scholarly journals Petrographical characteristics and post-depositional alteration affecting porosity and permeability of Oligocene sandstones, block 15-1/05, Cuu Long basin

2020 ◽  
Vol 4 (2) ◽  
pp. First
Author(s):  
Thanh Ngoc Do ◽  
Duyen Thi Pham ◽  
Phuong Kim Lieu
Keyword(s):  
Clay Minerals ◽  
Oil And Gas ◽  
Gas Storage ◽  
Early Diagenesis ◽  
Burial Depth ◽  
Reservoir Rocks ◽  
Potential Reservoir ◽  
Negative Effect ◽  
Porosity And Permeability ◽  
Grain Sorting

Petrographical characteristics and post-depositional alteration studies of sandstones are the two important factors to reservoir rocks, which affect oil and gas storage and permeability of reservoir rocks. This study revealed petrographical characteristics, post-depositional alteration, and their influence on the porosity and permeability of Oligocene sandstones, including C, D, and E and F sequences, block 15-1/05, Cuu Long Basin. The results show that most of the sandstones were arkose, lithic arkose, and sporadically interbedded by feldspathic greywacke. The post-depositional alteration was progressively increasing following the burial depth from early diagenesis of sequence C, to intermediate diagenesis of sequence D and advanced diagenesis of sequence E and F. The post-depositional alterations significantly influenced on the porosity of the Oligocene sandstone were the cementation and mechanical compaction. They reduced the porosity and permeability of the sandstone. Additionally, authigenic clay minerals have a negative effect on permeability in which sandstones were rich illite and illite-smectite clay minerals, and the permeability tended to decrease stronger than others. Our results showed that the potential reservoir rocks of Oligocene sandstones, block 15-1/05 were sequence E and F sandstones that are in well grain sorting, well grain roundness shape, and contained a small number of cement, particularly the absence of illite and illite-smectite.

scholarly journals Generation of authigenic clay minerals during diagenesis and their influences on porosity and permeability of Oligocene sandstone reservoir rocks, from a well in the west of Cuu Long basin

2014 ◽  
Vol 17 (3) ◽  
pp. 21-26
Author(s):  
Toan Minh Ho ◽  
Phuong Kim Lieu ◽  
Thuy Thi Doan ◽  
Phuong Thi Ngoc Bui
Keyword(s):  
Clay Minerals ◽  
Fluid Flows ◽  
Reservoir Rock ◽  
Burial Depth ◽  
High Porosity ◽  
Pore Waters ◽  
The West ◽  
Reservoir Rocks ◽  
Porosity And Permeability ◽  
Sandstone Reservoir

Porosity and permeability play a prerequisite role for hydrocarbon reservoirs and fluid flows, especially in sandstone reservoir rocks. The rocks with high porosity decrease down to lower porosity with increasing burial depth due to compaction, cementation and precipitation of authigenic minerals in pores from over saturated solution of minerals. The detailed study of the authigenic clay mineral formation in pore spaces of sandstone reservoir rocks is therefore crucial to estimate the degree of reservoir rock quality. In this study 20 sandstone cores taken from the interval burial depths of 3,700 m - 4,200 m from Oligocene sandstone sequence of a well in the West of the Cuu Long basin, offshore Vietnam, were analyzed by SEM and thin section. Authigenic clay minerals were formed due to temperature and chemistry changes and owing to dissolution of less stable minerals in these burial depths. Authigenic chlorite mineral appears quite abundantly and illite is less frequently. Chlorite was formed from the elements Al and Si, which were released from dissolved grains and Fe and Mg supplied from breakdown of the ferromagnesian minerals of rock fragments and matrix components into pore waters in the burial stage. Illite is associated with the expense of grain dissolution of feldspar, volcanic fragment. Chlorite mostly appears as a coating or mats comprising of small pseudo-hexagonal crystals arranged perpendicular to detrital grain surfaces. Grainrimming chlorites on quartz grain are responsible for the preservation of the porosity in the sandstones because they limit the formation of quartz overgrowth. Additionally fibrous or flaky illite bridging the pores between the grains creates permeability barriers to fluid flows through the sandstones. Thus illite significantly reduces the permeability but to lesser extent affect porosity. Locally, smectite mixes with illite or chlorite and is not abundant in the studied samples. It therefore has no significant impact on the porosity and permeability as well. The variations of the porosity and the permeability of the studied sandstones depend on the generated degree and the arranged patterns of chlorite and illite in pore spaces.

Diagenetic peculiarities of potential Lower Jurassic reservoir sandstones, Troms 1 area, Off Northern Norway, and their tectonic significance

Clay Minerals ◽  
1986 ◽  
Vol 21 (4) ◽  
pp. 565-584 ◽  
Author(s):  
P. Riches ◽  
I. Traub-Sobott ◽  
W. Zimmerle ◽  
U. Zinkernagel
Keyword(s):  
Pore Space ◽  
High Energy ◽  
Lower Jurassic ◽  
Burial Depth ◽  
Secondary Porosity ◽  
Reservoir Rocks ◽  
Diagenetic Alteration ◽  
Potential Reservoir ◽  
Porosity And Permeability ◽  
Reservoir Sandstones

AbstractIn the Troms 1 area, sediments of Early to Middle Jurassic age, ranging from alluvial plain deposits at the base, passing through coastal plain/tidal flat sediments up into high-energy nearshore shallow-marine sands, mark a transgression. The sandstones, classified as mineralogically and texturally mature quartz-arenites, are potential reservoir rocks in the eastern part of the area. The apparent supermaturity, however, is of secondary origin because unstable detrital components were dissolved during diagenesis. The succession of complex diagenetic processes was: (i) mechanical compaction and simultaneous pressure solution, (ii) partial dissolution with corrosion of detrital quartz and dissolution of unstable fragments, (iii) silica cementation, (iv) calcite cementation, (v) partial carbonate dissolution, (vi) kaolinite/Fe-carbonate cementation in the remaining pore space. Porosity and permeability of the sandstones are controlled by the degree of silicification and by dissolution processes. Two dissolution stages led to partial ‘skeletonization’ of the detrital framework and to elimination of unstable detrital grains. The first stage was a basic process leading to corrosion of detrital quartz and creating transitory secondary porosity; the second stage was acidic leading to the present preserved secondary porosity. Diagenetic dissolution channels formed. The degree of diagenetic alteration was much higher than normally observed in sandstones of such burial depth. Hydrothermal solutions rising from deep-seated faults may have led to this unusual alteration and triggered a rift-related type of complex diagenesis.

scholarly journals PETROGRAPHIC CHARACTERISTICS OF THE RESERVOIR ROCKS IN THE BAT-UPPER JURASSIC DEPOSITS OF THE SOUTH OF WESTERN-SIBERIAN PETROLEUM BASIN

2019 ◽  
Vol 2 (1) ◽  
pp. 25-31
Author(s):  
Lyudmila Vakulenko ◽  
Aleksey Popov ◽  
Sergey Rodyakin ◽  
Evgeniy Khabarov ◽  
Peter Yan
Keyword(s):  
Oil And Gas ◽  
Upper Jurassic ◽  
The South ◽  
Reservoir Properties ◽  
Petrographic Composition ◽  
Reservoir Rocks ◽  
Regional Sources ◽  
Porosity And Permeability ◽  
Maximum Parameters ◽  
Petroleum Basin

The features of the petrographic composition of the bath-upper Jurassic silt-sand rocks exposed by wells in the South of the West Siberian oil and gas basin are considered. The study is focused on the parameters that had a significant influence on the reservoir properties of rocks: granulometric and mineral-petrographic composition of the clastic part of rocks, cement content, structure and composition. Some conclusions are drawn on the spatial distribution of rocks of different composition within the subisochronous sedimentary complexes. It is assumed that significant variations in their composition are caused by a complex combination of varying degrees of interdependent factors: influence of local and regional sources of clastic material, peculiarities of redistribution of material during its transportation and sedimentation, and post-sedimentation changes. Most variable values of reservoir properties, with a recorded maximum parameters of porosity and permeability are obtained for the rocks of Medium-Upper Oxford complex on Verkhnetarskaya, Dedovskaya, Basinskaya, Veselovskaya, to a lesser extent, Kasmanskaya, Vostochnaya and Tai-Dasskaya drilling sites.

scholarly journals Oil and gas prospects in the Cretaceous-Tertiary basin of West Greenland

1969 ◽  
Vol 22 ◽  
pp. 1-63
Author(s):  
G Henderson
Keyword(s):  
Marine Sediments ◽  
Oil And Gas ◽  
Source Rocks ◽  
Considerable Part ◽  
West Greenland ◽  
Reservoir Rocks ◽  
True Source ◽  
Potential Reservoir ◽  
Greenland Basin ◽  
Good Potential

The West Greenland basin contains marine and non-marine sediments ranging in age from Lower Cretaceous (Barremian-Aptian) to Paleocene (Upper Danian). The marine sediments are at least 1500 m thick in parts of Nûgssuaq and may reach 2000 m; the non-marine sediments attain a thickness of 1500 m in Nûgssuaq and Disko. Sediments older than those exposed may be present at depth. In a considerable part of the area the sediments are overlain by Tertiary basalts, which locally attain a thickness of about 8 km. The basin is fault-bounded and its coastline was probably largely fault-determined from the onset of sedimentation. Sandstone and shale are the main sedimentary types, and bituminous shales are an important part of the succession. Recent chemical analyses have shown that the bituminous shales include true source rocks; additional evidence in support of the existence of source rocks in the basin is provided by the presence of migrated hydrocarbons in sandstone close to a fault and by the presence of bitumen amongst the fluids brought to the surface in a mud volcano. The sandstones are regarded as good potential reservoir rocks, and there are good possibilities for the presence of structural and stratigraphic traps at depth. The first indications are encouraging and invite further exploration for oil and gas.

scholarly journals Overview of Lower Cretaceous Achimov Formation: Physical Properties and Their Distribution Pattern in West Siberian Basin, Russia

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Mingyu He ◽  
Qingbin Xie ◽  
A. V. Lobusev ◽  
M. A. Lobusev ◽  
Xinping Liang
Keyword(s):  
Physical Properties ◽  
Oil And Gas ◽  
Distribution Patterns ◽  
Burial Depth ◽  
Reservoir Properties ◽  
Reservoir Rocks ◽  
Oil And Gas Fields ◽  
Genetic Mechanisms ◽  
Gas Fields ◽  
West Siberian Basin

The Achimov Formation is one of the most important oil- and gas-bearing strata in the West Siberian basin in Russia. The total estimated reserves of this stratum exceed one billion tons. The formation was first explored in 1981, but it remains largely underdeveloped due to its deep burial depth and poor physical properties. Therefore, further research on the genetic mechanisms and distribution characteristics of the reservoirs in the formation can contribute to its further exploitation. The Achimov Formation is dominated by of fine- to medium-grained sandstones interbedded with shale. Based on analysis of well logging data, hand specimens, and previous research, this study analyzed the properties of three members (Ach1, Ach2, and Ach3) of the Achimov Formation and summarized their distribution patterns. Research on reservoir rocks from different oil and gas fields reveals varying physical properties across the formation with permeability and porosity increasing from the northern to central areas and decreasing from the central to the southern areas. Burial depth is one of the major controlling factors for reservoir properties in the formation. Reservoirs in both the northern and southern parts of the formation are buried deeper than those in the central areas, resulting in a disparity in reservoir quality.

scholarly journals Diagenetic Clay Minerals and Their Controls on Reservoir Properties of the Shahbazpur Gas Field (Bengal Basin, Bangladesh)

Geosciences ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 250
Author(s):  
Md Nahidul Hasan ◽  
Rumana Yeasmin ◽  
M. Julleh Jalalur Rahman ◽  
Sally Potter-McIntyre
Keyword(s):  
Clay Minerals ◽  
Clay Mineralogy ◽  
Bengal Basin ◽  
Burial Depth ◽  
Reservoir Properties ◽  
Electron Microscopic ◽  
Gas Field ◽  
Kübler Index ◽  
Porosity And Permeability ◽  
Index Value

Clay mineralogy and diagenesis affect the reservoir quality of the Neogene Surma Group in the Hatiya trough of Bengal Basin, Bangladesh. X-ray diffraction and scanning electron microscopic analyses of diagenetic clay minerals from Shahbazpur#2 well reveal that on average illite is the dominant clay mineral (50%), followed by chlorite (24%), kaolinite (23%) and smectite (2.50%). The absence of smectite at Core-2 (3259.80 m to 3269 m) results from the total transformation of smectite to illite owing to burial depth and high K–feldspar. The diagenetic changes are a result of chemical processes such as cementation, chlorite authigenesis, dissolution, alteration and replacement that have significantly affected the reservoir properties. Cementation plays an important role in reducing reservoir properties with pore and fracture filling cement. The relative percentage of illite and smectite minerals (>90% illite in I/S mixed layer) and Kübler index value (0.34° to 0.76° Δ2θ) indicate a diagenetic zone with subsurface temperatures of 120–180 °C in the studied samples. The temperature range determined using clay percentages and the Kübler index as a geothermometer is supported by observed diagenetic features such as quartz overgrowths, smectite to illite transformations and chlorite coatings. The diagenetic features cause variable reservoir porosity and permeability that are critical in planning exploration and development programs of this field or analog fields across the Bengal Basin.

scholarly journals A preliminary assessment of carbon storage suitability in deep underground geological formations of New Brunswick, Canada

2015 ◽  
Vol 51 (1) ◽  
pp. 269 ◽  
Author(s):  
Dave Keighley ◽  
Crystal Maher
Keyword(s):  
New Brunswick ◽  
Carbon Storage ◽  
Oil And Gas ◽  
Reservoir Rock ◽  
Limited Information ◽  
Gas Field ◽  
Offshore Area ◽  
Potential Reservoir ◽  
Porosity And Permeability ◽  
Carbon Dioxide Co2

An assessment of the surface and subsurface geology in New Brunswick has identified several regions, close to Large Final Emitters (industrial sites releasing carbon dioxide, CO2, into the atmosphere), underlain by large volumes of various sedimentary rocks that could act as either the reservoir or seal in a carbon storage operation. There is a lack of subsurface data with which to make an assessment for the New Brunswick Platform, the Gulf of St. Lawrence, and Northumberland Strait. In the Moncton Basin, the McCully Gas Field is hosted in tight gas sands where it would be difficult to pump down CO2 at an economical rate. The Stoney Creek Oil and Gas Field south of Moncton is not at sufficient depth for CO2 to be in a supercritical state, necessary for compressed storage. Saline reservoirs could underlie suitably large areas around these fields, but again there is limited information on the quality of the potential reservoir rock. In the Bay of Fundy, south of Saint John, one borehole indicates a prospective location that includes a saline reservoir with suitable thickness and wireline-calculated porosity and permeability, a seal with suitable thickness, and limited faulting to potentially compartmentalize the reservoir or, conversely, compromise the continuity of the seal. The major uncertainty is trap volume, which is particularly difficult to assess based on the borehole being the only data point within a 50 km radius. This is also an environmentally sensitive offshore area. Until data deficiencies are addressed, no locations can be recommended for carbon storage.

scholarly journals Calculation of Pore Throat Radius Percentiles (25, 50 & 75) From Porosity and/or Permeability: Algyo Oil and Gas Field, Hungary

2021 ◽  
Vol 906 (1) ◽  
pp. 012004
Author(s):  
Nahla A. El Sayed ◽  
El sayed Abdel Moktader A.
Keyword(s):  
Size Distribution ◽  
Oil And Gas ◽  
Reservoir Characterization ◽  
Size Analysis ◽  
Pore Throat ◽  
Throat Radius ◽  
Gas Field ◽  
Reservoir Rocks ◽  
Oil And Gas Field ◽  
Porosity And Permeability

Abstract Pore throat size distribution of reservoir rocks has a great importance in hydrocarbon migration and entrapment. It is used for study permeability barriers, reservoir characterization and stratigraphic traps. In the present study 51 core samples obtained from Algyo oil and gas field were conducted to MICP laboratory technique to study pore throat size distribution. The inclusive graphical measures of gain size analysis were borrowed for pore throat size examination. Various pore throat radius percentiles such as 25,50 and 75 were calculated and related to both rock porosity and permeability. The obtained models were robust and reliable to use for pore throat radius percentiles (25,50 and 75) calculation. One of these models which is predicting the 50 percentiles was verified. It shows reliable coefficients of correlation (R2 = 0.77 and 0.79) as it is estimated from permeability and porosity, respectively.

scholarly journals Integrated petrophysical study to validate water saturation from well logs in Bahariya Shaley Sand Reservoirs, case study from Abu Gharadig Basin, Egypt

2020 ◽  
Vol 10 (8) ◽  
pp. 3139-3155
Author(s):  
Mohamed El-Bagoury
Keyword(s):  
Clay Minerals ◽  
Oil And Gas ◽  
Water Saturation ◽  
Exchange Capacity ◽  
Fine Tuning ◽  
Well Logs ◽  
Gas Reservoirs ◽  
Reservoir Rocks ◽  
Resistivity Logs ◽  
Petroleum Fields

Abstract Water saturation is a key parameter in evaluating oil and gas reservoirs and calculating OIIP and GIIP for petroleum fields. The late Cretaceous Bahariya reservoir contains variable amounts of clay minerals. Bore hole logs are affected with those clay minerals particularly the density and resistivity logs. Several methods are acknowledged to determine the true water saturation from well logs in shaley sand reservoirs. Each method assumes a sort of corrections to amount of shale distributed in the reservoir. The scope of this petrophysical study is to integrate core analysis and bore hole logs to investigate the characteristics of water saturation in the Bahariya reservoirs. Comparison between most of the significant shaley sand methods is presented in this research. Reservoir lithology and mineralogy are explained by Elan-model while bore hole images are used for fine-tuning the electrofacies. Siltstone, shaley sand and clean sandstones are the main electrofacies that is characterizing the Bahariya reservoir rocks. For accurate saturation results, some core samples have been used for validating the log-derived water saturation. Dean stark and cation exchange capacity experiments are integrated with bore hole logs to calculate the error in water saturation for each method for best calibration. The successful integration between logs and core measurements led to convenient log evaluation and accurate understanding for the Bahariya reservoir in the prospective part of Abu Gharadig basin.

scholarly journals THE COMPOSITION AND PHYSICOCHEMICAL PROPERTIES OF RESERVOIR-ROCKS OF SPAN SERIES OF THE PRIBUG STRUCTURE OF THE PODLESSE-BREST DEPRESSION

2018 ◽  
Vol 54 (3) ◽  
pp. 349-358
Author(s):  
V. G. Levashkevich ◽  
V. P. Samodurov ◽  
S. E. Shpak
Keyword(s):  
Physical Properties ◽  
Clay Content ◽  
Data Interpretation ◽  
Gas Storage ◽  
Laboratory Studies ◽  
Rock Series ◽  
Underground Gas Storage ◽  
Reservoir Rocks ◽  
Porosity And Permeability ◽  
Well Data

The results of laboratory studies of the composition and physical properties of span series rocks of the Pribug structure within the eponymous underground gas storage (UGS), have been presented. The rocks are represented by a finegrained quartz sandstone with various sorting and grain roundness, type of cementation and clay content. The character of section suites changes for the material composition of the rocks and their physical properties have been set. The examined properties specify reservoir rocks characteristics which are widely used for integrated geophysics well data interpretation, geological and hydrogeological UGS modeling, making recommendations for increasing efficiency of pore volume usage during gas storage operation. Rock intervals with poor porosity and permeability are detected inside the examined rock series.

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