Geochemical Characteristics,Genesis and Source Correlation of Permian Formation Water in the Western Sulige Gas Field and the Northern Part of Tianhuan Depression,Ordos Basin,China
The western Sulige gas field and the northern part of Tianhuan depression are significant natural gas rich zones within Ordos Basin.The relationship between gas and water is complicated,with gas-water coexistence observed in the Upper Paleozoic Permian gas reservoirs.At present,the study on the genesis and source correlation of Permian formation water in these two regions is relatively weak.By analyzing geochemical characteristics of Permian formation water samples from 35 wells in the above two regions,and the differences in formation water genesis,source,and preservation conditions were furtherly elucidated.The results show that the formation water from both regions are mainly CaCl2-type,and the average TDS is 31.4 and 34.6 g·L-1,respectively.The northern part of Tianhuan depression exhibits superior sealing characteristics based on various hydrochemical parameters,and the data also indicate strong water-rock interaction in the above two regions and good preservation conditions for oil and gas.The distribution pattern of gas and water in Sulige gas field is controlled by near-source migration characteristics,hydrocarbon generation intensity,and reservoir heterogeneity.Additionally,a series of structural fracture systems in the northern part of Tianhuan depression play a significant role in regulating the distribution of gas and water within this region.The formation water in the above two regions is mainly the original sedimentary formation water,and the albitization and dolomitization of plagioclase occur in the formation,showing the characteristics of Ca2+enrichment,Na+slight loss and Mgi+loss.The analysis data consistently indicate that the interface between gas and water in the western Sulige gas field lacks uniformity,and local well locations are affected by external water and other fluids,while the formation water in the northern part of Tianhuan depression may belong to a unified fluid field.
geochemistryformation waterion compositionpreservation conditionPermianSulige gas fieldTianhuan depressionOrdos Basin
NETL
NSTL
万方数据
