scholarly journals The dynamic effect in capillary pressure during the displacement process in ultra-low permeability sandstone reservoirs

Capillarity ◽  
2018 ◽  
Vol 1 (2) ◽  
pp. 11-18 ◽  
Author(s):  
Ying Li ◽  
Haitao Li ◽  
Jianchao Cai ◽  
Qirui Ma ◽  
Jianfeng Zhang
Keyword(s):  
Capillary Pressure ◽  
Dynamic Effect ◽  
Low Permeability ◽  
Sandstone Reservoirs

Mechanism of Overpressure Formation in Deeply Burial Sandstone

2013 ◽  
Vol 295-298 ◽  
pp. 2736-2739
Author(s):  
Hai Yan Hu
Keyword(s):  
Hydrostatic Pressure ◽  
Capillary Pressure ◽  
Driving Force ◽  
Low Permeability ◽  
Gas Generation ◽  
Tight Sandstone ◽  
Gas Accumulation ◽  
Fine Grained ◽  
Sandstone Reservoirs ◽  
Induced Fractures

Overpressure is often encountered in the Jurassic tight and the overpressure is closely associated with gas generation. The pressure transfer from the over-pressurized mudstones to adjacent tight sandstones might occur through overpressure induced-fractures. The fine-grained coal containing Jurassic sandstone is sensitive to compaction, and the porosity decreases dramatically with the increase of overlying load. As gas migrates into the tight sandstones, it must overcome the capillary pressure which is greater than the hydrostatic pressure. The gas charging pressure in the tight sandstone must be higher than the capillary pressure, resulting in an overpressure buildup within the tight sandstones. Gas shows, low permeability and strong diagenesis in the overpressure of the tight sandstone system have been observed. Additionally, capillary seals are identified as playing an important role in the mechanism of the overpressure formation in tight sandstone reservoirs. Overpressure might be a driving force to create induced fractures in the interval, which has applications for crossing-formation migration and gas accumulation.

Investigation of Dynamic Effect of Capillary Pressure in Ultra-Low Permeability Sandstones

2014 ◽  
Vol 45 (1) ◽  
pp. 79-88 ◽  
Author(s):  
Haiyong Zhang ◽  
Shunli He ◽  
Chunyan Jiao ◽  
Guohua Luan ◽  
Shaoyuan Mo ◽  
...  
Keyword(s):  
Capillary Pressure ◽  
Dynamic Effect ◽  
Low Permeability

scholarly journals Dynamic effect of capillary pressure in low permeability reservoirs

2012 ◽  
Vol 39 (3) ◽  
pp. 405-411 ◽  
Author(s):  
Shubao TIAN ◽  
Gang LEI ◽  
Shunli HE ◽  
Limin YANG
Keyword(s):  
Capillary Pressure ◽  
Dynamic Effect ◽  
Low Permeability ◽  
Low Permeability Reservoirs

The Influence of Dynamic Capillary Pressure on the Seepage of Ultra-Low Permeability Reservoir

2014 ◽  
Vol 7 (1) ◽  
pp. 55-63 ◽  
Author(s):  
Haiyong Zhang ◽  
Shunli He ◽  
Chunyan Jiao ◽  
Guohua Luan ◽  
Shaoyuan Mo
Keyword(s):  
Capillary Pressure ◽  
Low Permeability ◽  
Low Permeability Reservoir ◽  
Dynamic Capillary Pressure

A COMPREHENSIVE MODEL FOR OIL–WATER RELATIVE PERMEABILITIES IN LOW-PERMEABILITY RESERVOIRS BY FRACTAL THEORY

Fractals ◽  
2020 ◽  
Vol 28 (03) ◽  
pp. 2050055
Author(s):  
HAIBO SU ◽  
SHIMING ZHANG ◽  
YEHENG SUN ◽  
XIAOHONG WANG ◽  
BOMING YU ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Capillary Pressure ◽  
Relative Permeability ◽  
Fractal Theory ◽  
Low Permeability ◽  
Comprehensive Model ◽  
Relative Permeabilities ◽  
Oil Water ◽  
Seepage Characteristics ◽  
Low Permeability Reservoirs

Oil–water relative permeability curve is an important parameter for analyzing the characters of oil and water seepages in low-permeability reservoirs. The fluid flow in low-permeability reservoirs exhibits distinct nonlinear seepage characteristics with starting pressure gradient. However, the existing theoretical model of oil–water relative permeability only considered few nonlinear seepage characteristics such as capillary pressure and fluid properties. Studying the influences of reservoir pore structures, capillary pressure, driving pressure and boundary layer effect on the morphology of relative permeability curves is of great significance for understanding the seepage properties of low-permeability reservoirs. Based on the fractal theory for porous media, an analytically comprehensive model for the relative permeabilities of oil and water in a low-permeability reservoir is established in this work. The analytical model for oil–water relative permeabilities obtained in this paper is found to be a function of water saturation, fractal dimension for pores, fractal dimension for tortuosity of capillaries, driving pressure gradient and capillary pressure between oil and water phases as well as boundary layer thickness. The present results show that the relative permeabilities of oil and water decrease with the increase of the fractal dimension for tortuosity, whereas the relative permeabilities of oil and water increase with the increase of pore fractal dimension. The nonlinear properties of low-permeability reservoirs have the prominent significances on the relative permeability of the oil phase. With the increase of the seepage resistance coefficient, the relative permeability of oil phase decreases. The proposed theoretical model has been verified by experimental data on oil–water relative permeability and compared with other conventional oil–water relative permeability models. The present results verify the reliability of the oil–water relative permeability model established in this paper.

scholarly journals Experimental Investigation on the Effects of CO2 Displacement Methods on Petrophysical Property Changes of Ultra-Low Permeability Sandstone Reservoirs Near Injection Wells

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 327 ◽  
Author(s):  
Qian Wang ◽  
Shenglai Yang ◽  
Haishui Han ◽  
Lu Wang ◽  
Kun Qian ◽  
...  
Keyword(s):  
Physical Properties ◽  
Pore Size ◽  
Mineral Dissolution ◽  
Co2 Injection ◽  
Low Permeability ◽  
Co2 Flooding ◽  
Formation Water ◽  
Injection Wells ◽  
Rock Interaction ◽  
Sandstone Reservoirs

The petrophysical properties of ultra-low permeability sandstone reservoirs near the injection wells change significantly after CO2 injection for enhanced oil recovery (EOR) and CO2 storage, and different CO2 displacement methods have different effects on these changes. In order to provide the basis for selecting a reasonable displacement method to reduce the damage to these high water cut reservoirs near the injection wells during CO2 injection, CO2-formation water alternate (CO2-WAG) flooding and CO2 flooding experiments were carried out on the fully saturated formation water cores of reservoirs with similar physical properties at in-situ reservoir conditions (78 °, 18 MPa), the similarities and differences of the changes in physical properties of the cores before and after flooding were compared and analyzed. The measurement results of the permeability, porosity, nuclear magnetic resonance (NMR) transversal relaxation time (T2) spectrum and scanning electron microscopy (SEM) of the cores show that the decrease of core permeability after CO2 flooding is smaller than that after CO2-WAG flooding, with almost unchanged porosity in both cores. The proportion of large pores decreases while the proportion of medium pores increases, the proportion of small pores remains almost unchanged, the distribution of pore size of the cores concentrates in the middle. The changes in range and amplitude of the pore size distribution in the core after CO2 flooding are less than those after CO2-WAG flooding. After flooding experiments, clay mineral, clastic fines and salt crystals adhere to some large pores or accumulate at throats, blocking the pores. The changes in core physical properties are the results of mineral dissolution and fines migration, and the differences in these changes under the two displacement methods are caused by the differences in three aspects: the degree of CO2-brine-rock interaction, the radius range of pores where fine migration occurs, the power of fine migration.

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