Formation mechanism of the Upper Triassic Yanchang Formation tight sandstone reservoir in Ordos Basin—Take Chang 6 reservoir in Jiyuan oil field as an example

Ren, Dazhong; Zhou, Desheng; Liu, Dengke; Dong, Fengjuan; Ma, Shuwei; Huang, Hai

doi:10.1016/j.petrol.2019.03.021

Cited by 83 publications

(50 citation statements)

References 12 publications

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“…The sedimentary pattern shows that the shoreline of the lake moves outward and the scope of lake transgression expands 20 . The eastern and northeastern deltas, especially the northern of Ansai delta, have been largely leveled, mainly by distributary channel deposits, and the northern part has been leveled and swamped 21 . The Shigouyi fan delta in the western margin continues to exist, while the Fuxian delta and Huangling delta extend to the west of Hulu River-Taibai and to the deep lake area of Guchengchuan area, which becomes the main material source of this area.…”

Section: Methodsmentioning

confidence: 99%

Water-flooding characteristics of lithologic reservoir in Ordos basin

Liu

Zhu

et al. 2021

Sci Rep

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Due to the poor situation of water-flooding mechanism research on Chang 4 + 5 reservoir of Ordos basin, the authors quantitatively studied the influence factors of water-flooding characteristics by sedimentology, casting thin sections, constant-speed mercury injection, scanning electron microscope as well as production records. The size and distribution of pore-throat were also found closely related with the water-flooding seepage law. The results show that the microscopic seepage paths of Chang 4 + 5 reservoir include uniform displacement, finger displacement and peak displacement, and their correspondent oil displacement efficiency reduces in turn under the same conditions. Reservoir heterogeneity, reservoir properties, distribution of pore structure and wettability play a decisive role in water-flooding efficiency. Generally, When the intra-layer range is greater than 4.65, the breakthrough coefficient is greater than 3.54, the coefficient of variation is greater than 0.7, the distribution frequency of inter-layer is greater than 0.5 per meter, and the distribution density is greater than 0.435%, the range between layers is greater than 6.86, the breakthrough coefficient is greater than 2.58, the coefficient of variation is greater than 0.51, and the thickness of inter-layer is greater than 7.54 m. the increasing trend of oil displacement efficiency will be obviously weakened.

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Section: Methodsmentioning

confidence: 99%

Water-flooding characteristics of lithologic reservoir in Ordos basin

Liu

Zhu

et al. 2021

Sci Rep

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“…It is often used to simulate the fracture characteristics and movement laws of overlying strata. In this research, JSET command is used to generate vertical and horizontal joint groups, and CHANGE command is used to change the material properties of blocks and joints [44][45][46][47]. Because the tensile strength of rock is significantly lower than the compressive strength, the Mohr-Coulomb elastoplastic model is chosen as the block constitutive model.…”

Section: Numerical Simulationmentioning

confidence: 99%

The Key Stratum Structure Morphology of Longwall Mechanized Top Coal Caving Mining in Extra‐Thick Coal Seams: A Typical Case Study

et al. 2020

Advances in Civil Engineering

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Longwall mechanized top coal caving mining (LMTCCM) in extra-thick coal seams has its own characteristics. The law of mining pressure and overlying strata failure height in extra-thick coal seams are much larger than those of medium-thick and thick coal seams. The key stratum structure morphology also has an important influence on the law of overlying strata movement and stability of surrounding rock. Based on the engineering geological conditions, this paper used the method of theoretical analysis and numerical simulation to study the key stratum structure morphology of LMTCCM in extra-thick coal seams. The results show that under the condition of LMTCCM in extra-thick coal seams, the key stratum forms the structure of low cantilever beam and high hinged rock beam. With the increase of coal seam thickness, the breaking position of cantilever beam is closer to the coal wall. Through theoretical calculation, it is obtained that the breaking length of cantilever beam is 31.5 m and the breaking position of cantilever beam is 15.4 m away from coal wall. With the increase of cycle, key strata will undergo the evolution law from the generation of longitudinal cracks to the hinged structure and then to the cantilever beam structure. The breakage of key strata will cause the expansion of longitudinal cracks and the overall synchronous movement of overlying strata. With the increase of coal seam thickness, the distribution of longitudinal cracks will gradually transfer from the upper part of goaf to the deep part of coal body in space and increase in quantity. This research is of great significance for improving the stability of overlying strata and ensuring the safe and efficient mining of extra-thick coal seams.

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“…Under different geological processes, the rock masses contain various discontinuities such as joints, fissures, cracks, and faults [1][2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Crack Initiation Behaviors of Granite Specimens Containing Crossing‐Double‐Flaws with Different Lengths under Uniaxial Loading

Pan

Yin

Ning

et al. 2020

Advances in Civil Engineering

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Crack initiation is an important stage in the failure process of rock masses. In this paper, crack initiation behaviors (crack initiation model, crack initiation location, crack initiation angle, and crack initiation stress) of granite specimens containing crossing-double-flaws with different lengths were investigated using PFC2D software. Crack initiation models were all tensile wing cracks, which did not exactly initiate from the main flaw with a length of 30 mm. They can initiate from the secondary flaw with a length 20 mm at α of 30° (included angle between main flaw and horizontal direction) and β of 90° (included angle between main and secondary flaws) and from main and secondary flaws at α of 30° and β of 60°. These were mainly induced by the superposition of stress fields around the main and secondary flaws as β varied from 0° to 90°, especially the tensile force concentration zones superposition. The tensile forces concentration zone around flaw shrank towards flaw tips with the increase of flaw’s inclinations measured horizontally. Under stress field superposition effects, the crack initiation stress decreased firstly and then increased with β at α of 30° and 45°. Crack initiation locations were close to flaw tips but not restricted to them. The distances between crack initiation locations and flaw tips, and the crack initiation angles depended on the flaw where first macrocracks initiated from. Microdisplacement field distributions of granite specimens to reveal the mesomechanism of crack initiation behaviors were discussed.

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Formation mechanism of the Upper Triassic Yanchang Formation tight sandstone reservoir in Ordos Basin—Take Chang 6 reservoir in Jiyuan oil field as an example

Cited by 83 publications

References 12 publications

Water-flooding characteristics of lithologic reservoir in Ordos basin

Water-flooding characteristics of lithologic reservoir in Ordos basin

The Key Stratum Structure Morphology of Longwall Mechanized Top Coal Caving Mining in Extra‐Thick Coal Seams: A Typical Case Study

Crack Initiation Behaviors of Granite Specimens Containing Crossing‐Double‐Flaws with Different Lengths under Uniaxial Loading

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