Investigations of water saturation and fractal characteristics in tight sandstone gas reservoirs using centrifugation and NMR experiments

2021 ◽  
Vol 26 (4) ◽  
pp. 405
Author(s):  
Aifen Li ◽  
Weibing Tian ◽  
Xiaoxia Ren ◽  
Shuaishi Fu ◽  
Dongdi Cui ◽  
...  
Keyword(s):  
Water Saturation ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
Fractal Characteristics

Investigations of water saturation and fractal characteristics in tight sandstone gas reservoirs using centrifugation and NMR experiments

2020 ◽  
Vol 1 (1) ◽  
pp. 1
Author(s):  
Min Ma ◽  
Yapcheptoyek Josephine ◽  
Aifen Li ◽  
Weibing Tian ◽  
Xiaoxia Ren ◽  
...  
Keyword(s):  
Water Saturation ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
Fractal Characteristics

scholarly journals Change of water saturation in tight sandstone gas reservoirs near wellbores

2018 ◽  
Vol 5 (6) ◽  
pp. 589-597
Author(s):  
Hongyu Ma ◽  
Shusheng Gao ◽  
Liyou Ye ◽  
Huaxun Liu ◽  
Wei Xiong ◽  
...  
Keyword(s):  
Water Saturation ◽  
Gas Reservoirs ◽  
Tight Sandstone

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 Study of the Effect of Movable Water Saturation on Gas Production in Tight Sandstone Gas Reservoirs

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4645 ◽  
Author(s):  
Jie Zhang ◽  
Xizhe Li ◽  
Weijun Shen ◽  
Shusheng Gao ◽  
Huaxun Liu ◽  
...  
Keyword(s):  
Clay Mineral ◽  
Mineral Content ◽  
Water Saturation ◽  
Gas Production ◽  
Water Production ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
Gas Field ◽  
Gas Drive ◽  
Production Characteristics

The movable water saturation of tight sandstone reservoirs is an important parameter in characterizing water production capacity, and there is a great need to understand the relationship between movable water saturation and water production characteristics. However, movable water behavior in this context remains unclear. In this study, four groups of tight sandstone cores from the Sulige gas field are measured to understand the movable water saturation characteristics. Then, the effects such as reservoir micropore throat, clay mineral and physical properties on movable water saturation are analyzed, and the movable water saturation and water production characteristics are discussed. The results show that higher movable water saturation will result in a greater amount of water in the gas drive. There is a critical pressure difference of the gas drive, and a large amount of movable water will flow out. Movable water saturation is independent of the porosity, permeability and initial water saturation, while it is closely related to the reservoir micropore throat and clay mineral content. Movable water is mainly distributed in the medium and large pores; the larger the proportion of such pores, the higher the degree of movable water saturation. A lower mineral content will lead to higher movable water saturation in tight sandstone gas reservoirs. These results provide clues for identifying gas–water bearing reservoirs and evaluating and predicting the water production characteristics in gas wells in tight sandstone gas reservoirs.

The threshold pressure gradient effect in the tight sandstone gas reservoirs with high water saturation

Fuel ◽  
2018 ◽  
Vol 226 ◽  
pp. 221-229 ◽  
Author(s):  
Weibing Tian ◽  
Aifen Li ◽  
Xiaoxia Ren ◽  
Yapcheptoyek Josephine
Keyword(s):  
Pressure Gradient ◽  
Water Saturation ◽  
High Water ◽  
Threshold Pressure ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
Threshold Pressure Gradient ◽  
Gradient Effect

Experimental Study on the Saturation Model of Volcanic Rock Based on Fluid Distribution

2021 ◽  
Vol 62 (4) ◽  
pp. 422-433
Author(s):  
Baozhi Pan ◽  
◽  
Weiyi Zhou ◽  
Yuhang Guo ◽  
Zhaowei Si ◽  
...  
Keyword(s):  
Volcanic Rock ◽  
Oil And Gas ◽  
Water Saturation ◽  
Early Stage ◽  
Evaluation Model ◽  
Acoustic Velocity ◽  
Distribution Model ◽  
Fluid Distribution ◽  
Water Drainage ◽  
Gas Reservoirs

A saturation evaluation model suitable for Nanpu volcanic rock formation is established based on the experiment of acoustic velocity changing with saturation during the water drainage process of volcanic rock in the Nanpu area. The experimental data show that in the early stage of water drainage, the fluid distribution in the pores of rock samples satisfies the patchy formula. With the decrease of the sample saturation, the fluid distribution in the pores is more similar to the uniform fluid distribution model. In this paper, combined with the Gassmann-Brie and patchy formula, the calculation equation of Gassmann-Brie-Patchy (G-B-P) saturation is established, and the effect of contact softening is considered. The model can be used to calculate water saturation based on acoustic velocity, which provides a new idea for the quantitative evaluation of volcanic oil and gas reservoirs using seismic and acoustic logging data.

Stress Sensitivity of Low Permeable and Water-Bearing Gas Reservoir without Gas Slippage Effect

2014 ◽  
Vol 962-965 ◽  
pp. 570-573
Author(s):  
Jian Yan ◽  
Xiao Bing Liang ◽  
Qian Wu ◽  
Qing Guo
Keyword(s):  
Water Saturation ◽  
Stress Sensitivity ◽  
Testing Methods ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Gas Well ◽  
Well Production ◽  
Gas Slippage ◽  
Slippage Effect ◽  
Function Relationship

Because of the gas slippage, the testing methods of stress sensitivity for gas reservoir should be different from that for oil reservoir. This text adopts the method that imposing back pressure on the outlet of testing core to weaken the gas slippage effect and tests the stress sensitivity of low permeability gas reservoirs, then analyzes the influence of permeability and water saturation on stress sensitivity. The results show that: low permeable and water-bearing gas reservoirs have strong stress sensitivity; the testing permeability has the power function relationship with net stress, compared to the exponential function, the fitting correlation coefficient is larger and more suited to the actual; the lower the permeability is and the higher water saturation is, the stronger the stress sensitivity is. The production of gas well is affected when considering the stress sensitivity, so the pressure dropping rate should be reasonable when low permeable gas reservoirs are developed. The results provide theoretical references for analyzing the well production and numerical simulation.

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