Previous studies have postulated the contribution of present-day low-total organic carbon （TOC） marine carbonate source rocks to oil accumulations in the Tabei Uplift, Tarim Basin, China. However, not all present-da...Previous studies have postulated the contribution of present-day low-total organic carbon （TOC） marine carbonate source rocks to oil accumulations in the Tabei Uplift, Tarim Basin, China. However, not all present-day low-TOC carbonates have generated and expelled hydrocarbons; therefore, to distinguish the source rocks that have already expelled sufficient hydrocarbons from those not expelled hydrocarbons, is crucial in source rock evaluation and resource assessment in the Tabei Uplift. Mass balance can be used to identify modern low-TOC carbonates resulting from hydrocarbon expulsion. However, the process is quite complicated, requiring many parameters and coefficients and thus also a massive data source. In this paper, we provide a quick and cost effective method for identifying carbonate source rock with present-day low TOC, using widely available Rock-Eval data. First, we identify present-day low-TOC carbonate source rocks in typical wells according to the mass balance approach. Second, we build an optimal model to evaluate source rocks from the analysis of the rocks＇ characteristics and their influencing factors, reported as positive or negative values of a dimensionless index of Rock-Eval data （IR）. Positive IR corresponds to those samples which have expelled hydrocarbons. The optimal model optimizes complicated calculations and simulation processes; thus it could be widely applicable and competitive in the evaluation of present-day low TOC carbonates. By applying the model to the Rock-Eval dataset of the Tabei Uplift, we identify present-day iow-TOC carbonate source rocks and primarily evaluate the contribution equivalent of 11.87×10^9 t oil.展开更多
The kinetic parameters of hydrocarbon generation from the marine carbonate source rocks were determined and calibrated through kinetic simulating experiment. The kinetic parameters of hydrocarbon generation then were ...The kinetic parameters of hydrocarbon generation from the marine carbonate source rocks were determined and calibrated through kinetic simulating experiment. The kinetic parameters of hydrocarbon generation then were extrapolated to geological condition by using the relative software. The result shows that gaseous hydrocarbons (C_1, C_2, C_3, C_(4-5)) were generated in condition of 150℃<T< 220℃(1.0%<Ro <3.0% ). Light hydrocarbons (C_(6-13)) and heavy hydrocarbons ( C_(13)^+ ) were generated in condition of 100 ℃ <T<170 ℃ (0.5%<Ro<1.5%). A quantitative reference to examine the natural evolution of hydrocarbon of marine carbonate source rocks can be established through the results. It also provides a new method for evaluating the highly mature marine carbonate source rock more reasonably.展开更多
Tight-sand gas in the Jurassic and shale gas within the fifth member of Xujiahe Formation （T3xs） in the Western Sichuan Basin （WSD） are currently regarded as the most prolific emerging unconventional gas plays in ...Tight-sand gas in the Jurassic and shale gas within the fifth member of Xujiahe Formation （T3xs） in the Western Sichuan Basin （WSD） are currently regarded as the most prolific emerging unconventional gas plays in China. This study conducted a conventional evaluation of T3x5 source rocks in the WSD, and investigated their hydrocarbon generation and expulsion characteristics, including intensity, efficiency and amount. The results show that, the T3x5 source rocks are thick （generally 〉200 m）, and have a high total organic content （TOC）, ranging from 2.5 to 4.5 wt%. It is thus indivative of a great hydrocarbon generation potential when they underwent high thermal evolution （Ro〉1.2%） in the area. In addition, an improved method of hydrocarbon generation potential is applied, indicating that the source rocks reached a hydrocarbon expulsion threshold with vitrinite reflectance （Ro） reaching 1.06%. and that the comprehensive hydrocarbon expulsion efficiency is about 60%. The amount of hydrocarbon generation and expulsion from Tax5 source rocks is 3.14x10^10 t and 1.86x10^10 t, respectively, with a residual amount of 1.28x10^10t within them. Continuous-type tight-sand gas is predicted to have developed in the Jurassic in the Chengdu Sag of the WSD because of the good source-reservoir configuration; the Jurassic sandstone reservoirs are tight, and the gas expelled from the T3xs source rocks migrates for very short distances vertically and horizontally. The amount of gas accumulation in the Jurassic reservoirs derived from T3x5 source rocks is up to 9.3x10s t. Geological resources of shale gas are up to 1.05x10TM t. Small differences between the amounts calculated by the volumetric method and those obtained by hydrocarbon generation potential method may be due to other gas accumulations present within interbedded sands associated with gas shales.展开更多
Tibet plateau is a vast hydrocarbon\|bearing region which is the biggest in area, the lowest in exploration and the poorest in knowing, especially, knowing a little for Mesozoic marine petroleum geology problem (parti...Tibet plateau is a vast hydrocarbon\|bearing region which is the biggest in area, the lowest in exploration and the poorest in knowing, especially, knowing a little for Mesozoic marine petroleum geology problem (particularly for Mesozoic marine source rock) in Chinese land. The research of oil and gas generation for Mesozoic marine source rock have been accomplished on basis of a large number of data for source rock samples appeared on the weather (29 items, about 4000 samples, 23976 sample times and 200000 data) in Tibet Plateau. Full text is composed of following four parts:1\ Regional geology\;Summarized regional geology briefly, emphasized on regional structures, sedimentary facies and stratum characteristics related closely with source rock.展开更多
基金supported by the China Postdoctoral Science Foundation (grant No. 2017M611108)the National Science and Technology Major Project of China (grant No. 2016ZX05006006-001)the National Basic Research Program of China (grant Nos. 2011CB2011-02 and 2014CB239100)
文摘Previous studies have postulated the contribution of present-day low-total organic carbon （TOC） marine carbonate source rocks to oil accumulations in the Tabei Uplift, Tarim Basin, China. However, not all present-day low-TOC carbonates have generated and expelled hydrocarbons; therefore, to distinguish the source rocks that have already expelled sufficient hydrocarbons from those not expelled hydrocarbons, is crucial in source rock evaluation and resource assessment in the Tabei Uplift. Mass balance can be used to identify modern low-TOC carbonates resulting from hydrocarbon expulsion. However, the process is quite complicated, requiring many parameters and coefficients and thus also a massive data source. In this paper, we provide a quick and cost effective method for identifying carbonate source rock with present-day low TOC, using widely available Rock-Eval data. First, we identify present-day low-TOC carbonate source rocks in typical wells according to the mass balance approach. Second, we build an optimal model to evaluate source rocks from the analysis of the rocks＇ characteristics and their influencing factors, reported as positive or negative values of a dimensionless index of Rock-Eval data （IR）. Positive IR corresponds to those samples which have expelled hydrocarbons. The optimal model optimizes complicated calculations and simulation processes; thus it could be widely applicable and competitive in the evaluation of present-day low TOC carbonates. By applying the model to the Rock-Eval dataset of the Tabei Uplift, we identify present-day iow-TOC carbonate source rocks and primarily evaluate the contribution equivalent of 11.87×10^9 t oil.
文摘The kinetic parameters of hydrocarbon generation from the marine carbonate source rocks were determined and calibrated through kinetic simulating experiment. The kinetic parameters of hydrocarbon generation then were extrapolated to geological condition by using the relative software. The result shows that gaseous hydrocarbons (C_1, C_2, C_3, C_(4-5)) were generated in condition of 150℃<T< 220℃(1.0%<Ro <3.0% ). Light hydrocarbons (C_(6-13)) and heavy hydrocarbons ( C_(13)^+ ) were generated in condition of 100 ℃ <T<170 ℃ (0.5%<Ro<1.5%). A quantitative reference to examine the natural evolution of hydrocarbon of marine carbonate source rocks can be established through the results. It also provides a new method for evaluating the highly mature marine carbonate source rock more reasonably.
基金supported by the National Natural Science Foundation of China(U6212205)the Chinese Postdoctoral Science Foundation(2014M550984)
文摘Tight-sand gas in the Jurassic and shale gas within the fifth member of Xujiahe Formation （T3xs） in the Western Sichuan Basin （WSD） are currently regarded as the most prolific emerging unconventional gas plays in China. This study conducted a conventional evaluation of T3x5 source rocks in the WSD, and investigated their hydrocarbon generation and expulsion characteristics, including intensity, efficiency and amount. The results show that, the T3x5 source rocks are thick （generally 〉200 m）, and have a high total organic content （TOC）, ranging from 2.5 to 4.5 wt%. It is thus indivative of a great hydrocarbon generation potential when they underwent high thermal evolution （Ro〉1.2%） in the area. In addition, an improved method of hydrocarbon generation potential is applied, indicating that the source rocks reached a hydrocarbon expulsion threshold with vitrinite reflectance （Ro） reaching 1.06%. and that the comprehensive hydrocarbon expulsion efficiency is about 60%. The amount of hydrocarbon generation and expulsion from Tax5 source rocks is 3.14x10^10 t and 1.86x10^10 t, respectively, with a residual amount of 1.28x10^10t within them. Continuous-type tight-sand gas is predicted to have developed in the Jurassic in the Chengdu Sag of the WSD because of the good source-reservoir configuration; the Jurassic sandstone reservoirs are tight, and the gas expelled from the T3xs source rocks migrates for very short distances vertically and horizontally. The amount of gas accumulation in the Jurassic reservoirs derived from T3x5 source rocks is up to 9.3x10s t. Geological resources of shale gas are up to 1.05x10TM t. Small differences between the amounts calculated by the volumetric method and those obtained by hydrocarbon generation potential method may be due to other gas accumulations present within interbedded sands associated with gas shales.
文摘Tibet plateau is a vast hydrocarbon\|bearing region which is the biggest in area, the lowest in exploration and the poorest in knowing, especially, knowing a little for Mesozoic marine petroleum geology problem (particularly for Mesozoic marine source rock) in Chinese land. The research of oil and gas generation for Mesozoic marine source rock have been accomplished on basis of a large number of data for source rock samples appeared on the weather (29 items, about 4000 samples, 23976 sample times and 200000 data) in Tibet Plateau. Full text is composed of following four parts:1\ Regional geology\;Summarized regional geology briefly, emphasized on regional structures, sedimentary facies and stratum characteristics related closely with source rock.
