Assessment on Pore Structure of Western Sichuan Reservoir through Mercury Intrusion Porosimetry

2012 ◽  
Vol 226-228 ◽  
pp. 2082-2087
Author(s):  
Chi Guan ◽  
Zhang Hua Lou ◽  
Hai Jian Xie
Keyword(s):  
Pore Structure ◽  
Mercury Intrusion Porosimetry ◽  
Water Saturation ◽  
Absolute Permeability ◽  
Tight Gas ◽  
Gas Reservoir ◽  
Western Sichuan ◽  
Mercury Intrusion ◽  
Irreducible Water Saturation ◽  
Tight Gas Reservoir

Mercury intrusion porosimetry injection is important in assessing microscopic pore structure of reservoirs. This paper introduces an estimated function for investigating the pore characteristic of western Sichuan tight gas reservoir based on VG model. Better correlations between the measured and estimated results have been obtained using VG model. Representative parameters were obtained by fitting the predictions of VG model to the experimental data, and then the estimated formulation was proposed for the studied reservoir. Correlation analysis of the parameters of VG model confirms that absolute permeability and irreducible water saturation are important in mercury injection porosimetry. The approach applied in this paper is helpful in investigating tight reservoirs, especially in the common cases when measurement is difficult to carry out, partly because of complicated variability in the field, and partly because measuring is time-consuming and expensive.

Stimulation Mechanism of SDS Nanoemulsion in Tight Gas Reservoirs

2011 ◽  
Vol 418-420 ◽  
pp. 82-85
Author(s):  
Ming Liang Luo ◽  
Jia Lin Liu ◽  
Le Jun Liao ◽  
Zi Long Jia ◽  
Hou Tai Sun
Keyword(s):  
Water Saturation ◽  
Sodium Dodecyl ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Initial Water ◽  
Core Flow ◽  
Tight Gas Reservoir ◽  
Water Block ◽  
Flow Experiments

The stimulation mechanisms of sodium dodecyl sulfate (SDS) nanoemulsion in tight gas reservoir were analyzed by capillary force, core spontaneous imbibitions, cleanup effect and core flow experiments. The results show that SDS nanoemulsion could hold back capillarity effectively, reduce the water absorption and reduce water block damage. The initial water saturation of core decreases by 85.12% and the gas effective permeability regains by 42.03%, which improves the stimulation effect in tight gas reservoir substantially

scholarly journals Threshold Pore Pressure Gradients in Water-Bearing Tight Sandstone Gas Reservoirs

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4578
Author(s):  
Yong Wang ◽  
Yunqian Long ◽  
Yeheng Sun ◽  
Shiming Zhang ◽  
Fuquan Song ◽  
...  
Keyword(s):  
Water Saturation ◽  
High Water ◽  
Linear Regression Method ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
Gas Reservoir ◽  
Gas Seepage ◽  
Tight Gas Reservoir ◽  
Core Permeability

Tight gas reservoirs commonly occur in clastic formations having a complex pore structure and a high water saturation, which results in a threshold pressure gradient (TPG) for gas seepage. The micropore characteristics of a tight sandstone gas reservoir (Tuha oilfield, Xinjiang, China) were studied, based on X-ray diffraction, scanning electron microscopy and high pressure mercury testing. The TPG of gas in cores of the tight gas reservoir was investigated under various water saturation conditions, paying special attention to core permeability and water saturation impact on the TPG. A mathematical TPG model applied a multiple linear regression method to evaluate the influence of core permeability and water saturation. The results show that the tight sandstone gas reservoir has a high content of clay minerals, and especially a large proportion of illite–smectite mixed layers. The pore diameter is distributed below 1 micron, comprising mesopores and micropores. With a decrease of reservoir permeability, the number of micropores increases sharply. Saturated water tight cores show an obvious non-linear seepage characteristic, and the TPG of gas increases with a decrease of core permeability or an increase of water saturation. The TPG model has a high prediction accuracy and shows that permeability has a greater impact on TPG at high water saturation, while water saturation has a greater impact on TPG at low permeability.

scholarly journals Calculation Model of Relative Permeability in Tight Sandstone Gas Reservoir with Stress Sensitivity

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Jin Yan ◽  
Rongchen Zheng ◽  
Peng Chen ◽  
Shuping Wang ◽  
Yunqing Shi
Keyword(s):  
Relative Permeability ◽  
Pore Radius ◽  
Water Saturation ◽  
Stress Sensitivity ◽  
Tight Sandstone ◽  
Gas Reservoir ◽  
Two Phase ◽  
Permeability Model ◽  
Irreducible Water Saturation ◽  
Tight Gas Reservoir

During the development of tight gas reservoir, the irreducible water saturation, rock permeability, and relative permeability change with formation pressure, which has a significant impact on well production. Based on capillary bundle model and fractal theory, the irreducible water saturation model, permeability model, and relative permeability model are constructed considering the influence of water film and stress sensitivity at the same time. The accuracy of this model is verified by results of nuclear magnetic experiment and comparison with previous models. The effects of some factors on irreducible water saturation, permeability, and relative permeability curves are discussed. The results show that the stress sensitivity will obviously reduce the formation permeability and increase the irreducible water saturation, and the existence of water film will reduce the permeability of gas phase. The increase of elastic modulus weakens the stress sensitivity of reservoir. The irreducible water saturation increases, and the relative permeability curve changes little with the increase of effective stress. When the minimum pore radius is constant, the ratio of maximum pore radius to minimum pore radius increases, the permeability increases, the irreducible water saturation decreases obviously, and the two-phase flow interval of relative permeability curve increases. When the displacement pressure increases, the irreducible water saturation decreases, and the interval of two-phase flow increases. These models can calculate the irreducible water saturation, permeability and relative permeability curves under any pressure in the development of tight gas reservoir. The findings of this study can help for better understanding of the productivity evaluation and performance prediction of tight sandstone gas reservoirs.

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