Fracture detection in oil-based drilling mud using a combination of borehole image and sonic logs

Lai, Jin; Wang, Guiwen; Fan, Zhuoying; Wang, Ziyuan; Chen, Jing; Zhou, Zhong‐Zhen; Wang, Shu-Chen; Xiao, Chengwen

doi:10.1016/j.marpetgeo.2017.03.035

Cited by 128 publications

(45 citation statements)

References 71 publications

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“…4 Fractures with a wide range of dip angles and apertures are detected by core observation (Figure 2). 10,43,57 The microfractures are strongly related to the core-observed macrofractures, 44 and they can also act as major pathways for fluid flow (Figure 3). The open fracture could constitute a favorable natural fracture system in the fault-block reservoirs.…”

Section: Fracture Observationmentioning

confidence: 99%

“…10 Many scholars have revealed that the presences of natural fractures will cause a significant decrease in resistivity (RT, Rxo) and in bulk density (DEN), and will result in an increase in sonic transit time F I G U R E 8 Well log expressions of sealed fractures (N208) (AC) in case of water-based drilling muds. 10,12,44 The dip angle of the fractures can be indicated by the amplitude of the sin wave, while the dip direction is estimated as the lowest point of the sine wave ( Figure 9). 43,51,67 For instance, the manually traced natural fractures in Figure 9 have a dip direction of 70°-80°, and the dip angle is about 60°-70° (Figure 9).…”

Section: Well Log Expressions Of Open Fracturesmentioning

confidence: 99%

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In‐situ stress determination and fracture characterization using image logs: The Paleogene Dongying Formation in Nanpu Sag, Bohai Bay Basin, China

Niu

Liu

Lai

et al. 2019

Energy Science & Engineering

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Fracture detection and in‐situ stress determination via well logs are important for exploration and exploitation of subsurface hydrocarbons. Cores, thin sections, and image logs are used to describe and interpret the subsurface fractures and in‐situ stress in the Paleogene Dongying sandstones in Nanpu Sag, Bohai Bay Basin, China. The maximum horizontal stress (SHmax) indicates a nearly east‐west trend according to the borehole breakouts and drilling‐induced fractures. Natural fractures in the Dongying sandstones are classified into: (1) open fractures and (2) closed fractures. The cement‐filled (closed) fractures are commonly detected by image logs as bright discontinuous sinusoidal waves due to resistive filling materials, while the open fractures are evident on image logs appearing as dark sine waves. The open fractures are of dominantly high dip angles, and the rose diagrams confirm the presences of two sets of fractures: northwest‐southeast and northwest‐southeast orientation. Fractures with strikes approximately parallel to the SHmax have good connectedness, making a significant contribution in hydrocarbon production. In addition, the oil‐bearing layers are mainly associated with the intervals with open fractures. The presence of natural fractures provides important pore spaces and fluid flow conduits. Insights can be provided into the subsurface fracture (natural and induced) detection and characterization using image logs.

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Section: Fracture Observationmentioning

confidence: 99%

Section: Well Log Expressions Of Open Fracturesmentioning

confidence: 99%

In‐situ stress determination and fracture characterization using image logs: The Paleogene Dongying Formation in Nanpu Sag, Bohai Bay Basin, China

Niu

Liu

Lai

et al. 2019

Energy Science & Engineering

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“…Intergranular pores, intercrystalline pores and dissolved pores can be observed in some samples. Moreover, microfractures with an aperture of less than 0.1 mm (Anders et al, 2014;Lai et al, 2017) are widely distributed in the Xiahuapidianzi Formation.…”

Section: Pore Types Of Reservoir Spacementioning

confidence: 99%

“…There are many different geophysical methods to evaluate a reservoir, which include nuclear magnetic resonance logs, a full stack seismic inversion technique, sub-seismic techniques and borehole image logs (Chatterjee et al, 2012;Ou et al, 2015;Lai et al, 2017). Moreover, several analytical technologies for estimating an unconventional reservoir have also been widely applied, including thin section, field emission scanning electron microscopy (FE-SEM), mercury intrusion porosimetry (MIP) and nuclear magnetic resonance (NMR) (Wang et al, 2016a;Ge et al, 2017;Zhang et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Controlling factors and physical property cutoffs of the tight reservoir in the Liuhe Basin

Tan

Wang

et al. 2017

Adv. Geo-Energ. Res.

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Tight gas sandstone reservoirs of the Lower Cretaceous Xiahuapidianzi Formation are the main exploration target in the Liuhe Basin in China. Petrology characteristics, reservoir space (pore space), controlling factors and physical property cutoffs of the tight sandstone reservoir in the Liuhe Basin were determined through the integrated analysis of several methods including: casting thin section, field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), nuclear magnetic resonance (NMR) and nitrogen gas adsorption (N2GA). The sandstones dominated by lithic arkoses and feldspathic litharenites are characterized by low porosity, low permeability and strong microscopic heterogeneity. The porosity has a range between 0.48% and 4.80%, with an average of 2.26%. Intercrystalline pores, intergranular pores, dissolved pores and microfractures can be observed through the casting thin section and FE-SEM images. Compaction and carbonate cementation are the two primary mechanisms resulting in the low porosity of the Liuhe sandstones. Microfractures improve the permeability of the tight sandstones and provide pathways for fluid migration and the storage of hydrocarbon accumulations. Moreover, the theoretical cutoff of the porosity in the Xiahuapidianzi Formation tight sandstones is 3.3%.

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“…With the continuous reduction of conventional oil and gas resources, unconventional tight sandstone gas has become the most promising field of oil and gas exploration and development, showing a vigorous development momentum (Bai, Sun, Liu, & Guo, ; Camac & Hunt, ; Chang et al, ; Jamison, ; Ju & Wang, ; Lai, Wang, Cai, et al, ; Lai, Wang, Fan, et al, ; Yin et al, ). Previous explorations of tight sandstone gas were mainly focused on the interior areas of sendimentary basins.…”

Section: Introductionmentioning

confidence: 99%

Developmental characteristics and distribution law of fractures in a tight sandstone reservoir in a low‐amplitude tectonic zone, eastern Ordos Basin, China

Yin

Tian²,

2019

Geological Journal

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In recent years, a large number of vertical and horizontal sliding fractures were found in the Upper Palaeozoic sandstones in the eastern margin of the Ordos Basin, China, However, the effect of fractures on the distribution of tight sandstone gas is still unclear. Therefore, in this paper, a large number of cores, thin sections, petrophysical property test results, conventional and FMI (Formation MicroScanner Image) image logs, and gas‐testing results were used to study the developmental characteristics of fractures and the gas control effects in a tight sandstone reservoir, in the eastern margin of the Ordos Basin. It was found that the average linear density of the core fractures is generally less than 2 m−1, and the microfractures are characterized as ruptures of quartz particles. The underlying Taiyuan and Benxi formations have the highest fracture development degrees, and the fracture index (FI) values are 0.68 and 0.72, respectively. However, the fracture development degrees in the overlying Shanxi to Shiqianfeng formations are significantly lower, and the FI values are generally less than 0.63. There is a good positive correlation between the fracture development degree and the contents of quartz mineral or brittle minerals (quartz + feldspar). On the whole, the fractures in the uplift and slope parts of the low‐amplitude structure areas are more developed, while in the depression zones, the fractures are generally less developed. The fractures in the Zijinshan Uplift area are extremely well developed; thus, the preservation conditions of the reservoir are poor. In this case, the fractures are unfavourable for the accumulation of natural gas. For the gentle tectonic zones, the over‐developed fractures in the Benxi and Taiyuan formations are unfavourable for the preservation of natural gas. However, the moderately developed fractures in the overlying Shanxi to Shiqianfeng formations are beneficial to the enrichment of natural gas. Finally, we compared the relationship between fracture index (FI) and open‐flow productivity of the gas wells, and it was found that FI values of commercial gas wells (Types I, II, and III gas wells) are generally greater than 0.55, while the FI values of Type IV low‐yield gas wells are generally less than 0.55.

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Fracture detection in oil-based drilling mud using a combination of borehole image and sonic logs

Cited by 128 publications

References 71 publications

In‐situ stress determination and fracture characterization using image logs: The Paleogene Dongying Formation in Nanpu Sag, Bohai Bay Basin, China

In‐situ stress determination and fracture characterization using image logs: The Paleogene Dongying Formation in Nanpu Sag, Bohai Bay Basin, China

Controlling factors and physical property cutoffs of the tight reservoir in the Liuhe Basin

Developmental characteristics and distribution law of fractures in a tight sandstone reservoir in a low‐amplitude tectonic zone, eastern Ordos Basin, China

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