scholarly journals Total Organic Carbon Enrichment and Its Impact on Pore Characteristics: A Case Study from the Niutitang Formation Shales in Northern Guizhou

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1480 ◽  
Author(s):  
Liu ◽  
Tang ◽  
Xi
Keyword(s):  
Fractal Dimension ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Vitrinite Reflectance ◽  
Guizhou Province ◽  
Type I ◽  
Pore Characteristics ◽  
Hill Model ◽  
Recovery Coefficient ◽  
Niutitang Formation

This study analyzes samples from the Lower Cambrian Niutitang Formation in northern Guizhou Province to enable a better understanding of total organic carbon (TOC) enrichment and its impact on the pore characteristics of over-mature marine shale. Organic geochemical analysis, X-ray diffraction, scanning electron microscopy, helium porosity, and low-temperature nitrogen adsorption experiments were conducted on shale samples. Their original TOC (TOCo) content and organic porosity were estimated by theoretical calculation, and fractal dimension D was computed with the fractal Frenkel–Halsey–Hill model. The results were then used to consider which factors control TOC enrichment and pore characteristics. The samples are shown to be dominated by type-I kerogen with a TOC content of 0.29‒9.36% and an equivalent vitrinite reflectance value of 1.72‒2.72%. The TOCo content varies between 0.64% and 18.17%, and the overall recovery coefficient for the Niutitang Formation was 2.16. Total porosity of the samples ranged between 0.36% and 6.93%. TOC content directly controls porosity when TOC content lies in the range 1.0% to 6.0%. For samples with TOC < 1.0% and TOC > 6.0%, inorganic pores are the main contributors to porosity. Additionally, pore structure parameters show no obvious trends with TOC, quartz, and clay mineral content. The fractal dimension D1 is between 2.619 and 2.716, and D2 is between 2.680 and 2.854, illustrating significant pore surface roughness and structural heterogeneity. No single constituent had a dominant effect on the fractal characteristics.

scholarly journals Hydrocarbon source rock evaluation of the Lower Cretaceous system in the Baibei Depression, Erlian Basin

2017 ◽  
Vol 36 (3) ◽  
pp. 355-372 ◽  
Author(s):  
Hua Liu ◽  
Jinglun Ren ◽  
Jianfei Lyu ◽  
Xueying Lyu ◽  
Yuelin Feng
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Source Rock ◽  
Lower Cretaceous ◽  
Vitrinite Reflectance ◽  
Source Rocks ◽  
Main Stage ◽  
Type I ◽  
Potential Source Rock ◽  
Erlian Basin

The K1s, K1d, K1t, and K1a Formations are potential source rock intervals for hydrocarbon formation, all of which are part of the Lower Cretaceous system in the Baibei Depression in the Erlian Basin in China. However, no well has found oil flow because the hydrocarbon-generating potential of the source rocks has not been comprehensively evaluated. Based on organic geochemical and petrological analyses, all the source rocks possess highly variable total organic carbon and S1 + S2 contents. Total organic carbon and S1 + S2 contents indicate that the K1a2 Formation through the K1d1 Formation are source rocks that have fair to good generative potential and the K1d2 Formation through the K1s Formation are source rocks that have good to very good generative potential. The organic matter in the K1a2 Formation is dominated by Type I and II kerogen; thus, it is considered to be oil prone based on H/C versus O/C plots. Most of the analyzed samples were deposited in reducing environments and sourced from marine algae; thus, they are oil prone. However, only two source rock intervals were thermally mature with vitrinite reflectance values in the required range. Hydrocarbon-generating histories show that the K1t and K1a2 intervals began to generate hydrocarbons during the depositional period of the K1d2 and K1d3 Formations, respectively, and stopped generating hydrocarbons at the end of the depositional period of the late Cretaceous. Therefore, the main stage of hydrocarbon migration and accumulation was between the depositional period of the K1d2 and K1s Formations, and the critical moment was the depositional period of the late K1s Formation. The generation conversion efficiency reached approximately 55% in the K1a2 Formation and 18% in the K1t Formation at the end of the Cretaceous sedimentary stage. In general, the effective oil traps are those reservoirs that are near the active source rock in the generating sags in the Baibei Depression.

scholarly journals Evaluation method for resource potential of shale oil in the Triassic Yanchang Formation of the Ordos Basin, China

2020 ◽  
Vol 38 (4) ◽  
pp. 841-866
Author(s):  
Qiulin Guo ◽  
Xiaoming Chen ◽  
Xiaoxue Liuzhuang ◽  
Zhi Yang ◽  
Man Zheng ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Calculation Method ◽  
Evaluation Method ◽  
Ordos Basin ◽  
Oil Yield ◽  
Shale Oil ◽  
Recovery Coefficient ◽  
Evaporative Loss ◽  
Total Oil

The widely distributed, thick Chang 7 Shale is the richest shale oil formation in China. A calculation method for the evaporative hydrocarbon recovery coefficient based on formation volume factor is proposed considering the correction of heterogeneity-based total organic carbon differences to improve the adsorbed oil calculation method, and light hydrocarbon evaporative sampling losses, which can make mobile and total oil calculations more accurate. The adsorbed oil, S1 evaporative loss, total oil yield, and movable oil yield of 200 shale samples from the Chang 7 Member were calculated using the new methods. Results show that S1 evaporative loss accounts for 29% of S1, total oil yield is 3.5 times S1, and movable oil yield accounts for 37% of total oil yield. Based on the calculated total oil yield and movable oil yield results, the relationships among total oil yield, movable oil yield, and total organic carbon of the Chang 7 were established yielding total oil yield and movable oil yield estimates of 11.12 × 109 t and 4.01 × 109 t, respectively, revealing its tremendous shale exploration potential.

Sign in / Sign up

Export Citation Format

Share Document