Genesis and distribution pattern of carbonate cements in lacustrine deep-water gravity-flow sandstone reservoirs in the third member of the Shahejie Formation in the Dongying Sag, Jiyang Depression, Eastern China

2018 ◽  
Vol 92 ◽  
pp. 547-564 ◽  
Author(s):  
Tian Yang ◽  
Yingchang Cao ◽  
Henrik Friis ◽  
Keyu Liu ◽  
Yanzhong Wang ◽  
...  
Keyword(s):  
Distribution Pattern ◽  
Deep Water ◽  
Eastern China ◽  
Gravity Flow ◽  
Jiyang Depression ◽  
Dongying Sag ◽  
The Third ◽  
Carbonate Cements ◽  
Shahejie Formation ◽  
Sandstone Reservoirs

Origin of multiple-phase carbonate cements in the sandstones of the third member of the Shahejie Formation in the Niuzhuang Sag, Bohai Bay Basin

2020 ◽  
Vol 8 (3) ◽  
pp. SM83-SM101
Author(s):  
Yongwang Zhang ◽  
Feng Li
Keyword(s):  
Early Phase ◽  
Late Phase ◽  
Bohai Bay ◽  
Bohai Bay Basin ◽  
Rock Interaction ◽  
The Third ◽  
Carbonate Cements ◽  
Shahejie Formation ◽  
Sandstone Reservoirs ◽  
Ferroan Dolomite

Authigenic carbonate cement is one of the most abundant diagenetic minerals in sandstone reservoirs. Determining its origin and distribution may provide useful information for understanding the sandstone reservoir quality. In this study, we report results from a suite of analytical techniques to investigate the origin and evolution of carbonate cements in the third member of the Shahejie Formation in the Bohai Bay Basin. Our data indicate that the carbonate cements mainly occur in three phases: the early-phase calcite, late-phase ferroan calcite, and late-phase ferroan dolomite and/or ankerite. The early-phase calcites show depleted δ18O of the early-phase calcite (−11.8% to −7.8%), suggesting an 18O-depleted fluid origin from the mixing between lacustrine and meteoric waters. They were precipitated earlier than the quartz overgrowth at 40°C–63°C based on the oxygen isotope. The late-phase calcites were precipitated at 70°C–115°C, and they originated from water-rock interaction modified pore water at the same time or later than feldspar leaching. They show a lower average δ13C value (1.27%) than the early-phase calcite (1.65%), indicating that the interbedded shales within the sandstones most likely provided the required components for the precipitation of the late-phase calcite. Also, some Fe2+ was released during the organic acid release and then precipitated the late-phase ferroan calcites. The late-phase ferroan dolomite and/or ankerite were precipitated at 90°C–137°C in a deep diagenetic condition. They show depleted δ13C values (mean [Formula: see text]), and the carbons were mainly sourced from the thermal decarboxylation of organic matter and lacustrine carbonate. The early-phase calcite inhibits compaction while filling the pores, and the dissolution of ferroan calcite cements was the main reason for the development of secondary pores in the sandstone reservoirs. The late-phase ankerite reduces the reservoir porosity.

Hydrocarbon generation and evolution of the source rocks of the lower Es3 and upper Es4 members of the Shahejie Formation in the Niuzhuang Sub-sag, Jiyang Depression, Bohai Bay Basin, eastern China

2018 ◽  
Vol 6 (4) ◽  
pp. SN11-SN21
Author(s):  
Zhenkai Huang ◽  
Maowen Li ◽  
Quanyou Liu ◽  
Xiaomin Xie ◽  
Peng Liu ◽  
...  
Keyword(s):  
Activation Energy ◽  
Eastern China ◽  
Source Rocks ◽  
Bohai Bay ◽  
Hydrocarbon Generation ◽  
Bohai Bay Basin ◽  
Jiyang Depression ◽  
Generation Threshold ◽  
Oil Generation ◽  
Shahejie Formation

Systematic organic petrology and geochemistry analyses have been conducted in the source rocks of the lower Es3 and upper Es4 members of the Shahejie Formation in the Niuzhuang Sub-sag, Jiyang Depression, Bohai Bay Basin, eastern China. The results indicate that the main organic types of shale and nongypsum mudstone in the lower Es3 and upper Es4 member are I-II1 kerogen, and the predominant ([Formula: see text]) activation energy frequencies range from 57 to [Formula: see text]. The similar distribution characteristics in the two source rocks indicate that they have a similar hydrocarbon maturation process. An extensive pyrolysis analysis indicates that the source rocks of the upper Es4 member do not have an obvious double peak hydrocarbon generation model. Previous studies indicate that the hydrocarbon index peak at a depth of 2500–2700 m is affected by migrating hydrocarbon. Major differences are not observed in the hydrocarbon generation and evolution process of the shale and nongypsum mudstone. The primary oil generation threshold of the lower Es3 and upper Es4 members is approximately 3200 m, and the oil generation peak is approximately 3500 m. The activation energy distribution of the gypsum mudstone of the upper Es4 member is wider than that of the shale and nongypsum mudstone, and lower activation energies account for a larger proportion of the activation energies. The above factors may lead to a shallower oil generation threshold for gypsum mudstone compared with that for shale and nongypsum mudstone.

Gravity flow event beds in the middle section of Watermelon Formation in Luanping Basin，eastern China：A new interpretation for its Discovery and genesis.

2021 ◽  
Author(s):  
Cheng Wang
Keyword(s):  
Deep Water ◽  
Eastern China ◽  
Water Reservoir ◽  
Gravity Flow ◽  
Research Progress ◽  
Tectonic Activity ◽  
Climate Index ◽  
Middle Section ◽  
Short Term ◽  
Sliding Surfaces

<p>Gravity flow sediment is an important part of hydrocarbon source rock reservoir and an essential reservoir type in international deep water oil and gas exploration. Therefore, the study of gravity flow genesis type, sedimentary characteristics, control factors and sedimentary model in the middle section of Watermelon Formation in Luanping Basin is helpful to improve the understanding of basin evolution and the prediction of deep water reservoir. By using deep water sediment theory and gravity flow research progress, combined with logging, core, outcrop data and sheet analysis, the gravity flow in the middle section of Watermelon Formation in Luanping Basin is interpreted as slide-slump gravity flow, and the middle section of Watermelon Formation is divided into four sliding-slumping periods. The petrological analysis shows that the sediments are mainly granular supported massive conglomerate, coarse sandstone, tuff and volcanic limestone. According to the different causes, it is divided into two types: slide and slump, in which a large number of sliding surfaces are identified at the bottom of the sliding gravity flow, and sliding surfaces, small crumpled structures, faults, collapse deformation structures and drainage structures are identified in the slumping gravity flow. The paleogeomorphology and source supply of Luanping Basin during the period of Watermelon Formation, the obvious transformation of regional geological stress field, the tectonic slope fold belt developed along the source direction, the commonly used geochemical index Sr/Cu and the characteristics C climate index, the short-term eruption of volcano and the induced earthquake jointly reveal: paleogeomorphology, source supply, paleoclimate, tectonic activity, short-term volcanic eruption and induced seismic activity jointly control the formation of gravity flow sediments in the study area. this study provides practical examples and guidance for future evolution in other ancient lacustrine basins and modern basins.</p>

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