Forming mechanism of hydrocarbon reservoirs in Yingshan Formation of Yuqi block in Akekule arch, Tarim Basin

Abstract

The reservoir conditions, oil and gas charge history and accumulation phases were studied for Yingshan Formation of Yuqi block, and an oil and gas accumulation model was established by using the techniques of reservoir prediction, fluorescence thin section and fluid inclusion analysis under the guidance of the theories of oil and gas accumulation. The results indicate that the main rock types in Yingshan Formation are micrite and calcarenite. The carbonate reservoirs are of cave, fracture-pore and fracture types, and their physical properties are intermediate; there are at least four oil/gas charges, i.e. late Hercynian, Yanshanian, early Himalayan and middle Himalayan (Cenozoic). The most important charge periods are late Hercynian, early Himalayan and middle Himalayan; the oil and gas accumulation model is self source-lateral expulsion of hydrocarbon-multistage accumulation, or hydrocarbon sourced from and preserved in the same old rocks-long term expulsion of hydrocarbon-multistage accumulation.

Timing and mechanism of reservoir forming in the Upper Triassic Halahatang Formation, Yuqi block, Tarim Basin, northwestern China

“…Analysis of hydrocarbon sources, fluid properties, hydrocarbon charge and accumulation periods, and establishment of reservoirforming mechanism models are based mainly on studies of fluorescence thin sections and homogenization temperatures of fluid inclusions (Kuang et al, 2007(Kuang et al, , 2008a.…”

“…In recent years, fluorescent bitumen observation of fluorescent thin section has become an important method to study reservoir formation (Kuang et al, 2007(Kuang et al, , 2008a. The properties and basic fluorescent characteristics of the samples from Wells YQ3 and YQ4 are shown in Table 3.…”

“…The properties and basic fluorescent characteristics of the samples from Wells YQ3 and YQ4 are shown in Table 3. The hydrocarbon charge phases and corresponding geologic times can be inferred from the color and existed states of fluorescence bitumen, and their interrelationship, in combination with the diagenetic evolution sequence of the area (Table 3; Kuang et al, 2007Kuang et al, , 2008a. There are compaction, cementation and dissolution in the Yuqi block on the basis of the analysis results of rock thin section observation, casting thin sections, scanning electron microscope and cathode luminescence from Wells YQ3 and YQ4.…”

“…In the Yuqi block, the reservoir type, oil/gas charge history, accumulation period, and reservoir formation history of the Lower-Middle Ordovician Yingshan Formation carbonate (O 1-2 y) have been studied by several authors (Wang et al, 2004(Wang et al, , 2008Kuang et al, 2006Kuang et al, , 2007Kuang et al, , 2008aJin et al, 2008), but little is known about Triassic clastic rocks that have significantly different timing and mechanism of reservoir formation from those of the O 1-2 y (Pang et al, 2007;Kuang et al, 2007Kuang et al, , 2008a.…”

“…From the perspective of sequence stratigraphic framework and by using combined fluorescence thin section (Kuang et al, 2007(Kuang et al, , 2008a and fluid inclusion techniques (Tao, 2004;Haszeldine et al, 1984;Mclimmans, 1987), this paper presents an integrated study on the hydrocarbon resources, fluid properties, hydrocarbon charge history and accumulation periods of the T 3 h in the Yuqi block, and establishes a model for reservoir formation and hydrocarbon charging.…”