Tar mats were firstly discovered and determined accurately in terrestrial oil and gas reservoirs associated with Lower Tertiary sandstone reservoirs in the Yaha field of the Tarim Basin, China, by thin layer chromatog...Tar mats were firstly discovered and determined accurately in terrestrial oil and gas reservoirs associated with Lower Tertiary sandstone reservoirs in the Yaha field of the Tarim Basin, China, by thin layer chromatography flame ionization detector (TLC FID) and Rock Eval analysis. The relative content of asphaltene in gross composition of tar mat extracts accounts for more than 30%, that in the corresponding oil leg less than 20%. In the geochemical description profile of oil and gas reservoirs, drastic changes in asphaltene contents between tar mats and oil legs could be discovered. This is an important marker to determine tar mats. Distribution characteristics of saturated and aromatic hydrocarbons from reservoir core extracts and crude oils in the Yaha oil and gas reservoirs in the Tarim Basin are described systematically in this paper, and the results show there are similarities among n alkane distribution characteristics, biomarker distribution characteristics and their combined characteristics of saturated hydrocarbons, and the geochemical characteristics of aromatic hydrocarbons for tar mats, oil leg, asphaltic sand and crude oil. These characteristics suggest the hydrocarbons in these samples were originated from the common source rocks. However, the geochemical characteristics of tar mats revealed that the mechanism of formation of tar mats is the precipitation of asphaltene from crude oils in petroleum reservoirs caused by increased dissolved gas in oil legs (gas injection).展开更多
The analyses of light hydrocarbons in oils from the Tarim Basin show that the Man-go’s parameter K is about unity except those oils trapped in the eastern part of the Tazhong (Central Tarim) Fault Uplift. The regular...The analyses of light hydrocarbons in oils from the Tarim Basin show that the Man-go’s parameter K is about unity except those oils trapped in the eastern part of the Tazhong (Central Tarim) Fault Uplift. The regular variance of K may indicates the accumulation and admixture of the oil populations in the eastern part of the Tazhong Fault Uplift.展开更多
This paper is mainly concentrated on the geochemical characteristics and origin of gas of Kekeya field in the Tarim basin, NW China. This study shows that Permian mudstone is the main source rock of oil and gas. Based...This paper is mainly concentrated on the geochemical characteristics and origin of gas of Kekeya field in the Tarim basin, NW China. This study shows that Permian mudstone is the main source rock of oil and gas. Based on the carbon isotopes of C 1-C 4, the carbon isotope of gas in Kekeya field is a little heavier than that in the typical marine-derived gas. The relationship between carbon isotopes of methane and ethane is coincident with Faber equation of gas derived from organic matter Ⅰ/Ⅱ. The majority of gas maturity is estimated, based on the formula, at 1.8 %-2.2 % besides K2 and K18 wells. In addition, the gas derived from 0.9 %-1.2 % R o source rocks may also be mixture. 40Ar/ 36Ar and 3He/ 4He ratios from the gas samples also support the mixing process. Moreover, the gas in this region is mainly generated from more mature source rocks although the low mature gas exists.展开更多
文摘Tar mats were firstly discovered and determined accurately in terrestrial oil and gas reservoirs associated with Lower Tertiary sandstone reservoirs in the Yaha field of the Tarim Basin, China, by thin layer chromatography flame ionization detector (TLC FID) and Rock Eval analysis. The relative content of asphaltene in gross composition of tar mat extracts accounts for more than 30%, that in the corresponding oil leg less than 20%. In the geochemical description profile of oil and gas reservoirs, drastic changes in asphaltene contents between tar mats and oil legs could be discovered. This is an important marker to determine tar mats. Distribution characteristics of saturated and aromatic hydrocarbons from reservoir core extracts and crude oils in the Yaha oil and gas reservoirs in the Tarim Basin are described systematically in this paper, and the results show there are similarities among n alkane distribution characteristics, biomarker distribution characteristics and their combined characteristics of saturated hydrocarbons, and the geochemical characteristics of aromatic hydrocarbons for tar mats, oil leg, asphaltic sand and crude oil. These characteristics suggest the hydrocarbons in these samples were originated from the common source rocks. However, the geochemical characteristics of tar mats revealed that the mechanism of formation of tar mats is the precipitation of asphaltene from crude oils in petroleum reservoirs caused by increased dissolved gas in oil legs (gas injection).
文摘The analyses of light hydrocarbons in oils from the Tarim Basin show that the Man-go’s parameter K is about unity except those oils trapped in the eastern part of the Tazhong (Central Tarim) Fault Uplift. The regular variance of K may indicates the accumulation and admixture of the oil populations in the eastern part of the Tazhong Fault Uplift.
文摘This paper is mainly concentrated on the geochemical characteristics and origin of gas of Kekeya field in the Tarim basin, NW China. This study shows that Permian mudstone is the main source rock of oil and gas. Based on the carbon isotopes of C 1-C 4, the carbon isotope of gas in Kekeya field is a little heavier than that in the typical marine-derived gas. The relationship between carbon isotopes of methane and ethane is coincident with Faber equation of gas derived from organic matter Ⅰ/Ⅱ. The majority of gas maturity is estimated, based on the formula, at 1.8 %-2.2 % besides K2 and K18 wells. In addition, the gas derived from 0.9 %-1.2 % R o source rocks may also be mixture. 40Ar/ 36Ar and 3He/ 4He ratios from the gas samples also support the mixing process. Moreover, the gas in this region is mainly generated from more mature source rocks although the low mature gas exists.
