Reservoir-forming age and its exploration significance to stratigraphic reservoirs in southern Songliao Basin

Abstract

Despite many studies concerning the forming age, evolution characteristics and the age of petroleum charging in the Fuxin upheaval of southern Songliao Basin, no consensus has been reached so far. This paper presents the first K-Ar dating of autogenetic illite from stratigraphic petroleum reservoirs in the Fuyu oil layer of the Fuxin upheaval belt. Isotopic test and age calculation were carried out based on the separation and purification of illite mineral, X-diffraction analysis and the detection of scanning electron microscopy. The evolution characteristics of structure, sedimentation, reservoir-forming about the Fuxin upheaval belt were interpreted in terms of the synthetical analysis of "six-type geological history" evolution in southern Songliao Basin. The geologic background of petroleum evolution and reservoir formation are similar in the entire central depression region of southern Songliao Basin. The Changling sag and the Fuxin upheaval belt brought about obvious upheaval-sag separation after the hydrocarbon-generation peak of K 2 qn 1 and the main reservoir-forming period of the Fuyu oil layer, namely reservoir-forming happened before the Fuxin upheaval belt extensively raised. The reservoirs have three characteristics: the hydrocarbon source rock above the reservoir, the oil source in the locality, and the vertical migration. The geological cognition is corrected, that is, oil source came from the Changling sag and migrated from the side direction. The bulk process of petroleum charging in the stratigraphic hydrocarbon reservoirs in the Fuxin upheaval belt of southern Songliao Basin is determined according to the isotopic age of autogenetic illite in combination with the method of fluid inclusions. The cognition is helpful to exactly evaluate the resource potential and exploration direction in the Fuxin upheaval belt, Changling sag and their peripheral areas. The present results indicate that the combination of the two methods (the K-Ar dating of autogenetic illite and fluid inclusions) is an effective way to lay bare petroleum charging history and ascertain reservoir age.

Dawsonite occurrences related to the age and origin of CO2 influx in sandstone reservoirs: A case study in the Songliao Basin, NEChina

“…The illite K/Ar isotopic dating data of the dawsonite‐bearing sandstones, and combining the reported illite K/Ar ages in the study area [ Zou et al ., ; Yan et al ., ] were collected (supporting information Table S5). We can conclude that the distribution of authigenic illite K/Ar ages of the dawsonite‐bearing sandstone reservoir in the Central Depression of the Songliao Basin was from 92.5 to 58.8 Ma.…”

“…With an increase of depths, the K/Ar age decreases (supporting information Figure S6b), suggesting a long and slow hydrocarbon accumulation process. However, Ages earlier than 85 Ma could possibly be explained by the regional timing difference of oil influx [ Zou et al ., ]. The two obviously older samples (J23‐3 and Q48A‐44) are not confined to the study area.…”

“…Such treatments do not alter the K‐Ar isotopic system of the I/S [ Clauer et al ., ]. With the decreasing of fraction size, I/S content increased, chlorite content decreased, illite, and kaolinite disappeared gradually; <0.02 μm size fractions only contain I/S and chlorite without feldspar and illite debris [ Zou et al ., ; Zhang et al ., ]. Chlorite do not cause any influence on the K‐Ar dating results [ Zhang et al ., ].…”

Causes of Oil Accumulation of Isolated Bars in Lacustrine Delta

“…The sand bodies at the edge of river-mouth bars were transformed into ones with reverse rhythms separated from the main parts of bars, namely front bars. At the same time, sediment was re-deposited, which was re-carried by waves to form offshore bar sediment on offshore slopes and was connected with the delta front, forming highly destructive transgressive delta sediment transformed by (stormy) waves that are unique to the Daqingzijing area [6,7]. Controlled by sharp transgressive conditions, the delta sub-facies sediment in the transgressive delta system was narrow.…”

New insights into reservoir architecture of Fuyu oil layer in southern Songliao Basin based on analyses of water-flooding characteristics

“…Fuyu oil layer belonging to Quantou Formation, Lower Cretaceous is one of the principal reservoirs in southern Songliao Basin, NE China (Dou, 1997;Jing et al, 2014;Wei et al, 2010;Zhao et al, 2011;Zou et al, 2006Zou et al, , 2007. The studied area, Fuyu oilfield, with a flat topography and an elevation of 135-150 m, is located in the eastern edge of the central depression of Songliao Basin (Figure 1).…”