Integrated Petrophysical Approach for Determining Reserves and Reservoir Characterization to Optimize Production of Oil Sands in Northeastern Alberta
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Abstract The acquisition of triple-combo logging data, borehole imaging data, dipole sonic, and select magnetic resonance data, offered the unique opportunity to study a specific set of wells in the McMurray Formation of northeastern Alberta. Each one of the data sets provided valuable information about the geologic setting, fluid properties, or rock properties. The true value of the logging data comes from combining the analyses and interpretations to produce a complete picture of the geology, reservoir potential, and production potential. This integrated approach is based on the interpretation of results from the image data, while incorporating standard log data, including electric, nuclear, and acoustic measurements; dipole sonic data; and nuclear magnetic resonance data. Subsequently, shaly sand analysis from these measurements was added to provide key reservoir petrophysical information. Finally, the addition of nuclear magnetic resonance data supplied insight into the producibility of the reservoir. Traditionally, dipmeter and image results are used for mapping of channel sands in the McMurray Formation. For this application, however, the image data provided high-resolution delineation of shale beds. This use of the image data leads to a critical reservoir heterogeneity description, which is required for vertical permeability information to optimize production. Shaly sand analysis results (volume of shale, sand calculations, water saturation, and permeability) are combined with core data, when available, and both the core and shaly sand analysis results were incorporated along with the image interpretations. Finally, nuclear magnetic resonance data was added for the key wells, providing comparison of bound to free water, as well as permeability and lithology-independent porosity. When combined, each data set adds either qualitative or quantitative information that is iteratively used to refine and complete the integrated petrophysical analysis. In this investigation of the McMurray sand characteristics, initial interpretation of the image data revealed that the depositional environment does not match that of the typical fluvial-estuarine sands; subsequently, an interpretation of all wireline data was performed. The results of this interpretation indicate a shoreface environment. Integrating all petrophysical measurements enabled geoscientists to obtain a more complete picture of the subsurface.Keywords:
Petrophysics
Formation evaluation
Saturation (graph theory)
Water saturation
Petroleum reservoir
Economic geology
Petrophysics
Formation evaluation
Water saturation
Lithology
Saturation (graph theory)
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Abstract Quantitative petrophysical evaluation in high-angle and horizontal (HA/HZ) wells has remained elusive primarily because of the presence of complex log responses and lack of appropriate modeling capabilities. Recent advances in numerical simulation of nuclear and resisitivity logs in HA/HZ wells have significantly improved interpretation of log responses in complex borehole-formation geometries. Additionally, developments in fast simulation methods have enabled application of log response modeling in conjunction with field measurements. Although a full understanding of nuclear and resistivity logs response in HA/HZ wells is yet to be resolved, application of advanced interpretation techniques to field measurements yields more reliable petrophysical analyses. In this paper, we implement processing methods that more effectively combine short- and long-spaced density measurements together with forward modeling of azimuthal nuclear and scalar resisistivity logging-while-drilling (LWD) logs to construct a common subsurface model. This log response-coherent model constructed from field measurements is then used for conventional petrophysical analysis. To demonstrate our workflow, we analyze four horizontal wells penetrating sand-silt sequences in the Chayvo field (northeast coast of Sakhalin Island, Russia) with apparent dip angles ranging between 80 and 90 degrees. The wells were drilled with oil-base mud (OBM) and include standard LWD triple-combo logs. Field-based log response-coherent models of resistivity, density, and neutron measurements are used to estimate lithology volumetrics, porosity, and water saturation. Results from depth coherence processing and forward modeling show improved resolution and estimation of formation layer petrophysical properties which yield more accurate estimates of reserves in place compared to those initially estimated from field logs. Additionally, the average properties in high- and low-net intervals from the HA/HZ wells are compared to properties estimated in near offset vertical wells, which include core samples.
Petrophysics
Formation evaluation
Economic geology
Logging while drilling
Saturation (graph theory)
Lithology
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Abstract The first multicomponent induction instrument available to the industry provides vertical and horizontal resistivity data for an improved delineation and evaluation of low resistivity, low contrast pay zones frequently encountered in offshore hydrocarbon exploration. This instrument surveys the formation in three dimensions with multicomponent transmitter-receiver induction coil arrays to derive the true horizontal and vertical formation resistivities. The horizontal and vertical resistivities obtained from the multicomponent induction measurements can be interpreted jointly with standard array induction and image log interpretation data. Conventional array induction data assists 3DEX™ resistivity data interpretation by removing deeper invasion effects through 2D inversion methods. A realistic example derived from field data including anisotropic sands demonstrates how vertical and horizontal resistivity from a multicomponent induction instrument can be jointly interpreted with NMR data to provide additional reservoir information. A second field data example demonstrates how new petrophysical evaluation methods utilizing the new multicomponent induction instrument's resistivity anisotropy data improve the economic evaluation of low resistivity, low contrast pay zones. These areas range from marginally economic or nearly depleted regions to the capital-intensive offshore deepwater plays. For these areas the multicomponent induction data interpretation provides additional information to enhance the economic value of offshore exploration and development drilling programs. Petrophysical interpretation utilizing vertical and horizontal resistivity, nuclear, and NMR data yields a more accurate and reliable formation water saturation evaluation in anisotropic thinly bedded, laminated sand shale sequences. Conventional induction logging instruments have the transmitter and receiver array orientation aligned parallel to the tool and borehole axis. Therefore, in vertical wells hydrocarbon-filled sand shale sequences conventional induction instruments measure a resistivity, which is greatly biased towards the low resistivity of shales. This results from the dominant current flow for the source/receiver configuration being horizontal and occurring mainly through the low resistivity shales: thus, horizontal resistivity is measured. This can lead to an underestimation of the sand laminae oil saturation. The multicomponent transmitter-receiver induction instrument configuration provides direct measurements to derive both horizontal and vertical resistivities. These resistivities allow an improved petrophysical evaluation of hydrocarbon-bearing, thinly bedded shaly sand formations. Field examples demonstrate the benefits of joint interpretation of multicomponent data with image logs to properly model and interpret resistivity anisotropy in zones with resistive streaks and variable laminated formation structures.
Petrophysics
Economic geology
Formation evaluation
Environmental geology
Electromagnetic induction
Gemology
Igneous petrology
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Abstract For reservoir simulation, one of the most important part of reservoir characterization is rock typing, where rock quality is evaluated and estimated for any simulation grid and OOIP (original oil in place) is calculated based on average petrophysical parameters for any layer. To allocate different rock types to simulation grids, rock types should be assigned according to ranges of parameters that differentiate different rock types. Based on the experience in carbonate reservoirs of XXXX oilfield and other oilfields, irreducible water saturation (Swi) is a critical differentiation parameter for rock typing, although it can be difficult and expensive to evaluate. In oil zones, water saturation from log data is assumed to be the irreducible water saturation. The problem arises in transition zone and water zone, where water saturation from log data is not equal to the irreducible water saturation of that rock. KNN(K-Nearest Neighbor) is an effective machine learning method for classification and regression in many industries including geo-science. Models can be trained and predict irreducible water saturation from the traditional logs such as GR, Density, Neutron, Sonic using KNN and other Machine Learning methods using labelled data from oil zones. Randomly selected 50% of the dataset was used for training and other 50% was used as testing dataset to be predicted. The prediction precision of KNN method can reach the minimum 92% line for all 25 wells studied and is most robust compared to other methods such as Random Forest and SVM. The trained model was used to predict all the rock types in the reservoir and was confirmed in wells with core data and other advanced measurements data. A new approach of petrophysical rock typing (PRT) for carbonate reservoir using KNN based on traditional wireline data and core analysis data is studied and the results show it can solve the PRT problems in carbonate reservoir simulation without acquiring extra data and additional cost. A new workflow was established to process wireline data and provide the PRT results based on wireline data for every newly drilled well on top of traditional "Porosity-Permeability-Saturation" petrophysical evaluation results. This paper presents the methodology, workflow, results, verification, as well as appropriate application scenarios of this new approach. Considering the requirements of the data input and the workflow of the approach, it could be applied widely in similar carbonate reservoirs.
Petrophysics
Water saturation
Petroleum reservoir
Saturation (graph theory)
Oil in place
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Petrophysics
Water saturation
Formation evaluation
Saturation (graph theory)
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A case study is presented in this paper to indicate that the modern logs significantly improved formation evaluations for complex reservoirs when combined with the conventional logs. Traditionally, petrophysical formation evaluation using conventional logs (Wireline and LWD) is a qualitative and subjective exercise that relies upon the simultaneous interpretation of multiple conventional wireline logs. In this study, an integrated petrophysical evaluation based on modern logs (e.g. XPT, NMR, FMI and DSI) has been undertaken to characterize complex reservoirs under the conditions of variable water salinities, high irreducible saturation and fractures. Our study results show that the conventional logs provided the typical qualitative reservoir parameters for formation evaluation. However, the usage of modern logs not only improved the traditional CPI interpretation but also minimized the effects of external factors and improved the reservoir characterization. The study based on a gas field from the East Irish Sea shows that the approach resulted in better identification of fluid types, the determination of gas-water contacts and permeability, as well as building saturation-height functions, fractures identification and AVO response analysis.
Wireline
Petrophysics
Water saturation
Formation evaluation
Natural gas field
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Abstract The first multicomponent induction instrument available to the industry provides vertical and horizontal resistivity data for an improved delineation and evaluation of low resistivity, low contrast pay zones frequently encountered in offshore hydrocarbon exploration. This instrument surveys the formation in three dimensions with multicomponent transmitter-receiver induction coil arrays to derive the true horizontal and vertical formation resistivities. The horizontal and vertical resistivities obtained from the multicomponent induction measurements can be interpreted jointly with standard array induction and image log interpretation data. Conventional array induction data assists 3DEX ? resistivity data interpretation by removing deeper invasion effects through 2D inversion methods. A realistic example derived from field data including anisotropic sands demonstrates how vertical and horizontal resistivity from a multicomponent induction instrument can be jointly interpreted with NMR data to provide additional reservoir information. A second field data example demonstrates how new petrophysical evaluation methods utilizing the new multicomponent induction instrument's resistivity anisotropy data improve the economic evaluation of low resistivity, low contrast pay zones. These areas range from marginally economic or nearly depleted regions to the capital-intensive offshore deepwater plays. For these areas the multicomponent induction data interpretation provides additional information to enhance the economic value of offshore exploration and development drilling programs. Petrophysical interpretation utilizing vertical and horizontal resistivity, nuclear, and NMR data yields a more accurate and reliable formation water saturation evaluation in anisotropic thinly bedded, laminated sand shale sequences. Conventional induction logging instruments have the transmitter and receiver array orientation aligned parallel to the tool and borehole axis. Therefore, in vertical wells with hydrocarbon-filled sand shale sequences, conventional induction instruments measure a resistivity that is greatly biased towards the low resistivity of shales. This results from the dominant current flow for the source/receiver configuration being horizontal and occurring mainly through the low resistivity shales: thus, horizontal resistivity is measured. This can lead to an underestimation of the sand laminae oil saturation. The multicomponent transmitterreceiver induction instrument configuration provides direct measurements to derive both horizontal and vertical resistivities. These resistivities allow an improved petrophysical evaluation of hydrocarbon-bearing, thinly bedded shaly sand formations. Field examples demonstrate the benefits of joint interpretation of multicomponent data with image logs to properly model and interpret resistivity anisotropy in zones with resistive streaks and variable laminated formation structures. Introduction A significant percentage of the world's estimated hydrocarbon reserves are contained in thinly laminated, low-resistivity, low-contrast, shaly sand formations typically encountered in deepwater turbidites. Evaluation of hydrocarbon reserves in these formations has been a challenge to petrophysicists. Recent statistical studies reveal that turbidites are in an immature exploration stage globally and will have an important economic role in the future of hydrocarbon exploration and production.1-3 The goals of a petrophysical reservoir analysis of a layered anisotropic reservoir are mainly for volumetric analysis and flow property determination. The volumetric reservoir description includes matrix volume fractions, porosity, and irreducible saturation. The flowproperties ar
Petrophysics
Economic geology
Formation evaluation
Environmental geology
Electromagnetic induction
Gemology
Igneous petrology
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Citations (11)
Habiganj gas field is one of the largest fields in Bangladesh. However, a very few amounts of analysis has been done on it. A study based on gravity and magnetic data of the Habiganj and adjoining areas has been made to delineate the structure and infer the general geology of the region. This study primarily encompasses formation evaluation and determination of petrophysical parameters of the gas-bearing zones in the Habiganj well no. 11 (HB # 11). As a result of detailed interpretation of various wireline logs of this well and using the cross-plots of logs, it is evident that there are two hydrocarbon (HC)-bearing zones in this field. The computed averages of shale volume, porosity, permeability, and gas and water saturation have been used to determine the reservoir interval pay zone, net, gross, net to gross, bulk volume of water, pore thickness, and HC pore thickness.
Petrophysics
Wireline
Formation evaluation
Water saturation
Natural gas field
Saturation (graph theory)
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Low resistivity, thinly bedded formations are typically less than a foot thick and are usually below the resolution of traditional logging tools. This paper discusses the improved characterisation of such formations by using routine and special core analysis data, wireline logs, well test data, core NMR measurements and FMI images. A variety of water saturation models (Archie, Indonesia, Waxman-Smits, Simandoux) were used and comparison of the results demonstrated that water saturation in low resistivity sands was high (approximately 60-85%). The issue of resistivity log resolution was not investigated. The results from well testing showed that dry gas was produced from a ‘wet’ interval. Subsequent NMR analyses showed that the water saturation was high due to a large volume of clay and capillary bound fluid that was immobile during production. Capillary pressure measurements also suggested high irreducible water saturation.
Wireline
Water saturation
Saturation (graph theory)
Capillary pressure
Formation evaluation
Formation water
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Abstract The Shaly formation can be evaluated with the value of porosity and water saturation which are derived from Well logging, whether it will produce hydrocarbon or not. Recently, values of water saturation of shaly farmation are mostly derived from Induction-Sonic Combiration. Porosity of shaly formation could be derived from Formation Density-Sonic Combination more reliably. The writer tried to predict the formation evaluation by well logging of the Minemiaga Oil field and the Matsuzaki gas field, taking the above mentioned method.
Water saturation
Natural gas field
Saturation (graph theory)
Formation evaluation
Formation water
Sonic logging
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