Water imbibition and drainage of high rank coals in Qinshui Basin, China

Shen, Jian; Zhao, Jincheng; Qin, Yong; Shen, Yue; Wang, Geoff

doi:10.1016/j.fuel.2017.09.039

Cited by 45 publications

(22 citation statements)

References 22 publications

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“…The fractal calculation in this section takes sample 11 as an example. The T 2 spectrum of movable water can be obtained by subtracting the T 2 spectrum in the centrifugal state from the T 2 spectrum in the saturated state. , Based on the T 2 spectrum of the saturated state, the fractal dimension of model 1 can be obtained using eq (Figure a). The results show that the curves of lg( T 2 ) and lg( V p ) for one sample type can be divided into two linear segments.…”

Section: Resultsmentioning

confidence: 99%

Comparative Evaluation of Pore Structure Heterogeneity in Low-Permeability Tight Sandstones Using Different Fractal Models Based on NMR Technology: A Case Study of Benxi Formation in the Central Ordos Basin

Zhang

2020

Energy Fuels

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Based on the NMR T 2 spectra of all of the samples, the applicability of the single fractal model and the multifractal model for the quantitative investigation of pore diameter distribution heterogeneity is analyzed. Then, the relationships between pore structures, physical properties, and fractal dimensions calculated by each model are discussed. The following results have been achieved. (1) Model 1 can be used to study the heterogeneity of different fluid states (including saturation and bound water) or partial pore size distribution, and the calculated fractal dimension has the best correlation with permeability. This model is mainly suitable for type I samples with macropores developed. (2) Models 2, 3, and 4 can quantitatively analyze the heterogeneity of the overall pore diameter distribution. These calculated fractal dimensions have a good linear relationship with porosity, T 2cutoff, T 2gm, and other physical parameters, which are mainly suitable for type II, III, and IV samples with micropores developed. (3) There is a negative correlation between multifractal dimensions calculated by model 4 and single fractal parameters calculated by models 2 and 3. Micropores and macropores are the key pore sizes that affect the variation of single fractal parameters, while mesopores are the key size affecting the variation of multifractal parameters. (4) The selection of a reasonable T 2 spectrum range has become a key to determine the calculation accuracy of models 2 and 3. Above all, models 1 and 4 should be given priority in characterizing pore distribution heterogeneity of tight sandstone gas reservoirs.

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Section: Resultsmentioning

confidence: 99%

Comparative Evaluation of Pore Structure Heterogeneity in Low-Permeability Tight Sandstones Using Different Fractal Models Based on NMR Technology: A Case Study of Benxi Formation in the Central Ordos Basin

Zhang

2020

Energy Fuels

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“…In fractured reservoirs, imbibition is an important process to improve oil and gas recovery from the matrix. , The spontaneous imbibition mechanisms in rock and coal are key issues that need to be focused upon to improve recovery in the development of the tight oil, , shale and tight gas, − and coalbed methane. , Spontaneous imbibition is the process of a wetting phase displacing a non-wetting phase in a porous media in the presence of capillary pressure. Depending upon the flow directions of wetting and non-wetting phases, spontaneous imbibition can be divided into cocurrent imbibition and countercurrent imbibition.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Studies of Spontaneous Imbibition with Different Boundary Conditions: Case Studies of Middle Bakken and Berea Cores

Zhang

Zhao

2019

Energy Fuels

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Tight oil and gas are becoming increasingly important energy sources in North America. Spontaneous imbibition is an important mechanism in oil and gas recovery from tight reservoirs. In this study, countercurrent spontaneous imbibition experiments and nuclear magnetic resonance (NMR) were combined to study the imbibition and the fluid distribution in eight core samples. NMR is able to detect fluid distribution in different sizes of pores ranging from micropores to fractures. Before the experiments, Middle Bakken and Berea cores were saturated with air. Then imbibition experiments with one end open (OEO) and two ends closed (TEC) boundary conditions were carried out. The numerical solutions of spontaneous imbibition models were matched with experimental results by choosing reasonable parameters. The capillary pressure and relative permeability were obtained from the matching. Moreover, the gravity effect on the spontaneous imbibition was analyzed. It was found that the gravity can be neglected for tight rocks. However, it has significant impacts on high-permeability rocks. The recovery factor of OEO imbibition exhibits a linear relationship with . However, the TEC imbibition shows a poor linear relationship with at the late stage. This research provides new methods to obtain capillary pressure and relative permeability from spontaneous imbibition experiments with OEO and TEC boundary conditions and advances crucial mechanisms for the development of tight reservoirs.

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“…The injecting pressure of sample SJ1 corresponding to water breakthrough at the outlet is obviously higher than that of sample XZ (0.6 MPa). Shen et al (45) and Yuan et al (46)found that the imbibition capacity for a given sample decreases with the increase of the sample contact angle and pore tortuosity when the pore size distribution is approximately similar. Therefore, the difference of pore tortuosity and wettability between the two samples leads to this phenomenon.…”

Section: Displacement Of Water In Various Pores By High-pressure Nitrogen Injectionmentioning

confidence: 99%

Experimental Simulation Study on Water Migration and Methane Depressurizing Desorption Based on Nuclear Magnetic Resonance Technology: A Case Study of Middle-Rank Coals from the Panguan Syncline in the Western Guizhou Region

et al. 2019

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Water migration and methane desorption characteristics directly affect the performance of coalbed methane wells. In this paper, migration and desorption variability of methane and water in adsorption pores, seepage pores, and fractures were studied by laboratory simulation using an improved nuclear magnetic resonance displacement device. The results are as follows: Both adsorbed and bulk methane decreased logarithmically with the increase of the desorption time under the condition of one-stop desorption. The desorption process can be divided into the early rapid decline stage and the later slow desorption stage. In comparison to one-stop desorption, step-by-step depressurizing desorption can effectively increase the loss rate of the methane amount. For the two desorption modes, the variation rate of bulk methane is much higher than that of adsorbed methane at the same desorption time. The sensitivity of large pores to displacement nitrogen pressure is stronger than that of adsorption pores. In the process of methane displacement by water, the variation of bulk methane is larger than that of adsorbed methane, whereas the variation of adsorbed methane is more sensitive to injecting water pressure than that of bulk methane. The above results indicate that the quantity of water injected into the coal seam and the water drainage rate have an effect on methane desorption in the adsorption pore. Therefore, the parameters of depressurization value should be fully considered in the drainage system setting of coalbed methane wells.

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Water imbibition and drainage of high rank coals in Qinshui Basin, China

Cited by 45 publications

References 22 publications

Comparative Evaluation of Pore Structure Heterogeneity in Low-Permeability Tight Sandstones Using Different Fractal Models Based on NMR Technology: A Case Study of Benxi Formation in the Central Ordos Basin

Comparative Evaluation of Pore Structure Heterogeneity in Low-Permeability Tight Sandstones Using Different Fractal Models Based on NMR Technology: A Case Study of Benxi Formation in the Central Ordos Basin

Experimental and Numerical Studies of Spontaneous Imbibition with Different Boundary Conditions: Case Studies of Middle Bakken and Berea Cores

Experimental Simulation Study on Water Migration and Methane Depressurizing Desorption Based on Nuclear Magnetic Resonance Technology: A Case Study of Middle-Rank Coals from the Panguan Syncline in the Western Guizhou Region

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