scholarly journals An unsteady seepage flow model considering kickoff pressure gradient for low-permeability gas reservoirs

2008 ◽  
Vol 35 (4) ◽  
pp. 457-461 ◽  
Author(s):  
Guo-qing FENG ◽  
Qi-guo LIU ◽  
Guang-zhi SHI ◽  
Zuo-hua LIN
Keyword(s):  
Pressure Gradient ◽  
Flow Model ◽  
Seepage Flow ◽  
Low Permeability ◽  
Gas Reservoirs

Influence of Back Pressure on Testing Starting Pressure Gradient in Low Permeability Gas Field

2012 ◽  
Vol 524-527 ◽  
pp. 1460-1464
Author(s):  
Jian Yan ◽  
Xiao Juan Liu
Keyword(s):  
Pressure Gradient ◽  
Gas Flow ◽  
Water Saturation ◽  
Flow Characteristics ◽  
Low Permeability ◽  
Gas Reservoirs ◽  
Gas Field ◽  
Outlet Pressure ◽  
Test Conditions ◽  
Starting Pressure Gradient

For the existence of formation water, the capillary force increases when the gas flow in the cores, so the flow may display starting pressure gradient. However, during the lab testing, sometimes it is found that the starting pressure gradient changes in different test conditions: when the outlet pressure is atmosphere, only the water saturation reaches critical value (Sw)c, the quasi starting pressure exists; but when the outlet pressure is not atmosphere; it is easy to find the quasi staring pressure in the same water saturation. And the quasi starting pressure under the later condition is larger than that in former condition. It is also found that the quasi starting pressures are both power function to the ratio of core coefficient and water saturation. The experimental results provide some theoretical references for recognizing the flow characteristics in low permeability gas reservoirs.

Effective use Model of Low Permeability Oil Reservoir

2013 ◽  
Vol 753-755 ◽  
pp. 53-57
Author(s):  
Liang Dong Yan ◽  
Zhi Juan Gao ◽  
Feng Gang Dai
Keyword(s):  
Fluid Flow ◽  
Pressure Gradient ◽  
Seepage Flow ◽  
Oil Field ◽  
Low Permeability ◽  
Oil Reservoir ◽  
Reservoir Fluid ◽  
Start Up ◽  
Well Pattern ◽  
Effective Use

The throat of low permeability oil reservoir is narrow and small, the reservoir fluid flow resistance is big, and with the start-up pressure gradient, compare with medium and high permeability reservoir fluid flow, the characteristics are obviously different in performance for non-darcy flow at low speed. This kind of oil field reservoir started in the process of mining scope is small, the degree of use and the development effect is low. To solve these problems, this paper established considering start-up pressure gradient of the new unstable seepage flow mathematical model of non-darcy radial flow which the analytical solution and the productivity equation is deduced, established the effective radius of the use of low permeability reservoirs, and systemicly researched the calculation method of area well pattern of different types of non-darcy seepage.

scholarly journals The Researches on Reasonable Well Spacing of Gas Wells in Deep and low Permeability Gas Reservoirs

2018 ◽  
Vol 38 ◽  
pp. 01038
Author(s):  
Yu Bei Bei ◽  
Li Hui ◽  
Li Dong Lin
Keyword(s):  
Pressure Gradient ◽  
Low Permeability ◽  
Well Testing ◽  
Gas Wells ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Gas Field ◽  
Well Spacing ◽  
Start Up ◽  
Starting Pressure Gradient

This Gs64 gas reservoir is a condensate gas reservoir which is relatively integrated with low porosity and low permeability found in Dagang Oilfield in recent years. The condensate content is as high as 610g/m3. At present, there are few reports about the well spacing of similar gas reservoirs at home and abroad. Therefore, determining the reasonable well spacing of the gas reservoir is important for ensuring the optimal development effect and economic benefit of the gas field development. This paper discusses the reasonable well spacing of the deep and low permeability gas reservoir from the aspects of percolation mechanics, gas reservoir engineering and numerical simulation. considering there exist the start-up pressure gradient in percolation process of low permeability gas reservoir, this paper combined with productivity equation under starting pressure gradient, established the formula of gas well spacing with the formation pressure and start-up pressure gradient. The calculation formula of starting pressure gradient and well spacing of gas wells. Adopting various methods to calculate values of gas reservoir spacing are close to well testing' radius, so the calculation method is reliable, which is very important for the determination of reasonable well spacing in low permeability gas reservoirs.

The Moving Boundary Movement of Vertical Fractured Well in Tight Oil Reservoir

2013 ◽  
Vol 868 ◽  
pp. 633-637
Author(s):  
Li Feng Liu ◽  
Xin Wang
Keyword(s):  
Pressure Gradient ◽  
Flow Model ◽  
Moving Boundary ◽  
Flow Characteristics ◽  
Seepage Flow ◽  
Threshold Pressure ◽  
Threshold Pressure Gradient ◽  
Tight Reservoir ◽  
Tight Reservoirs ◽  
Fractured Well

Because of the obvious non-Darcy characteristic of fluid flowing in tight reservoirs, there is a virtual moving boundary at the flow edge, and these percolation models of fractured wells with Darcy formula are no longer applicable. Based on the threshold pressure gradient effect, the unsteady seepage flow model of vertical fractured well was established in the drain area by means of Source and Green's Functions. With the flow characteristics at the boundary of tight reservoir, the motion equation of axes of moving boundary was obtained. By Example analysis, its proved that the moving boundary is approximate circular in the far-field, and it will move slower with the increase of the threshold pressure gradient.

A Model for Predicting Productivity of Multi-Staged Fractured Horizontal Wells in Ultra-Low Permeability Tight Gas Reservoirs

2014 ◽  
Vol 934 ◽  
pp. 143-149
Author(s):  
Chun Cheng Yang ◽  
Hong Jun Yin ◽  
Tang Qian Zhu ◽  
Lei Wang
Keyword(s):  
Pressure Gradient ◽  
Pressure Loss ◽  
Horizontal Wells ◽  
Low Permeability ◽  
Threshold Pressure ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Threshold Pressure Gradient ◽  
Tight Gas Reservoirs ◽  
Fractured Horizontal Wells

Based on the equivalent radius model and superposition potential, a productivity model for ultra-low permeability tight gas reservoirs was developed, which considered the influence of the threshold pressure gradient and the variable mass flow in fractures, and pressure loss inside the wellbore. With examples for capacity sensitive factors are analyzed. The results show that the threshold pressure gradient must be accounted to evaluate the productivity in ultra-low permeability tight gas reservoirs; after considering wellbore pressure loss; close toe fractures inflow velocity segment has been reduced; the larger matrix permeability, the greater the optimum fracture conductivity; When the number of fracture is more, the greater the impact on the capacity of the fracture angle. The research results provide a scientific basis for the design of multi-fractured horizontal wells in the ultra-low permeability tight gas reservoirs.

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

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.

Study on the Unstable Seepage Flow Model and the Productivity Characteristics in Tight Gas Heterogeneity Reservoir

2013 ◽  
Vol 868 ◽  
pp. 465-472
Author(s):  
Jia Deng ◽  
Wei Yao Zhu ◽  
Qian Ma ◽  
Huai Jian Yi
Keyword(s):  
Pressure Gradient ◽  
Gas Flow ◽  
Flow Model ◽  
Seepage Flow ◽  
Threshold Pressure ◽  
Tight Gas ◽  
Low Velocity ◽  
Threshold Pressure Gradient ◽  
Tight Gas Reservoir ◽  
Matlab Programming

In this paper, considering on the real threshold pressure gradient (TPG), the mathematical model for low velocity non-Darcy unstable gas flow was established for the tight gas reservoir. Based on the low velocity non-Darcy unstable gas flow model, the gas flow model in heterogeneity formation was developed, and the analytical solution was obtained on the condition of constant production for inner boundary. Then we calculated the model numerically by Matlab programming. Its analyzed that the pressure distribution and the influencing factors such as production rate, producing time, reservoir thickness and the threshold pressure gradient. We compared the heterogeneity formation with the homogeneous formation by the heterogeneity low velocity non-Darcy unstable gas flow model, which shows great difference and illustrate the significance of research on heterogeneity.

The Seepage Pressure Distribution and the Capacity of Low-Permeability Reservoirs Gas

2013 ◽  
Vol 734-737 ◽  
pp. 1317-1323
Author(s):  
Liang Dong Yan ◽  
Zhi Juan Gao
Keyword(s):  
Mathematical Model ◽  
Pressure Distribution ◽  
Low Permeability ◽  
Flow State ◽  
Klinkenberg Effect ◽  
Gas Reservoirs ◽  
Gas Well ◽  
Seepage Pressure ◽  
Slippage Effect ◽  
Low Permeability Reservoirs

Low-permeability gas reservoirs are influenced by slippage effect (Klinkenberg effect) , which leads to the different of gas in low-permeability and conventional reservoirs. According to the mechanism and mathematical model of slippage effect, the pressure distribution and flow state of flow in low-permeability gas reservoirs, and the capacity of low-permeability gas well are simulated by using the actual production datum.

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