Petrophysical Evaluation Research Articles

Source rock and petrophysical evaluation of the Late Cretaceous Haymana Formation, Haymana Basin, Central Anatolia, Turkey

This study investigates the petroleum potential of the mudstones of the Late Cretaceous Haymana Formation in the Haymana Basin, Turkey. Lithofacies, pore structure, and source rock characteristics of the mudstones are examined using stratigraphical, sedimentological, petrophysical, and organic geochemical methods along four stratigraphic sections and other sampling sites. The depositional model presents a facies distribution within a submarine fan system. According to bulk mineralogy, the identified lithofacies are mixed mudstone, mixed siliceous mudstone, marl, mixed carbonate mudstone, argillaceous/siliceous mudstone, and clay-rich siliceous mudstone. XRD and mercury intrusion measurements suggest that the macropores (> 50 nm) of the mudstones formed by dissolution of calcite, while mesopores (2 nm-50 nm) developed around the clay/quartz/feldspar. Of the analysed samples, no lithofacies class is distinct with any specific range of porosity or permeability, which suggests a strong heterogeneity in pore throat size, mineral content, and grain size. The black shale from the northwest of the basin with 1.19% TOC, 0.07 mg/g S 1 , 1.01 mg/g S 2 , and 441°C T max is a relatively more mature source rock although it still exhibits poor petroleum potential. Overall, the TOC values (avg. 0.38%) of the mudstones suggest organic-poor rock characteristics for the Haymana Formation in the studied parts of the Haymana Basin.

Seismic reflection data interpretation and petrophysical evaluation of the Meyal area, the Potwar Basin, Pakistan

Despite extensive exploration efforts in the Potwar Basin, a thorough understanding of the structural framework and reservoir characteristics within the Meyal Field remains critical for pinpointing potential hydrocarbon zones. This study aims to integrate geology and geophysics to emphasize the structural and stratigraphic interpretation of the Meyal Field, including reservoir characterization using seismic and well-log data. The seismic interpretation of six seismic lines focuses on four key reflectors: the Kamlial, Chorgali, Sakesar, and Salt Range Formations. The Eocene Chorgali and Sakesar Formations are of primary importance for exploration and production. Structural analysis revealed that the Meyal anticline is a plunging structure bounded by a back thrust to the north and a fore thrust to the south, suggesting a favorable location for hydrocarbon accumulation. Time-depth contour maps derived from seismic data further delineate potential sites for future investigations. The well correlation indicated an uplift toward the Meyal-2 compared with Meyal-5, signifying a shallowing trend attributed to thrust tectonics. This tectonic regime has rendered the area highly prospective for hydrocarbon exploration, with thrusting and oblique-slip faulting enhancing the reservoir qualities of Eocene Formations. The petrophysical evaluation revealed favorable reservoir characteristics, including an average porosity ranging from 0% to 12% with an effective porosity of approximately 7.5%, water saturation up to 42%, and hydrocarbon saturation reaching 58% within the pay zone of the reservoir. These findings suggest that the Sakesar and Chorgali Formations within the Meyal oil field hold promise as productive hydrocarbon reservoirs. The integrated study provides valuable insights into the structural framework and reservoir characterization, highlighting the potential of the Eocene Formations as productive hydrocarbon reservoirs supported by favorable structural configurations and petrophysical properties.

Depositional Environment, Petrophysical Evaluation and Electrical Properties of Zeit Formation, Northwestern Shore of Gulf of Suez, Egypt

Depositional Environment, Petrophysical Evaluation and Electrical Properties of Zeit Formation, Northwestern Shore of Gulf of Suez, Egypt

Petrophysical evaluation of the turbidite channels in Kafr Elsheikh Formation using wireline logging, West El-Burullus gas field, Offshore Nile Delta, Egypt

Petrophysical evaluation of the turbidite channels in Kafr Elsheikh Formation using wireline logging, West El-Burullus gas field, Offshore Nile Delta, Egypt

Petrophysical and seismic evaluation of pre rift sediments of the southern Gulf of Suez basin, Egypt

Petrophysical and seismic evaluation of pre rift sediments of the southern Gulf of Suez basin, Egypt

Reservoir characterization of GABO field in the niger delta basin using facies and petrophysical analyses

This study investigates the GABO field in the onshore Niger Delta Basin using well logs and core samples, with a focus on rock type distribution, reservoir continuity, and petrophysical properties to enhance hydrocarbon exploration accuracy. The research involved detailed analysis of core descriptions and images from GABO-20, along with petrophysical data from wells GABO-4, GABO-12, GABO-13, GABO-20, and GABO-51, aiming to identify rock types, evaluate reservoir quality, and determine the spatial distribution of petrophysical properties. The methodology included rigorous well log quality checks, data correlation between wells, petrophysical property evaluation, and lithofacies description. The analysis revealed thirty-five hydrocarbon-bearing zones, with GABO-20 showing average shale fraction values between 0.111 and 0.335, total porosity ranging from 0.242 to 0.329, and hydrocarbon saturation from 0.667 to 0.923, indicating substantial porosity and hydrocarbon saturation conducive to extraction. Well correlations demonstrated excellent sand-shale continuity within the reservoir intervals. Lithofacies analysis of the GABO-20 core identified eight distinct facies, including shale poles, liquid-rich shales, and sandstone poles, revealing a complex distribution of reservoir qualities with significant variations in potential. Cores 1 and 2 exhibited favourable conditions for hydrocarbon production, while Core 3 showed lower reservoir quality due to increased clay content. The depositional settings of the GABO field, particularly in the lower delta plain and delta front zones, showed well-developed reservoir bodies with moderate potential in the tidal zone and little potential in the shaly prodelta environment. This distribution highlights the complexity of the deltaic system and its implications for reservoir modeling and utilization. Reservoir zones associated with High-Quality Reservoir Facies exhibited strong petrophysical properties, suggesting excellent hydrocarbon production potential. The study underscores the importance of detailed reservoir characterization to optimize recovery strategies, offering valuable insights into the distribution and quality of reservoir sands, reducing subsurface uncertainty, and emphasizing the integration of facies and petrophysical approaches for a better understanding of reservoir characteristics in the GABO field.

Identification of the low resistivity-low contrast (LRLC) gas-bearing pay zones in Shaly sand reservoirs using acoustic data: a case study from the Messinian Abu Madi formation, onshore Nile Delta, Egypt

AbstractDetection of the low resistivity-low contrast (LRLC) reservoirs is among the main challenges in the oil industry. In this concern, the LRLC pay zones of the Upper Messinian Abu Madi clastic reservoirs in the onshore Nile Delta Gas fields became a main challenge for significant exploration. This type of reservoirs, including low resistivity-low contrast zones and thin-bedded intervals, are often overlooked using the conventional petrophysical evaluation techniques, especially in the wildcat exploratory wells or highly agitated shoreline depositional environments like the Nile Delta of Egypt. These hidden low contrast reservoirs are generally challenging due to the presence of many shale intercalations/laminations and/or due to increasing the shale volume represented in the form of dispersed distribution, and the dominance of conductive clay minerals. Therefore, in this study, the expected high resistivity values of the gas-bearing reservoir intervals of the Abu Madi Formation in the onshore Begonia gas Field, as a typical case study of the LRLC reservoirs, are masked due to the relatively high shale conductivity, particularly when the thickness of these intervals is less than the vertical resolution of the utilized conventional resistivity log. To verify the LRLC phenomena of the Begonia gas Field, the obtained data was compared to the South Abu El Naga gas Field as a normal case study with a relatively high resistivity gas-bearing pay zone. To overcome the impact of the conductive clay mineral content and identify these hidden low resistivity reservoir intervals, it is necessary to integrate the conventional logging data (gamma-ray, shallow and deep resistivity, density, and neutron) with the acoustic log data including shear and compressional sonic data. In this way, a useful relationship can be established enabling the detection of these hidden LRLC reservoir intervals. This integration is based on the principle that shear waves are not influenced by the fluids types, whereas the compressional sonic waves are influenced by the reservoir fluids. However, to effectively investigate these concealed LRLC reservoir intervals, which can boost production and increase the potential reserves, it is essential to have a low water cut value. The present study represents introduces an efficient workflow, which can be extended to other similar LRLC pay zones in the Nile Delta and northeast Africa. It is also extendible to the LRLC reservoirs in similar deltaic systems having conductive minerals-bearing reservoirs or thin beds.

Integrated geological quality evaluation using advanced wireline logs and core data: a case study on high clay shale oil reservoir in China

Abstract In the unconventional energy sector, shale oil is increasingly recognized as a crucial supplement to production. In recent years, China has made significant advancements in the development of shale oil. A unique type of pure shale reservoir in the Songliao basin, distinct from established shale oil reservoirs worldwide, has emerged as a focal point for exploration and research endeavors. This kind of shale exhibits enhanced heterogeneity, high clay content, intricate rock electricity relationship, posing significant challenges to formation evaluation. This study introduces conversion coefficients for the elements and minerals, a decision tree model, a variable T2 cutoff value method, and 2D NMR cluster analysis, all based on the integration of microimaging, spectroscopy, and 2D NMR logging. These novel approaches facilitate a comprehensive geological quality evaluation of key parameters, including mineral composition, lithology, effective porosity, total organic carbon content, fluid composition, and saturation characteristics within pure shale formations from the Songliao Basin. The established petrophysical model has been validated by core analysis data and successfully applied in exploration wells. Through systematic petrophysical analysis, the optimal landing point for horizontal wells was identified based on the identification of the best reservoir quality interval with high movable oil and oil saturation. The subsequent drilling of horizontal wells demonstrated the reliability of petrophysical evaluation in terms of oil production. This integrated evaluation method for pure shale holds reference significance for similar shale reservoirs in other blocks in the future.

Petrophysical evaluation of Bahariya sandstone reservoir in Al-Fadl and Al-Qadr Fields, North East Abu Gharadig Basin (NEAG), Western Desert

Petrophysical evaluation of Bahariya sandstone reservoir in Al-Fadl and Al-Qadr Fields, North East Abu Gharadig Basin (NEAG), Western Desert

A Petrophysical Properties Evaluation Study of a Niger Delta Field Using Well Logs and Core Data

A petrophysical properties evaluation study of an onshore field “NEMA” was carried out to assess the petrophysical characteristics of the field in the eastern portion of the Niger Delta Basin. This was done in an effort to determine the hydrocarbon prospect and oil productivity potential of the reservoirs. The net/gross thickness was one of the examined parameters. (pay zone thickness), porosity, permeability, fluid saturation which were all inferred from geophysical wireline logs and core data. The wireline logs used in the investigation included density, resistivity, gamma ray, and spontaneous potential logs for five different wells from the “NEMA” oil field. Five reservoirs designated, NEMA 01, NEMA 04, NEMA 07, NEMA 09, and NEMA 12 were identified and correlated across the five wells in the field using gamma ray logs and shale resistivity markers. Based on the computation of petrophysical parameters, the porosity of the reservoirs ranged from 0.22 (22%) to 0.31 (31%); the permeability ranged from 851.58 mD to 1005.05 mD; the average net-to-gross thickness of the reservoir sand bodies was 140 ft; the water saturation value was less than 45%, while the hydrocarbon saturation was greater than 55%. We equally observed that our computed petrophysical parameters from well log data correlated well with the core computed values in NEMA 09. In conclusion, the delineated reservoirs were categorized as good hydrocarbon reservoirs. These results suggest huge hydrocarbon potential and a reservoir system whose performance is considered satisfactory for hydrocarbon production.

Formation Evaluation and Petrophysical Analysis of Well Logging Data: an Example From Matruh-Shushan Basin, North Western Desert, Egypt

Petrophysical evaluation of well logging data is crucial for exploring and improving oil and gas reservoirs. This involves obtaining reliable information about the rocks and fluids in the reservoir to estimate reserves and make informed decisions about drilling, production, and development strategies. In this study, data from six wells in the Matruh-Shushan Basin were evaluated using Log Quality Control procedures. Two zones of interest, Lower and Upper Safa members, were identified, and quantitative interpretation was conducted to determine the most effective parameters defining reservoir quality: Shale Volume, Effective Porosity, and Water Saturation. Results were positive, with promising net pay for both reservoirs. Numerical models and statistical methods were used to account for data uncertainties and provide reliable estimates of reservoir properties. The study highlights the significance of correct interpretation in successfully exploring and producing hydrocarbons.

Petrophysical evaluation of Lower Bahariya Reservoir using integrated ‎well-logs and core data analysis in Yasser field, North Western Desert, ‎Egypt.‎

Petrophysical evaluation of Lower Bahariya Reservoir using integrated ‎well-logs and core data analysis in Yasser field, North Western Desert, ‎Egypt.‎

Structural assessment and petrophysical evaluation of the pre-Cenomanian Nubian sandstone in the October Oil Field, central Gulf of Suez, Egypt

The low quality of the seismic resolution of the studied Cambrian Pre-Cenomanian formations, which rest directly on the basement in the October Field in the Gulf of Suez, requires study, and the structure pattern controlling these formations is uncertain. The poor quality of the seismic data resolution in the Gulf of Suez is due to the presence of thick sequences of evaporites represented by the South Gharib and Zeit formations. Therefore, the current study used seismic reflection data integrated with well-log data to define the structural-stratigraphic setting of the pre-Cretaceous Nubian reservoir sequence. The study aims at locating and delineating zones having excellent reservoir potential within the Nubian sequence horizons (Nubian Transition, main Nubian, Nubian marker-1, and Nubia marker-2, referred to as NT, MN, M1 and M2, respectively) through the integration of the 3D static modelling and the petrophysical parameters deduced from the well-log data processing. A detailed petrophysical analysis, based on the wireline logs of some wells, was performed to determine the lithological units using two types of cross plots (Neutron-Density and M-N plots), and the different petrophysical parameters that characterize the various Nubian horizons were also computed. 3D modelling was used to visualise the lateral and vertical changes of the reservoir characteristics. The seismic mapping reveals that the Nubian structure is controlled by an NW-SE trending (Clysmic trend) of an NE-plunging asymmetrical anticlinal feature unconformably resting on a basement horst. The main structure is affected by two major normal faults, which trend NW, andis cut by two smaller sub-parallel faults that disturb the core of the structure, which is unaffected by the easterly oriented faults of the Aqaba trend. The petrophysical analyses indicate that the Nubian sandstones have intervals of good reservoir quality, with a total net-pay thickness of about 500 m, net sand ratios (60–90 %), effective porosity (10–25 %), and hydrocarbon saturation (85%), which may encourage further drilling, especially in the southeast portion. The result of this study can be extended to the other Nubia sandstones resting on the basement complex in the Gulf of Suez.

Petrophysical Evaluation of Arkoses Reservoirs Based on Well Logs and Plug Samples: A Case Study From Alagamar Formation, Southeastern Portion of Onshore Potiguar Basin, Brazil

The Potiguar Basin is a sedimentary basin located in northeastern Brazil. It covers about 48,000 km² and extends from onshore to offshore. The onshore basin is thought to have formed during the Late Cretaceous, as a result of the opening of the Equatorial South Atlantic Ocean, filled with a thick sequence of sedimentary rocks, including sandstones, shales, and limestones, which were deposited in a variety of processes, including marine, deltaic, and fluvial. The study area is in the southern portion of the basin and the reservoir is composed of arkose sandstones deposited by alluvial fan and fluvial systems of the Upanema Member of the Alagamar Formation, which belongs to the post-rift phase of the Potiguar Basin. Recently, new drilling campaigns revealed a reservoir heterogeneity in these deposits, which requested a new petrophysical approach. Using conventional well logs and petrophysical laboratory analysis of plug samples, this study evaluated the best way to calculate the effective porosity, and shale volume and to understand the stratigraphic controls in the distribution of these properties. Three reservoir zones were mapped: the basal one, Zone 3, has disconnected sand bodies, low porosity, and high shale content; Zone 2 has better petrophysical properties, lateral distribution, and connectivity between the fans and Zone 1 is the better reservoir zone with larger sand bodies, higher porosity values, and well-connected fans.

Petrophysical evaluation and parameters relations investigation of Nubia formation in October field, Gulf of Suez, Egypt.

Petrophysical evaluation and parameters relations investigation of Nubia formation in October field, Gulf of Suez, Egypt.

Właściwości złoża jurajskiej formacji Khatatba: Pole naftowe Tut, Pustynia Północno-Zachodnia, Egipt

The Tut oil field is in the North-western part of the Western Desert. This work aims to study the reservoir characteristics, to evaluate the hydrocarbon potentiality of the Upper and Lower Safa Members based on the available subsurface data obtained from open-hole well log records of four wells distributed in the study area. Numerous isopach and lithofacies maps have been constructed. The petrophysical evaluation, in terms of determining reservoir net-pay thickness, shale content (Vsh), effective porosity (∅eff), water saturation (Sw) and hydrocarbon saturation (Sh), were estimated. The vertical and the lateral distribution of the reservoir characteristics, in the form of litho-saturation cross-plots, iso-parametric maps and lithologic-matrix cross-plots were constructed. Three hydrocarbon charged zones in the Khatatba Formation were defined and represented by the Upper Safa-Top, Upper Safa-Bottom and Lower Safa-Top. The upper most part of Upper Safa Member (Upper Safa-Top) reservoir represents an oil producing zone where it consists of shallow marine to alluvial sediments. The Lower most part of Upper Safa Member (Upper Safa-Bottom) reservoir represents gas producing zone where it consists of a thick alluvial sand body. Finally, the upper most part of Lower Safa Member (Lower Safa-Top) reservoir represents an oil-gas producing zone consisting of shallow marine sediments with high terrestrial input. The iso-parametric maps show that Northern and central parts of the study area are the most favorable parts for hydrocarbon accumulation due to the increase in net-pay thickness and average effective porosity and decrease in water saturation toward these parts.

Focused reservoir characterization: analysis of selected sand units using well log and 3-D seismic data in 'Kukih' field, Onshore Niger Delta, Nigeria

This study focuses on the comprehensive reservoir characterization of the ‘Kukih’ Field within the onshore northeastern Niger Delta region, Nigeria. The absence of its detailed description with delineated reservoir properties, lateral continuity, and their use to identify potential reservoir quality and heterogeneity necessitated this study. Integrating well log and 3D seismic data, the investigation aims to elucidate reservoir properties, lithofacies, and depositional environments to unravel hydrocarbon potential. The geological setting, encompassing the Agbada Formation of Early and Middle Miocene age, is scrutinized through detailed geologic analysis. Petrophysical evaluation of four well logs (Kukih-1, Kukih-2, Kukih-3, and Kukih-4) facilitated the determination of key parameters such as shale volume, effective porosity, and water saturation. Seismic interpretation further enriched the structural characterization of the field. Results showcase three predominant reservoir sands (A, B, and C) with distinct lithofacies and thickness variations. Effective porosity ranges from Fair to Excellent, with permeability exhibiting high values for hydrocarbon reservoir potential. Water saturation trends, lithofacies distributions, and structural features were illuminated through iso-parametric maps and seismic analyses. Depositional environments were inferred through facies analysis, revealing the presence of funnel-, cylinder-, and bell-shaped successions that hint at intricate marine sedimentary processes. Challenges owing to limited core data were acknowledged, and the integration of methodologies emerged as a pivotal strategy for enhanced reservoir understanding. This study underscores the ‘Kukih’ Field's hydrocarbon potential, accentuating the significance of multidisciplinary approaches in deciphering complex reservoir systems. In light of the petrophysical analysis derived from the well logs and the identification of structural highs through the structural maps, this study recommends the drilling of unexplored zones exhibiting promising structural characteristics.

Petrophysical evaluation based on three-stream convolutional neural networks in the Berkine Basin, Algeria

Petrophysical evaluation is a key stage before formation test in exploration field, it allows the identification of the best plays in term of effective porosity, shale volume and hydrocarbon saturation. This paper introduces an innovative approach to petrophysical evaluation by leveraging deep learning techniques, our scheme is based on three streams, in each stream we predict a petrophysical parameter (Volume of shale, Effective Porosity and water saturation), each stream represents a convolutional neural network model that has been trained using traditional wireline logging data from the Silurien argilo-greseux reservoir units in the Berkine Basin, Algeria. experimental results show that our proposed method achieves stat-of-the-art predictions by giving correlated results in comparison against conventional analysis methods (calculated Shale Volume, Porosity and water saturation), furthermore assessment of test data shows also that our method gives good prediction in thin beds reservoirs and offers the ability to detect low resistivity pays. Because our method is based on Convolutional neural network models, it is fast and allows the petrophysical parameters prediction in real time.

Petrophysical evaluation and hydrocarbon potentiality of the Kareem sand reservoir at GS277 oil field, Gulf of Suez, Egypt

Petrophysical evaluation and hydrocarbon potentiality of the Kareem sand reservoir at GS277 oil field, Gulf of Suez, Egypt

Petrophysical analysis to determine the hydrocarbon prospectivity of sands in AA field, Niger Delta

Petrophysical analysis is a crucial process in the oil and gas industry. It entails the analysis and interpretation of well logs, fluid samples or core smaples to understand the behaviour of the embedded reservoirs in the subsurface. Three well logs from AA field were provided for this study, but two well data were finally loaded to the workstation due to absence of key well logs (such as gamma ray and density logs) from the third well. The quality control check of the data was done prior to the uploading of data. Delineation of lithologies and identification of hydrocarbon reservoirs were done; the identified reservoirs were correlated across the two wells; and the petrophysical evaluation (such as estimations of shale volume, porosity, permeability and water/hydrocarbon saturation) of the three pay zones (that is, Sand A, B and C) in AA field were done. The porosity of Sands A, B and C varied from 0.27 to 0.28, 0.24 to 0.30 and 0.27. The permeability of Sands A, B and C varied from 1012 to 1314 md, 884 to 1013 md and 692 to 892 md. Meanwhile, the hydrocarbon saturation for Sands A, B and C varied from 1 to 89%, 45 to 80% and 79 to 80%, respectively. It can be concluded that the order of hydrocarbon prospectivity of the reservoir sands correlated across Well AA-1 and Well AA-2 is Sand C > Sand B > Sand A.