Reservoir and development characteristics of the Da'anzhai tight oil in Sichuan Basin, SW China

Wang, Yongjun; Tong, Min; Sun, Yuanhui; Zhang, Yuan‐Zhong; Yuan, Dawei

doi:10.1016/j.ptlrs.2019.04.002

Cited by 4 publications

(3 citation statements)

References 6 publications

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“…Combined with the results of high-pressure mercury intrusion experiment, for limestone formation, the percentage of micron-and submicron-scale pores has a tendency to increase as permeability increases, but the nanoscale pores still account for a large proportion. While the main contribution to permeability is derived from the micron-and submicron-scale pores, the fluid storage does not match the flow space, resulting in high resistance gradient (Wang et al 2019;Qiao et al 2020;Zhang et al 2020).…”

Section: Resultsmentioning

confidence: 99%

Influence of reservoir lithology on porous flow resistance of gas-bearing tight oil reservoirs and production forecast

Rao

Yang

Zhang

et al. 2021

J Petrol Explor Prod Technol

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The release of dissolved gas during the development of gas-bearing tight oil reservoirs has a great influence on the effect of development. In this article, the high-pressure mercury intrusion experiment was carried out in cores from different regions and lithologies of the Ordos Basin and the Sichuan Basin. The objectives are to study the microscopic characteristics of the porous throat structure of these reservoirs and to analyze the porous flow resistance laws of different lithology by conducting a resistance gradient test experiment. A mathematical model is established and the oil production index is corrected according to the experiment results to predict the oil production. The experimental results show that for tight reservoirs in the same area and lithology, the lower the permeability under the same back pressure, the greater the resistance gradient. And for sandstone reservoirs in different areas, the resistance gradients have little difference and the changes in the resistance coefficients are similar. However, limestone under the same conditions supports a much higher resistance gradient than sandstone reservoirs. Furthermore, the experimental results are consistent with the theoretical analysis indicating that the PVT (pressure–volume-temperature) characteristics in the nanoscale pores are different from those measured in the high-temperature, high-pressure sampler. Only when the pressure is less than a certain value of the bubble point pressure, the dissolved gas will begin to separate and generate resistance. This pressure is lower than the bubble point pressure measured in the high-temperature and pressure sampler. The calculation results show that the heterogeneity of limestone reservoirs and the mismatch of fluid storage and flow space will make the resistance, generated by the separation of dissolved gas, have a greater impact on oil production.

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Section: Resultsmentioning

confidence: 99%

Influence of reservoir lithology on porous flow resistance of gas-bearing tight oil reservoirs and production forecast

Rao

Yang

Zhang

et al. 2021

J Petrol Explor Prod Technol

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“…The shelly limestone is a kind of unique lithology in the Da'anzhai member, which is different from other formations. Partial shelly limestone in the Da'anzhai member, which has a high argillaceous content and high oil and gas production, can be considered as a source rock [23,24]. The Da'anzhai member is vertically characterized by a complete transgression-retrogression sedimentary cycle.…”

Section: Geologic Settingmentioning

confidence: 99%

Quantitative Prediction of Fractures in Shale Using the Lithology Combination Index

Zhang

Yuan

et al. 2020

Minerals

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Fractures, which are related to tectonic activity and lithology, have a significant impact on the storage and production of oil and gas in shales. To analyze the impact of lithological factors on fracture development in shales, we selected the shale formation from the Da’anzhai member of the lower Jurassic shales in a weak tectonic deformation zone in the Sichuan Basin. We defined a lithology combination index (LCI), that is, an attribute quantity value of some length artificially defined by exploring the lithology combination. LCI contains information on shale content at a certain depth, the number of layers in a fixed length (lithology window), and the shale content in the lithology window. Fracture porosity is the percentage of pore volume to the apparent volume of the rock. In the experiment, fracture porosity was obtained using 50 samples from six wells, by observing rock slices under a microscope. The relationship between LCI and fracture porosity was analyzed based on machine learning, regression analysis, and weighting methods. The results show that LCI is able to represent the impact of multiple lithological factors (i.e., shale content at a certain depth, the number of layers in the lithology window, and the shale content in the lithology window). The LCI within a thickness of 2 m for the lithology window demonstrates a good linear relationship with fracture porosity. We therefore suggest LCI be used for fracture predictions of shale formations from weak tectonic deformation zones. Our proposed LCI and fracture prediction methods also provide implications for sandstone, mudstone, or carbonate formations under similar processes.

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“…In China, tight oil resources are mainly distributed in the Ordos Basin, Sichuan Basin, and Songliao Basin [7][8][9][10][11]. For example, the tight oil resources are abundant in the Taiyuan formation in the Ordos Basin and the Jurassic Da'anzhai Member in the Sichuan Basin, which are the typical lacustrine carbonate tight oil resources [12,13]. The tight limestone reservoir space of the Taiyuan formation is mainly composed of dissolution pores, residual organism cavities, intergranular pores, and microfractures, and the development of such reservoirs is mainly controlled by sedimentary microfacies, quasi-syngenetic karstification, and fractures, whereas the tight limestone reservoirs in the central Sichuan Basin are controlled by dissolution and tectonic processes [14], and the porosity and permeability of tight limestone are related to the calcite content [15].…”

Section: Introductionmentioning

confidence: 99%

Pore Structure Characterization and Fractal Characteristics of Tight Limestone Based on Low-Temperature Nitrogen Adsorption and Nuclear Magnetic Resonance

Lin,

Zhao,

et al. 2024

Fractal Fract

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Pore structure characterization and fractal analysis have great significance for understanding and evaluating tight limestone reservoirs. In this work, the pore structure of tight limestone, low-temperature nitrogen adsorption (LTNA), and low-field nuclear magnetic resonance (NMR) are characterized, and the fractal dimension of the pore structure of tight limestone is discussed based on LTNA and NMR data. The results indicate that the pores of tight limestone have H3 and H4 types, the pore size distribution (PSD) of the H3 type is a wave distribution ranging from 2 to 10 nm, and the PSD of the H4 type is a unimodal distribution ranging from 2 to 10 nm. The transverse relaxation time (T2) spectrum of tight limestone shows a single peak (DF), double peak (SF), and triple peak (TF), and the ranges for the T2 spectra for micropores, mesopores, and macropores are 0.1 to 10 ms, 10 to 100 ms, and greater than 100 ms, respectively. The LTNA fractal dimension of tight limestone (DL) ranges between 2.4446 and 2.7688, with an average of 2.5729, and the NMR fractal dimensions of micropores (DNMR1), mesopores (DNMR2), and macropores (DNMR3) are distributed between 0.3744 and 1.1293, 2.4263 and 2.9395, and 2.6582 and 2.9989, respectively. Moreover, there is a negative correlation between DL and average pore radius, a positive correlation between DL and specific surface area, and a positive correlation between DNMR2 and DNMR3 and micropore content, while DNMR2 and DNMR3 are negatively correlated with the content of mesopores and macropores.

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Reservoir and development characteristics of the Da'anzhai tight oil in Sichuan Basin, SW China

Cited by 4 publications

References 6 publications

Influence of reservoir lithology on porous flow resistance of gas-bearing tight oil reservoirs and production forecast

Influence of reservoir lithology on porous flow resistance of gas-bearing tight oil reservoirs and production forecast

Quantitative Prediction of Fractures in Shale Using the Lithology Combination Index

Pore Structure Characterization and Fractal Characteristics of Tight Limestone Based on Low-Temperature Nitrogen Adsorption and Nuclear Magnetic Resonance

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