the study consume lesser time compare to other types of projects. This is made possible due to enhancement of lenient process flow and utilization of newer tools. As production gain need to be realized this year too, low resistivity play should be considered as an opportunity to supplement the current production. Coupled the two niche scopes, quick monetization can be achieved to supplement the current production and reduce the idle wells.
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Data Analysis And Integration For Better Reservoir Understanding Of M Field
By K. MohamedSummaryThrough the integration of the early dynamic behaviour of the M field and the data acquired during the drilling stages, an improved structural framework was attained through performing comprehensive structural QAQC and an improved definition of the field compartmentalisation. Relay ramps were added between interpreted faults and thereafter inserted into the subsurface static models. The introduction of the relay ramps in the fault model was essential to improve the description of the structural uncertainty of the field as well as help assist the history matching process of the dynamic models without erroneous fault transmissibility descriptions which could detrimentally affect the model forecasts. The fault models also have geologically robust fault throw profiles with fault length to displacement ratio consistent with empirical data
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Petrophysical Estimation Of Toc For Assessment Of Hc Potential Of The Source Rock Shales, Assam Basin, India
More LessSummaryThe Assam basin of India, it is the very where the first commercial oil in Asia was produced, at Digboi in 1889. After more than one hundred years of conventional oil production one would be interested to look at possibilities of other unconventional hydrocarbon resources such as shale gas and shale oil existent in this foreland basin. To assess HC potential of such unconventional a comprehensive estimation of Total Organic Carbon (TOC) over thick source rock shale zones is needed. In this study, TOC has been successfully calculated for the three main source rocks of the Assam Shelf area, Barail, Kopili and Sythet by application of the method □logR on well log data, which could be further used in assessment of HC potential in this basin.
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Unlocking Barriers ∂13C1 Isotope Logging Unravelling Subsurface Compartments
Authors A. Di Daniel and C. MurlidharSummaryUtilisation of real-time δ13C1 Isotope logging service was used as a formation evaluation tool driven by successful field tests. Its capability of providing stable and high-resolution data under the difficult conditions on an offshore drilling site was favourable. (Niemann et al., 2010). Isotope data acquired is further integrated to enhance interpretation of barrier identification. Development wells were drilled in M Field offshore Sabah, of which 9 producers’ and 2 water injectors targeting stacked reservoirs M1 and M2. Highly deviated wells were drilled from a subsea template positioned slightly north west of the crestal producing structure in avoidance of placing facilities over a severely pockmarked seabed. During the drilling campaign, Health, Safety and Environment (HSE) and well delivery scopes were achieved. This is achievable by the amalgamation of data acquired from the exploration and appraisal wells in aiding us to reduce the uncertainties presented prior to developing the field. M field is complexly faulted where compartmentalisation is perceived as a risk. Thus, deploying this tool will allow us to improve M field economics.Development wells were drilled in M Field offshore Sabah, of which 9 producers’ and 2 water injectors targeting stacked reservoirs M1 and M2. Highly deviated wells were drilled from a subsea template positioned slightly north west of the crestal producing structure in avoidance of placing facilities over a severely pockmarked seabed. During the drilling campaign, Health, Safety and Environment (HSE) and well delivery scopes were achieved. This is achievable by the amalgamation of data acquired from the exploration and appraisal wells in aiding us to reduce the uncertainties presented prior to developing the field. M field is complexly faulted where compartmentalisation is perceived as a risk. Thus, deploying this tool will allow us to improve M field economics. Development wells were drilled in M Field offshore Sabah, of which 9 producers’ and 2 water injectors targeting stacked reservoirs M1 and M2.
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Improved High-Resolution Time-Frequency Decomposition for Detailed Reservoir Characterization
Authors M. Sajid and A.R. GhazaliSummaryTime-frequency localization has a wide range of application in geophysics. In seismic stratigraphic interpretation, high-resolution spectrogram have uses both for reservoirs that lie below and above the seismic resolution limits. In case of the reservoir where the thickness is greater than tuning thickness, high-resolution spectral decomposition provides an indicator of the area of interest, whereas, in case of thin-bed reservoirs, advance spectral decomposition helps to remove the tuning effects and improved frequency-dependent AVO analysis. Commonly methods help to enhance the resolution, visualize structural and stratigraphic features, estimate thin bed thickness, spectral balancing as well as direct hydrocarbon indication (Burnett et al., 2003; Chen et al., 2008; Xiaoyang et al., 2014). In the paper, we present a new modification to the Modified Stockwell transform (MST)(Li et al., 2016), and incorporate both the benefits of MST and Gabor decomposition into a single algorithm. By doing so the robustness of MST is improved for small window size. We named this algorithm MST2. The MST2, is perfectly reconstructable which leads to high time-frequency signal processing for better reservoir characterization. We compared the MST2 algorithm with MST, Gabor decomposition, and Continuous Wavelet Transform (CWT) for its time-frequency localization and characterization. In the example shown in this paper, we also demonstrate the use of MST2 usage for improved structural visualization.
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Geological Information Of Wave Attenuation And Velocity Dispersion Extracted From Vsp And Well Logs Data
Authors H. Hafit, N. Ngoc and B. NegenmanSummaryAnelastic attenuation of propagating seismic waves in a geological medium is caused by internal friction between rock particles during the process of the transfer of energy from the wave to the medium. Velocity dispersion can be correlated with anelastic attenuation, and this information is required for seismic data processing and interpretation. In this paper, the Quality Factor (Q) was estimated from zero offset VSP data using a centroid frequency shift method. Velocity dispersion for both Vp and Vs by was estimated by comparing VSP (Interval P & S velocities) versus sonic data in Well A. The VSP survey was conducted using three component geophones and an air gun array as a source. Well A is a deviated well with maximum inclination of 27 degrees. The analysis shows that frequency dependence of Q is reduced with depth, and changes in the Q gradients and velocity dispersion are consistent with sequence/ lithology boundaries, fluid type and pressure differences.
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A Feasibility Study Of Estimating A Robust Velocity Model for Complex Pre-Salt Structures Using Jmi
Authors M.A. Ishak, H. Ahmad Munif, M.H. Mad Zahir and A.R. GhazaliSummaryJoint Migration Inversion is a new method to estimate the velocity. Its ability in integrating transmission effects and higher order scatterings have allowed the estimation of velocity in complex media such as salts. The paper describes the work done using JMI to estimate the salt velocity in SEAM salt model
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