Characteristics and controlling factors of shale gas reservoir in the Fuling area, Sichuan Basin

Zhang, Xiaoming; Shi, Wanzhong; Zhai, Gangyi; Xu, Qinghai; Wang, Ren; Xu, Zhuang; Wang, Jian; Wang, Chao; Qi, Yuan

doi:10.1016/j.ptlrs.2016.12.001

Cited by 19 publications

(22 citation statements)

References 16 publications

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“…Therefore, the percentage of residual gas in the crushed core is high (69.7% on average in Ciye 1Well), which is in agreement with the result that the storage capacity for adsorbed gas accounts for 66.9% of the total reservoir storage capacity on average. However, in the case of Longmaxi Fm, similar agreement is seen with low residual gas percentages (Zhang et al, 2015c).…”

Section: Influences Of Reservoir Characteristics On Gas Occurrence Stsupporting

confidence: 69%

Characteristics of Shale Reservoir and Sweet Spot Identification of the Lower Cambrian Niutitang Formation in Northwestern Hunan Province, China

Qin

Cao

Jianhua

et al. 2019

Acta Geologica Sinica (Eng)

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The accumulation and productivity of shale gas are mainly controlled by the characteristics of shale reservoirs; study of these characteristics forms the basis for the shale gas exploitation of the Lower Cambrian Niutitang Formation (Fm), Southern China. In this study, core observation and lithology study were conducted along with X‐ray diffraction (XRD) and electronic scanning microscopy (SEM) examinations and liquid nitrogen (N2) adsorption/desorption and CH4 isothermal adsorption experiments for several exploration wells in northwestern Hunan Province, China. The results show that one or two intervals with high‐quality source rocks (TOC>2 wt%) were deposited in the deep‐shelf facies. The source rocks, which were mainly composed of carbonaceous shales and siliceous shales, had high quartz contents (>40 wt%) and low clay mineral (<30 wt%, mainly illites) and carbonate mineral (<20 wt%) contents. The SEM observations and liquid nitrogen (N2) adsorption/desorption experiments showed that the shale is tight, and nanoscale pores and microscale fractures are well developed. BJH volume (VBJH) of shale ranged from 2.144×10–3 to 20.07×10–3 cm3/g, with an average of 11.752×10–3 cm3/g. Pores mainly consisted of opened and interconnected mesopores (2–50 nm in diameter) or macropores (>50 nm in diameter). The shale reservoir has strong adsorption capacity for CH4. The Langmuir volume (VL) varied from 1.63 to 7.39 cm3/g, with an average of 3.95 cm3/g. The characteristics of shale reservoir are controlled by several factors: (1) A deep muddy continental shelf is the most favorable environment for the development of shale reservoirs, which is controlled by the development of basic materials. (2) The storage capacity of the shale reservoir is positively related to the TOC contents and plastic minerals and negatively related to cement minerals. (3) High maturity or overmaturity leads to the growth of organic pores and microfractures, thereby improving the reservoir storage capacity. It can be deduced that the high percentage of residual gas in Niutitang Fm results from the strong reservoir storage capacity of adsorbed gas. Two layers of sweet spots with strong storage capacity of free gas, and they are characterized by the relatively high TOC contents ranging from 4 wt% to 8 wt%.

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Section: Influences Of Reservoir Characteristics On Gas Occurrence Stsupporting

confidence: 69%

Characteristics of Shale Reservoir and Sweet Spot Identification of the Lower Cambrian Niutitang Formation in Northwestern Hunan Province, China

Qin

Cao

Jianhua

et al. 2019

Acta Geologica Sinica (Eng)

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“…For the above reasons, mudstone and shale of Mesozoic exhibit relatively low porosities with compact structure (Liu et al, 2017b;Yang et al, 1986;Zou et al, 2010), so we do not make corrections here. Besides, it also does not need to make corrections for mudstone and shale of Silurian and Cambrian whose porosities are lower than 6% (Ma et al, 2012;Yan et al, 2016;Zhang et al, 2015).…”

Section: Corrections Of Thermal Conductivitymentioning

confidence: 99%

Thermal conductivity of sedimentary rocks in the Sichuan basin, Southwest China

Tang

Zhu

et al. 2018

Energy Exploration & Exploitation

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The optical scanning method was adopted to measure the thermal conductivities of 418 drill-core samples from 30 boreholes in Sichuan basin. All the measured thermal conductivities mainly range from 2.00 to 4.00 W/m K with a mean of 2.85 W/m K. For clastic rocks, the mean thermal conductivities of sandstone, mudstone, and shale are 3.06 AE 0.73, 2.57 AE 0.42, and 2.48 AE 0.33 W/m K, respectively; for carbonate rocks, the mean thermal conductivities of limestone and dolomite are 2.53 AE 0.44 and 3.55 AE 0.71 W/m K, respectively; for gypsum rocks, the mean thermal conductivity is 3.60 AE 0.64 W/m K. The thermal conductivities of sandstone and mudstone increase with burial depth and stratigraphic age, but this trend is not obvious for limestone and dolomite. Compared with other basins, the thermal conductivities of sandstone and mudstone in Sichuan basin are distinctly higher, while the thermal conductivities of limestone are close to Tarim basin. The content of mineral composition such as quartz is the principal factor that results in thermal conductivity of rocks differing from normal value. In situ thermal conductivity of sandstones was corrected with the consideration of water saturation. Finally, a thermal conductivity column of sedimentary formation of the Sichuan basin was given out, which can provide thermal conductivity references for the research of deep geothermal field and lithospheric thermal structure in the basin.

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“…The matrix porosity of 5-15 mm samples from coal seam 8 1 determined from the combined test of MIP and low temperature nitrogen adsorption was 4.23%. With 50 nm as the demarcation point of MIP and low temperature nitrogen adsorption [39,40], volume data for pores (diameter > 50 nm) used MIP data, and pores (diameter < 50 nm) used low temperature nitrogen adsorption data. The comparison between combined methods and separate MIP was shown in Figure 8a.…”

Section: Porosity In the Particle Matrixmentioning

confidence: 99%

Experimental Study on Sensitivity of Porosity to Pressure and Particle Size in Loose Coal Media

Zhang

Pan³

et al. 2018

Energies

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A new experimental method for characterizing the porosity of loose media subjected to overburden pressure is proposed based on the functional relationships between porosity, true density, and bulk density. This method is used to test the total porosity of loose coal particles from the Guobei coal mine in Huaibei mining area, China, in terms of the influence of pressure and particle size on total porosity. The results indicate that the total porosity of loose coal under 20 MPa in situ stress is about 10.22%. The total porosity and pressure obey an attenuated exponential function, while the total porosity and particle size obey a power function. The total porosity of the loose coal is greatly reduced and the sensitivity is high with increased pressure when stress levels are low (shallow burial conditions). However, total porosity is less sensitive to pressure at higher stress when burial conditions are deep. The effect of particle size on the total porosity reduction rate in loose coal is not significant, regardless of low- or high-pressure conditions; i.e., the sensitivity is low. The total porosity remains virtually unchanged as particle size changes when pressure exceeds 20 MPa. Overall, the sensitivity of total porosity to pressure is found to be significantly higher than sensitivity to particle size.

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Characteristics and controlling factors of shale gas reservoir in the Fuling area, Sichuan Basin

Cited by 19 publications

References 16 publications

Characteristics of Shale Reservoir and Sweet Spot Identification of the Lower Cambrian Niutitang Formation in Northwestern Hunan Province, China

Characteristics of Shale Reservoir and Sweet Spot Identification of the Lower Cambrian Niutitang Formation in Northwestern Hunan Province, China

Thermal conductivity of sedimentary rocks in the Sichuan basin, Southwest China

Experimental Study on Sensitivity of Porosity to Pressure and Particle Size in Loose Coal Media

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