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

Abstract

Combined with the actual geological settings, tight oil is the oil that occurs in shale or tight reservoirs, which has permeability less than 1 mD and is interbedded with or close to shale, including tight dolomitic oil and shale oil. The Fengcheng area (FA), at the northwest margin of the Junggar Basin, northwest China, has made significant progress in the tight oil exploration of the Fengcheng (P1f) Formation recently, which indicates that the tight oil resources have good exploration prospects. Whereas the lack of recognition of hydrocarbon generation and expulsion characteristics of Permian P1f source rocks results in the misunderstanding of tight oil resource potential. Based on the comprehensive analysis of geological and geochemical characteristics of wells, seismic inversion, sedimentary facies, tectonic burial depth, etc., the characteristics of P1f source rocks were investigated, and the horizontal distributions of the following aspects were predicted: the thickness of source rocks, abundance and type of organic matter. And on this basis, an improved hydrocarbon generation potential methodology together with basin simulation techniques was applied to unravel the petroleum generation and expulsion characteristics of P1f source rocks in FA. Results show that the P1f source rocks distribute widely (up to 2039 km2), are thick (up to 260 m), have high total organic content (TOC, ranging from 0.15 to 4 wt%), are dominated by type II kerogen and have entered into low mature–mature stage. The modeling results indicate that the source rocks reached hydrocarbon generation threshold and hydrocarbon expulsion threshold at 0.5% Ro and 0.85% Ro and the comprehensive hydrocarbon expulsion efficiency was about 46%. The amount of generation and expulsion from the P1f source rocks was 31.85 × 108 and 15.31 × 108 t, respectively, with a residual amount of 16.54 × 108 t within the source rocks. Volumetrically, the geological resource of shale oil is up to 15.65 × 108 t. Small differences between the amounts calculated by the volumetric method compared with that by hydrocarbon generation potential methodology may be due to other oil accumulations present within interbedded sands associated with the oil shales. Copyright © 2015 John Wiley & Sons, Ltd.

Source rock characteristics of Permian Lucaogou Formation in the Jimusar Sag, Junggar Basin, northwest China, and its significance on tight oil source and occurrence

“…Based on the biomarker analysis, the Upper P 2 l Formation oil shows a close genetic relationship with the Upper P 2 l Formation source rocks, and the Lower P 2 l Formation oil also shows a close genetic relationship with the Upper P 2 l Formation source rocks, indicating that the tight oil is sourced from adjacent source rocks and that the migration of the oil is generated from the source rocks over very short distances in the vertical direction, which is similar to the tight oil accumulation characteristics of other areas (Jia et al ., ; Zou et al ., , ; Hu et al ., ).…”

“…However, prospect wells located out of these areas are oil show or even dry wells (Fig. ); this is probably because the amount of hydrocarbon generated by the source rock in this area does not satisfy the need of the multiform residual hydrocarbon, and thus hydrocarbon expulsion does not occur (Pang et al ., ; Hu et al ., ).…”

Multiple-stacked Hybrid Plays of lacustrine source rock intervals: Case studies from lacustrine basins in China

“…Recognizing the importance of many source rock intervals including the Lower Permian Fengcheng shales (Hu et al 2015;Xiang et al 2015), the Middle Permian Lucaogou and equivalent Pingdiquan Fm. are considered the most important source rock intervals due to wide distribution, large thickness, high TOC, and good hydrocarbon potential (Carroll 1998 (up to 31%) and an average S 1 ?…”

Geochemical and geological characteristics of the Jurassic continental black shale in the Southwestern Depression of Tarim Basin

“…Although a certain amount of progress had been made, large‐scale industrial production of shale gas has not yet begun in China because of delays in development and the need to determine particular geological issues. Most of the shale in the USA is marine deposits, whereas the main type in the Eastern and Northwestern China is continental deposits (Gao et al, ; T. Hu, Pang, Wang, & Jiang, ; T. Hu, Pang, Yu, Wang, & Pang, ; T. Hu, Pang, Wang, et al, ; W. H. Li, ; J. J. Li, Wang, et al, ; J. J. Li, Yin, et al, ; M. Wang, Sherwood, et al, ; M. Wang, Wilkins, et al, ; W. Wang, Xue, Tian, Wilkins, & Wang, ). Therefore, large differences exist between the geological and geochemical characteristics of the shale in both countries, and it is not possible for China to completely copy the exploration experiences associated with shale gas in the USA.…”

“…Most of the shale in the USA is marine deposits, whereas the main type in the Eastern and Northwestern China is continental deposits (Gao et al, 2013;T. Hu, Pang, Wang, & Jiang, 2017;T. Hu, Pang, Yu, Wang, & Pang, 2016; T. W.…”