Geological evaluation and gas bearing analysis for shale reservoir in Ziyun-Luodian typical area of southern Guizhou province, China

Abstract

The Ziyun-Luodian area of southern Guizhou province in China is chosen as the research area and the Dawuba formation in Carboniferous system is the target stratum in this paper. Combined with laboratory experiments and mathematical analyses, geological evaluations on organic geochemistry, physical property of the reservoir, and gas bearing feature are all studied, and geological controls on gas occurrence are then analyzed. The following conclusions are achieved. The organic type is mainly II2 or III. TOC is generally in a range of 1%–3%, and Ro,max ranges from 1.7% to 4.4%, with an average value of 2.4%. Mineral compositions are mainly clay and quartz, with a few calcite and dolomite. The Specific surface area ranges from 6.6 to 29.8 m2/g, with an average value of 15.2 m2/g, and the pore volume varies from 0.012 to 0.046 cm3/g, with an average value of about 0.02 cm3/g. There is a strongly and positively linear relationship between specific surface area and pore volume. The porosity is mostly in the range of 1%–3%, with an average value of 1.8%. Most of permeability is below 0.01 mD, with an average value of about 0.004 mD. There is an exponential and positive relationship between porosity and permeability. The gas content is generally below 2.0 m3/t. There are three obvious correlations for gas content versus buried depth ranges of 500–700 m, 700–1,000 m, and 2,700–3,000 m. TOC influences gas content in a linear mode, and Ro,max influences gas content positively. The gas content has a positive relationship with clay mineral and a negative relationship with sapropelic percentage. The porosity and permeability are both positively correlated with gas content. The pore volume has a positive trend with gas content, and the specific surface area has a positively and strongly linear relationship with gas content.

Modeling carbon dioxide and methane adsorption on illite and calcite: enhancing the simplified local density model through crystal structure modifications

“…In addition, compared to other studies on the specific surface area of minerals, the N 2 adsorption results were also small. 34,35 We hypothesize that this difference is mainly due to the limitations of nitrogen adsorption technology. Nitrogen gas-adsorption techniques can be used to characterize materials dominated by meso-pores.…”

Carbon and oxygen isotopes of the Lianglitage Formation in the Tazhong area, Tarim Basin: Implications for sea‐level changes and palaeomarine conditions

“…The Z values calculated from Z = 2.048 × (δ 13 C + 50) + 0.498 × (δ 18 O + 50) (Keith & Weber, 1964) ranged from 127.721 to 130.523, with an average of 126.25. When the Z value is greater than 120, it indicates that carbonate rocks are of seawater origin (Wang & Xia, 2000; Zhou et al, 2021). According to T(°C) = 16.9–4.2 × (δc − δw) + 0.13 × (δc − δw) 2 (Craig, 1965), δc − δw = δ 18 O + 0.22 (Shao, 1994) calculated that the sea water temperature during the deposition of Lianglitage Formation ranged from 14.16 to 28.46°C, with an average of 21.247°C.…”

“…130.523, with an average of 126.25. When the Z value is greater than 120, it indicates that carbonate rocks are of seawater origin(Wang & Xia, 2000;Zhou et al, 2021). According to T( C) = 16.9-4.2 Â (δc À δw) + 0.13 Â (δc À δw) 2(Craig, 1965), δc À δw = δ 18 O + 0.22(Shao, 1994) calculated that the sea water temperature during the deposition of Lianglitage Formation ranged from 14.16 to 28.46 C, F I G U R E 6 Palaeomarine conditions and sea-level changes in the Lianglitage Formation in well TZ72 in the Tazhong area with an average of 21.247 C. The calculated seawater temperature shows that the Lianglitage Formation was deposited in a tropical to subtropical climate and is consistent with the previous research results…”

Detrital Zircon Records of the Banxi Group in the Western Jiangnan Orogen: Implications for Crustal Evolution of the South China Craton

“…Numerous muscovite-bearing leucogranites (838.5 ± 1.5 Ma) intruded into the Fanjingshan Group, likely resulting from high temperature (> 875°C) partial melting of clayrich psammitic rocks (Wang et al, 2011). In northwest Hunan Province, it is proposed that Yiyang komatiitic basalts (~823 Ma) and mafic-ultramafic dykes from Aikou (~831 Ma) are the product of rift magmatism related to the mantle plume (Wang X L et al, 2007;Zhang et al, 2009).…”