Good Reservoir Research Articles

POTENSI BATUGAMPING TERUMBU GORONTALO SEBAGAI BAHAN GALIAN INDUSTRI BERDASARKAN ANALISIS GEOKIMIA XRF

Reservoir rocks are hollow rocks below the surface that are capable of storing and flowing groundwater that can be utilized by the community. The limestone facies is a good reservoir rock. The characteristics of the limestone facies in the Ombulo Region, Gorontalo Regency, which reach 3.42 km2, are very interesting to study. This study aims to analyze the porosity value of each limestone facies in the study area. The research method used consisted of field geological surveys and petrographic laboratory analysis. The results showed that the study area consisted of four limestone facies namely floatstone facies, mudstone facies, wackestone facies, and rudstone facies. The potential of limestone in the Ombulo area as reservoir rock is in the poor to very good category.

Carbonate facies patterns of the Lutetian-Priabonian strata from the western Indian plate margin: Reservoir potential and palaeoclimatic implications

The Lutetian–Priabonian (47.8–33.9 Ma) formations from the western Indian Plate margin (the Central Indus Basin of Pakistan) are investigated for reservoir potential assessment in the light of climatic implications using new well data based petrophysics combined with the statistical approach of cluster analysis. The electrofacies resulted from the distinctive patterns of the gamma ray (GR), sonic (DT), and density (RHOB) geophysical logs delineating carbonate reservoir heterogeneities across the study area. The Habib Rahi Limestone shows good reservoir intervals in the area. The findings suggest that the Lutetian–Priabonian Pirkoh and Habib Rahi Limestone are classified as class 3 (mud dominated) and class 2 (wackestone–packstone) type rock fabric based on the total porosity (φT) vs water saturation (Sw) cross plots, respectively. The study concludes eustatic dynamics as the dominant factor in controlling the carbonate deposition in the study area. Based on the investigated carbonates reservoir facies heterogeneity across the Central Indus Basin of Pakistan, it is proposed that the carbonates of Sulaiman Depression were likely deposited during major transgression-regression events, witnessing a climatic change from warmer in the Ypresian–Early Lutetian to cooler one in the Middle Lutetian to Priabonian. The depositional model proposed inner to middle shelf facies for the Pirkoh whereas middle to outer shelf slope facies for the Habib Rahi Limestone in the Central Indus Basin of Pakistan. The results of this study suggest that the carbonate reservoir heterogeneity occurrence in space and time may be traced to design a strategy for hydrocarbon exploration in the Central Indus Basin of Pakistan and in analogous settings around the world.

Upscaling of geological properties in a world-class carbonate geothermal system in France: From core scale to 3D regional reservoir dimensions

The greater Paris area has some 12 million inhabitants and 48 heating network production units that exploit the heat capacity of a 1.5 km deep aquifer, the Bathonian limestone. This is one of the most productive aquifers in the world for district heating, with an annual output of about 1.7 TWh of energy. The current challenge for Paris is to triple the number of heating networks using geothermal energy so as to reduce dependence on fossil fuels (40% in 2020 in France). As no detailed geothermal reservoir model is available, drilling involves geological risk. A recent well, drilled at Grigny (20 km south of Paris), turned out to be a failure in transmissibility because the bed of permeable limestones it tapped into was very thin (meter-scale). The main aim of this study is to create a digital database and a 3D geological model of this aquifer to minimize geological risks and optimize the location of future geothermal operations around Paris. By compiling data from 168 wells, a high-resolution 3D geological model of 360 km3 size is constructed (about 40 km x 50 km x 0.2 km), made up of 12.2 million cells and displaying sedimentary facies, sequence stratigraphy, porosity (Φ) and permeability (k). About 20% of the oolitic and bioclastic facies are of good reservoir quality (Φ > 13% and k > 350 mD), especially in two targeted, high-quality reservoir sequences. These facies of interest probably correspond to giant dunes and a shoal/barrier prograding from east to west. In these facies, permeable zones are generally 4 m thick and form patches of 1600 m x 1100 m, on average, elongated perpendicular to the depositional slope. 2D and 3D maps of temperature, salinity, porosity, transmissivity, and permeability allow us to understand the areas of interest for geothermal exploration, as demonstrated around Grigny. This model helps us to apprehend better the heterogeneous character of the reservoir for geothermal prospection and to reduce the risk of future doublets during well implantation. Detailed local models may be extracted to anticipate better the implantation of new doublets in areas with already densely spaced existing wells.

Characteristics and Geological Implications of Lacustrine Carbonate of Nantun Formation in Hailar Basin

Abstract Globally, lacustrine carbonate rocks are often found in rift lake basins. Because they often do not form large-scale conventional or unconventional reservoirs, they have not received enough attention in previous oil and gas exploration. Recent years, exploration examples in China show that lacustrine carbonate has close relationship with unconventional oil and gas. Mudstone with carbonate deposits always has a good exploration effect in the area. However, the genesis of lacustrine carbonate is still controversial. The sediment environment difference between carbonate and mudstone and its effects on unconventional hydrocarbon accumulation are not yet clear. This paper focuses on lacustrine carbonate found in the Nantun Formation in Hailar Basin. Through the analysis of lithofacies, geochemistry, and logging data, several findings have been obtained in the current study. (a) Two kinds of lacustrine carbonates, micrite dolomite and marlstone, which represent semideep to deep lake environments, have been identified in the research area. (b) Lacustrine dolomite (LD), whose genesis may relate to magmatic movement and deep hydrothermal processes, shows an extremely dry, hot paleoclimate and a saline, anaerobic ancient water condition. (c) Carbonate deposition in mudstone is related to the condensation section, and marlstone and micrite dolomite represent the beginning and end of the condensation section, respectively. Compared with mudstone around carbonate rocks, LD represents a drier, hotter, and saltier environment, which is of significance for sedimentary environment identification. In addition, the mudstone with lacustrine carbonate deposits has better organic matter characteristics and can form good unconventional oil and gas reservoirs that are of great significance for further exploration.

Reservoir characteristics of Datta Formation (Early Jurassic), Marwat-Khisor Ranges, sub-Himalayas, Pakistan

The present work has been accomplished to carry out a detailed study of the characteristics of the Early Jurassic Datta Formation of Trans-Indus Ranges, Pakistan. The discovery of Saib well-1 (Gas and condensate discovery from Jurassic limestone) in the study basin takes an active interest in carrying out extensive exploration activities in the same basin. Jurassic rocks especially Datta Sandstone and Samana Suk Limestone are acting as good reservoirs. The study unit consists of variegated sandstone interbedded with siltstone, carbonaceous clay, and shale and coal stringer. For the current work, two stratigraphic sections (Pezu and Abbo Wanda) have been measured. To examine its sedimentology, depositional environment, diagenetic settings, and reservoir characteristics, a detailed study was conducted and various laboratory techniques have been utilized. About 95 rock samples from the bottom to the top of both sections were collected, and 50 rock samples have been selected for thin section analysis and were examined under a polarizing microscope to show their mineralogical composition, diagenesis, and their reservoir characteristics. XRD (X-ray diffraction), Cathodoluminescence (CL), SEM (Scanning electron microscope) with EDS (Energy-dispersive spectroscope), and Core plug porosity and permeability analysis have been used to interpret its chemical and mineralogical composition and its reservoir characteristics, respectively. Based on field observations and thin section analysis, four depositional facies and six lithofacies have been established. The sedimentary structures, depositional facies, and lithofacies indicate that Datta Formation was deposited in a deltaic environment. Compactions, cementation, fracturing and dissolution can greatly affect the quality of reservoir rock. Based on thin section and SEM analysis, large numbers of primary pores, fracture and secondary pores were observed and connectivity between the pores is good, and at some places, these pores were filled through the authigenic clay minerals like kaolinite, mixed layers illite/smectite and chlorite that influences the reservoir characteristics. Primary pores (thin section) and secondary pores (dissolution pores) and core plug porosity and permeability data (porosity 13.23%–26.89% and permeability 0.12 to 149 mD) shows that Datta Formation has a good reservoir quality.

X-ray computed microtomography revealing the effects of volcanic, alteration, and burial processes on the pore structure of rocks from unconventional reservoirs (Songliao Basin, NE China)

The pore structure and storage volume of rocks are crucial parameters to evaluate the favorability of hydrocarbon reservoirs. The unconventional volcanic reservoirs in the Songliao Basin (NE China) include lava and pyroclastics of different composition. Here we apply the X-ray computed microtomography (micro-CT) to reconstruct the 3D pore space of selected samples (basaltic lava, rhyolitic lava and rhyolitic pyroclastics) at depths between 2283 and 3757 m. We reconstruct the morphology and size distribution of the pores. The pore structure records the effects of superimposed volcanic, alteration, and compaction-burial processes. This latter process produces fractures in the rhyolitic pyroclastic rocks. The basaltic lavas have larger, connected pores filled by alteration minerals with a prolate shape, and unconnected, smaller, blade-like, empty pores. The hydrothermal alteration reduces the porosity and the rock is impermeable being the smaller voids unconnected. The basaltic lavas are good cap rocks but very poor reservoir rocks. The rhyolitic lava flows and pyroclastics, some of which placed in the gas zone of the Songliao reservoirs, show prevailing interconnected fractures due to burial processes and minor pores around crystals formed by syn-eruptive heterogeneous gas nucleation. The pore connectivity is ensured by the fractures and the permeability may be high, also depending on the volume, more than on the number, of the pores. Rhyolites may be good reservoir rocks. We search for possible relationships between porosity and permeability and do not find a clear relation between these two parameters as well as between depth and permeability. Although our analysis is valid within a length scale between about 20 μm and 1 cm, the methodological approach used here can be extended to other reservoirs to study the evolution of the pore systems as a function of the different processes affecting the volcanic rocks.

Hydrocarbon dominant migration direction and accumulation mode in Qijiang area, Sichuan Basin, China

The high‐quality hydrocarbon source rocks developed in the Longtan Formation of the Qijiang area and the good reservoir capacity of the overlying dolomite of the Jialingjiang Formation indicate that the area has great exploration potential. To clarify the hydrocarbon migration and accumulation characteristics of the area, the fluid potential of the Longtan Formation in the Qijiang area in the Early Jurassic was determined. The direction of the maximum negative gradient of the fluid potential indicates the direction of the primary migration of hydrocarbons, and the structural ridge theory is used to analyse the direction of the secondary migration of hydrocarbons. The results show that the fluid potential of the hydrocarbon source rocks of the Longtan Formation in the Early Jurassic is characterized by the alternate distribution of high potential zones and low‐potential zones. The central syncline, eastern syncline and western syncline are drainage zones and high potential zones, while the Shiyougou structural belt and Fo'er Ya structural belt are supply zones and low‐potential zones. The oil and gas fluids migrate from the east–west direction to the anticlinal zone for the primary migration; the structural ridge controls the secondary migration of oil and gas in the low‐potential area along the north–south direction, resulting in a zonal distribution of oil and gas traps along the structural ridge. By combining fluid potential and structural ridge characteristics to determine the dominant direction of primary and secondary hydrocarbon migration, a model of hydrocarbon migration and accumulation in the Qijiang area is developed, which provides an important basis for finding hydrocarbon reservoirs.

Applying Facies Characterization to Build 3D Rock-Type Model for Khasib Formation, Amara Oil Field

Building a rock-type (facies) model is critical in the process of constructing the geological model.The facies model utilizes the facies obtained from the different characterization methods to represent the structure and the geology of the studied reservoir. Therefore, the importance of building a 3D rock-type model is to distribute the petrophysical properties depending on the rock facies to reflect the actual distribution and achieve a realistic model.Khasib formation in Amara oil field is mainly composed of limestone and exhibits a high degree of heterogeneities in its petrophysical and geological features, showing a complicated porosity-permeability relationship. Hence, the formation should be characterized by facies with specific property relationships and use these facies to build an accurate rock-type model to represent the geological rock modeling for this carbonate formation.The Rock-Type model for Khasib formation has been constructed using the facies obtained from flow zone indicator and cluster analysis characterization methods, these facies were distributed with the PETREL software by applying the sequential indicator simulation (SIS) algorithm.The 3D Rock- type model establishes that a different rock type characterized each unit within Khasib formation; the reservoir units (KH11, KH12, and KH2) were characterized by the presence of RT-1, RT-2,andRT-3, which represent the best, good, and intermediate reservoir quality rocks, respectively. The best rock type RT-1 with the best reservoir petrophysical properties was only noticed in unit KH2. The non-reservoir units (Khasib, Base KH11, Base KH12, and Base KH2) were characterized by RT-4 and RT-5, which reflect the bad rock quality with non-reservoir properties.

Reservoir quality evaluation using petrophysical, well-log analysis and petrographical description: A case study from the Carboniferous-Permian Kulshill group formations, southern Bonaparte Basin, Australia

The Carboniferous – Permian Kulshill Group formations are producing reservoirs in the Petrel subbasin, Australia. The studied Keyling and Kuriyippi formations were investigated by integrating petrophysical, petrographical, sedimentological, and well-log interpretations. The petrophysical study reveals that both formations Keyling and Kuriyippi have very good porosity (max. 30.9% and 25.2% respectively) and permeability values (max. 3053 mD and 1025 mD respectively) indicating good reservoir quality. Based on petrographic descriptions, both formations comprise very fine to coarse-grained sandstone and moderate to well-sorted with abundant intergranular porosity. Many diagenetic factors acting on the reservoir quality of the Kulshill Group formations are observed. Cementation and clay minerals as well as secondary porosity is more visible in both formations while at the same time the formations still holding good enough reservoir quality.The interpreted well-log data indicate that the Kuriyippi Formation is mostly oil bearing, whereas the Keyling Formation is water bearing reservoir. The average petrophysical parameters of both formations show that porosity values reaching up to 16.5–32.3% respectively, and clay volume up to 25.2% with abundance of montmorillonite, mixed clay layers, while glauconite, micas, and illites were found in few amounts in both formations. The hydrocarbon saturation recorded higher values (up to 80.4%) in the Kuriyippi Formation while the measured values in the Keyling Formation is less and the water saturation is always playing around the cutoff values. This can be attributed to the presence of the permeability barrier Treasury shale Formation underlying the high quality Keyling sandstone reservoir blocking the upward migration of hydrocarbon.

A dataset of microscopic images of carbonate rocks of Leikoupo Formation of Middle Triassic in the Central Sichuan

The abundance of widely-developed carbonate rocks of the Leikoupo Formation in Central Sichuan Basin shows good exploration prospects and great exploration potential. Carbonate reservoirs in central Sichuan Basin are well formed, and various pores are well developed and preserved. Supergene dissolution, buried dissolution, and dolomitization have improved reservoir physical properties and is conducive to the reservoir permeability. Pore types including intragranular dissolved pores, intergranular dissolved pores, mold pores, etc. brings out connected dissolution fractures. At the top, a good paleoweathering crust reservoir is formed under karstification. By collecting the strata of Leikoupo Formation encountered in Well LG 19, Well LG 173, Well ZT 1, Well TN 112, Well Y 105, and Well PL 19 in the Central Sichuan Basin as the research object, we produced a dataset of rock micro thin section data. Leikoupo Formation in the Central Sichuan Basin is mainly composed of algal laminar dolomite, sandy dolomite, and breccia dolomite. The sedimentary facies are carbonate evaporation limited platform facies. The subfacies can be divided into tidal flat and intra platform beach subfacies. The tidal flat has microfacies such as cloud flat and gypsum cloud flat. And the intra platform beach can be subdivided into bioclastic beach and sandy beach. This dataset can be used to divide the sedimentary microfacies of the Leikoupo Formation in this area, study the control of the formation and distribution of micro relative reservoirs, determine the favorable reservoir microfacies, and provide effective guidance for oil and gas exploration and development. The image dataset can further provide basic data support for the production of machine learning image dataset.

Seismic sequence stratigraphy and depositional modelling of the Lower Fahliyan Formation in the northwestern Persian Gulf, SW Iran

This study presents seismic stratigraphic-based sedimentary conceptual modelling through the integration of well data, seismic data, and literature in order to identify the architecture of the Berriasian-Early Valanginian Lower Fahliyan Formation in the northwestern Persian Gulf. The applied methodology is configured by interpreting seismic sections in terms of sequence stratigraphy and adapting them using well data facies associations and fossil assemblages. The time framework of these sediments is identified by their faunal/flora assemblage and extrapolated by seismic data because of their extensive coverage. Three third-order depositional sequences (DS-I, DS-II, and DS-III) were distinguished based on the facies changes, depositional geometries, and fossil assemblages. Regional and local tectonic activities and global sea-level changes controlled the sedimentation of the depositional sequences. The local tectonic activities were of higher importance as they strongly affected the thickness and facies type of the studied interval. The depositional sequences of the Lower Fahliyan Formation are deposited in the inner to outer settings of a carbonate shelf. It was concluded that DS-I and DS-II over the platform (Surmeh Platform), consisting of progradational parasequences, deposited during the highstand phase in shoal settings that due to primary texture and subsequent diagenetic imprints yield the best reservoir quality. The relationship of the parasequences with good reservoir quality was determined on seismic sections and the prepared regional correlation panel over the study area. Furthermore, the paleoenvironmentof the area was constructed and modelled for major stratal surfaces (Sequence boundaries and maximum flooding surfaces). According to the generated models, the distal setting (Garau Basin) migrated back gradually northward during the Berriasian-Early Valanginian so that it was completely replaced by a homoclinal ramp at the end of the DS-III deposition. Subsequently, the relief of Surmeh Platform was also flattened and it was recognized as the end of the first phase of the basin's activity.

NEW DATA ON PROMISING OIL AND GAS OBJECTS OF THE YAMNA SUITE OF THE PALEOCENE IN THE SOUTH-EASTERN PART OF THE SKІBA AND KROSNO COVERS OF THE UKRAINIAN CARPATHIANS

Thick sandstones of the Yamna suite are widespread throughout the Skіba cover, as well as in the south-eastern part of the Krosno cover. The research area is bounded by the Limnytsia River in the northwest and the Ukrainian-Romanian border in the southeast. Several promising structures comprising the Yamna sandstones (Brusturanska, Yanovetska, and Voronenkivska) are identified in this area. Among them, according to the number of positive indicators of oil and gas potential, the Voronenkivska structure (Nadvirna district of Ivano-Frankivsk region, near the settlements of Voronenka, Yablunytsya, Polyanytsya) is the most promising, localized in the Zelemyanka slice. The structure is divided by faults into four tectonic blocks and stretches for 8 km. Under the Oligocene rocks, crumpled into the anticlinal fold of the north-western extension, Paleocene-Eocene deposits are inferred according to the geological models, which contain thick sand strata of the Vyhoda (Middle Eocene) and Yamna suites of the total thickness over 300 m. Oil manifestations are documented in the Oligocene deposits on the surface. Potentially promising horizons may be in the depths range 1500-1800 m. The article extends the previous work devoted to the assessment of the oil and gas prospects of the Yamna suite of the Paleocene of the north-western part of the Skуba cover of the Ukrainian Carpathians. 4.2 million tons of oil were recovered from the Yamna sandstones of the Paleocene, which are characterized by good reservoir properties, in the fields localized in the north-western part of the Skiba cover. The Yamna sandstones in this sector of the Carpathians are also common in the Krosno cover. The uneven distribution of industrial oil potential between these two parts of the Carpathians is explained by lithological changes or the influence of structural and geochemical factors. A study of stratigraphy and reservoir properties of the Yamna sandstones, common in the deposits of the Skіba and Krosno covers, suggests that they comprise satisfactory reservoirs for hydrocarbons. Promising areas and structures have been identified and described.

Enhanced resistive switching performance of TiO2 based RRAM device with graphene oxide inserting layer

In this work, graphene oxide (GO)/TiO2 heterostructures for resistive random access memory devices were fabricated, and the composition and microstructure of TiO2 and GO were characterized by x-ray diffraction, Raman spectroscopy, scanning electronic microscopy, and transmission electron microscopy. The resistive characteristics of the fabricated devices were investigated, and the remarkable improvement in cycle-to-cycle uniformity and high ON/OFF ratio of the TiO2 thin film-based memory device were realized by introducing a thin GO layer. The formation/rupture of the conductive filament through the migration of oxygen vacancies in the TiO2 substrate was responsible for the resistive switching. Owing to the different activation energies of reduction and oxidation of the GO, the set voltage became larger than the reset voltage. According to the linear fitting of double logarithm I–V plots, the conduction mechanism in low and high resistance states was governed by the ohmic mechanism and trap-controlled space charge limited current, respectively. The oxygen migration-induced oxidation/reduction in GO rendered it a good oxygen vacancy reservoir, which is responsible for the enhanced cycle-to-cycle uniformity and high ON/OFF ratio.

Large physical simulation test of cavitation reservoir stimulation

The cavitation reservoir stimulation technology is a kind of reservoir stimulation technology proposed in recent years for refined stimulation of reservoirs near the wellbore wall. It has the characteristics of less equipment required, simple process, clean and environmentally friendly, and low operating cost, and can effectively improve the heterogeneity of reservoir. However, the understanding of this technology is insufficient to provide technical support for its engineering application due to the lack of experimental research foundation. Therefore, this study developed a large-scale test device, conducted a physical model test of cavitation reservoir stimulation, and revealed the mechanism and treatment effect of cavitation reservoir stimulation technology. In accordance with the analysis of vibration monitoring parameters, the cavitation effect can produce pulse vibration in the wellbore when the pump pressure≥6 MPa. In accordance with the analysis of pressure monitoring data, the pressure in the middle part of wellbore (10–30 D) is the highest, which is about 1300 kPa, whereas the pressure in the outlet area of cavitation device is the lowest, which can produce a “negative pressure effect” in the simulated wellbore. In accordance with the physical parameters of the rock samples before and after the experiment, the average compressive strength and elastic modulus of rock samples are reduced by 75% and 80% respectively, by the cavitation reservoir stimulation, the impurities in rock voids are effectively removed, and the porosity and permeability are increased by about 20% and 200% respectively, to achieve a good reservoir stimulation effect. The research results of this study will provide key technical support for the theoretical research and engineering application of cavitation reservoir stimulation.

Possible geological interpretation of the volcanic seismic facies based on volcanostratigraphy elements: A case analysis of the Yingcheng Formation in the Changling Fault Depression, Songliao Basin, NE China

Volcanic rocks in faulted depressions are one of the most interested areas for hydrocarbon exploration. In a frontier basin exploration, integrated interpretation of the seismic facies of volcanic rocks is a key success. The key information of boundary system and deposited unit in the volcanostratigraphy did not attract sufficient attention during the process of seismic stratigraphic interpretation of volcanic rocks. In this paper, the volcanic rocks of the Yingcheng Formation in the Changling Fault Depression of the Songliao Basin are taken as an example. According to the maximum average slope, the volcanic seismic facies were divided into three types: mounded seismic facies unit (MSFU), tabular seismic facies unit (TSFU), and mounded-tabular seismic facies unit (M-TSFU). MSFU consists of lava dome and simple lava flows, which has fewer reservoir layers, medium to poor reservoir quality with limited extension. The TSFU comprises more complex component of simple lava flow and base surges, and contains more layers, with good-medium reservoir quality and a large reservoir extension. The M-TSFU has numerous reservoir layers with good reservoir quality and a significant reservoir extension, as well as a higher proportion of braided lava flows and pyroclastic flows. Going from the most favorable reservoir targets to the least favorable, the following units were deposited in the Changling Fault Depression: pyroclastic flow, braided lava flow, base surge, simple lava flow, lava dome, and reworked volcanic clastic flow. The study suggested that mounded-tabular facies units are potential favorable exploration targets in the Songliao Basin. This paper provides a technical route for seismic facies interpretation of volcanic rocks and the analysis of favorable volcanic exploration targets in faulted volcanic basins.

Integrated Geological and Petrophysical Approaches for Characterizing the Pre-Cenomanian Nubian Sandstone Reservoirs in Ramadan Oil Field, Central Gulf of Suez, Egypt

The present study integrates multidisciplinary geological and petrophysical approaches to characterize and evaluate the potential of the pre-Cenomanian Nubian sandstone reservoirs in the Ramadan oil field, the central offshore part of the Gulf of Suez, Egypt. The different petrophysical parameters of the Nubian sandstone reservoirs (shale volume, porosity, water saturation as well as gross and net-pay thicknesses) were mapped, and 3D slicing models for the hydrocarbon phases saturation were constructed to understand the reservoir heterogeneity and the distribution of the best reservoir facies. The petrophysical results of the pre-Cenomanian Nubian succession highlight very good reservoir intervals in the Nubian C sandstones containing thick pay zones (> 120 m). On the other side, the Nubian A and B reservoir rocks are less prospective with pay zone horizons (< 10 m). Integrated reservoir models and wireline log analysis elucidate that clay volume is the most detrimental factor to the reservoir quality as the pay zone thickness and hydrocarbon saturation often increase where the clay volume decreases. Therefore, the presence of scattered pay zone intervals in Nubian A and B is mainly related to their elevated clay content which acts as barriers for fluids flowing within the reservoir facies. The Nubian C succession contains three different reservoir rock types (RRT) with variable compositional and petrophysical properties. RRTI and RRTII sandstones comprise quartzose sandstones with very low clay content (< 10%) and are characterized by an open pore system dominated by macropores. These sandstones are less impacted by overburden pressure and therefore can preserve their depositional porosity and permeability. On the other hand, RRTIII reservoir rocks are clay rich (> 10%) with abundant mesopores that are more prone to compressibility and hence reduction of the pore volume and pore throat. The present study highlights the significance of comprehensive integration between wireline logs, cores, and 3D reservoir models in directing exploration endeavors toward prospective reservoirs in mature basins.

Strata temperatures and geothermal resource evaluation in the Dongpu Depression, Bohai Bay Basin, North China

The development of geothermal resources in the Dongpu Depression can improve not only the economic benefits of the oilfield but also the ecological environment. Therefore, it is necessary to evaluate the geothermal resources in the region. Based on the heat flow, geothermal gradient and thermal properties, the temperatures and their distribution in different strata are calculated using geothermal methods, and the geothermal resource types of the Dongpu Depression are identified. The results show that the geothermal resources include low-temperature, medium-temperature and high-temperature geothermal resources in the Dongpu Depression. The Minghuazhen and Guantao Formations mainly include low-temperature and medium-temperature geothermal resources; the Dongying and Shahejie Formations include low-temperature, medium-temperature and high-temperature geothermal resources; the Ordovician rocks mainly include medium-temperature and high-temperature geothermal resources. The Minghuazhen, Guantao and Dongying Formations can form good geothermal reservoirs and are favorable layers for exploring low-temperature and medium-temperature geothermal resources. The geothermal reservoir of the Shahejie Formation is relatively poor, and the thermal reservoirs may be developed in the western slope zone and the central uplift. The Ordovician carbonate strata can provide thermal reservoirs for geothermal resources, and the Cenozoic bottom temperature is more than 150 °C except for most of the western gentle slope zone. In addition, for the same stratum, the geothermal temperatures in the southern Dongpu Depression are higher than those in the northern depression.

Petrophysical Properties of Mauddud Formation in Selected Wells in Al-Ahdab Oil Field, Middle Iraq

This paper aims to calculate the petrophysical properties in the Al-Ahdab field in the middle of Iraq within the Mauddud Formation. This study was based on the information available from well logs. The interactive petrophysical software IP (V4.5) was used to calculate the porosity, hydrocarbon saturation and shale volume, divide the formation into reservoir units and buffer units, and evaluate these units in each well. The Mauddud was divided into five units, two of them were considered good reservoirs having good petrophysical properties (high porosity, Low water saturation, and low shale volume). The other three are not reservoirs because of poor petrophysical properties.

Depositional and diagenetic modeling of the Margala Hill Limestone, Hazara area (Pakistan): Implications for reservoir characterization using outcrop analogues

Understanding the depositional and diagenetic processes is critical for the modeling and resource potential of carbonate reservoirs. The Lower Eocene Margala Hill Limestone forms hydrocarbon resources in Pakistan characterized by heterogeneity; however, there is a lack of details about the diagenetic modifiers of this formation in the southeastern Hazara, Pakistan, and an integrated study of outcrop analogues can help in the better exploitation of these important resources. This work focuses on clarifying of depositional environment, diagenesis, and reservoir characterization in five stratigraphic sections of Lower Eocene Margala Hill Limestone in the southeastern Hazara, Pakistan. The integrated sedimentological and stable isotopes analysis were used in this study to better understand reservoir characterization and potential. This study revealed that the Margala Hill Limestone in the studied outcrops is medium-to thickly bedded, nodular in places, and fractured. Based on petrographic studies and allochems to matrix ratio, six microfacies (wacke-to packestone) were identified in the studied formation. The Margala Hill Limestone was deposited in the inner to middle ramp setting. The various types of cement observed in the Margala Hill Limestone are non-Ferroan cements (i.e., granular, blocky, drusy, and microcrystalline) and ferroan cements are also observed. The observed diagenetic processes are cementation, biogenic alteration, neomorphism, compaction, dolomitization, fracturing, dissolution, and nodularity. The diagenetic and stable isotopes (δ13C and δ18O) studies indicate that the Margala Hill Limestone was affected by marine, meteoric, and burial diagenesis. The recorded porosity types include intragranular, intergranular, moldic, vuggy, and fractured porosity, indicating that the Margala Hill Limestone shows a good secondary reservoir for hydrocarbon accumulation. This study could prove a potential carbonate reservoir and help in the future exploration of the under-explored Eocene carbonates in the southeastern Hazara area, Pakistan.

Virus Inactivation Based on Optimal Surfactant Reservoir of Mesoporous Silica.

SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) caused a pandemic in 2019 and reaffirmed the importance of environmental sanitation. To prevent the spread of viral infections, we propose the application of a mesoporous silica (MS)-based virus-inactivating material. MS is typically synthesized using a micellar surfactant template; hence, the intermediate before removal of the surfactant template is expected to have a virus-inactivating activity. MS-CTAC particles filled with cetyltrimethylammonium chloride (CTAC), a cationic surfactant with an alkyl chain length of 16, were used to test this hypothesis. Plaque assays revealed that the MS-CTAC particles inactivated the enveloped bacteriophage φ6 by approximately 4 orders of magnitude after a contact time of 10 min. The particles also indicated a similar inactivation effect on the nonenveloped bacteriophage Qβ. In aqueous solution, CTAC loaded on MS-CTAC was released until the equilibrium concentration of loading and release on MS was reached. The released CTAC acted on viruses. Thus, MS is likely a good reservoir for the micellar surfactant. Surfactant readsorption also occurred in the MS particles, and the highest retention rate was observed when micellar surfactants with alkyl chain lengths appropriate for the pore size were used. The paper containing MS-CTAC particles was shown to maintain stable viral inactivation for at least three months in a typical indoor environment. Applying this concept to indoor wallpaper and air-conditioning filters could contribute to the inactivation of viruses in aerosols. These findings open possibilities for mesoporous materials with high surface areas, which can further develop into virus inactivation materials.