Geochemical and tight reservoir characteristics of sedimentary organic-matter-bearing tuff from the Permian Tiaohu Formation in the Santanghu Basin, Northwest China

Ma, Jian; Huang, Zhilong; Shijun, Liang; Liu, Zaizhen; Liang, Hao

doi:10.1016/j.marpetgeo.2016.03.017

Cited by 45 publications

(15 citation statements)

References 49 publications

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“…The geographical location of the TST oil reservoir is shown in Figure a. In Figure a, the geographical location is on the left and the stratigraphic distribution in the vertical direction is on the right . The cross section of the TST oil reservoir and the migration path of crude oil during reservoir formation are shown in Figure b …”

Section: Reservoir Backgroundmentioning

confidence: 99%

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The Law and Mechanism of the Sample Size Effect of Imbibition Oil Recovery of Tight Sedimentary Tuff

Yang

Dong

et al. 2022

ACS Omega

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Imbibition is an important mechanism to improve the recovery factor (RF) of a tight oil reservoir. Accurately evaluating the oil production capacity of tight oil reservoirs by imbibition is of great significance for the formulation of oilfield production plans and productivity prediction. However, there is currently no unified regulation on the selection of rock sample size in tight oil reservoir imbibition evaluation experiments, resulting in great differences in reservoir imbibition oil production capacity obtained from rock samples of different sizes, which brings great challenges to the efficient development of tight oil reservoirs. To clarify the law and mechanism of the rock sample size effect of tight core imbibition oil recovery, this paper takes the newly discovered tight sedimentary tuff (TST) oil reservoir as an example. First, several representative real cores were collected. Then, their wettability and pore structure characteristics were analyzed. Finally, physical simulation experiments of imbibition under different rock sample sizes were conducted. The results show that the TST has very favorable imbibition conditions, which are manifested in the following: (i) the wettability is weakly hydrophilic to hydrophilic; (ii) the mineral composition is tuffaceous minerals, calcite, and quartz, without clay minerals; (iii) micro-nanoscale pores are developed; and (iv) the pore throats are evenly distributed. In the imbibition experiments of rock samples of different sizes, the oil production characteristics of the core surface, the variation form of imbibition rate, pore production characteristics, and the influence mode of imbibition pressure on imbibition do not have the sample size effect. However, the RF of the spontaneous imbibition has an obvious sample size effect, and there is a good exponential function relationship between the imbibition RF and the specific surface area (SSA) of cores. The fundamental reason why the rock sample size effect of the TST imbibition oil recovery is relatively stable and has strong regularity is that its pore structure and wettability are relatively homogeneous and stable. The change of rock sample size does not have a great impact on the distribution of the core pore structure and wettability, resulting in no significant change in its imbibition power, resistance, and distance. Therefore, the main factor determining the imbibition RF of rock samples with different sizes is their SSA. The research results of this work can provide an important theoretical basis for understanding the law and mechanism of TST imbibition oil recovery and unifying the imbibition experimental results of small-sized rock samples.

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Section: Reservoir Backgroundmentioning

confidence: 99%

“…(b) Cross section of the TST oil reservoir and its oil and gas migration path in the process of reservoir formation. Reprinted with permission from ref . Copyright 2016 Marine and Petroleum Geology.…”

Section: Reservoir Backgroundmentioning

confidence: 99%

The Law and Mechanism of the Sample Size Effect of Imbibition Oil Recovery of Tight Sedimentary Tuff

Yang

Dong

et al. 2022

ACS Omega

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“…This is consistent with the low organic carbon content. The pores in tuff can be divided into two types: intergranular and intragranular mineral pores (Ma et al, 2015).…”

Section: Pore Types Of Tuffmentioning

confidence: 99%

“…The mineral composition of the tuff of the Chang 7 Member is relatively simple, mainly consisting of clay minerals, quartz and feldspar. Affected by decitrification, a large amount of intercrystalline pores are developed between the minerals in the tuff, which is the most important type of pores in the tuff (Ma et al, 2015).…”

Section: Pore Types Of Tuffmentioning

confidence: 99%

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Organic-rich formation and hydrocarbon enrichment of lacustrine shale strata: A case study of Chang 7 Member

Liu

Peng

Jin

et al. 2021

Sci. China Earth Sci.

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Lacustrine shale is an important target for the exploration of unconventional oil and gas in China beyond marine shale gas. However, the formation environment of lacustrine shale differs from that of marine shale, resulting in a different reservoir composition, organic matter, oil and gas content, and hydrocarbon mobility. In this study, the Chang 7 shale of the Yanchang Formation in the Ordos Basin was used to analyze the effect of volcanic activity on the paleoproductivity and preservation conditions during the formation of lacustrine shale. The results show that algae and bacteria were developed before the eruption. After the eruption, the number of bacteria declined, but the increased prosperity of algae reflects that the volcanic activity enhanced ancient productivity. The sulfate generated by volcanic activity promotes bacterial sulfate reduction, and the produced H 2 S leads to a strong reducing environment in the waterbody, which is conducive to the preservation of organic matter. Organic geochemical analysis shows that the black shale in the shale strata has a high total organic carbon (TOC) content and strong hydrocarbon generation potential, whereas the tuff has a low TOC content and can scarcely generate hydrocarbons, indicating that the tuff deposited by volcanic activity cannot be considered as effective source rock. In terms of storage space, shale is mainly laminar and dispersed, and it includes organic and inorganic pores. The development of organic pores is affected by thermal maturity, whereas inorganic pores mainly occur between detrital particles and crystals. Tuff is mainly supported by heterogeneous matrix and associated with alteration. Its pores include inter-and intragranular mineral pores. The development of tight sandstone pores is affected by compaction, cementation, and dissolution, which mainly consist of intra-and intergranular pores. The Chang 7 lacustrine shale generally contains oil, but different lithologies have different oil drainage efficiencies. Sandstone and shale exhibit the best and worst oil drainage efficiency, respectively. It is mainly affected by the pore size distribution, fluid properties, and rock wettability. Therefore, the development of shale oil should mainly focus on lacustrine shale formations with interbeds. The mutual dissolution of organic matter and hydrocarbons in the shale section leads to the poor mobility and difficult development of hydrocarbons.

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Characteristics and controlling factors of tuff reservoirs of Huoshiling Formation in Dehui Fault Depression, Songliao Basin, NE China

Fan,

Wang,

Song

et al. 2023

Geological Journal

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This study takes the tuff reservoir of the Huoshiling Formation in the Dehui Fault Depression, Songliao Basin, as an example to clarify the characteristics and primary controlling factors of tuff reservoirs. 3D seismic, core, image log, thin section, production dynamic and other data were used. Mineral x‐ray diffraction, core computerized tomography scanning, high‐pressure mercury injection, porosity, permeability, scanning electron microscopy, cathodoluminescence thin section, element testing and other experiments were conducted. The volcanic rocks in the study area are divided into andesite, volcanic breccia, lithic tuff and crystal tuff. The experiment results show that the mineral composition of tuff is primarily quartz, feldspar and clay minerals. The reservoir space comprises secondary pores and fractures, whereas primary pores are not developed. Average pore‐throat radius of most samples ranges from 0.017 to 0.131 μm, and the pore‐throat is primarily fine. The average porosity is 12.21% (a typical medium‐high porosity reservoir), and the average permeability is 0.072 mD (an extra‐low permeability reservoir). Tectonic fractures generated by tectonic movement are one of the reservoir spaces of tuff. Faults and tectonic fractures constitute a crucial migration channel of the fluid in the deep stratum. The tuff formed in the underwater environment, and the reservoir is affected by alteration. Devitrification is a crucial cause of medium‐high porosity and ultra‐low permeability in reservoirs. The alteration caused by hydrothermal fluid in deep fluids creates a considerable number of pores and fractures filled with clay minerals. Furthermore, acid fluid dissolves tuff along faults and fractures. In terms of time, the filling action is earlier than the dissolution action. The weathering indexes of CIA, CIW, PIA and WIP indicate that the tuff has suffered intense weathering, and the reservoir's physical properties have been improved to some extent.

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Geochemical and tight reservoir characteristics of sedimentary organic-matter-bearing tuff from the Permian Tiaohu Formation in the Santanghu Basin, Northwest China

Cited by 45 publications

References 49 publications

The Law and Mechanism of the Sample Size Effect of Imbibition Oil Recovery of Tight Sedimentary Tuff

The Law and Mechanism of the Sample Size Effect of Imbibition Oil Recovery of Tight Sedimentary Tuff

Organic-rich formation and hydrocarbon enrichment of lacustrine shale strata: A case study of Chang 7 Member

Characteristics and controlling factors of tuff reservoirs of Huoshiling Formation in Dehui Fault Depression, Songliao Basin, NE China

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