Characteristics and diagenetic evolution of dolomite reservoirs in the Middle Permian Qixia Formation, southwestern Sichuan Basin, China

Pei, Senqi; Wang, Xingzhi; Hu, Xin; Li, Rongrong; Long, Hongyu; Huang, Dong

doi:10.1007/s13146-021-00678-w

Cited by 2 publications

(4 citation statements)

References 30 publications

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“…Chen et al (2013) reported that the 87 Sr/ 86 Sr ratio (0.709174-0.710194) of the Middle Permian hydrothermal dolomites is greater than that of the coeval marine limestones. Jiang et al (2014), Meng et al (2017) and Pei et al (2021) reported the 87 Sr/ 86 Sr ratio varies within the variation range of the coeval seawater, which are similar to those measured in previous studies. Exceptionally in some dolomite samples, the 87 Sr/ 86 Sr values were measured higher than that of the coeval seawater.…”

Section: Strontium Isotopic Compositionsupporting

confidence: 85%

“…According to the research result of Jiang et al (2014) reported that the homogenization temperature of inclusions is 120 °C-195 °C, and the salinity of 70 percent of inclusions exceeds 16%. Pei et al (2021) reported that the homogenization temperature of primary inclusions in dolomites of the Middle Permian Qixia Formation, northwestern Sichuan Basin, ranges between 110 °C and 120 °C. It is concluded by this study that the salinity is 3-5 times higher than that of the coeval seawater, and the homogenization temperature of inclusions exceeds 100 °C, which are similar to those measured in previous studies.…”

Section: Fluid Inclusionsmentioning

confidence: 99%

“…Meng et al (2017) identified that the saddle dolomites distinctly characterized by the more negative δ 18 O values, which filled the geodes in the Qixia Formation in the northwestern Sichuan Basin, are the product of late hydrothermal fluid filling. Based on the study conducted by Pei et al (2021) on the Qixia Formation dolomites in the northwestern Sichuan Basin, a large amount of hydrothermal minerals such as celestite, barite, fluorite, quartz and sphalerite have not been observed, with a small amount of saddle dolomites locally. It is considered that the Qixia Formation dolomites have been affected by small-scale hydrothermal solution, and hydrothermal dolomitization is not its major development mode.…”

Section: Saddle Dolomite (D2)mentioning

confidence: 99%

“…Li et al (2020) inferred from the petrological and geochemical analyses that the Qixia Formation dolomites in the northwestern Sichuan Basin were formed early, and should have formed a certain scale in the sedimentary -penesedimentary period to the initial stage of shallow burial. From the homogenization temperature of inclusions and the single-well burial history of the Qixia Formation dolomites, Jiang et al (2014) and Pei et al (2021) concluded that the dolomites were probably formed earlier than the Middle-Late Triassic Period, with the reference to the paleo-geothermal gradient. The age of the Qixia Formation dolomites in the northwestern Sichuan Basin measured by Zeng et al (2020) is 228-257 Ma using the U-Pb radioisotope dating method, and the formation time of crystalline dolomite was determined as the Middle-Late Triassic Period.…”

Section: Saddle Dolomite (D2)mentioning

confidence: 99%

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Geochemical Characteristics and Fluid Properties of the Qixia Formation Dolomites of the Middle Permian in the Shuangyushi Block, NW Sichuan Basin, China

Zhou

Wan

et al. 2022

Front. Earth Sci.

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On the basis of petrology, in combination with analysis of the geochemical characteristics of major and trace elements, REE (rare earth elements), carbon isotopes, oxygen isotopes, strontium isotopes and fluid inclusions, the geochemical characteristics and fluid properties of the Qixia Formation dolomites of the Middle Permian Qixiain the Shuangyushi block in the NW Sichuan Basin were systematically studied. The analysis results of the samples show that the Qixia dolomites are mainly composed of medium, coarse, medium-coarse crystalline and dolomites with polymodal crystal size distribution, and cloudy centers and clear rims. They generally show dark purple cathodoluminescence (CL) colors in the centers and orange red CL colors in the rims. The Qixia dolomites are relatively highly ordered (0.79–0.95, averaging 0.90). The CaO and MgO contents show a negative correlation. They are characterized by higher Mg/Ca ratio (0.89–0.92, averaging 0.91), high Fe (94–2,991 ppm, averaging 622 ppm), high Mn (26–185 ppm, averaging 102 ppm), high Na (210–374 ppm, averaging 277 ppm) contents, low Sr (53–218 ppm, averaging 93 ppm) content and lower ∑REE (1.10–5.56 ppm, averaging 2.08 ppm) concentrations. The REE patterns of the dolomites are similar to those of the calcites (C1), and are characterized by light REE (LREE) enrichment, heavy REE (HREE) depletion (LREE/HREE = 5.38–9.58, averaging 7.10), and Eu (0.65–4.19, averaging 1.70) and Ce (0.99–9.52, averaging 2.61) positive anomalies. They have consistent δ13C (1.98–4.27‰ VPDB, averaging 3.01‰ VPDB) and δ18O (−9.54‰–−4.65‰ VPDB, averaging −7.09‰ VPDB) values with the coeval seawater. The salinity index Z is larger than 120, with diagenetic temperature higher than normal temperature. The average value of 87Sr/86Sr is positive (0.707150–0.712273, averaging 0.708669), while some samples are consistent to those of the coeval seawater. Their homogenization temperatures of fluid inclusions (96.3°C–105.0°C, averaging 101.1°C) exceed 100°C, which is equivalent to the buried paleogeothermal temperature, and their salinity (12.3%–14.3%, averaging 13.5%) is 3–5 times that of normal seawater. Based on the regional geological setting and previous research achievements, the dolomitized fluids in the Qixia Formation are probably derived from seawater or marine fluids sealed in pores under shallow-burial environment. The dolomites experienced late alternation by deep high-salinity hydrothermal fluids, and were formed before the Middle-Late Triassic Period.

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Section: Strontium Isotopic Compositionsupporting

confidence: 85%

Section: Fluid Inclusionsmentioning

confidence: 99%

Section: Saddle Dolomite (D2)mentioning

confidence: 99%

Section: Saddle Dolomite (D2)mentioning

confidence: 99%

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Geochemical Characteristics and Fluid Properties of the Qixia Formation Dolomites of the Middle Permian in the Shuangyushi Block, NW Sichuan Basin, China

Zhou

Wan

et al. 2022

Front. Earth Sci.

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Application of multi-component seismic data in identifying dolomite reservoirs in the Sichuan Basin

Chen,

Zhang,

et al. 2024

Journal of Geophysics and Engineering

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A comprehensive drilling of wells has been conducted in the Permian Qixia Formation in the central Sichuan Basin, revealing a significant number of dolomite reservoirs. High- and medium-porosity dolomite reservoirs are the main gas-producing reservoirs in the Qixia Formation. Seismic PP-wave data show a ‘bright spot’ for high-porosity dolomite reservoir formations but weak responses for medium-porosity dolomite reservoir formations, which is attributed to the inability of P waves to distinguish between medium-porosity reservoirs and limestone. However, medium-porosity dolomite and limestone have different S-wave velocities. Therefore, in this study, the identification of different-porosity dolomite reservoirs using multi-component seismic data was investigated. A comprehensive analysis of the elastic waves by forward modeling shows that the PS-wave amplitude is more sensitive to medium-porosity dolomite than the PP-wave amplitude. Therefore, medium-porosity dolomite reservoirs can be predicted using the amplitude attributes of the PS wave, and high-porosity dolomite reservoirs can be characterized using the PP wave. Meanwhile, the elastic parameter λρ (the product of Lame constant λ and density ρ), which is highly correlated with the dolomite content, can be used as an indicator of dolomite formations. Furthermore, compared to the results of PP-wave inversion, the elastic parameters derived from the joint inversion of PP- and PS-waves exhibited a better correspondence with the well-logging results. The comprehensive use of the seismic amplitude responses of PP and PS waves and multi-component seismic joint inversion can effectively predict high- and medium-porosity dolomite reservoirs. The predicted results can support the exploration and development of the Qixia Formation.

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Characteristics and diagenetic evolution of dolomite reservoirs in the Middle Permian Qixia Formation, southwestern Sichuan Basin, China

Cited by 2 publications

References 30 publications

Geochemical Characteristics and Fluid Properties of the Qixia Formation Dolomites of the Middle Permian in the Shuangyushi Block, NW Sichuan Basin, China

Geochemical Characteristics and Fluid Properties of the Qixia Formation Dolomites of the Middle Permian in the Shuangyushi Block, NW Sichuan Basin, China

Application of multi-component seismic data in identifying dolomite reservoirs in the Sichuan Basin

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