Study on the induced polarization model in the exploration for shale gas in southern China

Liu, Yan; Xiang, Kui; Li, Pengfei; Liu, Xuejun; Wang, Zhigang

doi:10.1190/segam2014-0186.1

Cited by 8 publications

(11 citation statements)

References 10 publications

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“…The Southern China have more sets of shale formation and a large number of studies have been carried out in the area on rock samples from shale gas reservoirs (Yan et al 2014). The shale in the Silurian Longmaxi formation to the Ordovician Wufen formation and the lower Cambrian Qiongzhusi formation have rich organic matter, high maturity and good conditions for storage of shale gas.…”

Section: Site Description and Available Datasetmentioning

confidence: 99%

“…Based on Cole-Cole dielectric dispersion model (Cole and Cole 1941), many other empirical models have been employed to fit the complex electrical response of rocks and soils. Yan et al (2014) attest that the relaxation model from Pelton et al (1978) is one of the most used model in which the resistivity of the mineralized porous rock is expressed as:…”

Section: Spectrum Parameters Inversionmentioning

confidence: 99%

“…Where ( ) t~ represents the complex resistivity, 0 t represents resistivity at zero frequency, m represents the intrinsic chargeability of sedimentary rocks, τ represents the time decay constant of the IP potential, while c represents the relaxation constant, ~ represents the angular frequency, and i is the imaginary number. In general, observation from experiments indicates that pyrite has lower conductivity, higher chargeability, and longer time decay constant, and is a mineral usually associated with strong IP effect which could be used to detect hydrocarbons, ores, and underground water (Yan et al 2014).…”

Section: Spectrum Parameters Inversionmentioning

confidence: 99%

“…On the other hand, controlled source electromagnetic (CSEM) method has played an important role in oil and gas exploration as an effective supplement technology to seismic exploration because of its advantages of great exploration depth, high efficiency, low cost, good adaptability, and direct detection of oil and gas. In recent years, the theoretical and experimental studies (Zhang et al 2013;Xiang et al 2014;Yan et al 2014) found that the rich organic shale is characterized by low resistance and high chargeability and the difference of electric characteristics is superior to seismic velocity. Thus, the physical basis of electromagnetic method in predicting shale gas sweet spot is superior to the seismic method and has great potential applications in the future.…”

Section: Introductionmentioning

confidence: 99%

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Predicting the characteristic parameters of shale sweet-spot with complex resistivity

Xu¹,

Liu²,

Xiang³

et al. 2020

Terr. Atmos. Ocean. Sci.

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It is important to predict the capacity related parameters of reservoir such as brittleness, total organic carbon (TOC), in-situ stress, maturity of organic carbon (Ro), and buried depth in shale gas exploration and exploitation. Among these parameters, brittleness and TOC are especially important for shale gas exploitation. The complex resistivity measurement and analysis show that the rich organic shale in southern China features low resistivity and high chargeability. These characteristics are a geophysical prerequisite for predicting the sweet spot characteristic parameters of shale, such as TOC and brittleness, with rapid developing of high resolution controlled source electromagnetic (CSEM) method prospecting which can give resistivity and chargeability distribution of underground. Based on the rich organic shale composition analysis and complex resistivity measurements in southern China, this paper analysed the presence of pyrite as an associated mineral in organic-rich shale, and examined its relationship to resistivity, chargeability, TOC content and brittleness, and the quantitative relationship between the models has been established. Therefore, this study provides a firm experimental foundation for predicting parameters of shale sweet spots with CSEM prospecting.

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Section: Site Description and Available Datasetmentioning

confidence: 99%

Section: Spectrum Parameters Inversionmentioning

confidence: 99%

Section: Spectrum Parameters Inversionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Predicting the characteristic parameters of shale sweet-spot with complex resistivity

Xu¹,

Liu²,

Xiang³

et al. 2020

Terr. Atmos. Ocean. Sci.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Xiang et al (2014) confirmed that the dispersion characteristics of a shale complex resistivity are correlated with the TOC content. Yan et al (2014) demonstrated that pyrite is a key to predicting shale TOC content. The complex resistivity charge rate and the resistivity anomaly range can effectively be utilized to match seismic "sweet spots".…”

Section: Introductionmentioning

confidence: 99%

Relationship Between Electrical Properties and Sedimentary Environment of the Longmaxi Formation Shale, Southern Sichuan

Yang

Zhang

Wang

et al. 2020

Acta Geologica Sinica (Eng)

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The Lower Silurian Longmaxi Formation in the south of Sichuan is a key player in the exploration and development of shale gas in China. Due to a highly complex topographic area, electromagnetic methods (EM) become important exploration means in this area. Many studies have been conducted on the shale mineral composition and electrical properties of shale, however, the correlation between sedimentary environments and the electrical properties of shale remain poorly understood. The electrical properties and sedimentary environment of the organic-rich shale of the Longmaxi Formation have been studied by means of X-ray diffraction, organic geochemistry, scanning electron microscopy and complex resistivity measurements. The discovered high quartz content of the Longmaxi Formation shale results in low resistivity. Deep-water shelf biogenic quartz contributes lower resistivity more than that of shallow-water terrigenous quartz. The deep-water anoxic and organic sedimentary environment led to major enrichment of pyrite, leading to a high polarization effect in shale. We present the correlation between the lithofacies types and electrical properties of Longmaxi Formation. The mixed siliceous shale lithofacies is the most favorable among the three lithofacies, which is characterized by high total organic carbon (TOC) content, high brittleness mineral content, high polarization and low resistivity ("three high and one low"). This feature is an effective identification of shale gas reservoirs by electromagnetic prospecting. Our study can provide constraints on electrical parameters of rocks for electromagnetic "sweet spot" exploration of shale gas, and so this has important geological significance to shale gas exploration and development.

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Advancements in Controlled Source Electromagnetic Methods for Prospecting Unconventional Hydrocarbon Resources in China

Yan

2023

Surv Geophys

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Globally, unconventional hydrocarbons, known for the symbiosis of their hydrocarbon source and reservoir, pose significant seismic exploration challenges due to their confined target regions, extensive burial depth, minimal acoustic impedance variation, marked heterogeneity, and strong anisotropy. Over the past decade, electromagnetic (EM) exploration has evolved markedly, improving resolution and reliability, thus becoming indispensable in unconventional hydrocarbon exploration. Focusing on China's application of the controlled source electromagnetic method (CSEM), this review examines the geological and electrical attributes of these reservoirs, notably the low resistivity, high polarization and strong electrical anisotropy of shale gas reservoirs. Despite the demonstrated positive correlation between induced polarization (IP) parameters and reservoir parameters, current methodologies emphasize the IP effect, inadvertently neglecting electrical anisotropy, which affects data precision. Moreover, single-source CSEM methodologies limit the observational components, acquisition density, and exploration area, impacting the accuracy and efficacy of data interpretation. Recently developed CSEM techniques in China, namely wide-frequency electromagnetic method (WFEM), time–frequency electromagnetic method (TFEM), long offset transient electromagnetic method (LOTEM), and wireless electromagnetic method (WEM), harness high-power pseudo-random binary sequence (PRBS) waveforms, reference observation and processing technology, hybrid inversion, and enhancing operational efficiency and adaptability despite the pressing need for multi-functional software for data acquisition. Case studies detail these methods' applications in shale gas sweet spot detection and continuous hydraulic fracturing monitoring, highlighting the immense potential of EM methods in unconventional hydrocarbon sweet spot detection and total organic content (TOC) predication. However, challenges persist in suppressing EM noise, streamlining 3D inversion processes, and improving the detection and evaluation of sweet spots.

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Study on the induced polarization model in the exploration for shale gas in southern China

Cited by 8 publications

References 10 publications

Predicting the characteristic parameters of shale sweet-spot with complex resistivity

Predicting the characteristic parameters of shale sweet-spot with complex resistivity

Relationship Between Electrical Properties and Sedimentary Environment of the Longmaxi Formation Shale, Southern Sichuan

Advancements in Controlled Source Electromagnetic Methods for Prospecting Unconventional Hydrocarbon Resources in China

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