Quick Evaluation of Present-Day Low-Total Organic Carbon Carbonate Source Rocks from Rock-Eval Data: Middle-Upper Ordovician in the Tabei Uplift, Tarim Basin

2018 ◽  
Vol 92 (4) ◽  
pp. 1558-1573 ◽  
Author(s):  
Junqing CHEN ◽  
Xiongqi PANG ◽  
Haijun YANG ◽  
Hong PANG ◽  
Bo PANG
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Tarim Basin ◽  
Source Rocks ◽  
Upper Ordovician ◽  
Rock Eval ◽  
Carbonate Source

scholarly journals Quantitative prediction model of present-day low-TOC carbonate source rocks: Example from the Middle–upper Ordovician in the Tarim Basin

2018 ◽  
Vol 36 (5) ◽  
pp. 1335-1355 ◽  
Author(s):  
Junqing Chen ◽  
Xiongqi Pang ◽  
Hong Pang
Keyword(s):  
Organic Carbon ◽  
Prediction Model ◽  
Total Organic Carbon ◽  
Tarim Basin ◽  
Quantitative Model ◽  
Source Rocks ◽  
Upper Ordovician ◽  
Oil Accumulation ◽  
Hydrocarbon Expulsion ◽  
Carbonate Source

Plenty of marine crude oil generated by the Middle–Upper Ordovician source rocks has been discovered in the Tabei Uplift, Tarim Basin. Previous studies on the extensively distributed low organic matter source rock total organic carbon ≤ 0.5%) imply that this contributes to oil accumulation. Thus, the identification of present-day low-total organic carbon source rocks that experience hydrocarbon expulsion and evaluation of their contribution is of considerable significance to analyze marine oil accumulation and to assess the resources in the Tarim Basin. Using the mass balance approach, we identify and verify present-day low-total organic carbon carbonate source rocks and present a quantitative model using well-logging data to predict the present-day low-total organic carbon carbonate source rocks in order to evaluate their contribution in the Tarim Basin. Hydrocarbon expulsion has occurred in the Yijianfang formation, which has present-day low-total organic carbon, between 6452 and 6487 m in the Yangwu 2 well. In the horizons depicting carbonates with hydrocarbon expulsion, the porosity is relatively high and the daily oil production is 0.19 m3 according to the perforation tests. The extracts have similar biomarker signatures to that of the crude oils in the Tabei Uplift. In this study, a quick and cost-effective quantitative model is developed using double lateral resistivity and uranium/thorium well-logging data. By applying the prediction model, the contribution of present-day low-total organic carbon carbonate source rocks in the Middle–Upper Ordovician formation of the Tarim Basin is primarily evaluated to be 363.38 × 109 bbl oil equivalent.

scholarly journals Method for identifying effective carbonate source rocks: a case study from Middle–Upper Ordovician in Tarim Basin, China

2020 ◽  
Vol 17 (6) ◽  
pp. 1491-1511
Author(s):  
Jun-Qing Chen ◽  
Xiong-Qi Pang ◽  
Song Wu ◽  
Zhuo-Heng Chen ◽  
Mei-Ling Hu ◽  
...  
Keyword(s):  
Crude Oil ◽  
Source Rock ◽  
Tarim Basin ◽  
Fluid Pressure ◽  
Source Rocks ◽  
Hydrocarbon Generation ◽  
Upper Ordovician ◽  
Carbonate Source Rock ◽  
Carbonate Source ◽  
Effective Source

AbstractHydrocarbon expulsion occurs only when pore fluid pressure due to hydrocarbon generation in source rock exceeds the force against migration in the adjacent carrier beds. Taking the Middle–Upper Ordovician carbonate source rock of Tarim Basin in China as an example, this paper proposes a method that identifies effective carbonate source rock based on the principles of mass balance. Data from the Well YW2 indicate that the Middle Ordovician Yijianfang Formation contains effective carbonate source rocks with low present-day TOC. Geological and geochemical analysis suggests that the hydrocarbons in the carbonate interval are likely self-generated and retained. Regular steranes from GC–MS analysis of oil extracts in this interval display similar features to those of the crude oil samples in Tabei area, indicating that the crude oil probably was migrated from the effective source rocks. By applying to other wells in the basin, the identified effective carbonate source rocks and non-source rock carbonates can be effectively identified and consistent with the actual exploration results, validating the method. Considering the contribution from the identified effective source rocks with low present-day TOC (TOCpd) is considered, the long-standing puzzle between the proved 3P oil reserves and estimated resources in the basin can be reasonably explained.

Comparisons of pyrolysis parameters between source rocks and their clay-sized fractions: Implication for source material of hydrocarbon generation

2022 ◽  
pp. 1-42
Author(s):  
Xiaojun Zhu ◽  
Jingong Cai ◽  
Feng Liu ◽  
Qisheng Zhou ◽  
Yue Zhao ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Source Material ◽  
Source Rocks ◽  
Natural Environments ◽  
Hydrocarbon Generation ◽  
Petroleum Systems ◽  
Organic Mineral ◽  
Organic Clay ◽  
Organo Clay ◽  
Rock Eval

In natural environments, organic-clay interactions are strong and cause organo-clay composites (a combination between organic matter [OM] and clay minerals) to be one of the predominant forms for OM occurrence, and their interactions greatly influence the hydrocarbon (HC) generation of OM within source rocks. However, despite occurring in nature, dominating the OM occurrence, and having unique HC generation ways, organo-clay composites have rarely been investigated as stand-alone petroleum precursors. To improve this understanding, we have compared the Rock-Eval pyrolysis parameters derived from more than 100 source rocks and their corresponding <2 μm clay-sized fractions (representing organo-clay composites). The results show that all of the Rock-Eval pyrolysis parameters in bulk rocks are closely positively correlated with those in their clay-sized fractions, but in clay-sized fractions the quality of OM for HC generation is poorer, in that the pyrolysable organic carbon levels and hydrogen index values are lower, whereas the residual organic carbon levels are higher than those in bulk rocks. Being integrated with the effects of organic-clay interactions on OM occurrence and HC generation, our results suggest that organo-clay composites are stand-alone petroleum precursors for HC generation occurring in source rocks, even if the source rocks exist in great varieties in their attributes. Our source material for HC generation comprehensively integrates the original OM occurrence and HC generation behavior in natural environments, which differs from kerogen and is much closer to the actual source material of HC generation in source rocks, and it calls for further focus on organic-mineral interactions in studies of petroleum systems.

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