Combining pressure-controlled porosimetry and rate-controlled porosimetry to investigate the fractal characteristics of full-range pores in tight oil reservoirs

Wang, Xixin; Hou, Jiagen; Song, Suihong; Wang, Dongmei; Gong, Lili; Ma, Keping; Liu, Yuming; Li, Yongqiang; Lin, Yan-Bo

doi:10.1016/j.petrol.2018.07.050

Cited by 90 publications

(52 citation statements)

References 40 publications

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“…This phenomenon sharply contradicts previous research findings. In this study, comprehensive analysis of seismic, lithofacies, temperature, pressure (Guo et al 2017a, b;Rui et al 2017a, b;Wang et al 2018), and CO 2 content data suggests that there should be at least two sets of volcanic reservoirs, i.e., Fs6 and Fs7 are in one reservoir body, and Fs701, Fs9-1, and Fs9 are in the other. The GR inversion data, collected by CNPC (Fig.…”

Section: Reservoir Distribution In the East Changde Gas Fieldmentioning

confidence: 55%

Origin, migration, and accumulation of carbon dioxide in the East Changde Gas Field, Songliao Basin, northeastern China

Liu

Yang

Rui³

et al. 2018

Pet. Sci.

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CO 2 reservoirs are widely distributed within the Yingcheng Formation in the Songliao Basin, but the extreme horizontal heterogeneity of CO 2 content causes difficulties in the exploration and exploitation of methane. Former studies have fully covered the lithology, structure, and distribution of the reservoirs high in CO 2 content, but few are reported about migration and accumulation of CO 2 . Using the East Changde Gas Field as an example, we studied the accumulation mechanisms of CO 2 gas. Two original types of accumulation model are proposed in this study. The fault-controlled accumulation model refers to gas accumulation in the reservoir body that is cut by a basement fault (the West Xu Fault), allowing the hydrocarbon gas generated in the lower formation to migrate into the reservoir body through the fault, which results in a relatively lower CO 2 content. The volcanic conduit-controlled accumulation model refers to a reservoir body that is not cut by the basement fault, which prevents the hydrocarbon gas from being mixed in and leads to higher CO 2 contents. This conclusion provides useful theories for prediction of CO 2 distribution in similar basins and reservoirs.Petroleum Science (2018) 15:695-708 https://doi.org/10.1007/s12182-018-0259-5( 0123456789().,-volV) (0123456789().,-volV)

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Section: Reservoir Distribution In the East Changde Gas Fieldmentioning

confidence: 55%

Origin, migration, and accumulation of carbon dioxide in the East Changde Gas Field, Songliao Basin, northeastern China

Liu

Yang

Rui³

et al. 2018

Pet. Sci.

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“…Lu [51] reported the relative permeability and maximum saturation of gas in reservoirs with or without fractures. It The permeability only defines the flow performance of single-phase fluids, which is rare in real world [56][57][58]. The characteristics of multiphase fluid flow are more meaningful, in which the relative permeability of natural gas is a function of water saturation.…”

Section: Impact Of Fractures On Gas Seepagementioning

confidence: 99%

Fracture Characteristics and Their Influence on Gas Seepage in Tight Gas Reservoirs in the Kelasu Thrust Belt (Kuqa Depression, NW China)

Yang

Fan

et al. 2018

Energies

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Natural fractures were generally accepted as a key factor influencing the gas seepage performance in tight gas reservoirs in Kelasu Thrust Belt (KTB). However, the mechanism was not fully clarified, especially from a microscopic perspective. Based on observation of core samples and cast thin sections and gas charging experiment on core plugs, the parameters of fractures and seepage performance in fractured tight reservoirs are studied; further, the controlling effect of fractures on gas seepage was discussed. The results show that in KTB fractures could be categorized by the size of their apertures as macro-fractures (aperture width ranges from 0.1 to 2 mm) and micro-fractures (aperture width ranges from 5 to 100 µm), which appear in the form of fractures networks. Tectonic deformations and abnormal high fluid pressure control the fracture density: near faults or anticlines (folds), fracture density increases, and fluid pressure of 15 MPa increases the aperture by 50%, and induces new fractures. The fracture networks with high linear density significantly improves tight reservoir quality and seepage performance: it enhances the reservoir permeability by 1-4 orders of magnitude, and the relative gas permeability by 2-10 magnitude; by enhancing permeability, the fracture networks reduce the initial flowing gradient from as high as 0.41 MPa/cm to 0 Mpa/cm, and make the gas flowing possible.Energies 2018, 11, 2808 2 of 22 basins like the Ordos Basin in China [13,14], Sichuan Basin in China [15], Western Canadian Basin in Canada [16], the reduction of tight gas reservoirs in KTB is several times higher. Studies have been carried out on the tectonic evolution [17][18][19][20][21][22][23][24], structural characteristics [25,26], stratigraphy [27,28], reservoirs [29][30][31][32], and hydrocarbon migration histories [33,34] in KTB, to explain why tight gas reservoirs in KTB have such high gas reserves and production at such great depths. It is generally agreed that tectonic faults and fractures played an important role in enhancing gas migration and production efficiency. Tao [35] fully described the characteristics of the natural fractures in KTB using FMI images and cores, and explain the relationship between fracture formation and in-situ stress. Sun [36] further studied the fracture-pore systems using cast thin sections, and identified a fracture zone in KTB. On this basis, Shen [24] determined gas source faults as key elements in natural gas migration and accumulation, and evaluated their effectiveness combining geochemistry and fluid potential analysis method. However, these studies explained the high reserve of KTB tight reservoirs in a macro view, and had not clarified the microscopic mechanism of gas seepage in gas charging or production process, including but not limited to pathways, characteristics, and controlling factors; whereas, a deep understanding of above could help explain and predict gas saturation and distribution, which is of great value to further explorations.The effects of fractures in improving p...

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“…15,16 However, it is difficult to characterize the pore structure because of the wide PSD from nanoscale to micron scale in tight oil reservoirs. In recent years, many advanced methods have been employed to investigate pore characteristics of rocks, such as Scanning electron microscopy (SEM), [17][18][19] pressure-controlled mercury injection (PMI), 20 nuclear magnetic resonance (NMR), 21 Low-temperature N 2 adsorption (LTNA) and Low-temperature CO 2 adsorption (LTCA), 22 X-ray computed tomography (CT) 23,24 and so on. However, it is noteworthy that all these methods have shown advantages and disadvantages in characterizing pore structure of unconventional reservoirs because of their working mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Overall PSD and Fractal Characteristics of Tight Oil Reservoirs: A Case Study of Lucaogou Formation in Junggar Basin, China

et al. 2019

Self Cite

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Lucaogou tight oil reservoir, located in the Junggar Basin, Northwest of China, is one of the typical tight oil reservoirs. Complex lithology leads to a wide pore size distribution (PSD), ranging from several nanometers to hundreds of micrometers. To better understand PSD and fractal features of Lucaogou tight oil reservoir, the experiment methods including scanning electron microscope (SEM), rate-controlled mercury injection (RMI) and pressure-controlled mercury injection (PMI) were performed on the six samples with different lithology. The results indicate that four types of pores exist in Lucaogou tight oil reservoir, including dissolution pores, clay dominated pores, microfractures and inter-granular pores. A combination of PMI and RMI was proposed to calculate the overall PSD of tight oil reservoirs, the overall pore radius of Lucaogou tight oil reservoir ranges from 3.6[Formula: see text]nm to 500[Formula: see text][Formula: see text]m. The fractal analysis was carried out based on the PMI data. Fractal dimension (Fd) values varied between 2.843 and 2.913 with a mean value of 2.88. Fd increases with a decrease of quartz content and an increase of clay mineral content. Samples from tight oil reservoirs with smaller average pore radius have stronger complexity of pore structure. Fractal dimension shows negative correlations with porosity and permeability. In addition, fractal characteristics of different tight reservoirs were compared and analyzed.

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Combining pressure-controlled porosimetry and rate-controlled porosimetry to investigate the fractal characteristics of full-range pores in tight oil reservoirs

Cited by 90 publications

References 40 publications

Origin, migration, and accumulation of carbon dioxide in the East Changde Gas Field, Songliao Basin, northeastern China

Origin, migration, and accumulation of carbon dioxide in the East Changde Gas Field, Songliao Basin, northeastern China

Fracture Characteristics and Their Influence on Gas Seepage in Tight Gas Reservoirs in the Kelasu Thrust Belt (Kuqa Depression, NW China)

Overall PSD and Fractal Characteristics of Tight Oil Reservoirs: A Case Study of Lucaogou Formation in Junggar Basin, China

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