Hydrocarbon generation and expulsion characteristics of Lower Permian P1f source rocks in the Fengcheng area, northwest margin, Junggar Basin, NW China: implications for tight oil accumulation potential assessment

2015 ◽  
Vol 51 (6) ◽  
pp. 880-900 ◽  
Author(s):  
Tao Hu ◽  
Xiongqi Pang ◽  
Sa Yu ◽  
Xulong Wang ◽  
Hong Pang ◽  
...  
2020 ◽  
pp. 014459872095629
Author(s):  
Yue Feng ◽  
Zhilong Huang ◽  
Tianjun Li ◽  
Enze Wang ◽  
Hua Zhang ◽  
...  

In recent years, new oil reservoirs have been discovered in the middle Jurassic tight mixed rocks of the Turpan–Hami Basin. However, the generation potential of the J2q2 source rocks remains poorly understood. Petrographic, petrological, and geochemical analyses were carried out to assess the quality of the J2q2 source and reservoir rocks. The hydrocarbon generation potential method was utilized to evaluate the hydrocarbon generation and expulsion potentials. The results indicated that the rocks can be classified as high-quality source rocks with a relative lower degree of maturity. The hydrocarbon bearing zones are classified as tight reservoirs (average porosity of 5.90% and permeability of 0.18 mD) with an average pore throat radius >150 nm, which is higher than the cut-off pore-throat radius. The source rocks start to expel hydrocarbons when Ro% is 0.56%. Bulk hydrocarbon generation and expulsion intensities in the center of the study area were calculated with the values of 900 × 104 t/km2 and 400 × 104 t/km2, while the weights of these hydrocarbons were 48.8 × 108 t and 27.3 × 108 t, respectively. The tight oil reservoir-forming conditions are superior, and the hydrocarbon generation and expulsion intensities are more remarkable in controlling the tight oil distribution. This study provides an important example for the Jurassic source rocks in Western China, and indicates that middle Jurassic lacustrine source rocks deserve attention in future exploration.


2021 ◽  
pp. 014459872110238
Author(s):  
Zhijun Qin ◽  
Dongming Zhi ◽  
Kelai Xi

The Mahu Sag in the Junggar Basin, China, is a hydrocarbon-rich sag. Abundant hydrocarbon source rocks were developed in the late Paleozoic there across the Carboniferous–Permian boundary. However, studies of the source rocks have focused mainly on the lower Permian Fengcheng Formation. Here we compare the Fengcheng Formation with other Carboniferous rocks and those of the lower Permian Jiamuhe and middle Permian Lower-Wuerhe formations. Based on organic petrological and geochemical data, the organic matter precursors, sedimentary facies, and resource potential of these source rocks were investigated. The bio-precursors of Carboniferous, Jiamuhe, and Lower-Wuerhe Formations were dominantly estuarine higher plants, Nematothallus -higher plants, and spores, respectively. The bio-precursors of Fengcheng Formation were mainly bacteria and algae, and the organic matter is abundant, with a high hydrocarbon-generating capacity and significant shale oil potential. In contrast, the other three formations contain poor-quality source rocks, although the Lower-Wuerhe Formation has a higher organic matter abundance than the Jiamuhe Formation. The Carboniferous organic matter contains mainly type II kerogen, whereas the Jiamuhe and Lower-Wuerhe formations contain type III kerogen. The thermal maturities determined from Tmax values is larger than those indicated by biomarkers. The biomarkers show that the three studied formations contain a mixture of terrestrial higher plants and bacteria–algae, with the contribution of green algae being higher than that of bacteria in most samples. However, the ratio of algae to bacteria is lower than that of the Fengcheng Formation. The Fengcheng Formation was deposited in a strongly reducing, high-salinity, and water-stratified sedimentary environment. The other three formations were deposited in an oxidizing–reducing, low-salinity, and water-unstratified environment. They are characterized by the predominance of mudstone over carbonate rocks and the descending distribution type of tricyclic terpenes. Our results provide a basis for research on upper Paleozoic source rocks in western China, and useful information for oil and gas exploration in the Mahu Sag.


2012 ◽  
Vol 39 (6) ◽  
pp. 700-711 ◽  
Author(s):  
Lichun KUANG ◽  
Yong TANG ◽  
Dewen LEI ◽  
Qiusheng CHANG ◽  
Min OUYANG ◽  
...  

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