The lower limit of the flowing pore throat radius in the extra-low permeability reservoir

The relation of microscopic features and the macroscopic properties such as permeability, porous and oil displacement efficiency in low permeability reservoir is much more complex than in conventional reservoir. Understanding the microscopic features and its influence law to macroscopic properties in low permeability reservoir is key to tapping remain oil. In this paper, the microscopic and macroscopic features and their relationship is studied. Studies suggest that in low permeability reservoir the main reservoir spaces include micro cracks, intergranular pore, intragranular pore and intracrystalline pore. The contribution of micro-cracks to porosity is not big, but its influence to permeability cannot be ignored. Porosity mainly effect by the development degree of pore throat, the bigger radius of pore throats are, the porosity is higher. The permeability and mercury efficiency are affected by feature structure coefficient, which reflect the characteristics of connectivity, it showed a positive correlation between the Coefficient and permeability, but Mercury efficiency and the Coefficient have positive correlation in mesopore reservoir, they have Negative Correlation in low or super-low porosity.

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Study on the Minimum Flow Pore Throat Radius and the Lower Limit of Petrophysical Properties of a Reservoir Under Three Seepage States

Chemistry and Technology of Fuels and Oils ◽

10.1007/s10553-021-01239-6 ◽

2021 ◽

Author(s):

Jinyou Dai ◽

Lixin Lin

Keyword(s):

Lower Limit ◽

Petrophysical Properties ◽

Pore Throat ◽

Throat Radius ◽

Minimum Flow

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The Simulation and Pilot Application of Low Salinity Water Flooding for Offshore Low Permeability Reservoir

10.2523/iptc-21257-ms ◽

2021 ◽

Author(s):

Hongfu Shi ◽

Yingxian Liu ◽

Yifan He ◽

Wankun Xu

Keyword(s):

Oil Recovery ◽

Production Performance ◽

Recovery Factor ◽

Water Flooding ◽

Low Permeability ◽

Throat Radius ◽

Low Permeability Reservoir ◽

Low Salinity ◽

Low Salinity Water ◽

Salinity Water

Abstract The use of LSWF (Low Salinity Water Flooding) is becoming more prevalent in recent years which can both improve the recovery factor and reduce the cost compared to other EOR (enhanced oil recovery) technics. This is especially important for the offshore oilfield development at present. Moreover, good quality of injected water is more applicable to low permeability sand which is characterized as smaller pore-throat radius and is easier damaged. Therefore, LSWF technology is proposed to address the above production problem while reduce the investment of equipment upgrade. In this paper, we presented the optimization and implementation of LSWF for offshore low permeability reservoir. Firstly, we provided a critical review of LSWF included the main mechanisms, laboratory test and field effect. Secondly, we designed and conducted several laboratory core flood tests. Thirdly, a lot of synthetic models were established to simulate the effects of LSWF and to optimize the field program. Finally, the production performance of the pilot wells was discussed. After LSWF, the water injection well presents the phenomenon of "scissors" - the injection pressure drops significantly below the safety pressure while the injection volume increases. Moreover, the decline of pilot well groups decreased by 20% ~ 26% compared with non-water flooded. The estimated recovery factor increased by 12%, which is consistent with other field tests worldwide. In summary, LSWF is a feasible, neconomic and efficient method for offshore low permeability reservoir production.

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Characteristics of Pore-Throat Structure and Mass Transport in Ultra-Low Permeability Reservoir

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.562-565.1455 ◽

2013 ◽

Vol 562-565 ◽

pp. 1455-1460

Author(s):

Qian Hua Xiao ◽

Zheng Ming Yang ◽

Xue Wu Wang

Keyword(s):

Mass Transport ◽

Size Distribution ◽

Low Permeability ◽

Pore Throat ◽

Porous Flow ◽

Low Permeability Reservoir ◽

Flow Capacity ◽

Reservoir Permeability ◽

Key Factor ◽

Small Tube

Low permeability reservoir is one of the most important petroleum reserve types in China. Therefore, some basic scientific problems about low permeability reservoir such as pore-throat size distribution, principle of porous flow should be deeply studied. Pore-throat size distribution, based on 69 cores from Changqing and Daqing oilfield of China, has been measured by comprehensive using Constant-Rate Mercury Injection and Nuclear Magnetic Resonance. It has been found that the Nano-pore-throat takes more than 60 percent of the total pore-throat of the low permeability reservoir and it is the key factor affecting the flow capacity when the permeability is less than 0.5×10-3μm2. The nano-pore-throat takes less than 40 percent of the total pore-throat and micron-pore-throat takes more than 45 percent when the permeability is larger than 5×10-3μm2. And Micron-pore-throat is the key factor affecting the flow capacity of low permeability reservoir. But when the reservoir permeability is between 0.5×10-3μm2 and 5×10-3μm2, its flow capacity is determined by the sub-micron-pore-throat and the amount of micron-pore-throat. Additionally, the key forces in micro-, sub-micro- and nanoscale pore-throat has been got by analyzing. The electrokinetic coupling matrix of mass transport has been gotten by analyzing the characteristics of the mass transport in small tube at different Debye ratio and pore-throat size distribution of ultra-low permeability.

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A New Method to Determine the Lower Limit of Reservoir Physical Properties—Corrected Minimum Flow Pore-throat Radius Method

E3S Web of Conferences ◽

10.1051/e3sconf/202129003004 ◽

2021 ◽

Vol 290 ◽

pp. 03004

Author(s):

Jinyou Dai ◽

Lixin Lin ◽

Rui Wang

Keyword(s):

Physical Properties ◽

Lower Limit ◽

Traditional Method ◽

Oil And Gas ◽

Correction Method ◽

New Method ◽

Pore Throat ◽

Throat Radius ◽

Minimum Flow ◽

Gas Accumulation

The lower limit of reservoir physical properties is an important parameter for identifying reservoirs and determining effective thickness in reserves evaluation, and is also an important basis for selecting perforated test intervals in oilfield exploration and development. There are many methods to determine the lower limit of reservoir physical properties, and the minimum flow pore throat radius method is one of the commonly used methods. The method uses 0.1μm as the minimum flow pore-throat radius, and uses this to calibrate the lower limit of reservoir physical properties. However, according to the water film theory, the minimum radius of the reservoir's flowing pore throat is not a definite value, but varies with the displacement dynamics. Therefore, there is no exact basis for using 0.1μm as the minimum flow pore-throat radius, so it needs to be corrected. To this end, a new method for determining the lower limit of reservoir physical properties—the corrected minimum flow pore-throat radius method is proposed. The correction method comprehensively considers the factors of oil and gas accumulation dynamics, and determines the lower limit of reservoir physical properties by obtaining the minimum flow pore-throat radius value suitable for oil and gas accumulation dynamics. A case study of Chang 63 reservoir in A Oilfield shows that the minimum flow pore radius of oil and gas determined by the correction method is 0.08 μm, and the lower limit of reservoir physical properties (porosity 9.1%, permeability 0.117 × 10-3 μm2). The traditional method has a minimum flow pore-throat radius of 0.1 μm and a lower limit of reservoir physical properties (porosity of 9.8% and permeability of 0.133 × 10-3 μm2). Due to full consideration of the impact of oil and gas accumulation dynamics, the minimum flow pore-throat radius determined by the correction method is more reliable than the traditional method, and the lower limit of the reservoir physical property calibrated by it has practical significance.

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Quantitative Evaluation of Micro Pore Throat Characteristics in Extra Low Permeability Sandstone Oil Reservoir of Yanchang Group in Ordos Basin Using Constant Rate Mercury Penetration Technique

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.361-363.408 ◽

2011 ◽

Vol 361-363 ◽

pp. 408-413

Author(s):

Hui Gao ◽

Wei Sun

Keyword(s):

Pore Radius ◽

Ordos Basin ◽

Low Permeability ◽

Oil Reservoir ◽

Pore Throat ◽

Throat Radius ◽

Distribution Ranges ◽

Constant Rate ◽

Permeability Distribution ◽

The Difference

Micro pore throat characteristics of extra low permeability sandstone oil reservoir of Yangchang group in Ordos basin are analyzed using constant rate mercury penetration technique. The results show that pore radius distributes similarly, in 100～200μm, peak values are about 140μm in extra low permeability sandstone oil reservoir. The lower the permeability is, the narrower the distribution ranges of throat are, content of smaller throats become high and variation is more sensitive to permeability, distribution ranges of pore throat radius ratio are wide and permeability has bigger influence on input mercury saturation of throat in extra low permeability sandstone oil reservoir. The difference of pore throat characteristics mainly depends on throat in extra low permeability sandstone oil reservoir. The impacts of pore and throat on total capillary curve are various to different permeability cores, Throat development should be paid more attention in middle or later stage of oil development to extra low permeability sandstone oil reservoir.

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A Finite Element Analysis of Pore Throat Ratio on the Characteristics of Flow Structure through Low Permeability Reservoir

SINDH UNIVERSITY RESEARCH JOURNAL -SCIENCE SERIES ◽

10.26692/surj/2017.12.58 ◽

2017 ◽

Vol 49 (004) ◽

pp. 785--792

Author(s):

Z. A. BALOCH ◽

S. B. SHAH ◽

H. SHAIKH ◽

M. E. BALOCH

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Flow Structure ◽

Low Permeability ◽

Pore Throat ◽

Element Analysis ◽

Low Permeability Reservoir

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Application and Study on Nonlinear Percolation Area Distribution Range Calculation Method in the Low Permeability Reservoir

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.962-965.905 ◽

2014 ◽

Vol 962-965 ◽

pp. 905-909

Author(s):

Wei Mao ◽

Hong Bing Jia ◽

Dong Xu Yu ◽

Peng Ju Du

Keyword(s):

Pressure Gradient ◽

Seepage Flow ◽

Production Performance ◽

Distribution Area ◽

Low Permeability ◽

Production Well ◽

Throat Radius ◽

Low Permeability Reservoir ◽

Well Spacing ◽

Starting Pressure Gradient

Based on the minimum start-up pressure gradient have been obtained from experiment, and the relationship between the minimum starting pressure gradient with maximum starting pressure gradient and the throat radius, first put forward the calculating the limit shear stress, then calculating the maximum starting pressure gradient method. Non-linear seepage corresponding to the pressure gradient range are obtained by regression analysis, nonlinear seepage flow in low permeability reservoir distribution area can be derived. Two well group examples of the Bei301 block of Hailaer oilfield, shows that calculating the method of nonlinear seepage flow area is available, and the results can reflect the symmetry oil well production performance, this method has application value. The On the basis of the formula of pressure gradient between oil wells and injection wells, New method to calculate the limit injection production well spacing is proposed. It is of importance for injection production well spacing in oilfield development plan.

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