Assessment on gas accumulation potential and favorable plays within the Xu-1, 3 and 5 Members of the Xujiahe Formation in the Sichuan Basin

Zhao, Wenzhi; Bian, Congsheng; Xu, Chao; Wang, Hongjun; Wang, Tongshan; Shi, Zhensheng

doi:10.1016/s1876-3804(11)60041-4

Cited by 42 publications

(11 citation statements)

References 5 publications

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“…Therefore, the Xujiahe reservoir can readily capture the natural gas generated from coal measures in the adjacent layers. In large areas in the middle of the Sichuan Basin, the hydrocarbon source rock in the Xujiahe Formation is at a mature or highly mature stage (Xie et al., 2008; Zhao et al., 2010, 2011). The carbon isotope values of methane in natural gas are consistent with the maturity of their presumed source rocks.…”

Section: Discussionmentioning

confidence: 99%

Geochemical characteristics of natural gases from different petroleum systems in the Longgang gas field, Sichuan Basin, China

Qin

Zhou

et al. 2018

Energy Exploration & Exploitation

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Located in the Sichuan Basin, China, the Longgang gas field consists of three vertically developed petroleum systems with the Triassic Leikoupo Formation as a dividing interface. There is one marine petroleum system below the interface and one continental petroleum system above it. The marine petroleum system is composed of coal measures, the main source rock in the Longtan Formation, and marine reef reservoirs in the Changxing and Feixianguan formations. The continental petroleum system can also be subdivided into two sets. One is the Xujiahe petroleum system sourced from the Xujiahe coal measures in the Upper Triassic formation. The other is a Jurassic petroleum system that is sourced from Jurassic lacustrine black shales. The gas pools in the marine system contain H 2 S gas. The gases are very dry and the d 13 C 1 and d 13 C 2 values display less negative values with an average of À29.2 and À25.0&, respectively. The gases are humic origin generated at highly to over mature stages from coal measures of the Longtan Formation. The natural gas in the continental petroleum system does not contain H 2 S. The natural gases from the Xujiahe petroleum system are mainly wet gases with a few dry gases, and belong to typical humic type sourced from coal measures of the Xujiahe Formation. All the gases from this Jurassic petroleum system are wet gases and the alkane gases show more negative carbon isotopic values typical of sapropels. These are derived from the lower Jurassic lacustrine black mudstone. The three sets of petroleum systems in the Longgang gas field are vertically well separated. Each system has its own source rock, and there are no gases from other sources

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Section: Discussionmentioning

confidence: 99%

Geochemical characteristics of natural gases from different petroleum systems in the Longgang gas field, Sichuan Basin, China

Qin

Zhou

et al. 2018

Energy Exploration & Exploitation

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“…Except for the locally developed paralic facies deposition in the first Member, all the other intervals in Xujiahe Formation are terrestrial deposition (Zhang et al 2009;Zhu et al 2009;Zhao et al 2011). From the basin margin to the subsidence-depositional center of the basin, the sedimentary facies has the distribution characteristics of successively alluvial fan facies, fan delta facies, fluvial facies, fluvial delta facies, and lacustrine facies (Fig.…”

Section: Reservoir Characteristics Sedimentary Environment and Litholmentioning

confidence: 99%

Reservoir characterization and origin of tight gas sandstones in the Upper Triassic Xujiahe formation, Western Sichuan Basin, China

Gong

Zeng

Gao

et al. 2015

J Petrol Explor Prod Technol

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The Western Sichuan Basin, which is located at the front of Longmen Mountain in the western Sichuan Province, China, is a foreland basin formed in the Late Triassic. The Upper Triassic Xujiahe formation in the Basin includes several tight gas sandstone reservoirs, whose porosity is less than 6.0 % and permeability less than 0.1 md. According to data of cores, thin sections, FMI, SEM and experiments, we summarize the reservoir characteristics, analyze the origin of these tight gas sandstones, and discuss the factors controlling the formation of relatively high-quality reservoirs. Xujiahe Formation is a set of terrestrial clastic rocks with low compositional maturity, low cement content, and medium textural maturity. Secondary dissolution pores are abundant, but pore spaces are small with narrow pore throats and high capillary pressures. Due to the existence of abundant fractures and intense diagenesis, these tight gas reservoirs are characterized by high reservoir heterogeneity, complex seepage system, and strong stress sensitivity. The original sedimentary facies belt and later tectonism co-control the distribution of favorable reservoirs. The intense compaction and cementation are the main factors making the Xujiahe formation to be tight.

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“…The Upper Triassic Xujiahe Formation source rocks of the Sichuan Basin are distributed in the Xu1, Xu3, and Xu5 Members, with coal seam thicknesses of 5-15 m on average, distributed stably horizontally. Coal measure mudstones have thicknesses of 100-800 m, thinning out from the western to the central Sichuan Basin, basically covering the whole basin (Zhao et al 2011). Thermal evolution history shows that substantial gas generation and expulsion occurred in the source rocks of the two basins in the geological history.…”

Section: Geological Settingmentioning

confidence: 99%

Contribution of moderate overall coal-bearing basin uplift to tight sand gas accumulation: case study of the Xujiahe Formation in the Sichuan Basin and the Upper Paleozoic in the Ordos Basin, China

et al. 2015

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Tight sand gas is an important unconventional gas resource occurring widely in different petroleum basins. In coal-bearing formations of the Upper Triassic in the Sichuan Basin and the Carboniferous and Permian in the Ordos Basin, coal measure strata and tight sandstone constitute widely distributed source-reservoir assemblages and form the basic conditions for the formation of large tight sand gas fields. Similar to most tight gas basins in North America, the Sichuan, and Ordos Basins, all experienced overall moderate uplift and denudation in MesoCenozoic after earlier deep burial. Coal seam adsorption principles and actual coal sample simulation experiment results show that in the course of strata uplift, pressure drops and desorption occurs in coal measure strata, resulting in the discharge of substantial free gas. This accounts for 28 %-42 % of total gas expulsion from source rocks. At the same time, the free gases formerly stored in the pores of coal measure source rocks were also discharged at a large scale due to volumetric expansion resulting from strata uplift and pressure drop. Based on experimental data, the gas totally discharged in the uplift period of Upper Paleozoic in the Ordos Basin, and Upper Triassic Xujiahe Formation in the Sichuan Basin is calculated as (3-6) 9 10 8 m 3 /km 2 . Geological evidence for gas accumulation in the uplift period is found in the gas reservoir analysis of the above two basins. Firstly, natural gas discharged in the uplift period has a lighter carbon isotope ratio and lower maturity than that formed in the burial period, belonging to that generated at the early stage of source rock maturity, and is absorbed and stored in coal measure strata. Secondly, physical simulation experiment results at high-temperature and high-salinity inclusions, and almost actual geologic conditions confirm that substantial gas charging and accumulation occurred in the uplift period of the coal measure strata of the two basins. Diffusive flow is the main mode for gas accumulation in the uplift period, which probably reached 56 9 10 12 m 3 in the uplift period of the Xujiahe Formation of the Sichuan Basin, compensating for the diffusive loss of gas in the gas reservoirs, and has an important contribution to the formation of large gas fields. The above insight has promoted the gas resource extent and potential of the coal measure tight sand uplift area; therefore, we need to reassess the areas formerly believed unfavorable where the uplift scale is large, so as to get better resource potential and exploration prospects.

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Assessment on gas accumulation potential and favorable plays within the Xu-1, 3 and 5 Members of the Xujiahe Formation in the Sichuan Basin

Cited by 42 publications

References 5 publications

Geochemical characteristics of natural gases from different petroleum systems in the Longgang gas field, Sichuan Basin, China

Geochemical characteristics of natural gases from different petroleum systems in the Longgang gas field, Sichuan Basin, China

Reservoir characterization and origin of tight gas sandstones in the Upper Triassic Xujiahe formation, Western Sichuan Basin, China

Contribution of moderate overall coal-bearing basin uplift to tight sand gas accumulation: case study of the Xujiahe Formation in the Sichuan Basin and the Upper Paleozoic in the Ordos Basin, China

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