Implications of organic matter source and fluid migration from geochemical characteristics of stylolites and matrix in carbonate rocks: A case study from the Carboniferous and the Ordovician in the Sichuan Basin, SW China

Liu, Shiju; Gao, Gang; Gang, Wenzhe; Qu, Tong; Dang, Wenlong; Zhang, Weiwei; Yang, Shangru; Zhu, Kangle

doi:10.1016/j.petrol.2019.106606

Cited by 11 publications

(5 citation statements)

References 27 publications

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“…e crude oil has approached or reached the maturity stage [29], which is basically consistent with the analysis results of the mudstone in well G43 in the study area.…”

Section: Characteristics Of Source Rockssupporting

confidence: 89%

Characteristics and Controlling Factors of the Chang 8 Oil Reservoir in the Yanchi Area of the Ordos Basin: A Case Study of Well G20

et al. 2022

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In the Ordos Basin, the Chang 8 oil reservoir of the Triassic Yanchang Formation is the main target of oil exploration and development and there are many factors affecting the hydrocarbon accumulation. Well G20 is an important exploration well in the Yanchi area in the northwestern part of the basin, and the core of the Chang 8 reservoir was sampled and tested to determine the source rocks, trace element composition, mineral composition, reservoir physical properties, and oil-bearing properties. The results show that the rock retrieved exhibits delta plain subfacies; the range of the Chang 8 water body was large, with a gentle slope, and the climate was relatively dry. These findings suggest that this reservoir was deposited in an environment in which sedimentary sand body could easily form. The Chang 8 sandstone reservoir pores are dominated by intergranular pores and feldspar intragranular dissolution pores, indicating that the Chang 8 reservoir is a low-porosity and low-permeability reservoir. Chang 7 source rocks from this area have a type I-II1 hydrocarbon-generating potential, with an average total organic carbon (TOC) content of 5.99% and vitrinite reflectance (Ro) value of 0.48%. Combined with the regional sedimentary evolution, tectonic movement, and reservoir distribution, it is considered that due to the lack of lithologic traps or low-amplitude structural traps, G20 produced water in well testing. The Chang 8 oil reservoir in the Yanchi area can be divided into structural reservoirs and structural-lithologic reservoirs. The conventional oil and gas reservoir exploration ideas of “thick sand belt” and “reservoir sweet spot” are not applicable here. The lithology traps or low-amplitude structural traps and areas with good preservation conditions are the main directions for the next phase of exploration in the northwestern part of the Ordos Basin.

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“…e crude oil has approached or reached the maturity stage [29], which is basically consistent with the analysis results of the mudstone in well G43 in the study area.…”

Section: Characteristics Of Source Rockssupporting

confidence: 89%

Characteristics and Controlling Factors of the Chang 8 Oil Reservoir in the Yanchi Area of the Ordos Basin: A Case Study of Well G20

et al. 2022

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“…Compared with their host rocks, rock volumes that contain or are affected by stylolites typically show anomalous porosity and permeability (Laronne Ben-Itzhak et al, 2012;Rustichelli et al, 2015;Ehrenberg et al, 2016;Morad et al, 2019). On the one hand, stylolites can provide pathways for fluid flow parallel to them (Heap et al, 2014;Martín-Martín et al, 2018), and can thus act as conduits for the migration of dissolved materials and hydrocarbon (Ehrenberg et al, 2016;Ehrenberg and Wu, 2019;Liu et al, 2020a). On the other hand, stylolites can also act as barriers to stylolite-normal flow (Sassen and Moore, 1988;Leythaeuser et al, 1995;Mehrabi et al, 2016;Beigi et al, 2017;Bruna et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Relationship between stylolite morphology and the sealing potential of stylolite-bearing carbonate cap rocks

Fan

Gomez‐Rivas

et al. 2022

GSA Bulletin

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We analyzed the sealing effectiveness of cap rocks bearing different types of stylolites using a combination of petrographic, petrophysical, pore structure, and sealing capacity characterization techniques. This study was based on examples of carbonate cap rocks that seal ultradeep hydrocarbon reservoirs of the Tarim Basin (China). Samples from both drill cores and their outcrop analogues were investigated to quantify how morphology influences the sealing capacity of different types of stylolite-bearing rocks. The study cap rocks consisted of mudstone, wackestone to packstone, grainstone, and dolomitic limestone. Four types of stylolites were identified: rectangular layer, seismogram pinning, suture and sharp peak, and simple wave-like types. The difference in the sealing capacity of carbonate cap rocks is attributed to their pore structure connections and the types of stylolites they develop. Samples bearing simple wave-like stylolites showed the best sealing capacity, followed by those with rectangular layer and suture and sharp peak types, whereas carbonates hosting seismogram pinning types had the lowest sealing capacity. The impact of stylolite segments on the rock sealing properties, however, differed from one segment to another. Rectangular layer−type stylolites could be divided into three distinct segments (with good, moderate, and poor sealing, respectively). Both the seismogram pinning and suture and sharp peak stylolite types were divided in two parts, with the former one having moderate and poor sealing and the latter exhibiting good and moderate sealing. The simple-wave−like type had a good sealing capacity all along the pressure-solution seam. The most effective sealing barriers for vertical fluid flow form when (1) calcite and siliceous cements are pervasively distributed in the vicinity of stylolites, forming highly cemented zones with lower porosity and permeability than their surrounding host rocks; (2) stylolites are enriched in insoluble residues; and (3) rare microfractures and dissolution vugs are found along the stylolites. This work provides useful examples for the prediction of the sealing potential of stylolite-bearing carbonate rocks according to stylolite morphology in other geologic settings.

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“…16,17 Due to the fractionation effect of the formation, the proportion of heavy components decreases during migration, indicating the migration path of hydrocarbons. 16 However, the precision of QGF and QGF-E is insufficient for characterizing shortdistance migration of shale oil, the commonly used geochemical methods are difficult to directly reveal the dynamic migration and accumulation processes, and the physical simulation experiments widely used in the study of conventional hydrocarbon accumulation mechanism are also difficult to apply to the very tight shale reservoirs. 18 It is of great significance to clarify the migration mechanism to analyze the microscopic dynamics in shale.…”

Section: Introductionmentioning

confidence: 99%

“…The source–reservoir-separated shale oil generally migrates over a long distance, the source–reservoir-coexisted shale oil migrates at the centimeter level, and the pure shale oil is distributed in shale by very short-distance migration in the nanometer–micrometer scale. , Previous studies on conventional hydrocarbon migration have been carried out by QGF and QGF-E, geochemical methods such as gas chromatography–mass spectrometry, and carbon isotopes. Geochemical methods have the advantage of quantitatively characterizing the chemical changes of hydrocarbons during migration and can indicate the migration path of hydrocarbons. , Due to the fractionation effect of the formation, the proportion of heavy components decreases during migration, indicating the migration path of hydrocarbons . However, the precision of QGF and QGF-E is insufficient for characterizing short-distance migration of shale oil, the commonly used geochemical methods are difficult to directly reveal the dynamic migration and accumulation processes, and the physical simulation experiments widely used in the study of conventional hydrocarbon accumulation mechanism are also difficult to apply to the very tight shale reservoirs .…”

Section: Introductionmentioning

confidence: 99%

“…Geochemical methods have the advantage of quantitatively characterizing the chemical changes of hydrocarbons during migration and can indicate the migration path of hydrocarbons. 16,17 Due to the fractionation effect of the formation, the proportion of heavy components decreases during migration, indicating the migration path of hydrocarbons. 16 However, the precision of QGF and QGF-E is insufficient for characterizing shortdistance migration of shale oil, the commonly used geochemical methods are difficult to directly reveal the dynamic migration and accumulation processes, and the physical simulation experiments widely used in the study of conventional hydrocarbon accumulation mechanism are also difficult to apply to the very tight shale reservoirs.…”

Section: Introductionmentioning

confidence: 99%

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Using Spontaneous Imbibition to Evaluate the Hydrocarbon Migration and Accumulation Potential of Shale Reservoirs: A Case Study of the Permian Fengcheng Formation in the Mahu Sag, Junggar Basin

Wang

Gao

et al. 2022

Energy Fuels

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Spontaneous imbibition (SI) has been used widely to characterize shale wettability and pore structures, which can significantly affect the migration and accumulation processes of shale oil. However, the application of SI in the enrichment mechanism of shale oil is quite limited. Therefore, focusing on the Permian Fengcheng Formation shale deposited in an alkaline lake environment in the Mahu Sag of Junggar Basin, this study conducts systematic SI experiments with complementary experiments such as contact-angle measurement, optical microscopy, field emission scanning electron microscopy, micro-CT, high-pressure mercury intrusion porosimetry, and N 2 adsorption to clarify the controlling factors of SI behavior of different fluids in shale and attempts to evaluate the migration and accumulation potential of shale reservoirs using SI. The results show that the more hydrophobic the sample is, the stronger the absorption of n-decane is, and the SI of n-decane reaches equilibrium quickly. The development of an alkaline mineral layer that is several millimeters thick in Fengcheng Formation shale could promote hydrocarbon migration due to the large particles of alkaline minerals (200−400 μm) and more development of intergranular microfractures, which can be indicated by the higher SI slope and imbibed oil volume. Using SI parameters, the shale hydrocarbon migration−accumulation index H m was proposed in this study; the greater the H m of the shale reservoir is, the more conducive to the migration and accumulation of shale oil the shale reservoir is. Four migration−accumulation patterns were established for different lithofacies in the study area, and the migration and accumulation potential of different lithofacies of shale from strong to weak is in the order of siltstone, shale with an alkaline mineral layer, laminated shale, and then massive shale, which is generally in line with the order of shale oil content. The validity of the proposed shale hydrocarbon migration−accumulation index is also confirmed using data from the literature.

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Implications of organic matter source and fluid migration from geochemical characteristics of stylolites and matrix in carbonate rocks: A case study from the Carboniferous and the Ordovician in the Sichuan Basin, SW China

Cited by 11 publications

References 27 publications

Characteristics and Controlling Factors of the Chang 8 Oil Reservoir in the Yanchi Area of the Ordos Basin: A Case Study of Well G20

Characteristics and Controlling Factors of the Chang 8 Oil Reservoir in the Yanchi Area of the Ordos Basin: A Case Study of Well G20

Relationship between stylolite morphology and the sealing potential of stylolite-bearing carbonate cap rocks

Using Spontaneous Imbibition to Evaluate the Hydrocarbon Migration and Accumulation Potential of Shale Reservoirs: A Case Study of the Permian Fengcheng Formation in the Mahu Sag, Junggar Basin

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