Gas genetic type and origin of hydrogen sulfide in the Zhongba gas field of the western Sichuan Basin, China

Self Cite

Over the past five years, oil and gas exploration to marine facies carbonate rock in China took on a fast-growing tendency, and a lot of large-scale oil and gas fields were discovered in succession. Particularly in the north of Tarim Basin, the large-scale Rewapu oil field was recently discovered in the Ordovician carbonate rock layer system with buried depth of 7,000 meters, manifesting that a significant potential of exploration exists in Tarim Basin's deep layer and ultra deep layer of Tarim basin. The results indicate that reservoirs of Rewapu oilfield are low porosity and low permeability layers karst reservoirs, reservoir temperature is around at 160 ℃ with oil, and the crude oil comes from the upper Ordovician source rock of the Manjaer depression. The hydrocarbon accumulation time is in the Late Permian, and since the Triassic sedimentation, the reservoir is in the continuous process of burying. It belongs to the old oil and gas system. Due to low geothermal gradient and late quick deep burial, oil reservoir has yet to be cracked, so well-preserved old oil reservoir can be discovered at the depth of 7000 m. The Ordovician carbonate reservoir in Rewapu was a fracture-cavity oil reservoir, and the oil and gas distribution and enrichment are controlled not by the local structure, but by the distribution and the development degree of Ordovician carbonate reservoir. The reservoirs of Rewapu block are mainly distributed in the Ordovician Yijianfang formation and at the top Yingshan formation, and the reservoir development degree was controlled by the karstification, the degree of fracture development and the sedimentation facies, concentrating into belts in plane and not controlling by the depth vertically. The overlying strata are limestone of Tumuxiuke formation and marls and limestone of Sangtamu formation in the upper Ordovician. Rewapu oil reservoir features stratified oil and mainly contains normal oil with low viscosity and high wax. Research results show that Ordovician reservoirs in Rewapu block have relatively large depth of burial, but they are still favorable in quality and sit along the path for the oil and gas's northward migration. Therefore, this block has immense resources potential and boasts good exploration and development outlook. In this paper, we study Rewapu block oil reservoir's geological features and hydrocarbon accumulation mechanism, which is of important significance for directing the exploration to oil and gas at the deep layer and ultra deep layer of Tarim Basin.

Section: Introductionmentioning

confidence: 99%

Geology and Hydrocarbon Accumulation of the Large Ultra-Deep Rewapu Oilfield in Tarim Basin, China

Zhu

Liu

Zheng

et al. 2015

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“…the Sichuan and Tarim basins), and igneous-hosted oil and gas fields (e.g. the Sichuan and Tarim basins; Li et al, 2015;Liu et al, 2010;Zhu et al, 2011;Zou et al, 2008). Laboratory simulations in this Special Collection include: (1) simulation of the dissolution of gypsum-bearing rocks; (2) experiments on the cracking and hydrolysis of hydrocarbons; and (3) simulations of the influence of magmatism on hydrocarbon generation.…”

Section: General Methodologies Applied To Petroliferous Basins In Wesmentioning

confidence: 99%

Special Issue: Advances of petroleum exploration and geology research in West China's petroliferous basins

Cao

Wang

2018

“…Following nearly 200 years of development of the world petroleum industry, fewer and fewer high-abundance hydrocarbon-enriched blocks are discovered, and some low-abundance lithologic reservoirs and unconventional reservoirs have been highlighted as important exploration targets in order to ensure stable energy supply. In recent years, major advances have been made in exploration of continuously distributed carbonate reservoirs across China, including basins such as Tarim, Ordos, and Sichuan, where the proved oil reserves in carbonate reservoirs have reached 12×10 8 t, and the exploration of unconventional reservoirs is expanding from large low-abundance sandstone oil and gas fields to quasi-layered continuous carbonate fracture-cavity reservoirs (Zhu et al, 2011a;2011b;Sun et al, 2009a;Liu et al, 2010). In particular, a group of large carbonate oil and gas fields have been proved consecutively at the Lianglitage reef flats of the Ordovician carbonates and the Yijianfang-Yingshan karstic reservoirs in the Tarim Basin (Zhang et al, 2007;Lü et al, 2009;Zhao et al, 2009;Zhu et al, 2011a;Zhou et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, major advances have been made in exploration of continuously distributed carbonate reservoirs across China, including basins such as Tarim, Ordos, and Sichuan, where the proved oil reserves in carbonate reservoirs have reached 12×10 8 t, and the exploration of unconventional reservoirs is expanding from large low-abundance sandstone oil and gas fields to quasi-layered continuous carbonate fracture-cavity reservoirs (Zhu et al, 2011a;2011b;Sun et al, 2009a;Liu et al, 2010). In particular, a group of large carbonate oil and gas fields have been proved consecutively at the Lianglitage reef flats of the Ordovician carbonates and the Yijianfang-Yingshan karstic reservoirs in the Tarim Basin (Zhang et al, 2007;Lü et al, 2009;Zhao et al, 2009;Zhu et al, 2011a;Zhou et al, 2010). The Yingshan karstic reservoirs in the Tazhong area are buried at 5000~6500m generally, covering a continuous area of approximately 1.0×10 4 km 2 (Yang et al, 2007a;; with 3P reserves up to 7×10 8 t, they are characterized by large low-abundance accumulation and large-span quasi-layered distribution.…”

Section: Introductionmentioning

confidence: 99%

Characteristics and Accumulation Mechanism of Quasi-Layered Ordovician Carbonate Reservoirs in the Tazhong Area, Tarim Basin

Wang

Jin

Zhu

et al. 2013

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Weathered crust reservoirs of marine carbonate rocks and large-area quasilayered carbonate reservoirs controlled by massive unconformity surfaces have become an important play for exploration of marine hydrocarbons across China. In the Tazhong area, oil and gas originating from the marine facies of the Ordovician Yingshan formation, present large-scale integrated continuous accumulation along massive structures. In particular, they are accumulated continuously in layered form in carbonate fracture-cavity reservoir system, and not controlled by tertiary structural belts. Moreover, the Yingshan reservoirs are complex in types, comprising cross distribution of high gas/oil ratio (GOR) condensate gas reservoirs, volatile oil reservoirs and normal oil reservoirs, and large burial depth span and high heterogeneity of quasi-layered reservoirs. The complexity in diagenesis and accumulation lead to the unique distribution and enrichment of carbonate reservoirs in the Tazhong area. The analysis of blowdown and leakage depths, heterogeneity, and physical properties of pores, caves and fractures of the Yingshan formation carbonate reservoirs indicates that the interstratal karsts have superimposed with faults and fractures to form fracture zones, so that the reservoir bodies present integrated continuous distribution characteristics spatially, providing favorable conditions for quasi-layered continuous enrichment of oil and gas. During late periods, a massive amount of natural gas had been filled along the gas-source faults. Based on the variations of relative contents of light hydrocarbons and aromatic naphthalene homologs in crude oil, it is found that the quasi-layered continuous carbonate reservoirs in the Tazhong area are different in terms of the properties of oil and gas and the types of oil reservoirs as a result of the formation of high GOR high-yield condensate gas reservoirs near the oil/gas-source faults due to gas washing, migration and fractionation. Late gas charge and transformation process acting on earlier oil reservoirs is an important geochemical action in the formation mechanism of carbonate reservoirs in the Tazhong area.