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Origin of late charged gas and its effect on property of oils in the Ordovician in Tazhong area.
- Source :
-
Journal of Petroleum Science & Engineering . Oct2014, Vol. 122, p83-93. 11p. - Publication Year :
- 2014
-
Abstract
- Natural gases in Ordovician reservoirs of the Tazhong area of the Tarim Basin appear derived by oil-cracking gas. The gases show very different geochemical characteristics. Most of the gases in the middle and eastern part of the No. 1 fault-slope zone are characterized by high gas dryness coefficients and have methane δ 13 C 1 values heavier than primary gas. These features are different from gases in the western part of the No. 1 fault-slope zone. Thus, we propose that there existed mixing between more mature, 13 C-rich methane dominated gas and less mature wet gas with 13 C-depleted methane. The hypothesis is supported by (1) roughly a positive correlation between the gas dryness coefficient and methane δ 13 C 1 value, (2) significantly heavier δ 13 C 1 values in the eastern part of the study area than in the west, and (3) significantly heavier δ 13 C 1 values than anticipated for unaltered gas co-generated with C 2 –C 4 . The charge and mixing of the dry gas into the Ordovician pools may have resulted in increase in wax contents of the oils, gas/oil ratios, gas dryness coefficients and methane δ 13 C values, leading to a positive correlation between gas/oil ratio and paraffin wax content as a result of continuous fractionation and removal of light components of an oil with progressive gas influx and thus gas washing. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 09204105
- Volume :
- 122
- Database :
- Academic Search Index
- Journal :
- Journal of Petroleum Science & Engineering
- Publication Type :
- Academic Journal
- Accession number :
- 99062752
- Full Text :
- https://doi.org/10.1016/j.petrol.2014.06.020