Hydrocarbon accumulation and exploration prospect of mound-shoal complexes on the platform margin of the fourth member of Sinian Dengying Formation in the east of Mianzhu-Changning intracratonic rift, Sichuan Basin, SW China

The northwestern Sichuan region experienced the evolutionary process of a marine Craton basin in the Sinian-Middle Triassic and a continental basin in the Mesozoic-Cenozoic. Several regional tectonic activities cause the complicated stratigraphic distribution and structural deformations in deep layers. During key tectonic periods, the characteristic sedimentary and deformation structures were formed, including the platform margin of Dengying formation, the western palaeohigh at the end of Silurian, and the passive continental margin of late Paleozoic-middle Triassic. The Meso-Cenozoic intra-continental compressional tectonic processes since the late Triassic controlled the formation of complex thrusting structures surrounding and inside the basin. The northern Longmenshan fold-thrust belt has footwall in-situ thrust structures, controlled by two sets of detachments in the Lower Triassic and the Lower Cambrian, presenting a multi-level deformation structure with shallow folds, the middle thin-skin thrusts and the deeper basement-involved folds. From the perspective of structural geology, the Dengying formation of the Upper Sinian is mainly distributed in the eastern and northern areas of the northwest Sichuan basin where the Jiulongshan fold is the favorable exploration belts. Using the three-dimensional seismic reflection data, we recognize the structural characteristics of the platform margin of Dengying formation. Meanwhile, we apply new methods of two-dimensional and structural restoration based on mechanical constrains to gain insights into the development of the Jiulongshan anticline which forms the trap for the Jiulongshan field. The result of structural restoration indicates that, the formation of the Jiulongshan anticline is controlled by two-stage contractional thrusts. In the early days, there was no significant relief in Jiulongshan area, and the southwestern top of the Sinian Dengying formation was the paleo-high. The anticline was gradually formed in the Late Jurassic-the Early Cretaceous, presenting an approximately E-W strike structure. This structure was transformed by the N-E contractional stress to become an anticline in NE-SW direction. &#160;

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Seismic sequence stratigraphy and sedimentary evolution of carbonate reservoirs in the Sinian Dengying Formation, Middle Sichuan Basin, Southwest China

Interpretation ◽

10.1190/int-2013-0032.1 ◽

2013 ◽

Vol 1 (1) ◽

pp. SA21-SA34 ◽

Cited By ~ 2

Author(s):

Guangfa Zhong ◽

Yalin Li ◽

Dingjin Liu

Keyword(s):

Shallow Water ◽

Deep Water ◽

Sichuan Basin ◽

Southwest China ◽

Seismic Sequence ◽

Sedimentary Evolution ◽

Dengying Formation ◽

Platform Margin ◽

Basin Topography ◽

Basin Region

The Sinian Dengying Formation in the Sichuan Basin, southwest China, mainly consisting of dolomites, is one of the most ancient gas-producing series in the world. During the past half-century, gas exploration in the formation has been largely based on the lithostratigraphic correlation, but a regional correlation scheme of time significance is usually insufficient, resulting in the difficulty of lateral correlation of strata between gas fields. Aiming to overcome the problem, we completed an interpretation of about 2500-km 2D regional seismic lines by using the seismic sequence analysis method. As a result, a sequence stratigraphic framework was successfully constructed, which consists of two sequences and five systems tracts. By integrating analysis of isopatch maps with stratal stacking patterns, we identify three depositional facies belts within the formation, which are a shallow-water platform facies belt in the eastern and southern regions, a relatively deep-water (intraplatform) basin facies belt in the northwestern region, and a northwest-dipping slope facies belt between them. During the development of sequence one in the lower of the Dengying Formation, retrogradation and aggradation dominated in the eastern and southern platform region whereas depositional condensation prevailed in the northwestern basin region. At that time, the depocenter was located on the eastern and southern platform region. However, sequence two in the upper of the Dengying Formation is dominated by the northwest-dipping sigmoid, oblique and shingled prograding packages of the platform-margin slope facies belt, indicating that the depositional center was shifted to the previous basin region in the northwest. As a result, the basin was filled gradually, and the platform-slope-basin topography was finally evolved into a northwest-dipping ramp. Our study suggests that the Late Sinian Sichuan Basin would consist of a series of shallow-water platforms separated by relatively deep-water depressions or (intraplatform) basins, which provides important clues for gas exploration.

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Breakthrough and significance of technology on internal multiple recognition and suppression: A case study of Sinian Dengying Formation in Central Sichuan Basin, SW China

Petroleum Exploration and Development ◽

10.1016/s1876-3804(18)30106-x ◽

2018 ◽

Vol 45 (6) ◽

pp. 1023-1035 ◽

Cited By ~ 2

Author(s):

Lideng GAN ◽

Fusen XIAO ◽

Xiaofeng DAI ◽

Hao YANG ◽

Youping XU ◽

...

Keyword(s):

Sichuan Basin ◽

Sw China ◽

Dengying Formation ◽

Central Sichuan Basin

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Strike-slip faults and their significance for hydrocarbon accumulation in Gaoshiti–Moxi area, Sichuan Basin, SW China

Petroleum Exploration and Development ◽

10.1016/s1876-3804(18)30088-0 ◽

2018 ◽

Vol 45 (5) ◽

pp. 851-861 ◽

Cited By ~ 1

Author(s):

Debo MA ◽

Zecheng WANG ◽

Shufu DUAN ◽

Jianrong GAO ◽

Qingchun JIANG ◽

...

Keyword(s):

Sichuan Basin ◽

Strike Slip ◽

Hydrocarbon Accumulation ◽

Sw China

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Sedimentary and Diagenetic Features and Their Impacts on Microbial Carbonate Reservoirs in the Fourth Member of the Middle Triassic Leikoupo Formation, Western Sichuan Basin, China

Energies ◽

10.3390/en13092293 ◽

2020 ◽

Vol 13 (9) ◽

pp. 2293

Author(s):

Yuanchong Wang ◽

Weimin Jiang ◽

Hangyu Liu ◽

Bo Liu ◽

Haofu Zheng ◽

...

Keyword(s):

Sichuan Basin ◽

Depositional Environments ◽

Sw China ◽

Western Sichuan ◽

Microbial Carbonates ◽

Rock Types ◽

Multi Stage ◽

Leikoupo Formation ◽

Western Sichuan Basin ◽

Fourth Member

In recent years, the discovery of two gas fields in the fourth member of the Leikoupo Formation in the Western Sichuan Basin of SW China confirmed the exploration potential of microbial carbonates. The aim of the present study is to clarify the formation mechanism of the microbial reservoirs in the Leikoupo Formation. For this purpose, lithofacies, depositional environments, and diagenesis analyses were performed in samples collected from cores of 12 wells. The climate of study area was arid during Anisian time, and the water body was restricted. In such a climate, an evaporitic environment was developed, where ten types of lithofacies, dominated by microbial carbonates and gypsum rocks, were recognized. Thrombolites and stromatolites are the main high-quality reservoirs rock types in the fourth member of the Leikoupo Formation in the Western Sichuan Basin of SW China, which developed as microbial mounds, with reservoir space of microbial inter-clot pores, intra-clot pores, fenestral pores, inter-crystalline pores, and cracks. The microbial inter-clot pores are the main reservoir space, formed by trapping and binding of marls by benthic microbial communities. These pores were partially filled with evaporites because of the arid climate, which were subsequently dissolved (mainly gypsum) in the syn-depositional period, thus greatly improving the quality of reservoirs. Although some pores were occluded by multi-stage cements during the burial stage, major pores were well preserved own to the early dolomitization, rapid burial of the Leikoupo Formation, and early charging of hydrocarbon. The early dolomitization enhanced the anti-compaction ability of microbial carbonates during the burial stage. Rapid burial of the Leikoupo succession slowed down early cementation, and it also accelerated the maturation and expulsion process source rock to promote early charging of hydrocarbon in pores, which created a closed system, inhibiting strong burial cementation.

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