Great quantities of light oil and gas are produced from deep buried hill reservoirs at depths of 5,641 m to 6,027 m and 190 ℃ to 201 ℃ in the Niudong-1 Well, representing the deepest and hottest commercial hydrocarb...Great quantities of light oil and gas are produced from deep buried hill reservoirs at depths of 5,641 m to 6,027 m and 190 ℃ to 201 ℃ in the Niudong-1 Well, representing the deepest and hottest commercial hydrocarbons discovered in the Bohai Bay Basin in eastern China. This discovery suggests favorable exploration prospects for the deep parts of the basin. However, the discovery raises questions regarding the genesis and accumulation of hydrocarbons in deep reservoirs. Based on the geochemical features of the hydrocarbons and characteristics of the source rocks as well as thermal simulation experiments of hydrocarbon generation, we conclude that the oil and gas were generated from the highly mature Sha-4 Member （Es4） source rocks instead of thermal cracking of crude oils in earlier accumulations. The source kitchen with abnormal pressures and karsted carbonate reservoirs control the formation of high-maturity hydrocarbon accumulations in the buried hills （i.e., Niudong-1） in conjunction with several structural-lithologic traps in the ES4 reservoirs since the deposition of the upper Minghuazhen Formation. This means the oil and gas exploration potential in the deep parts of the Baxian Depression is probably high.展开更多
The composition characteristics of light hydrocarbons from crude oil,chloroform bitumen A,saturated hydrocarbon fraction,aromatic hydrocarbon fraction,and asphaltene fraction during cracking have been studied systemat...The composition characteristics of light hydrocarbons from crude oil,chloroform bitumen A,saturated hydrocarbon fraction,aromatic hydrocarbon fraction,and asphaltene fraction during cracking have been studied systematically. The results revealed that the content of n-alkanes,branched alkanes and cycloalkanes in light hydrocarbons from the samples gradually decreased as the simulation temperature increased,and finally almost depleted completely,while the abundance of methane,benzene and its homologues increased obviously and became the main products. The ratios of benzene/n-hexane and toluene/n-heptane can be used as measures for oil cracking levels. Variation characteristics of maturity parameters of light hydrocarbons,for example,iC4/nC4,iC5/nC5,isoheptane value,2,2-DMC4/nC6,and 2-MC6+3-MC6/nC7 for different samples with increasing pyrolysis temperature,are consistent with those in petroleum reservoirs,indicating that these parameters may be efficient maturity index.展开更多
文摘Great quantities of light oil and gas are produced from deep buried hill reservoirs at depths of 5,641 m to 6,027 m and 190 ℃ to 201 ℃ in the Niudong-1 Well, representing the deepest and hottest commercial hydrocarbons discovered in the Bohai Bay Basin in eastern China. This discovery suggests favorable exploration prospects for the deep parts of the basin. However, the discovery raises questions regarding the genesis and accumulation of hydrocarbons in deep reservoirs. Based on the geochemical features of the hydrocarbons and characteristics of the source rocks as well as thermal simulation experiments of hydrocarbon generation, we conclude that the oil and gas were generated from the highly mature Sha-4 Member （Es4） source rocks instead of thermal cracking of crude oils in earlier accumulations. The source kitchen with abnormal pressures and karsted carbonate reservoirs control the formation of high-maturity hydrocarbon accumulations in the buried hills （i.e., Niudong-1） in conjunction with several structural-lithologic traps in the ES4 reservoirs since the deposition of the upper Minghuazhen Formation. This means the oil and gas exploration potential in the deep parts of the Baxian Depression is probably high.
基金Supported by the National Natural Science Foundation of China (Grant No. 40573030)the National Key Science and Technology Program of China During the 10th Five-Year Plan Period (Grant No. 2004BA616A02-01-01-03)
文摘The composition characteristics of light hydrocarbons from crude oil,chloroform bitumen A,saturated hydrocarbon fraction,aromatic hydrocarbon fraction,and asphaltene fraction during cracking have been studied systematically. The results revealed that the content of n-alkanes,branched alkanes and cycloalkanes in light hydrocarbons from the samples gradually decreased as the simulation temperature increased,and finally almost depleted completely,while the abundance of methane,benzene and its homologues increased obviously and became the main products. The ratios of benzene/n-hexane and toluene/n-heptane can be used as measures for oil cracking levels. Variation characteristics of maturity parameters of light hydrocarbons,for example,iC4/nC4,iC5/nC5,isoheptane value,2,2-DMC4/nC6,and 2-MC6+3-MC6/nC7 for different samples with increasing pyrolysis temperature,are consistent with those in petroleum reservoirs,indicating that these parameters may be efficient maturity index.
