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EAGE Conference on Reservoir Geoscience
- Conference date: December 3-5, 2018
- Location: Kuala Lumpur, Malaysia
- Published: 03 December 2018
41 - 60 of 87 results
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An Industry First: Successful Formation Sampling while Drilling (Fswd) Under Pressurized Mud Cap Drilling (Pmcd)
Authors C. Shield, D. McKinney, N. Hardikar, M. Dulam, I. Kim, J. Pragt and F. AdegbolaSummaryThis paper describes the successful deployment, sampling and calibration of formation sampling while drilling (FSWD) under total losses and pressurized mud cap drilling conditions (PMCD); an industry first. The successful results emanate from excellent collaboration between well engineering, sub-surface, and third-party technology providers. LWD fluid sampling is traditionally applied for complex wellbore geometries, but in this case it is applied for difficult reservoirs that often contain karsts resulting in total losses. PMCD is a drilling technique commonly applied in these conditions and requires seawater to be pumped down the drill pipe with a light water-based mud on the backside for pressure control. Pre-job planning and operational procedures that resulted in the successful collection of gas samples will be discussed. The LWD fluid sample quality and gas contamination levels were confirmed by comparison with reference wireline fluid samples that were acquired in the ensuing side-tracked wellbore. Samples were found to be comparable in gas composition, OBM filtrate contamination, and H2S, CO2, and N2 levels. This study extends earlier work and confirms the validity of FSWD for H2S contamination accuracy in high H2S and very low H2S cases. Further studies are required to complete the calibration for low-level H2S reservoirs.
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Delivering A Horizontal Well In A Complex And Highly Faulted Reservoir Using Novel Data Acquisition Techniques
Authors V. Vevakanandan, T. Zhang, A. Ting, D. Mckinney, N. Ha and C. MurlidharSummaryThe M field is a complex faulted anticline structure occupied by 80–100ft of oil column in laminated sand shale formations, of which individual beds are typically below log resolution. The Phase 1 Development campaign targeted 2 reservoirs for production, the R1 and the R2 reservoir, both of which show a fining upwards stratigraphy. The reservoir is characterized by seismically mapped faults with throws up to 60 ft. Pre-production concerns were that these faults would be sealing on a production time scale, thus efficient sweep and ultimate recoveries were a major uncertainty. To maximize reservoir penetration and increase the productive intervals whilst avoiding damaging the production interval with excessive casing shoe penetration, 2 horizontal wells were designed to be optimally placed within the better-quality sands. To have the well straddle across different fault blocks, without having shales exposed and risk shale swelling and dispersion, the data acquisition strategy was designed to include novel technology that could characterize faults real time and assist the team in making informed decisions during drilling.
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Rejuvenate The Low Resistivity Pay Sand To Capture The Potential On Sarawak, Malaysia
Authors M.S. Ahmad Kassim and W.A. TolioeSummaryNowadays, the oil and gas companies still invest on exploration activity and expected to discover new reserves which can be developed to meet domestic and international needs. The oil and gas discovery has to meet the economic critera and be able to be developed. The upside potential, such as, the low resistivity-low contrast reservoir, can add the value to economic criteria by optimizing the hydrocarbon in-place. These kind of reservoirs were not as primary exploration target, but once the hydrocarbon was shown on this kind of reservoir, it needs to be evaluated with special and integrated analysis and should be included the in-place calculation. The low resistivty of thin laminated reservoirs is quite challenging to be determined on the first phase and comprehensive data acquisition need to be planned well. The low resistivity responses of this lamination shaly- sand reservoirs will lead the evaluation and assessment to be water bearing zone, especially by applying the conventional approach, although the hard data determine that zone as hydrocarbon bearing zone. Hence, more data needed to be used such as Nuclear Magnetic Resonance (NMR), Image log, Pressure and Sample is crucial for the interpretation. This data also help to solve any difficulty faces for normal reservoir
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De-Risking The Reservoir By Attenuating Interbed Multiples
Authors L. Do Hoang, C. Lam Choong, M.L. Ghazali, A. Bisset and S.L. AlfredSummaryInterbed Multiples can lead to spurious interpretation of primary reflection. Removal of these types of multiples is not properly handled by conventional demultiple techniques. In this case study, we will demonstrate application of Interbed Multiple Attenuation using Inverse Scattering Series Method (ISS-IMA). The result of Interbed Multiples Attenuation from the example shows a significant uplift in imaging clarity at reservoir level.
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Integration Of High Resolution Fwi Velocity Model And Broadband Data For Elastic Property Generation: A Low Frequency Overlap Case Study In The Norwegian Sea
Authors C. Reiser, T. Martin, A. Long, S. Naumann and D. CavalinSummaryObtaining absolute elastic attributes for lithology and fluid prediction requires a low frequency model. This was achieved by collocated co-kriging of seismic velocity and well information. Increasing the bandwidth with broadband seismic only requires a low frequency model for the 0 to 3 Hz range, reducing emphasis on the well information. Less a priori input is advantageous in attribute prediction; the results of pre-stack seismic inversion are primarily data driven. Full waveform inversion (FWI) creates high resolution velocity models. Both high resolution FWI models and broadband seismic data can provide the low frequency component of elastic property generation enabling well information to be a control point; Reservoir geoscientists can confidentially derive reliable elastic attributes such as acoustic impedance and Vp/Vs ratios away from the well locations. We present the results of a study varying the overlap point between a full wavefield FWI model and broadband seismic in an absolute elastic inversion and draw conclusions on the optimal data use for a volume from the Norwegian Sea.
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Multi-Survey Q-Fwi Enables Imaging Uplift And Robust Time-To-Depth Conversion In Deep Water Sabah Fi
Authors V. Goh, T.C. Hor, H. Van Voorst Vader, H. Dols, A. Tan, K. Mohamed and A. Jose VizamoraSummaryThe M field is a deep-water field in Sabah, Malaysia, in early stages of production. The field, composed of multiple turbidite reservoirs, is considered structurally complex heavily faulted and compartmentalised, and underlie a rugose sea bottom and complex overburden with presence of gas. After the first development phase, the velocity model was assessed against data acquired during drilling, e.g. well logs and other well-based information. Vertical incidence VSPs acquired in deviated and S-shaped wells indicated that the lateral velocity variations within the overburden is larger than previously modelled, due to a complex overburden. Further refinement of the velocity model is essential for further development planning, reservoir management, and updates to resource estimation.
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Full Wavefield Migration For Solving Gas Cloud Imaging: A Field Example
Authors M.H. Mad Zahir, A.R. Ghazali, S. Mad Sahad and M.A. IshakSummaryThe South East Asian offshore basin, were known to be prone of shallow gas accumulation. There are many imaging method being discussed to compensate the shallow anomalies so-called ‘gas clouds’ or ‘gas chimneys’ (Ghosh et al, 2010). PETRONAS has been successful in obtaining better seismic image below gas clouds (Akalin et al, 2010; El-Kady et al., 2012). However, almost every conventional imaging method are based on using primaries only, thus having less optimized estimation of the true reflectivities below gas cloud. Here, we believes that the multiple scattered energy from the gas cloud carries additional information that could provide ‘almost true amplitude’ reflectivities below gas cloud.
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A Novel Analytical Approach To Estimate Sand Production In Unconsolidated Reservoir: Case Study And Validation In Oil Field “N”
Authors D. Arianti, D. Septariany and S. Pheronica RanaSummarySand production is the migration of formation sand caused by the flow of reservoir fluids. This paper aims to develop an analytical model to predict sand production in oil field and validate it using 4 wells in Field “N”. Coupled sand failure mechanism considering static and dynamic criteria is used to models sand production. Rock particles strength is predominantly acting by drag and buoyancy forces, while sand particles are assumed as spherical and submerged when flowing. To capture fluid flow and pressure drop in porous medium, Darcy’s law is applied. The proposed analytical equation successfully models sand prediction accurately in 4 wells at range of cavity height 12–25 ft. At oil rate 1000 STB/day, calculated sand production in Well 1 is 0.005 lb/bbl, Well 2 is 0.007 lb/bbl, Well 3 is 0.005 lb/bbl, and Well 4 is 0.002 lb/bbl. Comparing to the field data in 4 wells, only 3% of analytical method to real data discrepancy is achieved.Sensitivity studies are conducted and show that cavity height, oil rate, fluid viscosity, and sand grain size put most of influencing parameters to calculate sand production. This study suggests at low and moderate oil production rates, cavity height is applied at 10–25 ft.
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Application Of Acoustic Noise And Temperature Logs In Idle Well Restoration And Qualitative Assessment Of Reservoir Performance
By S. HamzahSummaryThis paper presents the application of the acoustic noise and temperature logs in idle well restorations in Field A, offshore Malaysia and how the data is further utilized to qualitatively assess reservoir performance. Key logging strategies for successful leak detection and log interpretation analysis under complex borehole and reservoir environment settings are discussed. These strategies include designing a proper logging program under multiple borehole conditions whilst monitoring the surface tubing and casing pressures, optimizing the stationary acoustic noise data acquisition, and integrating the acoustic noise, temperature and pressure data to qualitatively analyse reservoir performance.
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Brine Estimation In Shale Gas Reservoirs Using Wireline Logging And Laboratory Data: A Case Study From Murteree Shale, Cooper Basin, South Australia
Authors M. Ahmad, E. Padmanabhan, M. Haghighi and M. RajabiSummaryThe argillaceous nature of unconventional gas reservoirs presents ultra-complex lithology, nano-scale porosity and permeability. Petrophysical and mineralogical evaluation of these formations challenge high resolution diversified evaluation techniques to investigate first the dual storage mechanisms of natural gas and later to help in designing hydraulic fracturing techniques for maximum recovery of gas. Research work and contents in this paper are intended to develop some insight about post depositional diagenetic events in shale gas formations which have direct impact on brine evaluation in these types of overly clay rich reservoirs. Insights will help in understanding, reasons of uncertainties and doubts about controversial application of true formation resistivity (Rt) values from resistivity wireline logs in seconds Archie’s (1942) Equation in shale gas reservoir. Direct evaluation and assessment of porosity in shale is not reliable from wire-line logs alone; thus, it is essential that logs be calibrated with lab direct measurements such as QEMSCAN, XRD, and FIB/SEM. In the following sections, the geological background of study area is first discussed followed by our literature review and methodology used to determine different parameters for water saturation evaluation. Results are presented with the sensitivity study of different parameters. Some conclusive results are given at the end.
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Practical Methods For Model Uncertainty Quantification In Geophysical Inverse Problems
Authors R. Mackie, M. Meju and F. MiorelliSummaryGeophysical inverse problems are non-unique. Through regularization and the use of a priori information we can derive stable and geologically reasonable inversion models. Providing an analysis of the model uncertainty is necessary for the critical task of separating inversion artefacts from robust geological features. In this work we explore the utility of “most-squares” analysis extended to nonlinear problems for quantifying uncertainty of models obtained by standard linearized iterative least squares methods, using 1D and 2D magnetotelluric examples to demonstrate its effectiveness.
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A Recipe To Address Time Frequency Non-Uniqueness: A New Tool For Spectral Decomposition
Authors P.K. Mishra and P.K. ChaudhuriSummarySpectral decomposition is a well-known technique with applications in, but not-limited to, analysing frequency dependant variation of amplitude with respect to time. Over the past few years, numerous algorithms have been developed (and published) to aid precision in spectral decomposition, however, all these methods, suffer from the Gabor’s uncertainty (similar to Heisenberg uncertainty principle, from quantum mechanics) i.e. the frequency and time for a specific amplitude cannot be isolated unambiguously. This has far reaching consequences with respect to seismic interpretation. e.g. after identifying a high amplitude channel in a window of 100ms zone at a specific frequency, locating the extents (vertical & lateral) of the channel within the seismic is still left to the subjective judgement of the interpreter. This introduces significant uncertainty in interpretation of spectral decomposition results. The method discussed in this paper, based on published mathematical foundations (after, Brevdo et. al., 2014, Herrera et.al. 2014, Said Gaci, 2018) aims at dealing with this spectral uncertainty in order to aid improved spectral interpretation.
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Improved Reservoir Imaging And Characterization And Its Impact On Subsurface Development In A Carbonate Buildup: Field A, Sarawak, Malaysia
Authors P. Wong, J. Kupecz and S.A.F. Syed Abdul HalimSummaryThe recent 2016 broadband seismic and anisotropic pre-stack depth migration has improved imaging in the carbonate buildup. It has helped with the identification of the talus and main buildup, as well as intra-carbonate faults. The joint impedance and facies inversion has been successfully applied and reflects the heterogeneity of the reservoir within the carbonate. This has allowed for an updated geologic model, which has incorporated the acoustic impedance for porosity modeling. The new interpretation also allowed for well optimization to mitigate risks and effectively target the swee-spot areas.
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Identifying Opportunities In Stratigraphic Traps: A Seismic Story In Pm-3 Caa
More LessSummaryIdentifying Opportunities in Stratigraphic Traps: A Seismic Story in PM-3 CAA
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A Geologically Constrained Seismic Modelling Method Connecting Geological Realism To Seismic Validation: A Real Field Example
Authors S. Rahman, A.R. Ghazali and I. FuadSummaryThis paper presents a new concept workflow utilizing scenario-based analysis to understand the complex relationships between geological understanding and seismic response. For an effective integration of geological realism and seismic validation, the workflow must tailored to exploit basin based rock physics information for lithological and hydrocarbon identification. Forward seismic modelling allows us to test the relationship between geology and seismic response, and potentially very well suited to improve the geological interpretation of seismic data. Modelling multiple realistic geological scenarios have opened before us manifold possibilities without going into a full inverse solution.
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Quantitative Evaluation Of Shale Pore Connectivity Using Spontaneous Imbibition And Mercury Intrusion Capillary Pressure Methods
More LessSummaryShale oil and gas can be recovered from the shale matrix through the interconnected pore networks. The migration of hydrocarbon molecules within the shale matrix is controlled by the pore connectivity. However, few studies have been done on pore connectivity of shale matrix. In this study, spontaneous imbibition and mercury intrusion capillary pressure methods were selected to quantitatively evaluate the pore connectivity of shale matrix. The pore connectivity should be characterized by the slope in the first imbibition stage and the small spontaneous imbibition slope values (mean 0.3963) indicate the poor pore connectivity of shale matrix. The permeability, effective and geometrical tortuosity obtained from MICP can quantitatively evaluate the pore connectivity, which agrees well with the spontaneous imbibition slope. Therefore, shale matrix pore connectivity can be effectively characterized by the spontaneous imbibition and MICP methods.
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Investigation Of Lcrc Reservoir Using Multicomponent Seismic Data And Low Gas Saturation Model
By E.W. PurnomoSummaryMulticomponent seismic data is used to identify, as well as to study, the distribution of the low-resistivity low-contrast (LRLC) hydrocarbon reservoir. Three attributes were derived i.e Attenuation, Density and Difference Impedance from a Malay Basin gas field multi component (3C) data. The three properties based on the laboratory low-saturated-gas (LSG) model by previous researcher was analyzed. It was found that all three approaches are able to locate the reservoir gas sand which associate with low-resistivity logs data value or apparently show no gas sand anomaly. This study informs that the field is abandon of thin 7% saturated gas gas reservoir sands. A 25 % gas sand, which is not anomalous in well log, is clearly delineated.
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New Approach To Reduce Uncertainty In Reservoir Characterization Of Unconventional Tight Gas Fields In Western U.S. Basins Using Saturation Height Modelling
Authors M. Tadayoni and A. AbdollahianSummaryUncertainty in permeability and in-situ water saturation values could be a challenge in a Tight Gas Sandstone (TGS) reservoir characterization. Implementing a new workflow based on Saturation Height Modelling (SHM) and using capillary pressure curves and well logs from 10 different wells in 4 different giant basins of western U.S. TGS reservoirs as the input data, this uncertainty has been reduced considerably. After applying some initial corrections and grouping the curves based on the corresponding cores sorting, size and texture, five SHM methods have been applied to each group. Using regression methods, the function of each model has been rewritten based on the cores petrophysical properties. A water saturation profile has been calculated for each well by entering its porosity and permeability logs and also Height Above Free Water Level (HAFWL) in rewritten functions. Using Standard Error of Estimate (SEE) analysis, the best SHM method has been recognized. Finally, precise permeability values have been calculated for each well by entering its porosity and water saturation logs and also HAFWL in saturation height function of the best method. The accuracy of the results have been approved by high coefficient of determination (R2) between the calculated and the core permeability profiles.
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Geological Characterisation Of Vaca Muerta Formation In La Amarga Chica (“Lac”) Block, Neuquén Basin, Argentina
Authors F. Vittore, M.D. Mohammad Khalid, F. Lozano and C. BernhardtSummaryLAC is one of the most prolific shale oil blocks in Vaca Muerta formation in the basin. The block is located in the southeast of the Neuquén Basin in the Centre-East sector of the province of Neuquén whereby the nearest town is Añelo, located 18 km southwest. The concession block, made up of a partnership between YPF and PEPASA, covers a total area of 186 km2, divided into 3 triangular areas, respectively known as the Southern Triangle (73 km2), the Central Triangle (56 km2) and the Northern Triangle (57 km2). A detailed characterization of geological structure, stratigraphic heterogeneity and reservoir properties within the Vaca Muerta formation in the block was done through an extensive data acquisition work, carried out during a three years’ pilot phase drilling campaign that involve vertical and horizontal wells drilling with full suite logging, drilling cutting analysis, fluid sampling, core and sidewall cores. Several surveillance tools such as chemical tracers and microseismic were also run to gain further understanding of the reservoir complexities that will steer the LAC development strategy.
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