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

Wang, Xixin; Liu, Yuming; Zhao, Peiqiang; Ma, Keping; Wang, Dongmei; Ren, Xiaoxu; Lin, Yan-Bo

doi:10.1142/s0218348x1940005x

Cited by 10 publications

(6 citation statements)

References 38 publications

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“…The pore types and sizes can be qualitatively observed by CT scan [12], scanning electron microscope (SEM) [13], field emission scanning electron microscope (FESEM) [14], and transmission electron microscope (TEM) [15]. Meanwhile, quantitative characterization methods include high pressure mercury injection (PMI) [16], constant rate mercury injection (RMI) [17], nuclear magnetic resonance (NMR) [18,19], low-temperature N 2 and CO 2 adsorption [20,21], small-angle and ultra-small-angle neutron scattering (SANS and USANS) [22], etc. Each method has its own advantages and disadvantages.…”

Section: Introductionmentioning

confidence: 99%

Pore Structure Characterization and the Controlling Factors of the Bakken Formation

Liu

Shen

Yang³

et al. 2018

Energies

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The Bakken Formation is a typical tight oil reservoir and oil production formation in the world. Pore structure is one of the key factors that determine the accumulation and production of the hydrocarbon. In order to study the pore structures and main controlling factors of the Bakken Formation, 12 samples were selected from the Bakken Formation and conducted on a set of experiments including X-ray diffraction mineral analysis (XRD), total organic carbon (TOC), vitrinite reflectance (Ro), and low-temperature nitrogen adsorption experiments. Results showed that the average TOC and Ro of Upper and Lower Bakken shale is 10.72 wt% and 0.86%, respectively. The Bakken Formation develops micropores, mesopores, and macropores. However, the Upper and Lower Bakken shale are dominated by micropores, while the Middle Bakken tight reservoir is dominated by mesopores. The total pore volume and specific surface area of the Middle Bakken are significantly higher than those of the Upper and Lower Bakken, indicating that Middle Bakken is more conducive to the storage of oil and gas. Through analysis, the main controlling factors for the pore structure of the Upper and Lower Bakken shale are TOC and maturity, while those for Middle Bakken are clay and quartz contents.

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Section: Introductionmentioning

confidence: 99%

Pore Structure Characterization and the Controlling Factors of the Bakken Formation

Liu

Shen

Yang³

et al. 2018

Energies

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“…The number of pores (radius > r) can be expressed by Equation ( 1) on the bas fractal principle [25]. When the pore radius is calculated, pores are regarded as ideal spheres, th formula in Equation ( 3) can be obtained after a series of mathematical transfor the detailed process was described in [26].…”

Section: Fractal Dimensions Calculated From Hmipmentioning

confidence: 99%

The Classification and Evaluation of an Interlayer Shale Oil Reservoir Based on the Fractal Characteristics of Pore Systems: A Case Study in the HSN Area, China

Lu,

Wang,

et al. 2024

Fractal Fract

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The evaluation of shale reservoir quality is of great significance for the exploration and development of shale oil. To more effectively study the distribution characteristics of shale reservoir quality, thin-section observation, scanning electron microscopy and pressure-controlled porosimetry were used to obtain the pore structure characteristics of shale in Chang 7, including pore types, pore size distribution, etc. In addition, the fractal dimensions of the shale samples were calculated based on pressure-controlled porosimetry data. The results show that residual interparticle pores, dissolution pores and clay-dominated pores were the main pore types. The overall pore size was mainly distributed between 3 nm and 50 μm. The pore system was divided into four types using fractal features, and the shale reservoir was divided into four types based on the proportion of different types of pore system. In different types of reservoirs, the production capacity of exploration wells varies significantly, as does the production capacity of horizontal wells. The classification of shale reservoirs using mercury intrusion fractal analysis proved to be suited for the efficient development of Chang 7 shale oil reservoirs.

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“…The smaller the pore aperture, the larger the fractal dimension, the more complex the pore structure, and the lower the permeability (Wang et al 2019a(Wang et al , 2020. Wang et al (2019b) reported that when the fractal dimension exceeded 2.586, a tight reservoir did not favor oil accumulation. If the fractal dimension was approximately 3, the porosity and permeability of the tight reservoir would decrease significantly (Wang et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Oil utilization degree at various pore sizes via different displacement methods

Gao

Wang

et al. 2022

J Petrol Explor Prod Technol

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A reasonable displacement method is essential to improve the oil displacement efficiency of tight reservoirs. In this study, three different displacement methods were utilized on the tight core samples obtained from the Yanchang Formation Chang 8 and Chang 9 tight oil reservoirs: spontaneous imbibition displacement, various water flooding rate displacement and water flooding displacement after spontaneous imbibitions; furthermore, the oil utilization degree of the residual oil in various pores was discussed. The oil displacement efficiency of the spontaneous imbibitions was approximately 26.91% and 29.56% for the Chang 8 and Chang 9 samples, respectively. With an increasing water flooding rate, the oil displacement efficiency features an inverse “V”-like tendency, and a water flooding rate of 0.06 mL/min was the optimal value as; the oil displacement efficiency achieved was 63.56% and 60.27% for the Chang 8 and Chang 9, respectively. When compared with spontaneous imbibitions, at a displacement rate of 0.06 mL/min after spontaneous imbibition, the oil displacement efficiency could be further increased to 50.02% and 30.35%, respectively. The differences in the oil displacement efficiency using various displacement methods are primarily related to the degree of utilization of residual oil in various pores. The progressively refined pore classification method is used to study the degree of oil utilization in various pores, and the pores in the tight reservoir can be divided into four types: P1, P2, P3 and P4. Regarding the spontaneous imbibition displacement, the displacement of the residual oil is dominantly determined by the residual oil present in the P2 and P3 pores; as the residual oil massively accumulates in the P2 pores, the discharging of the residual oil in this part finally determines the oil displacement efficiency when the water flooding rates changed. At a water flooding rate of 0.06 mL/min after spontaneous imbibition, the oil utilization degree of residual oil in various pores is enhanced, particularly for the P2, P3, and P4 pores, and the pore structure contributes to the increase in the oil displacement efficiency. Using the progressively refined pore classification method, the complexity of the distribution of residual oil in tight reservoirs could be studied quantitatively and elaborately, and the results can efficiently guide the development of residual oil in tight oil reservoirs.

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

Cited by 10 publications

References 38 publications

Pore Structure Characterization and the Controlling Factors of the Bakken Formation

Pore Structure Characterization and the Controlling Factors of the Bakken Formation

The Classification and Evaluation of an Interlayer Shale Oil Reservoir Based on the Fractal Characteristics of Pore Systems: A Case Study in the HSN Area, China

Oil utilization degree at various pore sizes via different displacement methods

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