Light hydrocarbon geochemical characteristics and their application in Upper Paleozoic, Shenmu gas field, Ordos Basin

Abstract

Light hydrocarbon has abundant geochemical information, but there are few studies on it in Shenmu gas field. Taking Upper Paleozoic in Shenmu gas field as an example, authors use gas chromatography technology to study light hydrocarbon systematically. The results show that (1) The Shenmu gas field is mainly coal-derived gas, which is mixed by partial oil-derived gas due to the experiment data. (2) Based on K 1 , K 2 parameter and Halpern star chart, the Upper Paleozoic gas in Shenmu gas field belongs to the same petroleum system and the depositional environment of natural gas source rocks should be homologous. (3) The source rocks are mainly from terrestrial higher plant origins and belong to swamp facies humic due to methyl cyclohexane index and Mango parameter intersection chart, which excluded the possibility of the Upper Paleozoic limestone as source rocks. (4) The isoheptane ranges from 1.45 to 2.69 with an average of 2.32, and n-heptane ranges from 9.48 to 17.68% with an average of 11.71%, which is below 20%. The maturity of Upper Paleozoic gas in Shenmu gas field is low-normal stage, which is consistent with R o data. (5) The Upper Paleozoic natural gas in the Shenmu gas field did not experience prolonged migration or secondary changes, thus can be analyzed by light hydrocarbon index precisely.

Geochemical characteristics and reasons for the carbon isotopic reversal of natural gas in the southern Jingbian gas field, Ordos Basin, China

“…The Ordos Basin can be divided into six tectonic units, i.e. the Yimeng Uplift, Weibei Uplift, Jinxi Fold Belt, Xiyuan Thrust Belt, Yi-Shaan Slope and Tianhuan Depression (Liu et al 2009;Yang et al 2014;Han et al 2017b;Li et al 2017;Shi et al 2019) (Fig. 1).…”

Petrological characteristics and the impact of mineral content on reservoir quality in coal-bearing strata of Linxing area, eastern margin of Ordos Basin, China

“…Ordos Basin is a superimposed cycle of cratonic basin that is the second largest sedimentary basin in China (Li and Hu, 2010; Wang et al, 2010). According to the structural feature and basement properties, the basin can be broadly subdivided into six major tectonic units that are the Yimeng uplift, Yishan slope, Weibei uplift, western margin thrust belts, Tianhuan depression, and Jixi fold belt (Han et al, 2016; Liu et al, 2015). Ordos Basin has experienced multiple tectonic cycles including Caledonian, Hercynian, Indosinian, Yanshan, and Himalayan cycles (Zhao et al, 2012).…”

Ordovician deep dolomite reservoirs in the intracratonic Ordos Basin, China: Depositional model and Diagenetic evolution

“…However, recent research has suggested that non-karstification-dominated carbonates could be targeted for gas exploration. It is well known that gas released from the overlying coal measures has migrated into the very tops of the karstification-dominated reservoirs and the upper Palaeozoic sandstone reservoirs (Han et al., 2017; He et al., 2005). Recently, a tectonics-driven coal-derived gas lateral migration model proposed that the lower sub-members (M 5 5 , M 5 6 , ……, M 5 10 ) situated east of the Central Paleo-uplift may have been charged from the overlying hydrocarbon kitchen (Li et al., 2017; Liu et al., 2015; Miao et al., 2011; Wei et al., 2017; Yang et al., 2011, 2013).…”