scholarly journals Sedimentology and depositional system of a transitional shallow marine – coastal complex, Lower Visean deposits in the Central Volga-Ural Petroleum Province, Orenburg

2021 ◽  
Author(s):  
Szilvia Szilágyi Sebők ◽  
István Csató ◽  
István Nemes
Keyword(s):  
Barrier Island ◽  
Well Log ◽  
Lower Carboniferous ◽  
Shallow Marine ◽  
Orenburg Region ◽  
Core Samples ◽  
Depositional System

AbstractThe paper presents a study of a Lower Carboniferous (Visean) clastic sequence commonly called Bobrikovsky Formation, deposited in the Volga-Ural Petroleum Province, Orenburg Region. Our investigation included sedimentological description of core samples from hydrocarbon wells and well log correlations. Facies were identified by well log patterns and calibrated by core sedimentology. The Bobrikovsky Formation is proposed to be interpreted as an overall transgressive-regressive succession in a nearshore-tidal environment. Transgressive lagoon-estuary and barrier island facies became regressional lagoon fill-type settings.

scholarly journals Lithostratigraphy and biostratigraphy of the Lower Carboniferous (Mississippian) carbonates of the southern Askrigg Block, North Yorkshire, UK

2016 ◽  
Vol 154 (2) ◽  
pp. 305-333 ◽  
Author(s):  
C. N. WATERS ◽  
P. CÓZAR ◽  
I. D. SOMERVILLE ◽  
R. B. HASLAM ◽  
D. MILLWARD ◽  
...  
Keyword(s):  
Shallow Water ◽  
Sea Level ◽  
Carbonate Ramp ◽  
Fault System ◽  
Lower Carboniferous ◽  
Shallow Marine ◽  
Sea Level Fluctuations ◽  
Algal Assemblages ◽  
Lower Palaeozoic ◽  
Southern Flank

AbstractA rationalized lithostratigraphy for the Great Scar Limestone Group of the southeast Askrigg Block is established. The basal Chapel House Limestone Formation, assessed from boreholes, comprises shallow-marine to supratidal carbonates that thin rapidly northwards across the Craven Fault System, onlapping a palaeotopographical high of Lower Palaeozoic strata. The formation is of late Arundian age in the Silverdale Borehole, its northernmost development. The overlying Kilnsey Formation represents a southward-thickening and upward-shoaling carbonate development on a S-facing carbonate ramp. Foraminiferal/algal assemblages suggest a late Holkerian and early Asbian age, respectively, for the uppermost parts of the lower Scaleber Force Limestone and upper Scaleber Quarry Limestone members, significantly younger than previously interpreted. The succeeding Malham Formation comprises the lower Cove Limestone and upper Gordale Limestone members. Foraminiferal/algal assemblages indicate a late Asbian age for the formation, contrasting with the Holkerian age previously attributed to the Cove Limestone. The members reflect a change from a partially shallow-water lagoon (Cove Limestone) to more open-marine shelf (Gordale Limestone), coincident with the onset of marked sea-level fluctuations and formation of palaeokarstic surfaces with palaeosoils in the latter. Facies variations along the southern flank of the Askrigg Block, including an absence of fenestral lime-mudstone in the upper part of the Cove Limestone and presence of dark grey cherty grainstone/packstone in the upper part the Gordale Limestone are related to enhanced subsidence during late Asbian movement on the Craven Fault System. This accounts for the marked thickening of both members towards the Greenhow Inlier.

The Sedimentary Control of Accumulation of Coalbed Methane in Hancheng Coalbed Methane Field

2013 ◽  
Vol 295-298 ◽  
pp. 3350-3353
Author(s):  
Xiao Hong Wang ◽  
Da Meng Liu ◽  
Yan Bin Yao ◽  
Ying Li ◽  
Chen Xie ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Barrier Island ◽  
Lower Permian ◽  
Upper Carboniferous ◽  
Shallow Marine ◽  
Sedimentary Environments ◽  
Taiyuan Formation ◽  
Delta System ◽  
Island System

This paper discusses how sedimentary controls on accumulation of coal and coalbed methane in Hancheng CBM field. Two major coal-bearing strata include the Upper Carboniferous Taiyuan formation (a marine and terrestrial sedimentation) and the Lower Permian Shanxi formation (a terrestrial sedimentation). The favorable sedimentary environments for accumulation of coalbed methane by decreasing order are the shallow marine and barrier island system, the delta system, and the shallow marine and plane coast system.

scholarly journals Calcareous Interlayer Causes and Logging Identification for the Shawan Formation of the Chunfeng Oilfield

2017 ◽  
Vol 10 (1) ◽  
pp. 134-142
Author(s):  
Qingjie Hou ◽  
Qiang Jin ◽  
Weizhong Li ◽  
Lamei Lin ◽  
Wenmin Jiang ◽  
...  
Keyword(s):  
Trace Element ◽  
Uranium Content ◽  
High Accuracy ◽  
Well Log ◽  
Residual Oil ◽  
Accurate Identification ◽  
Thin Sections ◽  
Core Samples ◽  
Quantitative Identification ◽  
Identification Function

Background: Many sets of calcareous interlayers are present in the Shawan Formation in the Chunfeng oilfield, which leads to scattered residual oil that is difficult to extract. Objective: Observations of core samples and thin sections, analyses of trace element compositions and interpretations of logging data were used to identify the calcareous interlayers and identify their possible origin. Method: First, the petrologic characteristics of the calcareous interlayers were identified; then, we developed a quantitative function for identifying the calcareous interlayers based on well log data. Finally, the possible origin of these calcareous interlayers was identified based on these findings. Conclusion: The results show that the quantitative function has a high accuracy of 91.8% and average uranium content of calcareous interlayers can reach as high as 27×10-6, indicating that the quantitative identification function provided accurate identification of the calcareous interlayers, and highly radioactive uranium is one explanation for the origin of the calcium cementation.

scholarly journals Porosity and Permeability Measurements Integration of The Upper Cretaceous in Balad Field, Central Iraq

2021 ◽  
Vol 54 (1B) ◽  
pp. 24-42
Author(s):  
Fawzi Al-Beyati
Keyword(s):  
Image Analysis ◽  
Log Analysis ◽  
Core Analysis ◽  
Well Log ◽  
Reservoir Properties ◽  
Thin Sections ◽  
Core Samples ◽  
Porosity And Permeability ◽  
Well Log Analysis ◽  
Porosity Range

The corrected porosity image analysis and log data can be used to build 3D models for porosity and permeability. This can be much realistic porosity obtainable because the core test data is not always available due to high cost which is a challenge for petroleum companies and petrophysists. Thus, this method can be used as an advantage of thin section studies and for opening horizon for more studies in the future to obtain reservoir properties. Seventy-two core samples were selected and the same numbers of thin sections were made from Khasib, Sa`di, and Hartha, formations from Ba-1, Ba-4, and Ba-8 wells, Balad Oilfield in Central Iraq to make a comprehensive view of using porosity image analysis software to determine the porosity. The petrophysical description including porosity image analysis was utilized and both laboratory core test analysis and well log analysis were used to correct and calibrate the results. The main reservoir properties including porosity and permeability were measured based on core samples laboratory analysis. The results of porosity obtained from well log analysis and porosity image analysis method are corrected by using SPSS software; the results revealed good correlation coefficients between 0.684 and 0.872. The porosity range values are 9-16% and 9-27% for Khasib and Sa’di in Ba-1 Well, respectively; 10-21%, 9-25%, and 16-27% for Khasib, Sa’di and Hartha in Ba-4 Well, respectively; and 11-24% and 15-24% for Khasib and Hartha in Ba-8 Well, respectively according to petrographic image analysis. By using the laboratory core analysis, the porosity range values are 12-26% and 17-24% for Khasib and Sa’di in Ba-1 Well, respectively; 6-28% and 14-27% for Sa’di and Hartha in Ba-4 Well, respectively; and 17-19% and 15-24% for Sa’di and Hartha in Ba-8 Well, respectively. Finally, the well log analysis showed that the porosity range values are 11-16% and 7-27% for Khasib and Sa’di in Ba-1 Well, respectively; 4-18%, 21-26%, and 16-19% for Khasib, Sa’di and Hartha in Ba-4 Well, respectively; and 9-24% and 15-23% for Khasib and Hartha in Ba-8 Well, respectively. The permeability range values based on laboratory core analysis are 1.51-8.97 md and 0.29-2.77 md for Khasib and Sa’di in Ba-1 Well, respectively; 0.01-24.5 md and 0.28-6.47 md for Sa’di and Hartha in Ba-4 Well, respectively; and 0.86-2.25 md and 0.23-3.66 for Sa’di and Hartha in Ba-8 Well, respectively.

scholarly journals Petrophysical Properties Estimation of Euphrates Reservoir in Qayyarah Oil Field Using Core and Well Log Data

2021 ◽  
Vol 54 (2E) ◽  
pp. 186-197
Author(s):  
Maan Al-Majid
Keyword(s):  
Water Saturation ◽  
Oil Field ◽  
Oil Reservoirs ◽  
Coefficient Of Determination ◽  
Well Log ◽  
Secondary Porosity ◽  
Log Data ◽  
The Core ◽  
Core Samples ◽  
True Resistivity

The Early Miocene Euphrates Formation is characterized by its oil importance in the Qayyarah oil field and its neighboring fields. This study relied on the core and log data analyses of two wells in the Qayyarah oil field. According to the cross-plot’s information, the Euphrates Formation is mainly composed of dolomite with varying proportions of limestone and shale. Various measurements to calculate the porosity, permeability, and water saturation on the core samples were made at different depths in the two studied wells Qy-54 and Qy-55. A relationship between water saturation and capillary pressure has been plotted for some core samples to predict sites of normal compaction in the formation. The line regression for this relationship was considered as a function of the ratio of large voids to the total volume of voids in the sample. The coefficient of determination parameter was used in estimating the amount of homogeneity in the sizes of the voids, as it was observed to increase significantly at the sites of shale. After dividing the formation into several zones, the well log data were analyzed to predict the locations of oil presence in both wells. The significance of the negative secondary porosity in detecting the hydrocarbon sites in the Euphrates Formation was deduced by its correspondence with the large increase in the true resistivity values in both wells. More than 90% of the formation parts represent reservoir rocks in both wells, but only about 75% of them are oil reservoirs in the well Qy-54 and nearly 50% of them are oil reservoirs in the well Qy-55.

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