scholarly journals Genesis Analysis of High-Gamma Ray Sandstone Reservoir and Its Log Evaluation Techniques: A Case Study from the Junggar Basin, Northwest China

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Liang Wang ◽  
Zhiqiang Mao ◽  
Zhongchun Sun ◽  
Xingping Luo ◽  
Yong Song ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Physical Property ◽  
Junggar Basin ◽  
Northwest China ◽  
Uranium Enrichment ◽  
Water Sensitivity ◽  
High Gamma ◽  
Sandstone Reservoir ◽  
Sandstone Reservoirs ◽  
Evaluation Techniques

In the Junggar basin, northwest China, many high gamma-ray (GR) sandstone reservoirs are found and routinely interpreted as mudstone non-reservoirs, with negative implications for the exploration and exploitation of oil and gas. Then, the high GR sandstone reservoirs’ recognition principles, genesis, and log evaluation techniques are systematically studied. Studies show that the sandstone reservoirs with apparent shale content greater than 50% and GR value higher than 110API can be regarded as high GR sandstone reservoir. The high GR sandstone reservoir is mainly and directly caused by abnormally high uranium enrichment, but not the tuff, feldspar or clay mineral. Affected by formation’s high water sensitivity and poor borehole quality, the conventional logs can not recognize reservoir and evaluate the physical property of reservoirs. Then, the nuclear magnetic resonance (NMR) logs is proposed and proved to be useful in reservoir recognition and physical property evaluation.

Genesis Analysis of High Gamma Ray (GR) Sandstone Reservoir: Taking Toutunhe Formation of Junggar Basin, Northwest China, as an Example

2013 ◽  
Vol 394 ◽  
pp. 585-590 ◽  
Author(s):  
Liang Wang ◽  
Zhi Qiang Mao ◽  
Zhong Chun Sun ◽  
Xing Ping Luo ◽  
Yong Song
Keyword(s):  
Oil And Gas ◽  
Gamma Ray ◽  
Junggar Basin ◽  
Northwest China ◽  
Formation Water ◽  
Uranium Enrichment ◽  
Specific Criterion ◽  
High Gamma ◽  
Sandstone Reservoir ◽  
Principles And Standards

On the basis of GR log analysis alone, the high GR sandstone reservoirs would probably have been regarded as mudstone and interpreted to be non-reservoir, which has greatly affected the exploration and exploitation of oil and gas reservoir to some extent. Therefore, the principles and standards to distinguish high GR sandstone reservoir from conventional sandstone reservoir, genesis of high GR sandstone reservoir have been systematically studied. Studies show that sandstone reservoir with apparent shale content calculated by GR log value greater than 50%, can be regarded as high GR sandstone reservoir. In the study area, the specific criterion of GR log value for high GR sandstone reservoir is 110API. The high GR characteristic of sandstone reservoir is mainly and directly caused by an abnormally high uranium enrichment, but not the tuff, feldspar or clay mineral. The study area has favorable conditions of abundant uranium source, favorable paleoclimate, and favorable lithology and lithofacies combination for uranium enrichment. In the process of oxygen bearing formation water migrating and leaching uranium bearing tuff, the U+4 can be oxidized to U+6, and uranium element transports in the form of UO2+2. In permeable sandstone reservoir saturated with uranium bearing formation water, the U+6 can be deoxidized into U+4 by oil and gas migrating through faults and stratigraphic unconformities, and accumulates in the form of UO2 in sandstones.

Characteristics of High-Gamma-Ray Sandstone Reservoirs for Yanchang Formation in Ordos Basin

2010 ◽  
Vol 53 (1) ◽  
pp. 154-163 ◽  
Author(s):  
Xiao-Li ZHANG ◽  
Qiao FENG ◽  
Pei SUN ◽  
Wei LI
Keyword(s):  
Gamma Ray ◽  
Ordos Basin ◽  
Yanchang Formation ◽  
High Gamma ◽  
Sandstone Reservoirs

scholarly journals Effect of Diagenetic Evolution and Hydrocarbon Charging on the Reservoir-Forming Process of the Jurassic Tight Sandstone in the Southern Junggar Basin, NW China

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7832
Author(s):  
Tianqi Zhou ◽  
Chaodong Wu ◽  
Xutong Guan ◽  
Jialin Wang ◽  
Wen Zhu ◽  
...  
Keyword(s):  
Early Stage ◽  
Junggar Basin ◽  
Forming Process ◽  
Tight Sandstone ◽  
Average Pore ◽  
Nw China ◽  
Hydrocarbon Charging ◽  
Sandstone Reservoir ◽  
Sandstone Reservoirs ◽  
Capillary Pressures

Deeply buried sandstones in the Jurassic, Toutunhe Formation, are a crucial exploration target in the Junggar Basin, NW China, whereas, reservoir-forming process of sandstones in the Toutunhe Formation remain unknown. Focused on the tight sandstone of the Toutunhe Formation, the impacts of diagenesis and hydrocarbon charging on sandstone reservoir-forming process were clarified based on the comprehensive analysis of sedimentary characteristics, petrography, petrophysical characteristics, and fluid inclusion analysis. Three diagenetic facies developed in the Toutunhe sandstone reservoirs, including carbonate cemented facies (CCF), matrix-caused tightly compacted facies (MTCF), and weakly diagenetic reformed facies (WDF). Except the WDF, the CCF and the MTCF entered the tight state in 18 Ma and 9 Ma, respectively. There was only one hydrocarbon emplacing event in sandstone reservoir of the Toutunhe Formation, charging in 13 Ma to 8 Ma. Meanwhile, the source rock started to expel hydrocarbons and buoyancy drove the hydrocarbon via the Aika fault belt to migrate into sandstone reservoirs in the Toutunhe Formation. During the end of the Neogene, the paleo-oil reservoir in the Toutunhe Formation was destructed and hydrocarbons migrated to the sandstone reservoirs in the Ziniquanzi Formation; some paleo-oil reservoirs survived in the WDF. The burial pattern and change of reservoir wettability were major controlling factors of the sandstone reservoir-forming process. The buried pattern of the Toutunhe Formation in the western section of the southern Junggar Basin was “slow and shallow burial at early stage and rapid and deep burial at late stage”. Hence, pore capillary pressure was extremely low due to limited diagenetic reformation (average pore capillary pressures were 0.26 MPa). At the same time, high content of chlorite coating increased the lipophilicity of reservoirs. Therefore, hydrocarbons preferably charged into the WDF with low matrix content (average 4.09%), high content of detrital quartz (average 28.75%), high content of chlorite films (average 2.2%), and lower pore capillary pressures (average 0.03 MPa). The above conditions were favorable for oil and gas enrichment.

scholarly journals Study on the sensitivities and damage mechanisms of ultra-low permeability sandstone reservoirs: taking Chang 6 reservoir in Jingbian oilfield as an example

2020 ◽  
Vol 194 ◽  
pp. 01037
Author(s):  
Xiulan Zhu ◽  
Yanlong Ran ◽  
Zhanjun Chen ◽  
Tai Xu ◽  
Shengling Jiang ◽  
...  
Keyword(s):  
Pore Structure ◽  
Ordos Basin ◽  
Small Hole ◽  
Low Permeability ◽  
Thin Sections ◽  
Acid Sensitivity ◽  
Water Sensitivity ◽  
Sensitivity Evaluation ◽  
Sandstone Reservoir ◽  
Sandstone Reservoirs

This paper takes the ultra-low permeability sandstone reservoir of Jingbian oilfield in Ordos Basin as the research object, analyzes the petrological characteristics, diagenesis, physical characteristics and pore structure characteristics of the reservoir, and carries out reservoir sensitivity evaluation by using rock casting thin sections, X-ray diffraction, and sensitive flow experiments. The research results show that the ultra-low permeability Chang 6 sandstone reservoir has weak velocity sensitivity, medium-weak water sensitivity, weak salt sensitivity, weak alkali sensitivity and strong acid sensitivity; the damage mechanism of reservoir sensitivity mainly depends on the composition of clay minerals and pore structure after diagenesis. The clay mineral content from high to low is chlorite, illite, a small amount of illite / smectite layer, and kaolinite, of which the chlorite content is as high as 75 %; the reservoir has poor physical properties, the types of small hole-thin throat and small hole-fine throat. The reservoir is prone to blockage such as bridge plugging. Therefore, ultra-low permeability sandstone reservoirs are prone to different degrees of sensitivity. The reservoir characteristics are consistent with the reservoir sensitivity evaluation results.

The Baer Depression Tuffaceous Sandstone Reservoir Characteristics and Logging Response Research Status, Problems

2012 ◽  
Vol 246-247 ◽  
pp. 614-618
Author(s):  
Si Yuan Su ◽  
Chun Wei Zhang ◽  
Hai Feng Chen ◽  
Qing Tian Zou ◽  
Peng Fei Li
Keyword(s):  
Physical Property ◽  
Coarse Grain ◽  
Secondary Porosity ◽  
Porosity Evolution ◽  
Mineral Components ◽  
Research Outcome ◽  
Sandstone Reservoir ◽  
Sandstone Reservoirs ◽  
Diagenetic Environment ◽  
Difficult Issue

In logging field, saturation evaluation in tuffaceous sandstone reservoirs has been a difficult issue to be solved urgently. It is mainly due to the effect of complex pore structures in tuffaceous sandstone reservoirs. Compared with the normal sandstones, the tuffaceous sands have the properties of diversity origination, complex mineral components, easily transformed mineral, complex digenesis and porosity evolution .The comprehensive analyses of cores, thin slices, SEM, mercury-injection data and former research outcome of Beier oilfield on the porous structure and reservoir physical property of sandstones. The tuffaceous alteration is different under different burial phase and diagenetic environment and has different effects on the porosity of coarse grain have a constructive affection to the secondary porosity.

scholarly journals Gamma-Ray Attenuation to Evaluate Soil Porosity: An Analysis of Methods

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Luiz F. Pires ◽  
André B. Pereira
Keyword(s):  
Gamma Ray ◽  
Particle Density ◽  
Pore Space ◽  
Physical Property ◽  
Soil Bulk Density ◽  
Soil Porosity ◽  
Porous System ◽  
Soil Pore Space ◽  
Gamma Ray Attenuation ◽  
Dry Soil

Soil porosity (ϕ) is of a great deal for environmental studies due to the fact that water infiltrates and suffers redistribution in the soil pore space. Many physical and biochemical processes related to environmental quality occur in the soil porous system. Representative determinations ofϕare necessary due to the importance of this physical property in several fields of natural sciences. In the current work, two methods to evaluateϕwere analyzed by means of gamma-ray attenuation technique. The first method uses the soil attenuation approach through dry soil and saturated samples, whereas the second one utilizes the same approach but taking into account dry soil samples to assess soil bulk density and soil particle density to determineϕ. The results obtained point out a good correlation between both methods. However, whenϕis obtained through soil water content at saturation and a 4 mm collimator is used to collimate the gamma-ray beam the first method also shows good correlations with the traditional one.

scholarly journals Study on oil displacement efficiency of offshore sandstone reservoir with big bottom water

2021 ◽  
Author(s):  
Jie Tan ◽  
Ying-xian Liu ◽  
Yan-lai Li ◽  
Chun-yan Liu ◽  
Song-ru Mou
Keyword(s):  
Bottom Water ◽  
High Water ◽  
Displacement Efficiency ◽  
Oil Displacement ◽  
Oil Displacement Efficiency ◽  
Sandstone Reservoir ◽  
Sandstone Reservoirs ◽  
High Water Cut Stage ◽  
High Water Cut ◽  
Water Cut

AbstractX oilfield is a typical sandstone reservoir with big bottom water in the Bohai Sea. The viscosity of crude oil ranges from 30 to 425 cp. Single sand development with the horizontal well is adopted. At present, the water content is as high as 96%. The water cut of the production well is stable for a long time in the high water cut period. The recoverable reserves calculated by conventional methods have gradually increased, and even the partial recovery has exceeded the predicted recovery rate. This study carried out an oil displacement efficiency experiment under big water drive multiple to accurately understand an extensive bottom water reservoir's production law in an ultra-high water cut stage. It comprehensively used the scanning electron microscope date, casting thin section, oil displacement experiment, and production performance to analyze the change law of physical properties and relative permeability curve from the aspects of reservoir clay minerals, median particle size, pore distribution, and pore throat characteristics. Therefore, the development law of horizontal production wells in sandstone reservoirs with big bottom water is understood. It evaluates the ultimate recovery of sandstone reservoirs with big bottom water. It provides a fundamental theoretical basis and guidance for dynamic prediction and delicate potential tapping of sandstone reservoirs with big bottom water at a high water cut stage.

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