Developmental characteristics, influencing factors and prediction of fractures for a tight gas sandstone in a gentle structural area of the Ordos Basin, China

The Lower Permian Xiashihezi Formation in the Ordos Basin, China, is a quartz-sandstone reservoir with low porosity and low permeability. We have acquired 3D seismic data and well data from 18 vertical and four horizontal wells to indicate the potential of seismic attribute analyses in locating seismic sweet spots for lateral placement of horizontal wells. Using the analytic wavelet transform with a Morse wavelet, the integration of high tuning spectral components, high sweetness and high spectral attenuation helped us to estimate the distribution of gas-bearing tight sands in the Xiashihezi Formation. Our results revealed that the principal target of horizontal drilling and production was gas-bearing massive point bars in the braided river delta setting of the Ordos Basin. The integrated workflow of the seismic attribute analysis contributes to the optimal horizontal well planning by mining and exposing critical geological information of a tight gas sand reservoir from within 3D seismic data.

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Pore‐Throat Combination Types and Gas‐Water Relative Permeability Responses of Tight Gas Sandstone Reservoirs in the Zizhou Area of East Ordos Basin, China

Acta Geologica Sinica - English Edition ◽

10.1111/1755-6724.13872 ◽

2019 ◽

Vol 93 (3) ◽

pp. 622-636 ◽

Cited By ~ 2

Author(s):

Mi LI ◽

Yinghai GUO ◽

Zhuangfu LI ◽

Huaichang WANG ◽

Jingxia ZHANG

Keyword(s):

Relative Permeability ◽

Ordos Basin ◽

Tight Gas ◽

Pore Throat ◽

Sandstone Reservoirs ◽

Tight Gas Sandstone

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A novel productivity evaluation approach based on the morphological analysis and fuzzy mathematics: insights from the tight sandstone gas reservoir in the Ordos Basin, China

Journal of Petroleum Exploration and Production Technology ◽

10.1007/s13202-019-00822-2 ◽

2019 ◽

Vol 10 (4) ◽

pp. 1263-1275

Author(s):

Shanyong Liu ◽

Gongyang Chen ◽

Yishan Lou ◽

Liang Zhu ◽

Daoyao Ge

Keyword(s):

Ordos Basin ◽

Gas Content ◽

Practical Significance ◽

Fuzzy Mathematics ◽

Tight Gas ◽

Test Results ◽

Gas Reservoirs ◽

Tight Gas Reservoirs ◽

Morphological Theory ◽

The Ordos Basin

AbstractTight gas reservoirs have rich potential resources, which are hot spots in unconventional oil and gas exploration and development. Due to their strong heterogeneity and complex pore structures, the conventional approaches of productivity evaluation always have difficulty in predicting the gas content. This study aims to devise a new method to interpret the productivity of LX Block in the Ordos Basin using the morphological theory and fuzzy mathematics. First, core test results were used to investigate the reservoir quality and physical properties. Then, the change law of gas content was defined by the morphological theory of logging and mud logging curves. Assignments of those factors that affected the final production were provided based on fuzzy mathematics. Finally, the prediction model of productivity was established. The results show that the lower limit of the reservoir thickness in the LX Block is 3.1 m, whereas the porosity and permeability are 5% and 0.15 × 10−3 μm2, respectively. The morphological characteristic of the gas logging curve for those layers with high potential production normally presents a box shape with a high relative number of serration. The reservoir in the studied area can be classified into four categories according to the relationship between the logging curve shape and daily production, and each category is automatically identified. The coincidence rate between the prediction results and the gas test results is 84.1%, which satisfies the demand on the field. The findings have important theoretical and practical significance for screening the location of fracturing spots and predicting the production of tight gas reservoirs.

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Seismic estimation of fluid saturation based on rock physics: A case study of the tight-gas sandstone reservoirs in Ordos Basin

Interpretation ◽

10.1190/int-2021-0124.1 ◽

2021 ◽

pp. 1-47

Author(s):

Chao Li ◽

Peng Hu ◽

Jing Ba ◽

José M. Carcione ◽

Tianwen Hu ◽

...

Keyword(s):

Ordos Basin ◽

Rock Physics ◽

Gas Production ◽

P Wave ◽

Quantitative Prediction ◽

Rock Fragment ◽

Tight Gas ◽

Fluid Saturation ◽

Sandstone Reservoirs ◽

Tight Gas Sandstone

Tight-gas sandstone reservoirs of the Ordos Basin of China are characterized by high rock-fragment content, dissimilar pore types and a random distribution of fluids, leading to strong local heterogeneity. We model the seismic properties of these sandstones with the double-double porosity (DDP) theory, which considers water saturation, porosity and the frame characteristics. A generalized seismic wavelet is used to fit the real wavelet and the peak frequency-shift method is combined with the generalized S-transform to estimate attenuation. Then, we establish rock-physics templates (RPTs) based on P-wave attenuation and impedance. We use the log data and related seismic traces to calibrate the RPTs and generate a 3D volume of rock-physics attributes for the quantitative prediction of saturation and porosity. The predicted values are in good agreement with the actual gas production reports, indicating that the method can be effectively applied to heterogeneous tight-gas sandstone reservoirs.

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